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In order to determine the effect of halogen bonding on supramolecular assemblies and photophysical properties of diaryl oxalates, diaryl oxalate itself and its derivatives with fluorine, chlorine, bromine, and iodine substituents in the p-position of phenyl rings were studied and compared. Their single-crystal structures were studied by geometrical analysis and theoretical calculation. The study reveals that different halogen bonds are formed with respect to different halogen atoms, such as C...F and X...X (bromine and iodine atoms) interactions, and molecular stacking modes would be affected by halogen bonds directly. Comparative studies of photophysical properties in dilute solution and solid state indicate that halogen substitutions would not affect the emission processes of diaryl oxalates in dilute solution; this is not the case for their solid state. This work has demonstrated that halogen bonds play an important role in regulating structures and photophysical properties of diaryl oxalates. [ABSTRACT FROM AUTHOR]

Three diaryl oxalate derivatives, bis(4-chlorophenyl)oxalate, bis(2, 6-dichlorophenyl)oxalate and bis(2, 4, 6-trichlorophenyl)oxalate, have been synthesized and characterized via X-ray single crystal diffraction, differential scanning calorimetry, thermogravimetric analysis and infrared spectra, for the purpose of studying the influence of chlorine substitution on the crystal structures of diaryl oxalate. This work has demonstrated that, depending on the position and number, chlorine substitution will influence the molecular geometries and stacking modes of diaryl oxalate by tuning the types and numbers of intermolecular interactions. [ABSTRACT FROM AUTHOR]

The quantitative visualizations and comparisons between the four pyrazinamide (PZA) polymorphs (α, β, γ and δ) have been investigated by graphical tools based on three-dimensional Hirshfeld surfaces and two-dimensional fingerprint plots. The comparisons were performed in terms of crystal structure, d, Shape index, Curvedness and d surfaces, and fingerprint plots. The results revealed that the α and γ forms featured with 1D chains and the π···π stacking motifs belong to γ-motif, rich in π···π interactions and form infinite face-to-face stacks, β and δ forms featured with dimer unit and the π···π stacking motifs belong to γ- and herringbone-motif, respectively, the herringbone motif of δ form rich in C-H···π and edge-to-face interactions. We also correlated the phase transformation points of α, β, and δ PZA forms with the ratio of the percentage surface coverage of the N-H···O hydrogen bonds over that of the N-H···N hydrogen bonds, and found a negative correlation. [ABSTRACT FROM AUTHOR]

Crystal structural investigations and Hirshfeld surface analysis of three methoxy- and methyl-substituted indole-3-acetonitriles (IAN) (4-OCH-IAN, 5-OCH-IAN and 7-CH-IAN) are reported in this work. Their structures were characterized by infrared spectra, elemental analyses, NMR spectra, differential scanning calorimetry, thermogravimetric analyses, and hot stage microscopy. The Hirshfeld surface analysis in terms of intermolecular interactions and π···π stacking motifs of the three substituted IANs was investigated in detail, and the results revealed that the different kinds of substituent groups as well as different substituted positions have a significant effect on the crystal structures, molecular π···π stacking motifs, melting points, and the types of intermolecular interactions. [ABSTRACT FROM AUTHOR]

For the development of dispersible tablets of itraconazole (ITR), techniques of thermal, Raman spectroscopy, and isothermal stress testing (IST) were used to assess the compatibility of ITR with selected excipients. Initially, differential scanning calorimeter (DSC) was used to evaluate the compatibility. Raman spectrum of drug-excipient mixture was also compared with that of pure drug and excipient. Compatibility of excipients defined in the prototype formula was tested using IST. Based on the DSC results alone, PEG-4000 was found to exhibit interaction with ITR. However, the results of Raman and IST studies showed that all the excipients used in the formula were compatible with ITR. Overall, compatibility of excipients with ITR was successfully evaluated using the combination of DSC, Raman spectroscopy, and IST techniques. [ABSTRACT FROM AUTHOR]

Two new 1-D coordination polymers [ M (3-Bzpy)(N(CN))] ( M = Cd ( 1), Cu ( 2), 3-Bzpy = 3-benzoylpyridine) have been synthesized and structurally characterized by single-crystal X-ray diffraction and IR. Single-crystal X-ray diffraction reveals that the complexes 1 and 2 are isostructural and all crystallize in monoclinic P2/ c space group with cell dimensions: a = 6.3889(16) Å, b = 7.6496(12) Å, c = 26.767(6) Å, β = 99.131(19)°, V = 1291.6(5) Å, Z = 2 for 1 and a = 6.4483(9) Å, b = 7.5449(10) Å, c = 25.965(4) Å, β = 98.559(10)°, V = 1249.2(3) Å, Z = 2 for 2. Structure analysis manifest that 1 and 2 are all 1-D chains structures which parallel to the crystallographic b axis through end-to-end coordination by bidentate bridging dicyanamide ligands. Magnetic property of complex 2 was further investigated. Graphical Abstract: The paper is about synthesis, crystal structure and magnetic property of two new 1-D coordination polymers. Perspective view down the a-axis of complex 1 with thermal ellipsoids drawn at the 50% probability level [Figure not available: see fulltext.]. [ABSTRACT FROM AUTHOR]

