A similar reaction of SnCl4 with 2 equiv. of Li[o-(C2H10B10)C(NiPr)(NHiPr)] unexpectedly afforded the known solvated pentachloridostannate(IV) salt [Li(THF)4][SnCl5(THF)] as the main reaction product. Small amounts of the new chlorido-tin(IV) bis(carboranylamidinate) bischloridotin(IV), SnIVCl[o-(C2H10B10)C(NiPr)(NHiPr)][o-(C2H10B10)C(NiPr)2] (2), were isolated as a by-product. Single-crystal X-ray structure analysis revealed a κC,κN-chelating coordination of the carboranylamidinate ligands in both 1 and 2. The Sn atom in 1 adopts a pseudo-trigonal–bipyramidal coordination under participation of a stereoactive lone pair. In 2, a trigonal–bipyramidal coordination of Sn is completed by a chlorido ligand.Reaction of 2 equiv. of the lithium carboranylamidinate Li[ RC(NR′)2]− are the nitrogen analogs of carboxylate anions. These versatile N,N′-chelating ligands form stable coordination compounds with nearly every metallic element in the Periodic Table. In view of this rich coordination chemistry, amidinate ligands are frequently regarded as ‘steric cyclopentadienyl equivalents’. Metal complexes comprising amidinato ligands are readily available by insertion of the 1,3-diorganocarbodiimide, R–-N=C=N—R, into an M—C bond of an organometallic precursor compound. Another common synthetic route involves salt metathetical reactions between lithium amidinates and metal halides 2]− is the fact that the substituents R and R′ attached to the N–C–N unit can be varied in many ways. With R = ortho-C2H11B10 (‘ortho-carboranyl’) we introduced a sterically demanding and chemically versatile moiety in the backbone of the amidinate ligand. Carboranes are of tremendous scientific and technological interest due to their various applications ever since their discovery in the 1960′s. These applications include the synthesis of polymers and ceramics, catalysts, radiopharmaceuticals and non-linear optics, as well as the BNCT (= boron neutron capture therapy) technique C(NiPr)(NHiPr)]− (= [HiLPr]−) was synthesized in our lab in 2010 by in situ lithiation of the parent o-carborane, ortho-C2H12B10 (= ortho-dicarba-closo-dodecaborane), followed by treatment with 1 equiv. of N,N′-diisopropylcarbodiimide , a proton is formally shifted from the carborane C atom to the amidinate unit, resulting in an amidine moiety that usually acts as a monodentate donor functionality as shown in Fig. 2a.A key advantage of the amidinate anions [RL]2–, whose favored coordination mode is still κC,κN . Derivatives of Si, P, Ge, SnII, SnIV, FeII and FeIII, RhI and IrI containing this ligand system have been prepared by double lithiation of the parent ortho-carboranylamidine followed by treatment with appropriate element chloride precursors C(NCy)(NHCy)]2  and SnIVCl[o-(C2H10B10)C(NiPr)(NHiPr)][o-(C2H10B10)C(NiPr)2] . Compound 2 is the first carboranylamidinate complex containing both mono- and dianionic carboranylamidinate ligands in a single molecule.Among the known carboranylamidinate complexes are only very few compounds with more than one carboranylamidinate ligand per metal atom, and these are exclusively of the type ortho-carboranylamidinate precursors Li[HLCy] and Li[HiLPr] were readily available following a published procedure by reaction of the mono-lithiated o-carborane Li-o-C2B10H11 with a stoichiometric amount of the carbodiimides iPrN=C=NiPr or CyN=C=NCy, respectively, in THF  as colorless, block-like single crystals after recrystallization from toluene. The low isolated yield of ca 20% can be traced back to the very high solubility of 1 even in non-polar organic solvents. In addition to the X-ray diffraction study, compound 1 was also characterized through elemental analysis and the usual set of spectroscopic methods. In the IR spectrum, a characteristic ν(NH) band at 3423 cm−1 confirmed the presence of monoanionic [HLCy]− ligands. The NH functionalities were also observed in the 1H NMR spectrum through a broad singlet at δ 4.50 ppm. A single 119Sn NMR resonance at δ −46 ppm was in agreement with the formation of a single Sn-containing species. The mass spectrum of 1 showed the molecular ion at m/z 818 with 27% relative intensity.The mono-lithio-4 with 2 equiv. of Li[HiLPr] was carried out with the aim of synthesizing the hitherto unknown tin(IV) bis(carboranylamidinate) Sn[iLPr]2. Cooling of the reaction mixture afforded a fairly large amount of well-formed, colorless crystals, which turned out to be the known solvated pentachloridostannate(IV) salt [Li(THF)4][SnCl5(THF)]. This compound was first prepared and structurally characterized by Junk & Leary (2000ca 5% isolated yield) of the unexpected tin(IV) carboranylamidinate SnCl[iLPr][HiLPr] (2) could be obtained. The X-ray crystal structure determination of 2 revealed the presence of the first complex containing both a mono- and a dianionic carboranylamidinate ligand in one molecule. As in 1, the IR spectrum of 2 showed a characteristic ν(NH) band at 3410 cm−1. Elemental analysis and a single resonance in the 119Sn NMR spectrum (δ 290 ppm) confirmed the purity of 2. In the mass spectrum, the molecular ion was observed at m/z 692 with 47% relative intensity.A similar reaction of SnCleary 2000. From th1 and 2 are illustrated in Figs. 3κC,κN-chelating mode. In the tin(II) complex Sn[HLCy]2 (1), the coordination of the metal atom can be described as pseudo-trigonal–bipyramidal, with the two N atoms defining the axial positions [N1—Sn—N3 157.76 (4)°]. The two Sn-C bonds are situated in the equatorial plane [C3—Sn—C18 100.12 (5)°], together with the stereoactive lone pair at Sn. The bite angles of the [HLCy]− ligands are 72.01 (5)° (N1—Sn—C3) and 73.27 (5)° (N3—Sn—C18). The coordination geometry of the Sn atom therefore resembles that in the related tin(II) bis(carboranylamidinate) Sn[HLiPr]2 . These values are in the same range as those observed in the isopropyl substituted analogue Sn[HiLPr]2 .The molecular structures of the title compounds iPr][HiLPr] (2) is structurally closely related to 1, as the Sn atom exhibits a trigonal–bipyramidal coordination with the two amidinate N atoms in the axial positions . The lone pair at Sn is formally replaced by a chlorido ligand, which is almost perpendicular to the Sn—N bonds . The Sn—C bond lengths are 2.160 (3) Å (Sn—C2) and 2.154 (3) Å (Sn—C11) and therefore considerably shorter than in compound 1. This finding can be traced back to the higher oxidation number of the Sn atom. Similar Sn—C bond lengths have been observed in the related tin(IV) derivatives SnCl3[HiLPr] [Sn—C 2.132 (3) Å] and SnCl2[iLPr](THF) − ligands and deprotonated [iLPr]2– ligands are virtually equal, the Sn—C(carborane) bond is obviously not noteworthily influenced by the bonding situation within the amidinate moiety. In contrast, in 2 the Sn—N contact to the deprotonated carboranylamidinate ligand  is considerably shorter than that to the protonated ligand . As has been discussed previously, the M—N contact in [iLPr]2– complexes can be regarded as a distinct single bond, while the M—N contact in [HiLPr]− complexes should be described as a secondary coordinative interaction  Å, SnCl2[iLPr](THF): Sn—N 205.0 (2) Å; Harmgarth et al., 2017The tin(IV) complex SnCl are clearly in the range of double bonds, while the C—N bonds to the protonated N atoms  can be regarded as single bonds. These values are consistent with those observed in other tin complexes with [HLR]− ligands (e.g. Sn[HLiPr]2: C=N(Sn) 1.287 (3), C—N(H) 1.347 (4) Å; Dröse et al., 20103[HiLPr]: C=N(Sn) 1.288 (4), C—N(H) 1.339 (4) Å; Harmgarth et al. 20172, however the difference is less pronounced in this case . The π electron density within the amidinate group in the [iLPr]2– ligand in 2 is clearly inverted, resulting in a long C—N(Sn) bond [C3—N1 1.372 (4) Å] and a short C=N bond to the non-coordinated N atom [C3—N2 1.269 (5) Å]. Similar values have been obtained in SnCl2[iLPr](THF) − and [RL]2– ligands always display a typical κC,κN-chelating mode, this may explain why the formation of the complex SnCl[iLPr][HiLPr] (2) is preferred over a homoleptic complex Sn[iLPr]2, where the Sn atom would be tetrahedrally coordinated. Nonetheless, the example of SnCl2[iLPr](THF)  (solv. = solvent) might exist.In summarizing the results reported here, in tin carboranylamidinates a trigonal–bipyramidal  Å] and between isopropyl groups in 2 [C5⋯C15 3.670 (7) Å], respectively. In both compounds, the free N—H groups are not involved in hydrogen bonding.In both aFor reviews on amidinate complexes, see: Collins 2011’ Edelmanet al.  spectrometer in THF-d8 at 295 (2) K. 1H and 13C NMR shifts are referenced to Si(CH3)4, 119Sn shifts to Sn(CH3)4 (each δ = 0 ppm). IR spectra were measured on a Bruker Vertex V70 spectrometer equipped with a diamond ATR unit, electron impact mass spectra on a MAT95 spectrometer with an ionization energy of 70 eV. Elemental analyses  were performed using a VARIO EL cube apparatus.All operations were performed under an argon atmosphere using standard Schlenk techniques. THF and toluene were distilled from sodium/benzophenone under argon. NMR spectra were recorded on a Bruker DPX400 (Cy]2 (1): oPreparation of Sn was treated in situ with SnCl2  and then stirred for 24 h. The solvent was subsequently removed in vacuo, the solid residue extracted with toluene (40 mL) and the insoluble matter filtered off. The filtrate was concentrated to a total volume of ca 10 mL. Cooling to 278 K for 2 d afforded colorless, block-like single-crystals of 1. Yield: 0.58 g (20%). Analysis calculated for C30H66B20N4Sn, M = 817.81 g mol−1: C 44.06, H 8.13, N 6.85%. Found: 43.66, H 8.00, N 6.25%. IR: ν 3423 w (ν NH), 2935 m (ν CH2), 2854 m (ν CH2), 2560 m (ν BH), 1623 m (ν C=N), 1448 m (δ CH2) cm−1. 1H NMR  K): δ 4.50 , 3.24 , 1.70–2.80 , 1.08–1.98  ppm. 13C NMR  K): δ 143.0 (NCN), 80.3 (C—Sn), 77.0 (C—CN2), 54.6 (CH Cy), 34.8 (CH2 Cy), 25.7 (CH2 Cy), 25.4 (CH2 Cy), 25.1 (CH2 Cy), 25.0 (CH2 Cy) ppm. 119Sn NMR  K): δ −46 ppm. MS: m/z (%) 818 (27) [M]+, 467 (19) [C15H32B10N2Sn]+, 350 (24) [C15H32B10N2]+, 269 (100) [C9H23B10N2]+, 143 (54) [C2H10B10]+.iPr] (2):Preparation of SnCl[L][SnCl5(THF)]. Yield: 2.13 g. In addition to the IR data reported by Junk & Leary (20007Li and 119Sn) data. 7Li NMR  K): δ = −0.76 ppm. 119Sn NMR  K): δ = −641 ppm. Concentration of the mother liquid to ca. 10 ml followed by cooling again to 278 K for several days afforded 0.13 g (5%) of 2 as colorless, plate-like single-crystals. Analysis calculated for C18H49B20ClN4Sn, M = 692.00 g mol−1: C 31.24, H 7.14, N 5.12%. Found: 31.02, H 6.88, N 4.98%. IR: ν 3410 w (ν NH), 2964 m, 2930 w , 2616 m, 2569 s (ν BH), 1628 m, 1596 vs (ν C=N), 1461 m, 1372 m  cm−1. 1H NMR  K): δ 5.56 , 4.33–4.39 , 3.30–3.42 , 1.7–3.2 , 1.23–1.56 , 0.96–1.05  ppm. 13C NMR  K): δ 140.6 (NCN), 139.1 (NCN), 74.4 (C—CN2), 73.2 (C—CN2), 69.8 (C—Sn), 52.0 (CH iPr), 48.3 (CH iPr), 25.5 (CH3), 23.1 (CH3) ppm. 119Sn NMR  K): δ 290 ppm. MS: m/z (%) 692 (49) [M]+, 656 (76) [C18H49B20N4Sn]+, 423 (48) [C9H24B10ClN2Sn]+, 388 (82) [C9H24B10N2Sn]+, 211 (100) [C5H13B10N2]+, 171 (18) [C3H10B10N]+.eary 2000, the com3 groups in 2 were allowed to rotate freely around the C—C vector, the corresponding C—H distances were constrained to 0.98 Å. C—H distances within CH2 groups were constrained to 0.99 Å, C—H distances within CH groups to 1.00 Å. H atoms attached to B and N atoms were located in the difference-Fourier map, B—H distances were restrained to 1.12 (2) Å and N—H distances to 0.88 (2) Å. The Uiso(H) values were set at 1.5Ueq(C) for the methyl groups in 2, and at 1.2Ueq(X)  in all other cases. For 1, the reflections (100) and  compound_1, compound_2. DOI: 10.1107/S2056989017012671/zl2714compound_1sup2.hklStructure factors: contains datablock(s) compound_1. DOI: 10.1107/S2056989017012671/zl2714compound_2sup3.hklStructure factors: contains datablock(s) compound_2. DOI: 1565456, 1565455CCDC references:  crystallographic information; 3D view; checkCIF reportAdditional supporting information:


