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A combined theoretical and experimental investigation on a pharmaceutically important binary complex 3,3'-[(3-benzimidazolyl)methylene] bis (4-hydroxy-2 H -1-benzopyran-2-one): 5-methyl-1,3-thiazol-2(3 H )-imine is presented in this manuscript. The compound crystallizes in the monoclinic crystal system with space group Cc with unit cell parameters: a = 19.8151(8) A, b = 15.2804(6) A, c = 8.3950(4) A, β = 94.0990(10)°, V = 2535.36(19) A 3 , Z = 4, T = 296(2) K, μ(MoKα) = 0.184 mm -1 , Dcalc = 1.490 g/cm 3 , 35833 reflections measured (5.332° ≤ 2Θ ≤ 56.678°), 6168 unique ( R int = 0.0467, R sigma = 0.0388) which were used in all calculations. The final R 1 was 0.0435 (I > 2σ(I)) and wR 2 was 0.1073 (all data). The crystal structure has been determined by the conventional X-ray diffraction method, solved by direct methods and refined by the full matrix least squares procedure. Intramolecular hydrogen bonding of the type C–H⋅⋅⋅O and O–H⋅⋅⋅O is present and the crystal structure stabilizes via N–H…O, C–H…N and O–H…N intermolecular interactions. The optimized structural parameters have been compared and the parameters like ionization potential, electron affinity, global hardness, electron chemical potential, electronegativity, and global electrophilicity based on HOMO and LUMO energy values were calculated at B3LYP/6-311G(d,p) level of theory for a better understanding of the structural properties of the binary complex.

The benzimidazole moiety found in a large number of biologically important drugs has not been completely realized as yet in respect of its strength and directionality of its molecular interactions. To understand the role played by the intermolecular interactions in the benzimidazole derivatives, lattice energy of a series of five important molecules has been computed and results accrued thereof have been discussed. Analysis of molecular packing based on the intermolecular interaction energies suggests existence of different molecular pairs that play an important role in the stabilization of the crystal structures. Interaction energy analysis of such motifs reveals that intermolecular interactions of the type N-H…N and C-H…N happen to be the major contributors to the stabilization of molecular packing in the unit cell. N-H…π and C-H…π type edge-to-face stacking interactions also contribute significantly to the stabilization of crystal packing. The pairs of N-H…N intermolecular hydrogen bonds link the molecules into centrosymmetric dimers making a contribution of -14 to -18.52 kcal/mol towards stabilization, whereas C-H…N bonds link the molecules into dimers in the energy range of -2 to -5 kcal/mol. Additionally, the role of π…π interactions has also been investigated in molecular stabilization.

A 1:1 stochiometric cocrystal of nicotinamide with picric acid (C12H8N5O8) has been synthesised successfully by solvent assisted grinding method and structure of the cocrystal is established by single crystal X-ray diffraction studies. The compound crystallizes in the orthorhombic space group Pbca with unit cell parameters: a = 7.7608 (11), b = 14.5110 (14), c = 24.751 (3) A and Z = 8. The crystal structure was solved by direct methods and refined to R = 0.0723 for 1755 observed reflections. Current study has primarily focused on hydrogen bonding which is the driving force for the formation of cocrystal. Hirshfeld surfaces and fingerprint plots indicate that the structures are stabilized by O⋯H, N⋯H intermolecular interactions. In order to make a better understanding supercell model of nicotinamide-picric acid cocrystal (NICPIC) is created with crystallographic data. Based on this hydrogen bonding population, radial distribution function (RDF) and bulk properties are simulated via Molecular Dynamics (MD). Furthermore, DSC/TGA analysis indicates that the NICPIC maintains its crystallinity up to 195 °C, suggesting its higher stability compared to individual components.

The X-ray diffraction analysis of bis(O-amyldithiocarbonato)bis(3,5-dimethylpyridine)nickel(II) which is one of the adducts of O-alkyldithiocarbonate is performed. The complex is found to crystallize in the Monoclinic space group P21/c with unit cell parameters a = 9.1674(2) A, b = 18.2553(4) A, c = 9.2999(2) A and β = 103.472(2)°. Crystal structure was solved by direct method and refined by full matrix least squares procedures to a final R-value of 0.0420 for 2278 observed reflections.