The compound {[Zn(μ-dicyanamide)(pyrazinamide)](pyrazinamide)} has been synthesized and further characterized by elemental analysis, single-crystal X-ray diffraction, and thermogravimetric analysis. Structural analysis revealed that the dicyanamide anion acted as bridging ligand in a μ-1,5 mode, resulting a polymeric 1-D chain structure. The pairwise N3-H3B···N1 and N9-H9B···N7, N3-H3A···O2 and N9-H9A···O1, N3-H3B···N7 and N9-H9B···N1 multiple hydrogen bonding interactions, impart enhanced stability to supramolecular structures. Hirshfeld surfaces and fingerprint plots were applied to arrive at the same conclusion, which is stabilised mainly by H-H, N-H, O-H interactions. DNA binding studies showed that the compound had interacted with DNA. [ABSTRACT FROM AUTHOR]

We here reported a series of co-crystal structure of pyrazinamide (PZA) with m-hydroxybenzoic acid (MHBA), p-hydroxybenzoic acid (PHBA) and 3,4-dihydroxy benzolic acid (3,4-DHBA) and obtained three co-crystals (co-crystal 1- 3, respectively) under the same conditions. These crystal structures were characterized by single-crystal X-ray diffraction, IR spectra, thermogravimetric analyses, differential scanning calorimetry, and Raman spectrum analysis. The images of single crystal diffraction revealed that 1 was a 1:1 (PZA:MHBA) co-crystal, 2 was a 1:1 (PZA:PHBA) co-crystal, and 3 was a 1:1 (PZA:3,4-DHBA). The strong O-H···O, N-H···O hydrogen bonding interactions between PZA and hydroxyl-substituted benzoic acid primarily made the structure of co-crystals stabilized. Hirshfeld surface and fingerprint plots of the three co-crystals showed that the structures were stabilized by H···H, O-H···O, N-H···O C-H···π, and π···π intermolecular interactions. [ABSTRACT FROM AUTHOR]

The crystals of two organic salts of tris(hydroxymethyl)aminomethane (THAM) with p-hydroxybenzoic acid (PHBA) and salicylic acid (SA) were obtained. Their crystal structures were characterized by single-crystal X-ray diffraction, IR spectra, differential scanning calorimetry, thermogravimetric analyses and hot stage microscopy. Wherein, 1 forms a 1:1 (THAM:PHBA) salt, and 2 forms a 2:2:1 (THAM:SA:HO) salt. The structure determination shows that the two salts are all primarily stabilized by strong O···H hydrogen bonds interaction between THAM and the two acids. The Hirshfeld surfaces and fingerprint plots of the reported salts were prepared and analyzed and reveal that the structures are stabilized by O···H, H···H, C···H, O···O and O···C intermolecular interactions. Graphical Abstract: The paper is about synthesis, crystal structure, thermal and Hirshfeld surfaces analysis of two THAM salts.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The co-crystallization of a benzimidazole derivative ( 1, CHNO, 3-[[[2-[[(4-Cyanophenyl) amino]methyl]-1-methyl-1H-benzimidazol-5-yl]carbonyl]pyridin-2-ylamino]propionic acid ethyl ester), with fumaric acid (FA) and maleic acid (MA), has been performed. The FA and MA molecules, both are connected with two molecules of CHNO, giving birth to a three-components compound ( 1·0.5FA, CHNO) and a four-components compound ( 1·MA, CHNO). Single-crystal X-ray diffractions show that the three different planar moieties (4-cyanophenyl, benzimidazol, and pyridin-2-yl) in compound CHNO display ' cis-form' conformation ( a) in the crystal of 1, while exhibiting 'intermediate-state' conformation ( b) and ' trans-form' conformation ( c) in compounds 1·0.5FA and 1·MA, respectively. Hirshfeld surfaces analysis, DFT calculations, DSC measurements, IR and Raman spectroscopy were performed, which revealed that the thermal stability of the three conformations follows the order c > b > a. [ABSTRACT FROM AUTHOR]

Single crystals of compound L (CHN): 4-(2-benzimidazole)-1,2,4-triazole and its hydrate were obtained via slow evaporation. The structures of the crystals were characterized by IR, TGA/DSC and X-ray diffraction analysis. Molecules in crystal 1 are linked by a combination of N-H···N and C-H···N hydrogen bonds into 2D layers, and further stacked into a 3D structure by π··· π stacking interactions. Compared to crystal 1, the water molecules play a key role in the construction of the crystal structure of hydrate 2. The 2D layers were formed via O-H···N, O-H···O, N-H···N hydrogen bonds, and further stacked by O-H···O hydrogen bonds and π··· π stacking interactions in crystal 2. A detailed analysis of the intermolecular interactions and crystal packing via Hirshfeld surface analysis and fingerprint plots reveals that the structures are stabilized mainly by N···H/H···N, C···H/H···C hydrogen bonds, H···H weak interactions and π··· π stacking interactions. [ABSTRACT FROM AUTHOR]

2,3-Dimethylpyrazine and 1,2-bis(4-pyridyl)ethane are both N-containing aromatic heterocyclics with two N atoms approximately in the para position. We here report two compounds derived from these heterocyclics (compounds 1 and 2). Compounds 1 and 2 both form a 1:1 2,3-dimethylpyrazine:perchloric acid (PA) and 1,2-bis(4-pyridyl)ethane:PA cocrystal, respectively. Their crystal structures were characterized by single-crystal X-ray diffraction, which revealed that the C-H⋯O and N-H⋯O hydrogen bonding interactions were found to stabilize the crystal structure in compounds 1 and 2. However, PA plays a necessary role for the one-dimensional structure in 1 and the three-dimensional structure in 2. Hirshfeld surfaces and fingerprint plots were applied to get the same conclusion. [ABSTRACT FROM AUTHOR]