II atoms are bridged by two carboxylate anions.The crystal structure of a dinuclear tetracarboxylate complex of manganese(II) is reported wherein the Mn 2(C7H4NO4)4(C6H7N)4] or [Mn2(μ-NBz)2(κ2-NBz)2(4-Mepy)4], where NBz is 4-nitrobenzoate and 4-Mepy is 4-methylpyridine, is a centrosymmetric dinuclear complex in which the MnII atoms are bridged by two NBz ligands with Mn⋯Mn = 4.1324 (4) Å. The MnII atom in this dimeric species is present in a distorted octahedral environment with the four coordinating O atoms forming the equatorial plane and the two pyridyl N atoms occupying the axial sites. An important structural feature of the dimeric complex is that each of the bridging carboxylate ligands binds to the metal ions in an asymmetric fashion involving bent and linear Mn—O—C units. The crystal packing is consolidated by C—H⋯O and C—H⋯π interactions.The title compound, [Mn While the former are in the range 56.95 (4)–150.77 (4)°, the latter are in the range 88.02 (5)–94.59 (5)°.The highly distorted nature of the MnOIn the title compound, the carboxyl –COO and –NOO planes of the chelating NBz anion deviate slightly from the phenyl ring plane, forming dihedral angles of 2.6 (3) and 23.6 (4)°, respectively. According to Kaduk 2000 and KaduI2 and –CO2 groups of the NBz ligand act as hydrogen acceptors (Table 2D⋯A separations for these weak contacts are in the range of 3.161 (2) to 3.369 (2) Å, the <C—H⋯O angles are generally lower than 130°, except in one case where a hydrogen bond with a greater D⋯A separation of 3.369 (2) Å forms has an angle of 172°. In addition, intermolecular C—H⋯π interactions involving the pyridyl ring π system of the 4-Mepy ligand link the complex molecules into chains along the a axis 2(κ2-O2CR)2L4] in Table 3I2(μ-OBz)2(κ2-OBz)2(py)4] , NaNBz  and 4-Mepy  was stirred mechanically in water (20 ml) at room temperature for 4 h. The yellow precipitate that appeared was washed thoroughly with water and then with methanol before being dried in a vacuum desiccator over fused CaCl2. Yield: 2.58 g (85% based on Mn). Light-yellow transparent crystals of I4·H2O (0.5 mmol) containing 4-Mepy (1 mmol) in methanol/water (1:1 v/v). Analysis calculated for C48H36N8O16Mn2: C, 52.84%; H, 3.30%; N, 10.27%; found: C, 52.04%; H, 3.02%; N, 9.8%; μeff (295 K)/Mn = 5.36 BM.A mixture of MnSOI2(μ-OBz)2(κ2-OBz)2(py)4]  set at 1.2–1.5Ueq(C).Crystal data, data collection and structure refinement details are summarized in Table 410.1107/S2056989016015589/vn2116sup1.cifCrystal structure: contains datablock(s) I. DOI: 10.1107/S2056989016015589/vn2116Isup2.hklStructure factors: contains datablock(s) I. DOI: 1508004CCDC reference: crystallographic information; 3D view; checkCIF reportAdditional supporting information:


A new 4-thiazolidinone derivative has been obtained from the cyclization reaction of 4-methyl-3-thiosemicarbazone and dimethyl acetylenedicarboxylate (DMAD). 16H21N3O3S, was obtained from the cyclization reaction of 4-methyl-3-thiosemicarbazone and dimethyl acetylenedicarboxylate (DMAD). The cyclohexylidene ring has an envelope conformation with the stereogenic centre C atom as the flap. Its mean plane makes a dihedral angle of 56.23 (9)° with the thiazolidine ring mean plane. In the crystal, molecules are linked by C—H⋯O hydrogen bonds forming chains propagating in the [001] direction. Within the chains there are offset π–π interactions between the thiazolidine rings of inversion-related molecules [centroid–centroid distance = 3.703 (1) Å]. The chains are linked by further C—H⋯O hydrogen bonds, forming slabs parallel to the ac plane.The new title 4-thiazolidinone derivative, C Its mean plane makes a dihedral angle of 56.0 (1)° with the mean plane of the cyclohexylidene ring (C8-C13). The methoxycarbonyl group (C1/O2/O3/C2) is also twisted slightly with respect to plane A, their mean planes being inclined to one another by 11.2 (2)°. The six-membered cyclohexylidene ring has an envelope conformation with atom C8 as the flap: puckering parameters are Q = 0.494 (2) Å, θ = 129.8 (2)° and φ = 180.8 (3)°. The C7=N3 and N2=C6 bond lengths are 1.282 (2) and 1.278 (2) Å, respectively, consistent with C=N double bonding. The C6—N2—N3—C7, C4—C3—C2—O3 and C3—C2—O3—C1 torsion angles are 175.5 (2), −172.4 (2) and 172.5 (2)°, respectively.The title compound ts Fig. 2. The comi hydrogen bonds, forming chains propagating along [001]; see Table 1Cg1⋯Cg1 = 3.703 (1) Å,where Cg1 is the centroid of the S1/N1/C4–C6 ring, interplanar distance = 3.468 (1) Å, slippage = 1.298 Å]. The chains are linked by further C—H⋯O hydrogen bonds, forming slabs lying parallel to the ac plane -4-oxo-3-phenyl-1,3-thiazolidin-2-ylidene]ethanehydrazonoyl}phenyl)amino]but-2-enedioate ° in the title compound, 172.1 (2)° in AGOMUG, −178.9 (2) and −165.5 (2)° in NIPPAF and −167.4 (5)° in RIMDIC.A comparison of the main C—N, N—N, C—S bond lengths in the title compound and the structures extracted from the CSD shows a good correlation. The C=N—N=C torsion angles indicate that in each case the four atoms are nearly planar, 2SO4 and then evaporated under reduced pressure. The obtained residue was chromatographed on a silica gel column using hexane as eluent, to give compound 3 . Yellow prismatic crystals were obtained from a petroleum ether solution, by slow evaporation of the solvent at room temperature.To a solution of 4-methyl-3-thiosemicarbazone  in ethanol (15 ml) was added dimethyl acetylenedicarboxylate (DMAD) . The mixture was stirred under reflux for 1 h, leading to the corresponding thiazolidinone. After cooling, the mixture was extracted with ethyl acetate (3 × 20 ml). The organic layer was washed with water, dried on anhydrous NaUiso(H) = 1.5Ueq(C-methyl) and 1.2Ueq(C) for other H atoms.Crystal data, data collection and structure refinement details are summarized in Table 210.1107/S2056989017014311/su5396sup1.cifCrystal structure: contains datablock(s) I, Global. DOI: 10.1107/S2056989017014311/su5396Isup2.hklStructure factors: contains datablock(s) I. DOI: Click here for additional data file.10.1107/S2056989017014311/su5396Isup3.cmlSupporting information file. DOI: 1577993CCDC reference:  crystallographic information; 3D view; checkCIF reportAdditional supporting information:


The dithiocarbamate moiety displays a unique coordination mode, comprising a ‘side-on’ π-coordinated K+ cation besides a commonly σ-chelated K+ cation. By bridging coordination of the CSS group, COO group and water molecules, the K+ cations are linked into a two-dimensional coordination polymer extending parallel to the ab plane. These layers are again interconnected by O—H⋯S hydrogen bonds.The molecular and crystal structure of the  Giovagnini et al., 2005et al., 2006et al., 2012l-proline-derived potassium salt K2(SSC–NC4H7–COO). This compound crystallizes from aqueous solution as a trihydrate, which has been structurally characterized in the course of this work.Natural amino acids react readily with carbon disulfide in an alkaline environment to give dithiocarbamate-functionalized carboxylates. Since the first report on a series of barium salts in the 1950s ·3H2O, crystallized as colourless plates in the orthorhombic space group P212121, with one formula moiety in the asymmetric unit  and the remaining two H2O molecules are coordinating in a μ-bridging mode (O4 and O5). The K—S distances at the σ-chelated K+ cation (K2) are 3.2176 (8) and 3.2650 (9) Å, while the K—S separations at the π-coordinated K+ cation (K1) are significantly longer at 3.2956 (9) and 3.4463 (8) Å. The coordination mode of the dithiocarbamate group in the title compound : δ 1.89–1.98 , 2.24 , 3.75 , 3.83 , 4.72 . 13C NMR : δ 24.6 (4-CH2), 31.5 (3-CH2), 55.7 (5-CH2), 69.5 (2-CH), 179.9 (COO), 205.8 (CSS).A slight excess of carbon disulfide  was added to a solution of Uiso(H) = 1.2Ueq(C). C—H distances within the CH2 groups were constrained to 0.99 Å and that within the CH group to 1.00 Å. The water H-atom sites were located in difference Fourier maps and refined using restraints on the O—H distance [target value = 0.84 (2) Å]. The corresponding Uiso(H) values were set at 1.5Ueq(O). The reflection (002) disagreed strongly with the structural model and was therefore omitted from the refinement.Crystal data, data collection and structure refinement details are summarized in Table 210.1107/S2056989017011999/zl2712sup1.cifCrystal structure: contains datablock(s) I. DOI: 10.1107/S2056989017011999/zl2712Isup2.hklStructure factors: contains datablock(s) I. DOI: 1569563CCDC reference:  crystallographic information; 3D view; checkCIF reportAdditional supporting information:


The herbicide penoxsulam crystallizes with two independent molecules in the asymmetric unit. The crystal structure is stabilized by C—F⋯π and π–π interactions that combine with C—H⋯F and C—H O hydrogen bonds and weak intermolecular F⋯F short contacts to form a three-dimensional network. 16H14F5N5O5S [systematic name: 2--N--6-(trifluoromethyl)benzenesulfonamide], is used as a herbicide. The asymmetric unit of this structure comprises two independent molecules, A and B. The dihedral angles between the ring planes of the triazolopyrimidine ring systems and the benzene rings are 68.84 (7)° for A and 68.05 (6)° for B. In the crystal, weak intermolecular π–π interactions, with centroid–centroid separations of 3.4456 (17) and 3.5289 (15) Å and C—F⋯π [3.5335 (17) Å and 107.92 (13)°] contacts link adjacent molecules into chains along [001]. C—H⋯O and C—H⋯F hydrogen bonds link type B molecules into chains parallel to (100). Additional C—H⋯F hydrogen bonds together with short F⋯F contacts further aggregate the structure into a three-dimensional network.The title compound, C The compound inhibits the synthesis of acetolactate and targets the biosynthesis of branch-chained amino acids, a metabolic pathway found in plants, fungi, and microorganisms. Acetolactate synthase (ALS) inhibitors are present in most effective herbicides. They are used in agriculture because they show a broad weed control spectrum, crop selectivity, are safe to humans, and can be applied at relatively low usage rates ° in B. All bond lengths and bond angles are normal and comparable to those observed in similar crystal structures for triazolopyrimidine , and type B with Cg2⋯Cg2vi = 3.5289 (15) Å . These combine with C25—F9⋯Cg3vii interactions involving the C3–C8 benzene ring to form chains along [001]  and 2.794 (2) Å] together with C1—H1A⋯F10i, C16—H16C⋯F3ii, C18—H18⋯F10iii and C32—H32C⋯F8iv hydrogen bonds generate a three-dimensional network with molecules stacked along the a-axis direction benzoate -one  = 0.88 Å, Uiso(H) = 1.2Ueq(C) for the N—H group, d(C—H) = 0.95 Å, Uiso(H) = 1.2Ueq(C) for aromatic C—H, d(C—H) = 0.98 Å, Uiso(H) = 1.5Ueq(C) for methyl group, d(C—H) = 0.99 Å, Uiso(H) = 1.2Ueq(C) for Csp3—H, and d(C—H) = 1.00 Å, Uiso(H) = 1.5Ueq(C) for Csp3—H.Crystal data, data collection and structure refinement details are summarized in Table 210.1107/S2056989017011458/sj5532sup1.cifCrystal structure: contains datablock(s) I, New_Global_Publ_Block. DOI: 10.1107/S2056989017011458/sj5532Isup2.hklStructure factors: contains datablock(s) I. DOI: Click here for additional data file.10.1107/S2056989017011458/sj5532Isup3.cmlSupporting information file. DOI: 1566461CCDC reference:  crystallographic information; 3D view; checkCIF reportAdditional supporting information:


Adoptive immunotherapy is gaining momentum to fight malignancies, whereby γδ T cells have received recent attention as an alternative cell source as to natural killer cells and αβ T cells. The advent of γδ T cells is largely due to their ability to recognize and target tumor cells using both innate characteristic and T cell receptor (TCR)-mediated mechanisms, their capacity to enhance the generation of antigen-specific T cell responses, and their potential to be used in an autologous or allogeneic setting.In this study, we explored the beneficial effect of the immunostimulatory cytokine interleukin (IL)-15 on purified γδ T cells and its use as a stimulatory signal in the ex vivo expansion of γδ T cells for adoptive transfer. The expansion protocol was validated both with immune cells of healthy individuals and acute myeloid leukemia patients.We report that the addition of IL-15 to γδ T cell cultures results in a more activated phenotype, a higher proliferative capacity, a more pronounced T helper 1 polarization, and an increased cytotoxic capacity of γδ T cells. Moreover γδ T cell expansion starting with peripheral blood mononuclear cells from healthy individuals and acute myeloid leukemia patients is boosted in the presence of IL-15, whereby the antitumor properties of the γδ T cells are strengthened as well.Our results support the rationale to explore the use of IL-15 in clinical adoptive therapy protocols exploiting γδ T cells. Cellular immunotherapy for cancer is a rapidly evolving field, endeavoring to deal with common relapse or resistance to conventional treatments. Herewith, most interesting are the γδ T cells, a T cell subset possessing a combination of innate and adaptive immune cell traits . ActivatAmong the various tumor targets of γδ T cells , we focuγδ T cells can be expanded, using combinations of cytokines and phosphoantigens ) or aminobisphosphonates  . The incLimitations on the use of IL-2, relating to among other its toxicity, invigorate the investment in exploring other cytokines of the IL-2 family  . IL-15 iThese results stressed the need for a detailed characterization of the sheer effect of IL-15 on untouched and isolated γδ T cells. The latter will be discussed in the first part of this paper, followed by the translation of the results into a γδ T cell expansion protocol for adoptive transfer.6 cells/mL) were cultured for 5 days in Iscove’s Modified Dulbecco’s Medium , supplemented with 10 % fetal bovine serum , IPP , and IL-2  or IL-15 . The Burkitt’s lymphoma tumor cell line Daudi was kindly provided to us by the laboratory of Prof. Kris Thielemans , and the multiple myeloma cell line U266 was a gift from Prof. Wilfred Germeraad .This study was approved by the Ethics Committee of the Antwerp University Hospital  under the reference number B300201419756. Experiments were performed using buffy coats derived from healthy volunteer whole blood donations  and blood samples from patients with AML obtained from the hematological division of the UZA (Table ® Fixable Aqua Stain (Life Technologies), CD56-PE (Becton Dickinson (BD); Erembodegem, Belgium), CD3-PerCP-Cy5.5 (BD), and γδ T cell receptor (TCR)-APC (Miltenyi) and analyzed using a FACSAria II cytometer (BD). γδ T cell proliferation was assessed by quantifying the percentage of proliferating (CFSE-diluted) cells within the viable (LIVE/DEAD−) CD3+γδTCR+ gate.To test the ability of IL-2 and IL-15, in combination with IPP, to induce γδ T cell proliferation, a 5,6-carboxyfluorescein diacetate succinimidyl ester  flow cytometry-based proliferation assay was performed with isolated γδ T cells. Unstimulated CFSE-labeled γδ T cells served as negative control. After 5 days, cells were stained with LIVE/DEAD6 cells/mL. Cell cultures were maintained at a cell density of 0.5–2 × 106 cells/mL and were replenished every 2 to 3 days by adding IL-2/IL-15-supplemented medium. Phenotypic and functional assays were performed on cells harvested at least 14 days after first stimulations.PBMC were resuspended in Roswell Park Memorial Institute (RPMI) supplemented with 10 % heat-inactivated human AB serum , zoledronate , IL-2 (100 IU/mL), and/or IL-15 (100 IU/mL) at a final concentration of 1 × 10® Fixable Aqua Stain was used to distinguish viable from non-viable cells. Data were acquired on a FACSAria II flow cytometer (BD). Corresponding species- and isotype-matched antibodies were used as controls.Freshly isolated and 5-day proliferated γδ T cells were membrane-stained with the following monoclonal antibodies; γδ TCR-FITC (Miltenyi), CD56-PE (BD), CD69-PE (BD), and HLA-DR-PE (BD). Propidium iodide  was added to exclude dead cells from phenotypic analysis. Data acquisition was performed on a FACScan multiparametric flow cytometer (BD). Phenotypic characterization of γδ T cells was examined pre- and post-expansion, using CD27-FITC (BD), CD69-FITC (BD), CD56-PE (BD), CD80-PE (BD), CD45RA-PE-Cy7 (BD), CD28-PerCP-Cy5.5 (BD), CD16-PB (BD), CD86-V450 (BD), γδ TCR-APC (Miltenyi), and HLA-DR-APC-H7 (BD). Live/Deadγδ T cell cultures were set up as described above. After 5 days of proliferation, cell-free supernatants were harvested and stored at −20 °C before analysis. Samples were assessed by using enzyme-linked immunosorbent assay (ELISA) for the presence of TGF-β  and by using electrochemiluminescence immunoassay , Rockville, MD, USA) for the presence of IFN-γ, TNF-α, IL-5, IL-10, and IL-17. Cytokine measurements were also performed on supernatant of γδ T cell cultures stimulated for an additional 4 h with the tumor cell lines Daudi and U266 at an effector-to-target (E:T) ratio of 5:1.6 cells/mL) and incubated for 3 h at 37 °C/5 % CO2. γδ T cells were then washed and incubated with Live/Dead® Fixable Aqua Stain, CD3-PerCP-Cy5.5 (BD) and γδ TCR-APC (Miltenyi) for 30 min at 4 °C. Subsequently, cells were fixed and permeabilized, using the Foxp3/Transcription Factor Staining Buffer Set (eBioscience), according to the manufacturer’s instructions. Intracellular staining antibodies  or the corresponding isotype control were added and allowed to bind for 1 h at 4 °C.After 14 days of γδ T cell expansion, IFN-γ and TNF-α production was measured using a flow cytometric-based intracellular staining assay. Measurements were also performed after an additional hour of stimulation with Daudi or U266 cells (E:T ratio = 5:1). Brefeldin A  was added to the different conditions (1 × 10−/PI−) cells within the PKH67+ tumor cell population using the following equation: % killing = 100 − [(% viable tumor cells with γδ T cells/% viable tumor cells without γδ T cells) × 100].A flow cytometry-based lysis assay was performed in order to determine the killing activity of γδ T cells against the tumor cell lines Daudi and U266. Tumor cells were labeled prior to co-culture with PKH67 Green Fluorescent Cell Linker dye (Sigma-Aldrich), according to the manufacturer’s protocol, and subsequently co-cultured with γδ T cells at different E:T ratios . After 4 h, cells were acquired on a FACSAria II flow cytometer following staining with annexin V-APC (BD) and PI. Killing was calculated based on the percentages of viable . GraphPad Prism software  was used for statistical calculations and artwork. Shapiro-Wilk normality test was performed to ascertain the distribution of the data. 6 and 2.18 ± 0.31 x106 γδ T cells, respectively. Furthermore, exposure of human peripheral blood γδ T cells to IL-15+IPP resulted in an improved activated phenotype. Surface expression of CD69 augmented from 1.63 ± 0.52 %  to 15.85 ± 3.80 % (IL-2+IPP) and 26.55 ± 3.83 % (IL-15+IPP), and HLA-DR expression went up from 12.16 ± 2.36 %  to 64.58 ± 5.63 % (IL-2+IPP) and 63.93 ± 7.63 % (IL-15+IPP). Notably, CD56 expression was significantly higher on IL-15+IPP stimulated γδ T cells (38.34 ± 4.83 %) than on unstimulated (19.20 ± 4.49 %) and on IL-2+IPP stimulated γδ T cells (28.14 ± 4.73 %).Stimulation of αβ T cell proliferation is a characteristic of both IL-2 and IL-15. To assess their effect on γδ T cells, in combination with IPP, a 5-day proliferation assay was performed using isolated γδ T cells  between both γδ T cell types. After 5 days, γδ T cell cultures were harvested and exposed to Daudi or U266 tumor cells, to verify their antitumor activity, including cytokine secretion . Next, it should be noted that in contrast to the 100 % success rate of γδ T cell expansion , a clear effect was detected Fig. . Despite culture , 34) staAt culture initiation (day 0) and termination day 14–15), we subjected the γδ T cell cultures to immunophenotyping. Whereas the four distinct effector/memory states were nearly evenly represented in terms of percentages by circulating γδ T cells of healthy donors at day 0, with a small preponderance for the naïve and central memory phenotype, the vast majority of expanded cells were effector memory γδ T cells and to a lesser extent central memory γδ T cells , as compared to IL-2+zoledronate (1.49 ± 0.43 %) Fig. . This mon = 3) and IL-2+15+zoledronate (n = 5) expansion protocols. For U266 killing, percentages of 24.89 ± 3.51 and 35.19 ± 4.96 % were true. Finally, for some AML patients e.g., patient A, cytotoxic capacity is highly dependent on the target cell line  and myeloid DCs, including our IL-15 DCs, feature cytotoxic activity, in addition to serving classical DC functions [When looking in detail at the phenotype of cultured γδ T cells, two findings stand out from our results. First, incubation with IL-15+IPP led to a significant upregulation of CD56 relative to IL-2+IPP stimulated and unstimulated γδ T cells. In addition to the stringent association of CD56 with NK cells, CD56 has also been detected on other lymphoid cells, including γδ T cells and activated CD8 T cells –55. Moreunctions , 57–59. unctions . This fu−/− knockout mice only produced small amounts of IFN-γ upon stimulation and showed significantly lower cytotoxicity against target cells as compared to wild-type mice [In view of the functionality of γδ T cells, our experiments clearly show that IL-15, in comparison with IL-2, has a superior Th1 polarizing effect on γδ T cells and markedly strengthens the γδ T cell cytotoxic capacity. These results are supported by in vivo data where intestinal γδ T cells of IL-15ype mice . This inype mice . In addiype mice . Althougype mice . All theype mice .Taken together, we have demonstrated that the addition of immunostimulatory cytokine IL-15 to in vitro γδ T cell cultures, derived from both AML patients and healthy blood donors, resulted in a more activated phenotype and significantly increased the antitumor functions of γδ T cells. This was manifested in a higher yield of expanded γδ T cells, a more pronounced Th1 polarization and an increased cytotoxic capacity, all desirable characteristics for their further use in adoptive immunotherapy. Therefore, our results strengthen the rationale to explore the use of IL-15 in clinical adoptive therapy protocols.