The X-ray structure of 2-(3,4-dimethoxyphenyl)-4,5-diphenyl-1H-imidazole, has been determined. It crystallizes in orthorhombic space group Pna21, with a = 9.5018(6) A, b = 21.636(2) A, c = 19.040(1) A and Z = 8. The structure has been solved by direct methods and refined by full matrix least squares procedures to a final R value of 0.0675 for 2733 observed reflections. The asymmetric unit contains two crystallographic independent molecules. C H…O and C H…N intermolecular interactions were observed and these interactions are of paramount importance in assembling the molecules leading to packing stability. To understand pharmacological importance of the title compound, molecular docking was performed against two anti-inflammatory drug targets; Myeloperoxidase (MPO) and Cyclooxygenase (COX-2). Docking studies show binding mode of the titled molecule to be similar to the known inhibitor in their respective active site of anti-inflammatory drug targets. Thus, the title molecule also has similar mode of drug action.

2-(4-Bromophenyl)-1-(3-chloro-2-methylphenyl)- 4,5-diphenyl-1H-imidazole (1) and 1-(3-chloro-2-methylphenyl)-2-(4-chlorophenyl)-4,5-diphenyl-1H-imidazole (2) were synthesized by one-pot four-component reactions. These compounds crystallize in the monoclinic crystal system with the space group P21/n. The crystal structures were solved by direct methods and refined by a full matrix least squares procedure to a final R value of 0.0572 (1) and 0.0588 (2) for 2748 and 2278 observed reflections, respectively. Molecular docking studies were implemented to understand the inhibitory activity of related compounds against glucosamine 6-phosphate (GlcN-6-P) synthase, the target protein for the antimicrobial agents.

A combined experimental and theoretical study is performed on DMSO solvated 7′-amino-1′,3′-dimethyl- 2,2′,4′-trioxo-1′,2′,3′,4′,4a′,8a′-tetrahydrospiro[indoline-3,5′-pyrano[2,3-d]pyrimidine]-6′-carbonitrile. The compound is studied by NMR, IR spectroscopy, and single crystal X-ray analysis. The crystal structure of the molecule is stabilized by intermolecular N–H…N, N–H…O, and C–H…π interactions. In the crystal, the molecules form hydrogen-bonded chains running along the b axis of the unit cell. In the present work, we have applied density functional theory (DFT) to explore the nonlinear properties of the molecule. The harmonic vibrational frequencies are calculated and compared with experimental FT-IR frequencies. The observed and calculated frequencies are found to be in good agreement. The calculated values of the HOMO-LUMO energy gap shows that a charge transfer occurs within the molecule.

2-(4-Chlorophenyl)-3-(phenylamino)-5-(thiophen-2-ylmethylidene)-3,5-dihydro-4H-imidazol-4-one, C20H14N3OSCl was synthesized and its crystal structure was determined by single crystal X-ray diffraction. The crystals are triclinic, sp. gr. P1, Z = 2. All three rings are planar, and imidazole ring is almost perpendicular to the phenyl ring with the dihedral angle of 88.65(2)°. In the crystal, pairs of O–H···O hydrogen bonds link molecules into inversion dimers, featuring R22(10) graph set motif. Crystal structure is further stabilized by π···π interactions.

The title compound (6bR,14bR,15R,15aR)-ethyl 5-bromo-14b-phenyl-1,6b,8,9,14,14b,15,15a- octahydrochromeno [3′,4′:2,3] indolizino [8,7-b] indole-15-carboxylate belongs to an indole derivative. The compound crystallizes in the triclinic crystal system with the space group P1. The asymmetric unit cell consists of two molecules. In the crystal, hydrogen bond interactions of the type N–H⋅⋅⋅O, C–H⋅⋅⋅O and C–H⋅⋅⋅N are present. Further, the molecular structure is stabilized by C–H⋅⋅⋅π interactions. Intermolecular interactions were analyzed using Hirshfeld surface analysis.