II cation is N,O,O′,O′′-chelated by a 2,2′-[N-(phenylphosphorylmethyl)azanediyl]diacetate dianion and coordinated by two 1H-benzo[d]triazole molecules in a slight distorted octahedral coordination.In the molecule, the Co 11H12NO6P)(C6H5N3)2]·C6H5N3, the 2,2′-[N-(phenylphosphorylmethyl-κO)azanediyl]diacetate dianion N,O,O′,O′′-chelates the CoII cation and two 1H-benzo[d]triazole molecules coordinate to the CoII cation to complete the slightly distorted octahedral coordination. In the crystal, classical O—H⋯O, N—H⋯O hydrogen bonds and weak C—H⋯N hydrogen bonds link the molecules into a three-dimensional supramolecular architecture. π–π stacking between the triazole and benzene rings and between the benzene rings is also observed in the crystal.In the title compound, [Co(C Research of its potential applications  of this and analogous complexes is currently being undertaken.In addition to their biological activities, aminophosphinic acids are also attracting interest in many areas such as the construction industry, aerospace and electronics for their excellent flame retardancy to polymeric materials phosphoryl]methyl}azanediyl)diacetate dianion and coordinates two 1H-benzo[d]triazole molecules in a slightly distorted octahedral coordination  and refluxed for 1 h under a nitrogen atmosphere. 50 ml of formaldehyde in hydrochloric acid (37%) was added dropwise under vigorous stirring, and the temperature was maintained at 378–383 K for 4 h. This solution was then concentrated under reduced pressure and allowed to cool to room temperature. 100 ml of acetone was added, and the white precipitate of 2,2′-({[(phenyl)phosphoryl]methyl}azanediyl)diacetic acid was collected by filtration. Colourless crystals of the title compound were obtained as follows: 2.38 g CoCl2·6H2O (0.01 mol) and 3.57 g 1H-benzo[d]triazole (0.03 mol) were added to a stirred hydrochloric acid solution , then 3.24 g of 2,2′-({[(phenyl)phosphoryl]methyl}azanediyl)diacetic acid (0.01 mol) were added in one portion. The mixture was stirred for 1 h, then filtered and left undisturbed. Single crystals were obtained by slow evaporation of the reaction mixture after several days.Phenylphosphinic acid  and iminodiacetic acid  were dissolved in hydrochloric acid (6 2 groups) were positioned geometrically and refined using a riding model with Uiso(H) = 1.2Ueq(C). The carboxyl H atom was refined as rotating group with Uiso(H) = 1.5Ueq(O).Crystal data, data collection and structure refinement details are summarized in Table 310.1107/S2056989017015079/xu5906sup1.cifCrystal structure: contains datablock(s) global, I. DOI: 10.1107/S2056989017015079/xu5906Isup3.hklStructure factors: contains datablock(s) I. DOI: 1573300CCDC reference:  crystallographic information; 3D view; checkCIF reportAdditional supporting information:


The crystal structure of the title molecular salt features N—H⋯Cl and C—H⋯Cl hydrogen bonds and π–π interactions; Hirshfeld surface analysis and fingerprint plots are reported. 5H8N3)2[CoCl4], the cations are protonated at their pyridine N atoms and the anion is an almost regular tetrahedron. The crystal structure consists of alternating inorganic layers, built from tetrachloridocobaltate anions, and organic layers formed by protonated cations of 2,6-diaminopyridinium. The crystal packing is governed by C/N—H⋯Cl hydrogen-bonding interactions between the organic and the inorganic ions and Cl⋯Cl interactions. Moreover, the cations show a π–π stacking interaction [intercentroid distance = 3.763 (2) Å]. The prevalence of these interactions is illustrated by an analysis of the three-dimensional Hirshfeld surface and by two-dimensional fingerprint plots.In the title molecular salt, (C These data are in agreement with those found in related compounds  = 0.004 and ΔI(Cl—Co—Cl) = 0.0019] show a slight distortion of the tetrahedra. The interanionic Cl⋯Cl contact distances between the nearest neighbor tetrahedra are 3.986 (2) Å along the a axis and 3.889 (2) Å along the c axis ns Fig. 1. The geois Fig. 2, compareet al., 2015Pyridinium cations always possess an expanded angle of C—N—C in comparison with the parent pyridine 2[MBr4]  2[CoBr4] ns Fig. 3, which iThe construction of the three-dimensional architecture is consolidated by N—H⋯Cl and C—H⋯Cl hydrogen bonds Table 1, generatfs Fig. 4.et al., 2017As can be seen from Fig. 5CrystalExplorer  , H⋯H  and C⋯H/H⋯C .The fingerprint plots of (I)et al., 20123 and surface area in the order of 648 Å2. With the porosity, the calculated void volume of (I)e.g. N—H⋯Cl and C—H⋯Cl.Fig. 92·6H2O (molar ratio 1:1) were dissolved in 10 ml of methanol; 3 ml of hydrochloric acid (37%) was added dropwise to the mixture and the resulting blue solution was put aside for crystallization at room temperature. After two weeks, blue crystals of (I)2,6-diaminopyridine and CoClCrystal data, data collection and structure refinement details are summarized in Table 210.1107/S2056989018003171/hb7732sup1.cifCrystal structure: contains datablock(s) I. DOI: 10.1107/S2056989018003171/hb7732Isup2.hklStructure factors: contains datablock(s) I. DOI: 1588020CCDC reference:  crystallographic information; 3D view; checkCIF reportAdditional supporting information:


Erratum to:Perspect Med Educ (2015) 4:308–313DOI 10.1007/s40037-015-0220-x−4 rather than 5.89 × 10−3. The exponent is correctly reported in the body text (page 311).In the version of the article originally published online, there was an error in Table 3 (page 312). The B coefficient for the variable “Anki” should be 5.89 × 10


In the title compound, C—H⋯O hydrogen bonds and aromatic π–π stacking combine to generate a three-dimensional network. A Hirshfeld surface analysis is presented. 18H20N2O7, the dihedral angle between the aromatic rings is 7.28 (7)° and the almost planar conformation of the molecule is supported by an intramolecular O—H⋯O hydrogen bond, which closes an S(6) ring. In the crystal, weak C—H⋯O hydrogen bonds and aromatic π–π stacking link the molecules into a three-dimensional network. A Hirshfeld surface analysis showed that the major contribution to the intermolecular interactions are van der Waals interactions (H⋯H contacts), accounting for 48.4% of the surface.In the title compound, C An intramolecular O—H⋯O hydrogen bond (Table 1S(6) ring and a C—H⋯O interaction is also observed. A Mogul geometry check found that all the bond lengths and angles are within typical ranges on Fig. 1; the C10d Table 1 closes aC⋯O7ii hydrogen bonds [C⋯O = 3.3694 (19) Å], which generate B⋯O6i hydrogen bond [C⋯O = 3.341 (3) Å]. In addition, weak and very weak π–π interactions  between benzene and pyrimidine rings  occur -trione -trione  I. DOI: 10.1107/S2056989017010374/hb7681Isup2.hklStructure factors: contains datablock(s) I. DOI: 1562022CCDC reference:  crystallographic information; 3D view; checkCIF reportAdditional supporting information:


In the title compound, a naphthalene derivative, the cyclohexa-1,3-diene ring of the 1,2-dihydronaphthalene ring system adopts a half-chair conformation. The mean plane of the 1,2-dihydronapthalene ring system make dihedral angles of 86.23 (6) and 64.80 (7)° with two phenyl rings. In the crystal, the molecules are linked by C—H⋯O, interactions and further stabilized by C—H⋯π and π–π interactions. 26H20O5, a 1,2-dihydronaphthalene derivative, the cyclohexa-1,3-diene ring of the 1,2-dihydronaphthalene ring system adopts a half-chair conformation. The mean plane of the 1,2-dihydronapthalene ring system makes dihedral angles of 86.23 (6) and 64.80 (7)° with two phenyl rings. The carbonyl O atom attached to the dihydronaphthalene ring system deviates from the mean plane of the 1,2-dihydronaphthalene ring system by 0.618 (1) Å. In the crystal, the molecules are linked into layers parallel to the bc plane via two kinds of C—H⋯O interactions, one of which forms a C(10) chain motif running along the c-axis direction and the other forms an R22(6) ring motif. Adjacent layers are further connected by C—H⋯π and offset π–π interactions [centroid–centroid distance = 3.6318 (9) Å].In the title compound, C Å, q3 = 0.1461 (14) Å, φ2 = 155.9 (3)° and θ = 64.7 (2)° and ΔCs = 4.41 (19). The dihedral angle between the C1–C6 and C5–C10 rings is 10.15 (6)°. The C11–C16 phenyl ring is almost perpendicular to the 1,2-dihydronaphthalene C1–C10 ring system with a dihedral angle of 83.83 (7)° between them. The other phenyl ring (C21–C26) makes dihedral angles of 64.80 (7) and 29.06 (8)° with the mean plane of C1–C10 ring system and the C11–C16 phenyl ring, respectively. Atom O1 of the carbonyl group deviates from the mean plane of the 1,2-dihydronaphthalene ring system by 0.647 (1) Å.In the title compound Fig. 1, the 1,2via C—H⋯O hydrogen bonds  zigzag chains running along the c-axis direction  Å, interplanar distance = 3.343 (1) Å and offset distance = 1.419 (1) Å; symmetry code: (iii) −x, 1 − y, −z; Cg1 and Cg3 are the centroids of the C1–C6 and C11–C16 rings, respectively].In the crystal, the molecules are linked on Fig. 2. In addiif Fig. 3, forming3·OEt2  was added and the reaction mixture was stirred at room temperature for 5 min. Removal of solvent followed by column chromatographic purification  gave the title compound as a colourless solid . Single crystals suitable for X-ray diffraction were prepared by slow evaporation of an ethyl acetate solution of the title compound at room temperature (m.p. = 454–456 K).To a solution of 1,3-diphenylisobenzofuran  in dry dichloromethane, dimethyl acetylenedicarboxylate  was added and the reaction mixture was stirred at room temperature for 1 h. Removal of solvent followed by column chromatographic purification  afforded isobenzofurandimethyl acetylenedicarboxylate adduct as a colourless solid . To a solution of the adduct  in dry dichloromethane, BFUiso(H) = 1.2Ueq(aryl C) and 1.5Ueq(methyl C), allowing for free rotation of the methyl groups.Crystal data, data collection and structure refinement details are summarized in Table 210.1107/S2056989018002360/is5487sup1.cifCrystal structure: contains datablock(s) I, global. DOI: 10.1107/S2056989018002360/is5487Isup2.hklStructure factors: contains datablock(s) I. DOI: 1823056CCDC reference:  crystallographic information; 3D view; checkCIF reportAdditional supporting information:


A new co-crystal of piroxicam and gentisic acid has been characterized, in which the ratio of piroxicam  to gentisic acid is 2:1. N-(pyridin-2-yl)-2H-1λ6,2-benzothiazine-3-carboxamide–2-pyridin-1-ium–2,5-dihydroxybenzoic acid, 2C15H13N3O4S·C7H6O4] has been synthesized using a microfluidic platform and initially identified using Raman spectroscopy. In the co-crystal, one piroxicam molecule is in its neutral form and an intramolecular O—H⋯O hydrogen bond is observed. The other piroxicam molecule is zwitterionic (proton transfer from the OH group to the pyridine N atom) and two intramolecular N—H⋯O hydrogen bonds occur. The gentisic acid molecule shows whole-molecule disorder over two sets of sites in a 0.809 (2):0.191 (2) ratio. In the crystal, extensive hydrogen bonding between the components forms layers propagating in the ab plane.A new 2:1 co-crystal of piroxicam and gentisic acid [systematic name: 4-hydroxy-1,1-dioxo- In the S2 molecule, free rotation about the C—C bond (C1 and C10) allows a second zwitterionic conformation in which intramolecular hydrogen bonds exist between the amine proton H2 and the enolate oxygen atom O4 [H⋯A = 1.85 (2) Å] and the pyridinium proton H3 and the amide oxygen atom O3 [H⋯A = 2.19 (2) Å]. Further details of the hydrogen bonding are provided in Table 1The asymmetric unit of this co-crystal consists of two piroxicam molecules and one gentisic acid molecule, with all atoms residing on general positions Fig. 1. One of A = 1.89 (3) Å]. The major orientation also participates in intermolecular hydrogen bonding. The minor orientation of the gentisic acid molecule also displays intramolecular hydrogen bonding between the O11B hydroxide substituent and the O9B oxygen atom of the carboxylic acid (H⋯A = 1.89 Å) but does not participate in intermolecular hydrogen bonding.The gentisic acid molecule shows whole molecule disorder over two orientations rotated by approximately 180° in the plane of the aromatic ring with site occupancies of 0.809 (2):0.191 (2). The major orientation participates in intramolecular hydrogen bonding between the O11 hydroxide substituent of the benzene ring and the O9 oxygen atom of the carboxylic acid [H⋯a-axis direction . The non-zwitterionic form of piroxicam accepts hydrogen bonds from the gentisic acid via O—H⋯N bonds between the carboxylic acid and the pyridine ring of piroxicam [H⋯A = 1.74 (3) Å] as well as N—H⋯O bonds between the carbonyl oxygen atom of gentisic acid and the amine nitrogen atom of piroxicam [H⋯A = 2.25 (2) Å]. The zwitterionic form of piroxicam accepts hydrogen bonds from the gentisic acid via O—H⋯O bonds between the 5-hydroxy substituent of gentisic acid and the enolate oxygen atom of piroxicam [H⋯A = 1.94 (3) Å]. The repeat units are linked together by N—H⋯O bonds between the pyridinium nitrogen atoms and the amide oxygen atoms of the zwitterionic form of piroxicam [H⋯A = 2.19 (2) Å].The repeating motif of the hexameric unit is formed by one gentisic acid molecule hydrogen bonded to two piroxicam molecules, one of each conformation (M). The resulting solution was introduced into a microfluidic platform. The microfluidic platform was a 6 × 6 array of single microwells (∼100 nl)  and gentisic acid (>=98.0%) were used as purchased from Sigma–Aldrich . Acetonitrile (>=99.9%) was used as purchased from Fisher Scientific . A 1:2 molar ratio of piroxicam:gentisic acid was dissolved in acetonitrile. The concentration of piroxicam in acetonitrile was near saturation  I. DOI: 10.1107/S2056989016017321/hb7625Isup2.hklStructure factors: contains datablock(s) I. DOI: Click here for additional data file.10.1107/S2056989016017321/hb7625Isup3.cdxSupporting information file. DOI: Click here for additional data file.10.1107/S2056989016017321/hb7625Isup4.cmlSupporting information file. DOI: 1512430CCDC reference: crystallographic information; 3D view; checkCIF reportAdditional supporting information:


Molecules are connected into a three-dimensional architecture by O—H⋯O,N hydrogen bonding.A distorted octahedral NS 6H12NOS2)2(C12H10N4)]2·2H2O, comprises a CdII atom, two dithiocarbamate (dtc) anions, a monodentate 3-pyridinealdazine ligand and a lattice water molecule. The binuclear molecule is constructed by the application of inversion symmetry. One dtc ligand simultaneously chelates one cadmium atom and bridges the centrosymmetric mate, while the other dtc ligand is chelating only. This leads to a centrosymmetric [Cd(dtc)2]2 core to which are appended two 3-pyridinealdazine ligands. The resulting NS5 donor set is based on an octahedron. The three-dimensional molecular packing is sustained by hydroxyl-O—H(hydroxyl) and water-O—H⋯O(hydroxyl) hydrogen bonding, leading to supramolecular layers parallel to (101) which are connected by water-O—H⋯N(pyridyl) hydrogen bonding; additional C—H⋯O, S π(chelate ring) interactions are also evident. The retention of the central [Cd(dtc)2]2 core upon adduct formation is unprecedented in the structural chemistry of the zinc-triad dithiocarbamates.The asymmetric unit in the title binuclear compound, [Cd(C The overwhelming majority of structures are binuclear, [Cd(S2CNRR′)2]2, arising from equal numbers of μ2-tridentate and bidentate (chelating) ligands furan-2-ylmethyl]2}3 2]n CH2CH2OH]2}n CH2CH(OMe)2]2}n CH2CH2OH]2}n species 2 is reacted with bases, e.g. pyridyl-donors, the original aggregate is disrupted in that no dtc links are retained between cadmium atoms. Thus, when archetypal, binuclear [Cd(S2CNEt2)2]2 ethylene ethane CH2CH2OH)]2}2 and 3-pyridinealdazine were isolated and shown by X-ray crystallography that despite having one potentially bidentate bi-pyridyl ligand per Cd[S2CN(iPr)CH2CH2OH)]2 unit, the central binuclear core CH2CH2OH)]2 entity, a 3-pyridinealdazine ligand and one water molecule of solvation. One dithiocarbamate (dtc) ligand coordinates in a chelating mode forming very similar Cd—S bond lengths, i.e. the difference between the Cd—Sshort and Cd—Slong bond lengths is only 0.033 Å; this equivalence is reflected in the equivalence in the associated C1—S1, S2 bond lengths, Table 1bridging bond lengths are close to being equal, differing by only 0.010 Å, and are longer by ca 0.1 Å than the non-bridging Cd—S4 bond length, Table 1anti disposition about both imine bonds, i.e. C18=N4 = 1.283 (3) Å and C19=N5 = 1.277 (3) Å; the central, azo bond is 1.415 (2) Å. The pyridyl-N atoms are also anti but there are twists in the 3-pyridinealdazine molecule, as seen in the value of the dihedral angle between the two pyridyl rings of 22.78 (12)°.The molecular structure of the binuclear title compound, isolated as a dihydrate, is shown in Fig. 1hydroxy—H⋯Ohydroxy—H⋯Owater—H}n chains are formed as shown in Fig. 2a. The water molecules also form water-O—H⋯N(pyridyl) hydrogen bonds on either side of the supramolecular layers sustained by O—H⋯O hydrogen bonds, Fig. 2b. The pendent pyridyl-N atoms of Fig. 2b are coordinating to cadmium atoms of successive layers so that a three-dimensional architecture results. Globally, and as seen from Fig. 32CN(iPr)CH2CH2OH)]2}2 and 3-pyridinealdazine with the key links between them being hydrogen and coordinate bonding. Within this framework stabilized primarily by hydrogen-bonding interactions, there are some second tier interactions worthy of comment  interactions are present  angle is 178°, in the inter-layer region, Table 2Significant O—H⋯O hydrogen bonding is found in the molecular packing of the binuclear title compound as would be expected from the chemical composition. Thus, molecules are assembled into layers approximately parallel to (101) by hydroxy-O—H⋯O(hydroxyl) and hydroxy-O—H⋯O(water) hydrogen bonds as detailed in Table 2et al., 20162-bridging 3-pyridinealdazine such as in the two most relevant compounds to the present study, namely {Cd[S2P(O-iPr)2]2}n 2]2}n 2]22·H2O}n (OH2)2]·2ClO4}n . A good number of zinc and mercury binary dithiocarbamates are also known to adopt related binuclear [M(S2CNRR’)2]2 aggregates owing to the presence of equal numbers of μ2-tridentate and chelating ligands 2(hmta)]2, where hmta is hexamethylenetetramine, for which an analogous centrosymmetric core and NS5 donor set as in the title compound was observed 2]2 cores in the structural chemistry of metal xanthates CH2CH2OH)]2  and 3-pyridinealdazine  were dissolved in 1-propanol (15 ml). The solution was carefully covered with hexanes. Yellow blocks were obtained via slow diffusion of hexanes into the 1-propanol solution over two weeks. m.p. 389–391 K. IR (cm−1): 1449 (m) ν(C=N), 1173 (s) ν(C—S). 1H NMR: δ 9.04 , 8.81 , 8.72 , 8.29 , 7.56 , 5.22 , 4.83 , 3.74 , 3.68 , 1.18 . TGA: three steps, corresponding to loss of water , loss of the 3-pyridinealdazine ligand , and decomposition down to cadmium sulfide .Cd[SUiso(H) set at 1.2–1.5Ueq(C). The oxygen-bound H atoms were located in a difference Fourier map but were refined with a distance restraint of O—H = 0.84±0.01 Å, and with Uiso(H) set at 1.5Ueq(O).Crystal data, data collection and structure refinement details are summarized in Table 310.1107/S2056989016012214/wm5312sup1.cifCrystal structure: contains datablock(s) I, global. DOI: 10.1107/S2056989016012214/wm5312Isup2.hklStructure factors: contains datablock(s) I. DOI: 1496352CCDC reference: crystallographic information; 3D view; checkCIF reportAdditional supporting information:


Acta Cryst. E71, o125-o126. The motivation for this redetermination follows from negligence of important features of the difference electron-density maps as well as from wrongly applied constraints, which significantly affect the structural model. The corrections affect mainly the positions of the H atoms involved in the hydrogen bonds (centered on the primary amine group for which the H atom turned out to be disordered over two positions about the centre of an N⋯H⋯O hydrogen bond) and the methyl group, which is disordered and has now been remodelled.The title structure, 4-aminobenzoic acid 4-methylpyridine/4-methylpyridinium 4-aminobenzoate 0.58/0.42, has been redetermined from the data published by Kumar  6H7N·C7H7NO2)·0.42(C6H8N+·C7H6NO2−), has been redetermined from the data published by Kumar et al.  Å], while the H atoms of the primary amine group account more realistically for the hydrogen-bond pattern after the removal of the positional constraints. All the O—H⋯N or N—H⋯O hydrogen bonds which are present in the title structure are of moderate strength.The title structure, 4-aminobenzoic acid 4-methylpyridine/4-methylpyridinium 4-aminobenzoate 0.58/0.42, 0.58(C al. 2015. Acta Cr Figs. 1et al.  = 1.2Ueq(Nprimary/secondary amine).In the course of recalculation of suspect structures that were retrieved from the CSD, the structure determination of the title structure by Kumar  al. 2015, CSD refet al., 2006et al.  (H1x) and 0.42(7) (H1y)  Figs. 1 and 2 ▸.x⋯N2iii/O1⋯H1yiii—N2iii  is quite long for an O⋯N hydrogen bond with a disordered bridging hydrogen atom, i.e. for a hydrogen atom the substantial part of its electron density is situated along the connecting line between the donor/acceptor atoms as happens in O1—H1x⋯N2iii/O1⋯H1yiii—N2iii of the title structure x hydrogen trioxofluorophosphate(1−)x monohydrate/2,4,6-triaminopyrimidinium(2+)x)(1– trioxofluorophosphate(2−)x) − pKa(acid) is close to 0 , or ionized, forming a salt  x + 1, y, z + 1] with a bridging hydrogen atom disordered over two positions (H1x and H1yiii) forms a finite D(3) pattern  −x + 1, −y, z − a--N1–H1b and atom O2iv /σ(i) < 0.6}. The indicators of the refinement of such a model were substantially higher: Robs = 0.0503, Rwobs = 0.1035, Rall = 0.0930, Rwall = 0.1119. The condition for the observed diffractions was I/σ(I) > 3, cf. Table 2It is worthwhile mentioning that the recalculation of the original model with 10.1107/S2056989017013226/su5390sup1.cifCrystal structure: contains datablock(s) global, I. DOI: 10.1107/S2056989017013226/su5390Isup2.hklStructure factors: contains datablock(s) I. DOI: Click here for additional data file.10.1107/S2056989017013226/su5390Isup3.cmlSupporting information file. DOI: 1574686CCDC reference:  crystallographic information; 3D view; checkCIF reportAdditional supporting information:


The packing of the title compound features short C—I⋯N contacts. 18H18I2N2O2, consists of one half-molecule, completed by the application of inversion symmetry. The molecule adopts the typical structure for this class of bis-benxozazines, characterized by an anti orientation of the two benzoxazine rings around the central C—C bond. The oxazinic ring adopts a half-chair conformation. In the crystal, molecules are linked by C—I⋯N short contacts [I⋯N = 3.378 (2) Å], generating layers lying parallel to the bc plane.The asymmetric unit of the title compound, C So, an iodine functional bis-1,3-benzoxazine, namely 3,3′-bis has been synthesized in high yield and purity.As the electrophilic character of the substituents affects the stability both of the reaction intermediates and the benzoxazine ring  bond  Å, θ =129.6 (2)°, φ = 283.6 (3)°: with respect to the plane formed by O1/C3/C4/C5, the deviations of C2 and N1 are 0.301 (3) and −0.320 (3) Å, respectively. The observed C—O bond length [1.376 (3) Å] is in a good agreement with the related p-fluoro and p-bromo structures . Moreover, the C2—N1—C1 [112.6 (2)°] and C5—N1—C1 [113.0 (2)°] angles are larger than the mean value of sp3 hybridization in ammonia  ,  monohydrate   set to 1.2Ueq of the parent atom.Crystal data, data collection and structure refinement details are summarized in Table 210.1107/S2056989017005047/hb7668sup1.cifCrystal structure: contains datablock(s) I. DOI: 10.1107/S2056989017005047/hb7668Isup2.hklStructure factors: contains datablock(s) I. DOI: Click here for additional data file.10.1107/S2056989017005047/hb7668Isup3.cmlSupporting information file. DOI: 1541561CCDC reference:  crystallographic information; 3D view; checkCIF reportAdditional supporting information:


II atoms in {Zn[S2CN(R)CH2CH2OH]2(pyridine)·pyridine}, for R = Me (I) and Et (II), are coordinated non-symmetrically by two dithiocarbamate ligands and by a pyridine ligand, resulting in an NS4 donor set that defines a distorted geometry in each case; the non-coordinating pyridine molecules are connected with the Zn-containing molecules via O—H⋯N(pyridine) hydrogen bonds. The molecular packing features significant (hydroxy)O—H⋯O(hydroxy) hydrogen bonding, in each case leading to supramolecular chains with zigzag (I) or helical (II) arrangements.The Zn 4H8NOS2)2(C5H5N)]·C5H5N (I) and [Zn(C5H10NOS2)2(C5H5N)]·C5H5N (II), which differ by having dithiocarbamate N-bound methyl (I) and ethyl (II) groups, is the coordination of each ZnII atom by two non-symmetrically chelating dithiocarbamate ligands and by a pyridine ligand; in each case, the non-coordinating pyridine molecule is connected to the Zn-containing molecule via a (hydroxy)O—H⋯N(pyridine) hydrogen bond. The resulting NS4 coordination geometry is closer to a square-pyramid than a trigonal bipyramid in the case of (I), but almost intermediate between the two extremes in (II). The molecular packing features (hydroxy)O—H⋯O(hydroxy) hydrogen bonds, leading to supramolecular chains with a zigzag arrangement along [10-1] (I) or a helical arrangement along [010] (II). In (I), π–π [inter-centroid distances = 3.4738 (10) and 3.4848 (10) Å] between coordinating and non-coordinating pyridine molecules lead to stacks comprising alternating rings along the a axis. In (II), weaker π–π contacts occur between centrosymmetrically related pairs of coordinating pyridine molecules [inter-centroid separation = 3.9815 (14) Å]. Further interactions, including C—H⋯π(chelate) interactions in (I), lead to a three-dimensional architecture in each case.The common structural feature of the title compounds, [Zn(C While many similarities are apparent in their coordination propensities ethylene (bpe). With Zn(S2COEt)2, a 1:1 compound can be prepared which crystallography shows to be a one-dimensional coordination polymer with a zigzag arrangement  group only the dimeric aggregate [Zn(S2COCy)2]2(bpe) could be isolated 2]2, in that 1:1 one-dimensional coordination polymers can be formed with bpe when R = i-Pr  dithiocarbamates of bpe, where only binuclear species, [Zn(S2CNR2)2]2(bpe), have been isolated, e.g. R = Me CH2CH2OH 2]2, where the dimeric aggregate, mediated by Zn—S bridges, self-assembles into a three-dimensional architecture based on hydrogen bonding CH2CH2OH]2}2(bipy), which allows for the construction of a doubly interpenetrated architecture. When the bridge is pyrazine, the three-dimensional architecture is sustained by (hydroxy)O—H⋯O(hydroxy) hydrogen bonding exclusively CH2N(H)C(=O)C(=O)N(H)CH2(3-pyridyl), i.e. LH2, the dimeric {Zn[S2CN(Me)CH2CH2OH)2]2}2(LH2) aggregates are interwoven into supramolecular chains sustained by hydrogen bonding CH2CH2OH]2(pyridine)·pyridine} for R = Me (I)In order to overcome the reluctance of zinc(II) dithiocarbamates to generate extended supramolecular architectures, the dithiocarbamate ligands can be functionalized with hydrogen-bonding potential, 2CN(R)CH2CH2OH]2(pyridine)·.pyridine}, for R = Me (I)long - Zn—Sshort. For the S1-dithiocarbamate ligand, ΔZn—S = 0.23 Å, but this decreases to 0.17 Å for the S3-ligand. From the data in Table 1τ, which ranges from 0.0 to 1.0° for ideal square-pyramidal to trigonal-bipyramidal, respectively τ is 0.56, indicating a small tendency towards trigonal–bipyramidal, certainly when compared with the coordination geometry for (I)i.e. 166.375 (19)°. As for (I)etc. The solvent molecule in (II)via a hydrogen bond.To a first approximation the structure of (II)2CN(R)CH2CH2OH]2 molecules in (I)Despite the relatively close agreement between the coordination geometries of the Zn. A view of the unit-cell contents is shown in Fig. 4b. As for (I)In the crystal of (II)e.g. as anti-cancer agents 2(pyridine), which was motivated by the desire to destroy the binuclear structure observed for the binary dithiocarbamate compound to form a lighter (i.e. lower molecular weight) species to facilitate chemical vapour deposition studies 2(pyridine) species. More sophisticated monodentate nitrogen-donor adducts are also known, such as substituted pyridines, e.g. 3-hydroxypyridine 2CNEt2)2(pyridine) adduct has also been characterized as a mono-pyridine solvate CH2CH2OH]2, R = Me and Et, precursors were prepared as per established procedures CH2CH2OH]2, R = Me and Et (50 mg), was dissolved in pyridine (10 ml) and carefully layered with hexanes (10 ml). Crystals were harvested directly from solution and mounted immediately onto the diffractometer to avoid loss of pyridine.The Zn[SUiso(H) set to 1.2–1.5Ueq(C). The O-bound H atoms were located in difference-Fourier maps but were refined with a distance restraint of O—H = 0.84±0.01 Å, and with Uiso(H) set to 1.5Ueq(O). For (I)−3, respectively, were located 1.03 and 1.02 Å from the Zn atom. For (II)−3, respectively, were located 1.02 and 0.61 Å from the Zn atom.Crystal data, data collection and structure refinement details are summarized in Table 410.1107/S2056989017010568/wm5406sup1.cifCrystal structure: contains datablock(s) I, II, global. DOI: 10.1107/S2056989017010568/wm5406Isup2.hklStructure factors: contains datablock(s) I. DOI: 10.1107/S2056989017010568/wm5406IIsup3.hklStructure factors: contains datablock(s) II. DOI: 1562767, 1562766CCDC references:  crystallographic information; 3D view; checkCIF reportAdditional supporting information:


The bridging mode of the organic ligands leads to the formation of a polymeric layer structure parallel to the ab plane.The zinc cation in the structure has a N 8H4O6S)(C10H8N2S)(H2O)]·0.26H2O}n, is characterized by a layered arrangement parallel to the ab plane. The zinc cation is five-coordinated in a slightly distorted trigonal–bipyramidal coordination environment defined by two pyridine ligands, two carboxylate groups of two thiophene dicarboxylate ligands, and by one water molecule. The ethylene bridge in the dioxine ligand is disordered over two sets of sites [occupancy ratio 0.624 (9):0.376 (9)]. Several hydrogen-bonding interactions of the types O—H⋯O, C—H⋯O, C—H⋯S and C—H⋯N ensure the cohesion within the crystal structure.The crystal structure of the title polymer, {[Zn(C The equatorial Zn1—N1 bond length is 2.1131 (18) Å, while the axial Zn1—N2 bond is longer, 2.2107 (18) Å. Similarly, the two equatorial Zn1—O  bond lengths, ranging from 1.9835 (15) to 2.0285 (15) Å, are shorter than the axial Zn1—O7 bond of 2.1375 (17) Å. These are typical values, numerical details of which are given in Table 1In the crystal structure of (1), the zinc ion is coordinated by four organic ligands and one water molecule, giving rise to a slightly distorted trigonal–bipyramidal coordination environment. Two nitrogen atoms are delivered by two symmetry-related pyridine ligands, two oxygen atoms of two carboxyl groups stem from two symmetry-related thiophene carboxylate ligands, and one O atom from the aqua ligand Fig. 1. In the ab plane  to the coordinating O5 atom of the carboxyl group. Another (pyridine)C—H group (C18—H18A) is hydrogen-bonded to the disordered O8 atom of the lattice water molecule. Three O—H⋯O interactions are present between the coordinating water molecule to either the carboxyl group oxygen atoms or the dioxine oxygen atom in the thiophene derivative with D⋯A distances ranging between 2.733 (2) and 3.123 (2) Å and corresponding O—H⋯O angles of 135 (2) and 159 (2)°. Numerous other C—H⋯O interactions are present between the disordered dioxine C—H groups and a carboxyl O atom (O6) or the lattice water atom O8. Other C—H⋯O interactions involve pyridyl C—H groups and the carboxyl O3 atom. In addition, one C—H⋯S interaction and one C—H⋯N interaction are found between pyridyl C—H groups and the sulfane S1 atom or the pyridyl N1 atom C—H group   was prepared as reported , H2ttdc , 4,4′-dithiodipyridine , 5 ml dimethylformamide and 3 ml water was mixed and heated at 353 K for 3 days. After cooling, 0.17 g light-yellow crystals were collected in a yield of 32%.2,3-Dihydrothieno could not be retrieved from difference maps and thus were not part of the model. Two carbon atoms of the dioxine moiety are disordered over two sets of sites and were refined in two parts (C3–C4/C3A–C4A) with a refined occupancy ratio of 0.624 (9)/0.376 (9). Soft restraints  were applied on the disordered atoms to keep their geometries and atomic displacement parameters reasonable.Crystal data, data collection and structure refinement details are summarized in Table 310.1107/S2056989017002031/wm5363sup1.cifCrystal structure: contains datablock(s) I. DOI: 10.1107/S2056989017002031/wm5363Isup2.hklStructure factors: contains datablock(s) I. DOI: 1528425CCDC reference:  crystallographic information; 3D view; checkCIF reportAdditional supporting information:


In this paper, we report the discovery of a “reciprocal” carbonyl-carbonyl interaction with substantial back and forth n→π* and π→π* electron delocalization between neighboring carbonyl groups. We have carried out experimental studies, analyses of crystallographic databases and theoretical calculations to show the presence of this interaction in both small molecules and proteins. In proteins, these interactions are primarily found in polyproline II (PPII) helices. As PPII are the most abundant secondary structures in unfolded proteins, we propose that these local interactions may have implications in protein folding.Carbonyl-carbonyl  π* non covalent interactions affect the structure and stability of small molecules and proteins. Here, the authors carry out experimental studies, analyses of crystallographic databases and theoretical calculations to describe an additional type of carbonyl-carbonyl interaction.Carbonyl-carbonyl  Intermolecular noncovalent interactions of varying magnitude are also responsible for the existence of different states of matter4. Carbonyl-carbonyl (C═O···C═O) n→π* interactions where one of the lone pairs (n) on the oxygen atom of a carbonyl group is delocalized over the antibonding π* orbital of a nearby carbonyl C═O bond (π*C═O) along the Bürgi-Dunitz trajectory5 (∠O···C ═ O ~ 109°) have attracted a great deal of attention in recent years11. Previous studies have shown that C═O···C═O n→π* interactions not only influence geometries of important small molecules15 but also play crucial roles in determining the three dimensional structures of polyesters16, peptides17, peptoids21 and proteins25. C═O···C═O interactions between the side-chain and backbone carbonyl groups of Asp, Asn, Glu, and Gln were also observed in the high-resolution crystal structures of proteins27. C═O···C═O n→π* interaction is characterized by a short O···C═O distance (d) of less than 3.22 Å [the sum of van der Waals radii of carbon and oxygen atom28], bond angle ∠O···C═O (θ) of ~109° and the pyramidality  of the acceptor carbon atom towards the donor oxygen atom29. Direct spectroscopic evidence for n→π* interaction was recently reported by using gas-phase infrared spectroscopy30.Nature effectively uses combinations of weak noncovalent interactions in the functional forms of various biologically important molecules such as nucleic acids and proteinsn→π* interaction both donor and acceptor C═O bonds will be polarized, which will make the acceptor carbonyl oxygen atom a better electron donor and the donor carbonyl carbon atom a better electron acceptor. The acceptor carbonyl oxygen, therefore, can donate electrons to another nearby carbonyl carbon either to form a sequential chain of O···C contacts 16 and proteins22, reciprocal n→π* interactions remained unexplored. Allen and coworkers reported anti-parallel arrangements of carbonyl groups in ketone dimers that were bound together by two intermolecular C═O···C═O short contacts of dipolar nature31. Maccallum et al reported a similar geometrical arrangement of carbonyl groups in right-twisted β-strands and observed two chemically distinct dipolar C═O···C═O short contacts32. However, these C═O···C═O short contacts were considerably longer than the sum of van der Waals radii of C and O atoms.We anticipated that due to cts Fig.  or it caons Fig. . Althougn→π* interactions should lead to back and forth donations between the carbonyl pairs. Based on our hypothesis, we discovered the presence of “reciprocal C═O···C═O interactions” both in small molecules and proteins. To establish the existence of reciprocal C═O···C═O interactions, we designed and synthesized model compounds and carried out X-ray crystallographic and theoretical studies. Further, we carried out Cambridge Structural Database (CSD)33 and Protein Data Bank (PDB)34 analyses to show that these interactions are widely present in small molecules and proteins. In proteins, these interactions are primarily found in random coils and turn regions. Based on our observations we propose that reciprocal C═O···C═O interactions may be a key local interaction that restricts the number of conformers of unfolded proteins and may have a role in protein folding.In this paper, we hypothesized that the polarization of the carbonyl groups by n→π* interactions, we have synthesized N,Nʹ-diacylhydrazines 1-8 having various substituents on either side of the carbonyl groups  crystallized in nonplanar form with the carbonyl groups oriented almost orthogonal to each other  , the two carbonyl groups stay far apart. The crystallographic distances d1 and d2  show no evidence of n→π* interaction , an increase in the acceptor ability of the carbonyl CO-II is expected, which should increase n→π* interaction from the oxygen atom of CO-I to the π*C═O orbital of CO-II. However, the inductive electron withdrawal of Cl can be negated by the electron donation from the Cl lone pairs into the antibonding orbitals (σ* and π*) of the adjacent carbonyl group (CO-II). In compound 4, we observed such electron delocalizations from the Cl lone pairs to both σ* and π* orbitals of the C=O bonds of CO-II group, which contributed 0.67 kcal mol−1 to the stabilization  and presence of NBO second order perturbation energy . As can be anticipated, the nature of the two atoms/groups between the interacting carbonyl groups plays a key role in keeping the two carbonyl groups non coplanar and provides them the conformation required for reciprocal interactions th amino acid residue is defined as d1. The distance between the carbonyl oxygen of (i + 1)th residue and carbonyl carbon of ith residue is defined as d2. The corresponding ∠O···C═O angles are defined as θ1 and θ2, respectively  deviates significantly from the Bürgi-Dunitz trajectory  studied here show that shorter distances d1 and d2 ≤ 3.2 Å fall within the tail of the full distribution  less than 10%, out of which 2184 showed the presence of reciprocal interactions in them. The PDB protein structures ranked by the number of reciprocal C═O···C═O interactions present in them are included in Supplementary Data nge Fig. . The angory Fig. . These o22, Bartlett et al reported one-sided n→π* interactions with d ≤ 3.20 Å and 99o ≤ θ ≤ 119o. As we have applied the same distance (d ≤ 3.20 Å) and resolution (<1.6 Å) criteria, the reciprocal interactions observed here for angles 99o ≤ θ1, θ2 ≤ 119o would be observed as one-sided n→π* interactions by using the criteria of Bartlett et al. As can be seen from Fig. θ1 and θ2 in the range of 99°–119°  is a very small percentage (6.5%) of the total number of reciprocal C═O···C═O interactions that are being reported here. This indicates that reciprocal C═O···C═O interactions are novel and distinct from one-sided n→π* interactions reported previously.In a previous study1 and d2 ≤ 3.20 Å) that covers the complete range of observed ∠O···C = O angle (θ) (70–110°) clearly showed the presence of reciprocal n→π* interactions , π→π* interactions were observed for θ1 and θ2 values <90° also (Table n→π* and two π→π* interactions) could be substantial to protein stabilization. Based on the NBO calculations at B3LYP/6-311 + G level, we observed that reciprocal C═O···C═O interactions contribute 0.27–4.41 kcal mol−1  to the stabilization of proteins per amino acid pair  . Secondary structure analyses using Stride38 show that reciprocal C═O···C═O interactions have considerable abundance in random coils (~20%) and turn regions (10%) of proteins but negligible presence in α-helices (0.35%)  : ]. We have confirmed this by plotting the φ, ψ angles of residues in the random coil regions having reciprocal interactions  Table . This isons Fig. . This isn→π* interactions are twisted  of the central two amino acids do not participate in any inter-residue hydrogen bonding. Therefore, we assume that these residues may participate in local reciprocal C═O···C═O interactions either between themselves or with their other neighbors, which should compensate for the lack hydrogen bonding interactions in them. A careful examination of the orientations of the carbonyl groups in various common β-turns indicated that reciprocal C═O···C═O interaction may be feasible between the first and the second residues of type Iʹ and II β-turns due to the favorable orientations of the two carbonyl groups but likely to be unfavoured in type I and IIʹ β-turns. In fact, analysis of the 10 protein crystal structures discussed above show that most of the reciprocal C═O···C═O interaction pairs found in β-turns were type II, followed by type IV (Supplementary Table n→π* interactions in α-helices and β-sheets22 (Pro > Gly > Ala). Analysis of distribution of reciprocal C═O···C═O interactions among the amino acid pairs in various proteins reveals that Pro–Pro is the most abundant pair  show a strong correlation  against the stabilization energies due to n→π* interactions [NBO second order perturbation energies E1n→π*)( and E2n→π*)(] reported in Tables En→π*)( for n→π* interactions decreases with an increase in the O···C (d) in synthetic molecules 1–8, molecules taken from CSD and interacting amino acid pairs obtained from PDB (Tables n→π* [En→π*)(] and π→π* [Eπ→π*)(] interaction energies reported in Tables n→π* interactions increases charge on donor oxygen lone pair (nO) and depletes it on acceptor carbonyl π*C═O orbital, which correlate well with the strength of O···C distances  between two dipoles could be used to understand the dipolar nature of interaction between them. As we know, antiparallel (T ~ 180°) dipoles attract and parallel dipoles (T ~ 0°) repel each other whereas two orthogonal dipoles (T ~ 90°) have net zero dipolar interaction. In case of reciprocal interaction, the C = O···C = O torsion angles show an orientational preference [C═O···C═O torsion angle falls in 60° to 90° (or −60° to −90°) range] as a consequence of the simultaneous restrictions on d1 and d2 (≤3.2 Å). However, the values of the C═O···C═O torsion angles (~90°) suggest that there would be almost net zero interaction between the dipoles, eliminating the possibility of strong dipolar interactions. Therefore, we conclude that orbital delocalization is the major driving force for the stabilization of reciprocal C═O···C═O interactions. An elaborate energy decomposition analysis may be required for the accurate deconvolution of various factors contributing to the stabilization of reciprocal C═O···C═O short contacts.The nature of C═O···C═O interactions has been debated in the literature. While some consider them on Figs. . In Fig.B Tables . The ovenO) and π*C═O orbital is weak. This weak donation from the first carbonyl group to the second is compensated by a back donation from the second carbonyl group to the first. In many cases, reciprocal π→π* interactions were also observed along with reciprocal n→π* interactions and their overall contributions to the stabilization of molecules having reciprocal C═O···C═O short contacts could be significant. In proteins, C═O···C═O n→π* interactions are present in all types of secondary structures. While one-sided n→π* interactions are prevalent in α-helices23, reciprocal interactions are abundant in PPII helices and turn regions. Prevalence of reciprocal C═O···C═O interactions in PPII helices and turn regions of proteins suggests a possible role for these interactions in protein folding. Further, the presence of reciprocal C═O···C═O interactions in distorted α-helices and twisted β-sheets suggests that these interactions could stabilize secondary structures that deviate from their regular geometries. The reciprocal C═O···C═O interactions present at the interface of two different types of secondary structures could also help in stabilizing the strained amino acid residues that are present at these interfaces. In future, it would be interesting to investigate the ability of amino acid pairs having high propensity to get involved in reciprocal C═O···C═O interactions to stabilize PPII helices and β-turns. It would also be interesting to investigate if some non-peptidic fragments obtained from the CSD search having strong reciprocal C═O···C═O interactions could be used to stabilize PPII conformation or design peptide-turns. Finally, an energy decomposition analysis would provide better understanding of the forces that contributes to the stabilization of reciprocal C═O···C═O interactions.We conclude that reciprocal carbonyl-carbonyl interactions exist both in small organic molecules and proteins. However, due to geometrical constraints associated with such interactions, the approach of the donor oxygen atoms to the acceptor carbon atoms deviates significantly from the Bürgi-Dunitz trajectory, and therefore, electron delocalization between the oxygen lone pair . Details of the crystallization conditions are given in Supplementary Table Single crystals of compounds 1–8 were determined by measuring X-ray intensity data. Bruker D8Venture APEX 342 single crystal home source X-ray diffractometer equipped with CMOS PHOTON 100 detector and Monochromated microfocus sources Mo Kα radiation (λ = 0.71073 Å) were used for data collection in phi (ϕ) and omega (ω) scan strategy at room temperature (298 K). The data was processed using SAINT43 and absorption correction was done using SADABS44 implemented in APEX 3. For structure solution XSHELL program based on SHELX45 was used. The non-hydrogen atoms were refined anisotropically and located in successive difference Fourier syntheses. The hydrogen atoms were fixed to neutron bond length using appropriate HFIX commands. ORTEP diagrams of compounds 1–8 (CCDC 1486577- 1486584) is provided in Supplementary Fig. 5 crystallized with a water molecule in the asymmetric unit. However, for clarity we have not shown the water molecule in its ORTEP diagram. Compound 7 has disorder at chlorine atom; the occupancy of disordered chlorine atom namely Cl1A and Cl1B was refined using the PART command. Similar ADP restraint SIMU46 and rigid bond restraint DELU46 was applied to stabilize the anisotropic refinement. SADI46 instruction was used to restrain the distance to equal. The anisotropic displacement parameter for disordered chlorine atom was fixed using EADP46 constraint.Single crystal structures of compound 33 (CSD version 5.21 Nov. 2015) using Conquest47 (version 1.18) program. The fragment chosen for the search is shown in Supplementary Fig. X is indicative for any atom. Only unique matching fragments were taken and the fragment was chosen in such a way that there are at least two carbonyl groups irrespective of their nature. Distances d1 (O2–C5) and d2 (O6–C1) are restricted to ≤3.2 Å. Angles [O2–C5–O6 (θ1) and O6–C1–O2 (θ2)] and dihedral angles (C1–O2–C5–O6 and C5–O6–C1–O2) were printed without any restriction. Only crystalline, non-ionic and non-polymeric organic molecules having no disorder and error with R factor ≤ 5% having at least three covalent bond separations between the carbonyl groups were considered in this search.Intramolecular C═O···C═O noncovalent interactions were searched and structural data were retrieved from Cambridge Structural Database34 using a search criterion of resolution <1.6 Å with redundancy (pairwise sequence identity) less than 10%, downloaded on 19 January 2016. Out of 2269 proteins, 2184 showed the reciprocal n→π* interaction. For proteins existing in polymeric form or for proteins containing amino acids in more than one conformation, Chain A and conformation A were chosen, except for 57 proteins where chain A is absent. Distance d1 is defined as distance between the ith amide oxygen to the subsequent (i + 1)th amide carbon, while d2 is defined as distance between the (i + 1)th amide oxygen to the ith amide carbon .A subset of 2269 protein was culled out from RCSB PDB48. The Hartree-Fock (HF)49 and the hybrid Becke 3-Lee-Yang-Parr (B3LYP)51 exchange correlation functional with 6-311 + G  basis set were used for the calculations. Natural bond orbital (NBO)35 analyses were performed on the crystal geometries of the synthetic molecules and small organic molecules obtained from CSD search. For proteins, the coordinates of the interacting amino acid residue pair were extracted using PyMOL52. The α-carbons of the amino acid residues adjacent to N and C termini of the amino acid pair were also included, so as to mimic a dipeptide with N and C termini capped with N(CO)Me and (CO)NMe, respectively. Finally, hydrogen atoms were added to the structure using PyMOL ( and Eπ→π*) level of theory.All the calculations were performed by using Gaussian09 suite of quantum chemistry programswww.ccdc.cam.ac.uk/.The authors declare that the data supporting the findings of this study are available within the paper and its Supplementary Information files, and also are available from the corresponding author upon reasonable request. X-ray crystallographic data for structures reported in this study have been deposited at the Cambridge Crystallographic Data Centre (CCDC), under deposition number CCDC 1486577-1486584. These data can be obtained free of charge from the CCDC via Supplementary InformationSupplementary Data 1Supplementary Data 2Supplementary Data 3Supplementary Data 4Supplementary Data 5Supplementary Data 6Supplementary Data 7Supplementary Data 8Supplementary Data 9Peer Review File