A new series of adducts of bis(O-butylxanthato)nickel(II) with substituted pyridines have been synthesized by treating bis(O-butylxanthato)nickel(II) with substituted pyridines in acetone. The complexes have been characterized by elemental analysis, conductivity measurements, magnetic susceptibility measurements, TGA/DTA studies, infrared and electronic spectral studies. X-ray studies of one of the adduct bis(O-butylxanthato)bis(3-chloropyridine)nickel(II) shows that the central metal is octahedrally coordinated within a trans-N2S4 donor set, with the Ni atom located on a centre of inversion. The complex crystallizes in the monoclinic space group P21/c with unit cell parameters a = 11.8088(8) A, b = 12.2042(7) A, c = 9.0252(5) A, β = 93.789(6), Z = 2. Crystal structure was solved by direct methods and refined by full matrix least squares procedures to a final R-value of 0.0380 (wR2 = 0.0885) for 2083 observed reflections. The butyl chain is disordered over two set of sites, with occupancy ratios of 0.741:0.259. These studies suggest a distorted octahedral structure and paramagnetic nature of the adducts.

(2E)-1-(anthracen-9-yl)-3-(4-chlorophenyl)prop-2-en-1-ones and (2E)-1-(anthracen-9-yl)-3-(4-nitrophenyl) prop-2-en-1-ones crystallize in the monoclinic crystal system with space group P2 1 /c. Single-crystal X-ray diffraction data for both the compounds were collected on an X’Calibur CCD area detector diffractometer (Oxford Diffraction) using MoKa radiation (λ= 0.7107 A) at 293(2) K. The crystal structures were solved by direct methods and refined by full-matrix least-square procedures to a final R value of 0.0468 [I] and 0.0486 [II]. The crystal structures as elucidated by X-ray diffraction methods show the presence of a few intermolecular interactions, and the nature and energetics associated with these interactions have been characterized using PIXEL software.

A series of six-coordinated Ni(II) complexes, with the general formula Ni(Xan)L2 (where Xan = = isoamyldithiocarbonato and L = 2-bromopyridine, 3-bromopyridine, 4-acetylpyridine, 3-hydroxypyridine and 2-methoxypyridine) are synthesized and characterized by the elemental analysis and various physicochemical techniques such as magnetic susceptibility and conductivity measurements, UV-visible and infrared spectral data. Based on the electronic spectra and magnetic susceptibility measurements, an octahedral geometry is proposed for all the complexes. IR spectral data show that in all these complexes substituted pyridines coordinate to the metal ion through nitrogen atoms occupying the fifth and sixth axial positions, whereas O-alkyldithiocarbonate acts as a monoanion bidentate ligand and occupies the planar positions of octahedral structures. The structure of the adduct with 3-bromopyridine is elucidated by the single crystal X-ray diffraction method. The complex crystallizes in the triclinic space group P-1 with unit cell parameters a = 6.5855(4) A, b = 9.4984(6) A, c = 12.4518(8) A, α = 87.944(5)°, β = 78.843(5)°, γ = 77.794(5)°. The crystal structure of the molecule is stabilized by intermolecular C–H…S and C–H…π interactions.

The asymmetric unit of the title compound, C8H15N3S, contains two independent molecules. In both molecules, the seven-membered cycloheptane ring adopts a chair conformation. An intramolecular N—H...N hydrogen bond is observed in both molecules, forming S(5) graph-set motifs. In the crystal, the two independent molecules are connected through N—H...S hydrogen bonds, forming dimers which are in turn further connected by N—H...S hydrogen bonds into chains along [010].

(2E)-3-(anthrance-9-yl)-1-(3,4-dichlorophenyl)prop-2-en-1-one [C23H14OCl2] is synthesized and its crystal structure is determined by single X-ray diffraction. There exist two molecules in the asymmetric unit. The dihedral angle between the benzene and anthracene moiety of the molecule A and B is 86.51(12)° and 76.42(13)°, respectively. No classical hydrogen bonds are observed and only van der Waals forces stabilize the crystal packing.

In the title compound, C11H8Cl2N2O3, the plane of the pyrrolidine ring (r.m.s. deviation = 0.065 Å) makes a dihedral angle of 52.9 (2)° with the plane of the benzene ring. The least-squares plane of the central amide fragment makes dihedral angles of 49.3 (7) and 77.9 (7)° with those of the benzene and pyrrolidine rings, respectively. In the crystal, molecules are linked via N—H...O hydrogen bonds, forming chains along the b-axis direction. π–π interactions link these chains into a two-dimensional network parallel to (100).

A new indoline derivative, tert-butyl 2′-amino-3′-cyano-6′-methyl-2-oxospiro[indoline-3,4′-pyran]-5′-carboxylate is eco-friendly synthesized, and its spectral properties and X-ray crystal structure are studied. In the molecule, the oxindole and pyran moieties are perpendicular to each other. The crystal structure is stabilized by intermolecular N−H···O and intramolecular C−H···O hydrogen bonds. Centrosymmetric dimer units are formed by intermolecular N−H···O hydrogen bonds. In addition, one C−H···π interaction is also observed.

The organic carbonitrile namely methyl (6-amino-5-cyano-2-methyl-4-(2-nitrophenyl)-4H-pyran)- 3-carboxylate is synthesized via one-pot multi-component reaction at room temperature using commercially available urea as inexpensive and environmentally benign organo-catalyst and its crystal structure is determined by X-ray technique. The crystals are monoclinic, sp. gr. C2/c, a = 12.3069(8) A, b = 9.7023(7) A, c = 24.812(2) A, β = 94.862(6)°, Z = 8. The dihedral angle between pyran and phenyl rings is 87.8(1)°; the pyran ring is almost planar The dihedral angle between the mean planes of phenyl ring and nitro group is 44.4(2)°. The crystal structure is stabilized by N−H···N and N−H···O hydrogen bonds. In addition, C−H···π interactions are also observed in the crystal structure.

Complex of iron(II) bis(2,4-dimethylphenyl)dithiophosphate with 4-ethylpyridine [{(2,4- (CH3)2C6H3O)2PS2}2Fe{NC5H4(C2H5)-4}2] is synthesized and characterized by elemental analysis, magnetic moment, IR spectroscopy and single crystal X-ray analysis. Complex crystallizes in the monoclinic sp. gr. P21/n, Z = 2. Crystal structure consists of mononuclear units with Fe(II) ion chelated by four S atoms of the two diphenyldithiophosphate ligands in bidentate manner. N atoms from two 4-ethylpyridine ligands are axially coordinated to the Fe(II) atom leading to an octahedral geometry.

An efficient and eco-friendly procedure has been developed for the synthesis of various 2,2’-arylmethylenebis(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) derivatives which were isolated and characterized by melting point, IR, 1H-NMR, 13C-NMR and mass spectrometric techniques. Out of the fourteen compounds synthesized, four compounds yielded crystals suitable for single crystal X-ray analysis which showed that 2,2’-phenylmethylenebis(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) crystallizes in the tetragonal system with space group I 4 1 /a, 2,2’-(3-nitrophenyl)methylenebis(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) crystallizes in the monoclinic system with space group P 2 1 /n, 2,2’-(4-nitrophenyl)methylenebis(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) crystallizes in the orthorhombic system with space group Pca21 and 2,2’-(4-chlorophenyl)methylenebis(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) crystallizes in the monoclinic space group P21/c.

The new indole derivative, 5,5′′-Difluoro-1H,1′′H-[3,3′:3′,3′′-terindol]-2′(1′H)-one C24H15F2N3O, is synthesized in 87% yield, and its crystal structure is determined by X-ray structure analysis. The crystals are monoclinic, sp. gr. P21/n, a = 15.4563(7), b = 10.8340(6), c = 16.4718(6) A, β = 102.403(4)°, Z = 4. Bicyclic indole moieties form dihedral angle of 61.92(5)° with each other; the oxindole ring is twisted with respect to them at angles of 85.70(5)° and 75.62(5)°. The crystal structure is stabilized by N–H···O and C–H···O hydrogen bonds involving both the DMSO solvent molecules. In addition, one C–H···π interaction is observed.

The title compound, 2-(thiophen-2-yl)-1-(5-thioxo-4,5-dihydro-1,3,4-oxadiazol-2-yl)ethenyl] benzamide:N,N-dimethylformamide (1: 1), (C15H11N3O2S2 · C3H7NO), was synthesized, and its structure was established by spectral analysis and X-ray diffraction studies. The compound crystallizes in the monoclinic space group P21/n with a = 10.8714(7), b = 9.0497(5), c = 19.8347(13) A, β = 91.093(5)°, Z = 4. The crystal structure is stabilized by N–H···S, C–H···O and N–H···O hydrogen bonds. The π···π interactions are also observed between the rings.

The title hydrate, C13H10ClN3O·H2O, is the orthorhombic polymorph of the previously reported monoclinic compound [Fun et al. (2012). Acta Cryst. E68, o2303–o2304). In the title compound, the dihedral angle between the pyridine and benzene rings is 18.0 (2)°. In the crystal, the Schiff base molecules and water molecules are linked via O—H...O, N—H...O and O—H...N hydrogen bonds, forming a two-dimensional network parallel to (001). In addition, the Schiff base molecules are linked end-to-end by weak C—H...Cl hydrogen along the c-axis direction, forming an overall three-dimensional network. Weak C—H...π interactions are also observed.

The asymmetric unit of the title compound, C30H33N5O3, contains two independent molecules,AandB. In moleculeA, thetert-butyl 4-methylpiperazine-1-carboxylate group was refined as disordered over two sets of sites with an occupancy ratio of 0.821 (4):0.179 (4). The piperazine ring adopts a chair conformation in both molecules. The dihedral angles between the pyrimidine ring and methoxyphenyl ring are 20.27 (14) and 8.72 (11)° for moleculesAandB, respectively. The quinoline ring system makes dihedral angles of 30.68 (11) and 37.76 (10)° with the pyrimidine ring in moleculesAandB, respectively. In the crystal, C—H...O hydrogen bonds link the molecules into chains along [100].

In the title compound, C26H27N5O, the piperazine ring adopts a chair conformation. The pyrimidine ring makes a dihedral angle of 1.5 (1)° with the methoxyphenyl ring and 33.1 (1)° with the quinoline ring system. In the crystal, molecules are consolidated in the crystal packing by weak C—H...π interactions and π–π stacking interactions.

The title compound, 2-amino-7,7-dimethyl-5-oxo-4-(pyridin-4-yl)-5,6,7,8-tetrahydro-4Hchromene-3-carbonitrile was synthesized by multicomponent reaction at room temperature using commercially available urea as inexpensive and environmentally benign organo-catalyst. Its structure was determined by X-ray structure analysis. The crystals are monoclinic, sp. gr. C2/c, a = 22.010(6), b = 11.0364(10), c = 17.147(4) A, β = 130.37(4)°, Z = 8, R = 0.0433 for 2377 observed reflections.

The title compound, C13H14O2N3Cl, has been synthesized by the reaction of chloroacetyl chloride with 4-aminoantipyrine in basic media and characterized by FT-IR, CHN elemental analysis, UV-Vis, TGA, DTA, DSC and single crystal X-ray diffraction. crystals are monoclinic, sp. gr. P21/c, a = 6.9994(6), b = 12.4035(13), c = 15.836(2) A, β = 100.367(9)°, Z = 4. The crystal structure is stabilized by N–H···O and C–H···O interactions, the former interactions result in the formation of dimers corresponding to R 2 2 (10) graphset motif and the dimers are further connected by C–H···O hydrogen bonding forming chains. In addition, the thermal stability of the compound was determined by TGA, DTA, DSC analysis, and absorption at λmax = 298 nm was determined by UV-Vis spectrophotometer.