Only one enantiomer was observed crystallographically, resulting from the combination of (S)-sec-butylamine with l-tartaric acid.The title hydrated molecular salt was prepared by deprotonation of enantiopure  4H12N+·C4H5O6−·H2O, was prepared by deprotonation of enantiopure l-tartaric acid with racemic sec-butylamine in water. Only one enantiomer was observed crystallographically, resulting from the combination of (S)-sec-butylamine with l-tartaric acid. The sec-butylammonium moiety is disordered over two conformations related by rotation around the CH–CH2 bond; the refined occupancy ratio is 0.68 (1):0.32 (1). In the crystal, molecules are linked through a network of O—H⋯O and N—H⋯O hydrogen-bonding interactions, between the ammonium H atoms, the tartrate hydroxy H atoms, and the interstitial water, forming a three-dimensional supramolecular structure.The title hydrated molecular salt, C Since enantiomers have identical physical properties, they cannot be separated by standard physical means such as distillation, crystallization, or chromatography. One common method to overcome this issue is to convert the racemic compound into a mixture of diastereomers through reaction with an enantiopure component -sec-butyl ammonium cation, the l-tartrate anion, and one molecule of water in the asymmetric unit. The Flack parameter [–2.7 (8)] was not of use in determining the absolute configuration of the sec-butylamine in the crystal. The absolute configuration of the (S)-sec-butyl ammonium cation is therefore based on the known absolute configuration of the l-tartaric acid used during compound preparation. The final structure is disordered, with the sec-butyl ammonium moiety taking on two different rotamers about the C2–C3 axis [refined occupancy ratio is 0.68 (1):0.32 (1)]. The major component takes on a conformation where the C4 methyl group and N9 ammonium are in a gauche relationship , while the minor component places the C4A methyl group antiperiplanar to the N9A ammonium . The C—C bond lengths in the amine and tartrate units average 1.523 (11) Å [1.516 (22) Å for the minor component of the disorder] and 1.532 (5) Å, respectively. The C—N bonds of the two components of the disorder average 1.498 (17) Å. The tartrate C—OH bonds average 1.411 (4) Å, while the C—O bonds of the carboxyl moieties average 1.257 (4) Å for the one involved in hydrogen bonding with the amine, and 1.258 (4) Å for the other. An intramolecular hydrogen bond [2.00 (3) Å] occurs with O12 acting as a hydrogen-bond donor to O11.The molecular structure of the title hydrated molecular salt is shown in Fig. 1ip Fig. 1a, whileum Fig. 1b. The CA atom of the sec-butyl ammonium cation acts as a hydrogen-bond donor to O11 of the tartrate anion [1.89 (2) Å], and the tartrate O13 donates a hydrogen bond to O16 of water [1.83 (3) Å]. The water in turn acts as a hydrogen-bond donor to O10 [2.01 (3) Å] and O15 [1.93 (4) Å] of two adjacent symmetry-related molecules. Three additional hydrogen bonds are formed from N9, with N9—H9B donating to O12 of an adjacent molecule [1.97 (3) Å], and N9—H9C donating to both O13 [2.16 (4) Å] and O15 [2.20 (4) Å] of a second adjacent molecule. Finally, O14 donates a hydrogen bond to O10 of an additional symmetry-related molecule [1.58 (5) Å]. A view of the crystal packing reveals the amine, tartrate, and water molecules form columns when viewed down the c axis  was added to 40 ml of water and stirred to ensure homogeneity. While stirring, l-tartaric acid  was slowly added. The solution was covered and allowed to stand at ambient temperature. After 24 h, crystal formation was evident. The crystallization process was allowed to continue undisturbed for one week, at which point a crystal for diffraction analysis was selected directly from the reaction mixture without further purification or isolation. The crystals can be isolated by vacuum filtration to yield a white crystalline solid .The title compound was prepared Uiso(H) = 1.5Ueq(C-methyl) and 1.2Ueq(C) for other H atoms. The sec-butyl ammonium moiety displays a twofold disorder arising from two different rotamers being present that is best described as a 0.68 (1):0.32 (1) ratio of the two possible conformations. In the final cycles of refinement SAME restraints were applied to the two components of the disordered sec-butyl ammonium moiety and DFIX restraints were applied to the N—H bonds [N—H = 0.91 (2) Å] and the ammonium H⋯H distances [H⋯H = 1.50 (2) Å], to improve the refinement and geometry.Crystal data, data collection, and structure refinement details are summarized in Table 210.1107/S2056989017005448/su5364sup1.cifCrystal structure: contains datablock(s) I, Global. DOI: 10.1107/S2056989017005448/su5364Isup2.hklStructure factors: contains datablock(s) I. DOI: Click here for additional data file.10.1107/S2056989017005448/su5364Isup3.cmlSupporting information file. DOI: 1543331CCDC reference:  crystallographic information; 3D view; checkCIF reportAdditional supporting information:


The two CPy ligands act as monodentate N(pyridine)-bonding ligands, while the two NB anions act as bidentate ligands through the carboxylate O atoms. The centrosymmetric dinuclear complex is generated by application of inversion symmetry, whereby the CdII atoms are bridged by the carboxylate O atoms of two symmetry-related NB anions, thus completing the distorted N2O5 pentagonal–bipyramidal coordination sphere of each CdII atom. The benzene and pyridine rings are oriented at dihedral angles of 10.02 (7) and 5.76 (9)°, respectively. In the crystal, C—H⋯N hydrogen bonds link the molecules, enclosing R22(26) ring motifs, in which they are further linked via C—H⋯O hydrogen bonds, resulting in a three-dimensional network. In addition, π–π stacking interactions between parallel benzene rings and between parallel pyridine rings of adjacent molecules , as well as a weak C—H⋯π interaction, may further stabilize the crystal structure.The asymmetric unit of the title compound, [Cd The two CPy ligands are monodentate (through the pyridine N atoms), while both NB anions act as bidentate ligands through their carboxylate O atoms  and its symmetry-related counterpart . Hence, this carboxylate group not only chelates to one CdII atom but also bridges two CdII atoms , one chelating NB anion (O1 and O2) and two 3-cyanopyridine (CPy) ligands (N3 and N5), resulting in a distorted pentagonal–bipyramidal environment. The five carboxylate O atoms  of the three NB anions around the CdII atom form a distorted pentagonal arrangement, with an average Cd1—O bond length of 2.42 Å (Table 1i separation in the binuclear molecule is 3.9360 (15) Å and is comparable to the corresponding M—M distances  in the structurally related transition metal(II) complexes . The metal atoms are bridged by two NA ligand N and O atoms in (III), (V) and (VI), while they are bridged by two carboxylate O atoms in (IV).The asymmetric unit of the title complex contains one Cdms Fig. 1. The cenms Fig. 2. Thus, eÅ Table 1. The disÅ Table 1 and 2 ▸.M—O  angles are 60.92 (12)° in (II), 53.50 (14)° in (IV), 57.61 (8)° in (V), and 54.22 (4) and 53.32 (5)° in (VI). The dihedral angles between the planar carboxylate groups (O1/O2/C1 and O5/O6/C8) and the adjacent benzene [A (C2–C7) and B (C9–C14)] rings in the title structure are 17.18 (13) and 3.36 (12)°, respectively, while the benzene (A and B) and pyridine [C (N3/C15–C19) and D (N5/C21–C25)] rings are oriented at dihedral angles of A/B = 10.02 (7)°, A/C = 72.70 (7)°, A/D = 74.72 (7)°, B/C = 82.28 (7)°, B/D = 84.54 (8)° and C/D = 5.76 (9)°.The near equalities of the C1—O1 [1.264 (3) Å], C1—O2 [1.241 (3) Å], C8—O5 [1.256 (3) Å] and C8—O6 [1.253 (3) Å] bonds in the carboxylate groups indicate delocalized bonding arrangements, rather than localized single and double bonds. The O1—Cd1—O2 and O5—Cd1—O6 bite angles are reduced to 54.33 (5) and 53.47 (5)°, respectively. The corresponding O—cpy⋯Oc (cpy = cyanopyridine and c = carboxylate) and C—Hnb⋯Oc (nb = nitrobenzoate) hydrogen bonds  hydrogen bonds (Table 2Cg1–Cg2i and Cg3–Cg4ii  may further stabilize the structure, with centroid–centroid distances of 3.885 (1) and 3.712 (1) Å, respectively. A weak C—H⋯π interaction  = 1.2Ueq(C). The maximum and minimum electron densities were found at 1.43 and 0.80 Å from atoms O2 and Cd1, respectively.The experimental details including the crystal data, data collection and refinement are summarized in Table 34·8H2O  in H2O (50 ml) and 3-cyanopyridine  in H2O (50 ml) with sodium 3-nitrobenzoate  in H2O (100 ml) at 333 K. The mixture was filtered and set aside to crystallize at ambient temperature for one week, giving colourless single crystals.The title compound was prepared by the reaction of 3CdSO10.1107/S2056989017002675/wm5366sup1.cifCrystal structure: contains datablock(s) I, global. DOI: 10.1107/S2056989017002675/wm5366Isup2.hklStructure factors: contains datablock(s) I. DOI: 1533101CCDC reference:  crystallographic information; 3D view; checkCIF reportAdditional supporting information:


The Zn-containing units are connected into a one-dimensional coordination polymer (zigzag topology) propagating in the [010] direction, with one dithiocarbamate ligand bridging in a μ2-κ3 mode, employing one pyridyl N and both dithiocarbamate S atoms, while the other is κ2-chelating. In each case, the resultant ZnNS4 coordination geometry approximates a square pyramid, with the pyridyl N atom in the apical position. In the crystal, the chains are linked into a three-dimensional architecture by methyl- and pyridyl-C—H⋯S, methylene-C—H⋯N(pyridyl) and pyridyl-C—H⋯π(ZnS2C) interactions. The connection between the chain and the 4-methylpyridine solvent molecule is of the type pyridyl-C—H⋯N(4-methylpyridine).The title compound, {[Zn(C Thus, a two-dimensional architecture is found in centrosymmetric {Zn[S2CN(Et)CH2py]2 residues, shown in Fig. 1i.e. Δ(Zn—S) = [Zn—S(long) − Zn—S(short)], for the S1-dithiocarbamate ligand of 0.32 Å is greater than the value of 0.10 Å for the S3-dithiocarbamate ligand. For the Zn2-molecule, these differences diminish to 0.23 and 0.09 Å for the S5- and S7-dithiocarbamate ligands, respectively. The similarity of the structures is emphasized in the overlay diagram of Fig. 22-κ3 mode, chelating one ZnII cation and simultaneously bridging another via the pyridyl N atom. It is noted that it is the dithiocarbamate ligand that forms the more equivalent Zn—S bond lengths in each residue that forms the bridging interactions. The resultant coordination geometry for each ZnII cation is based on an NS4 donor set.The asymmetric unit of (I)et al., 1984i.e. S1–S4 (r.m.s. deviation = 0.1721 Å), in the direction of the pyridyl N6 atom. For the Zn2-molecule, the deviation of the Zn2 cation from the S4 plane is 0.6018 (6) Å and the r.m.s. deviation through the S5–S8 atoms is 0.1273 Å.For five-coordinate species, the value computed for τ is a useful indicator of the adopted coordination geometry, with the values of τ ranging from 0 to 1 for ideal square-pyramidal and trigonal–bipyramidal geometries, respectively 2CN(Et)CH2py]2·3-methylpyridine}n, which was also isolated from an experiment attempting to coordinate isomeric methylpyridines to the heavy element −[S2CN(Et)CH2py], found in (I)2CN(Et)CH2py]2·3-methylpyridine}n  salt CH2py]2, for R = Me, nBu and Ph  interaction of 2.98 Å between the two molecules comprising the asymmetric unit. This result is consistent with surveys of diorganotin bis(dithiocarbamate)s in general 2, a recent survey indicated that secondary bonding interactions occur in only 10% of their crystal structures CH2py]2 (generated from the reaction of Zn(NO3)2·H2O and −[S2CN(Et)CH2py]) from 4-picoline. Suitable single crystals formed upon slow evaporation of the solvent (m.p. 337–339 K).The title compound was isolated from the recrystallization of Zn{[SUiso(H) values set at 1.2–1.5Ueq(C).Crystal data, data collection and structure refinement details are summarized in Table 310.1107/S2056989017010179/hb7691sup1.cifCrystal structure: contains datablock(s) I, global. DOI: 10.1107/S2056989017010179/hb7691Isup2.hklStructure factors: contains datablock(s) I. DOI: 1561011CCDC reference:  crystallographic information; 3D view; checkCIF reportAdditional supporting information:


A distinctive O—H⋯N-based synthon is present. Cl⋯Cl and π–π stacking interactions further stabilize the crystal structure, forming a two-dimensional network parallel to the bc plane.The asymmetric unit of the title compound, 2C In recent years, the physicochemical properties of active pharmaceutical ingredients have been improved widely with the use of co-crystals via O—H⋯N hydrogen-bonding interactions between (O1—H1) of the carboxyl group and the nitrogen (N1) of BPY  Å, C3—Cl1⋯Cl1iii = 151.71 (1)°; symmetry code: (iii) 1 − x, y, z]  Å; Cg1 is the centroid of the N1/C6/C7/C8/C9/C10 ring; symmetry code: (ii) 1 − x, 2 − y, 1 − z]. The perpendicular distance between two parallel molecules is 3.4812 (15) Å. This weak interaction holds the hydrogen-bonded chains together, supporting a two-dimensional supramolecular network parallel to the bc plane, as seen in Fig. 23TPC and BPY are interconnected Y Table 1. This O—et al., 2001N,N′-dioxide-3-hydroxy-2-naphthoic acid (1/2) , 10 ml of a hot methanolic solution of BPY  was added. The resulting solution was warmed over a water bath for half an hour and then kept at room temperature for crystallization. After a week, clear yellow plates were obtained. The crystal used for X-ray diffraction data collection was cut from a larger crystal.Uiso(H) = 1.2Ueq(C). The carboxylic acid hydrogen atom was freely refined, including its isotropic displacement parameter.Crystal data, data collection and structure refinement details are summarized in Table 210.1107/S2056989016013724/hg5476sup1.cifCrystal structure: contains datablock(s) I. DOI: 10.1107/S2056989016013724/hg5476Isup2.hklStructure factors: contains datablock(s) I. DOI: Click here for additional data file.10.1107/S2056989016013724/hg5476Isup3.cmlSupporting information file. DOI: 1501060CCDC reference: crystallographic information; 3D view; checkCIF reportAdditional supporting information: