Vijayan Viswanathan

A new organic NLO material isonicotinamidium picrate (ISPA): crystal structure, structural modeling and its physico-chemical properties

A novel organic nonlinear optical (NLO) crystal, isonicotinamidium picrate (ISPA) was synthesized and grown by the slow evaporation method. Formation of the new crystalline compound was confirmed by a single crystal X-ray diffraction study. The title compound crystallizes in the monoclinic crystal system with the space group of P21/n. DFT was carried out to calculate the bond lengths and bond angles. Structural parameters obtained from single crystal XRD and DFT studies are in good agreement with each other. The frontier energy gaps calculated theoretically are useful to understand the charge transfer taking place in the molecule. Polarizability of the ISPA compound is found using Penn gap analysis and the Clausius–Mossotti equation. The UV-vis-NIR spectral study showed that the grown crystal is transparent in the entire visible region with the lower cut-off wavelength of 469 nm. The four independent tensor coefficients of dielectric permittivity were found to be e11 = 1.42, e22 = 4.62, e33 = 6.23 and e13 = 5.56 from the dielectric measurements. The titular compound ISPA is thermally stable up to 229 °C assessed by thermogravimetric and differential thermal (TG-DTA) analyses. The specific heat capacity of ISPA is found to be 3.49 J g−1 K−1. The laser induced surface damage threshold of the grown crystal was measured to be 0.22537 GW cm−2 for 1064 nm Nd:YAG laser radiation. Nonlinear refractive index (n2), absorption coefficient (β) and third order nonlinear susceptibility (χ(3)) were determined using the Z-scan technique. The optical limiting study revealed that the transmitted output power increases linearly with the input power up to the irradiance of around 3.25 mW mm−2.

Crystal structure, molecular packing, FMO, NBO, nonlinear optical and optical limiting properties of an organic imidazolium diphenylacetate diphenylacetic acid single crystal

An organic nonlinear optical (NLO) crystal, imidazolium diphenylacetate diphenylacetic acid (IDA), was synthesized and grown by the slow evaporation method. Formation of the new crystalline compound was confirmed by single crystal X-ray diffraction study. The title compound crystallizes in the triclinic crystal system with the space group P. UV-vis-NIR spectral study showed that the grown crystal is transparent in the entire visible region with a lower cut-off wavelength of 275 nm. Density functional theory (DFT) calculations were carried out to calculate the frontier molecular orbitals and natural bonding orbitals of the IDA compound. The frontier energy gaps calculated theoretically were useful to understand the charge transfer taking place in the molecule. The natural bonding orbital analysis provides a convenient basis for the investigation of the charge transfer or conjugative interactions in the molecular system. Vickers microhardness study revealed that the title material belongs to the soft material category. The values of fracture toughness, brittleness index and yield strength have also been calculated for Palmqvist and median types of cracks. The title compound IDA is thermally stable up to 201 °C, as assessed by thermogravimetric and differential thermal (TG-DTA) analyses. The specific heat capacity of IDA is found to be 3.25 J kg−1 K−1 at 65 °C. The laser induced surface damage threshold of the grown crystal was measured to be 0.2645 GW cm−2 with 1064 nm Nd:YAG laser radiation. The nonlinear refractive index (n2), absorption coefficient (β) and third order nonlinear susceptibility (χ(3)) were determined using the Z-scan technique. An optical limiting study revealed that the transmitted output power increases linearly with the input power up to an irradiance of around 3.6 mW cm−2.

In vitro and in vivo anti-proliferative evaluation of bis(4′-(4-tolyl)-2,2′:6′,2″-terpyridine)copper(II) complex against Ehrlich ascites carcinoma tumors

The bis(4′-(4-tolyl)-2,2′:6′,2″-terpyridine)copper(II) complex [Cu(ttpy)2]Cl2 was synthesized and authenticated by single crystal analysis, which shows distorted octahedral geometry around copper(II) ion. The crystal packing is stabilized by C–H···π inter and intramolecular interactions. The complex was found to be lipophilic as determined by shake-flask method. In vitro cytotoxicity of the complex was tested against Ehrlich ascites carcinoma (EAC) and L6 myotube cell lines. The complex exhibit potent cytotoxicity with respect to the commercially available anticancer drug cisplatin. Hoechst 33258, AO/EB and PI (flow cytometry) staining methods suggest that the complex can induce apoptosis in EAC cells. Cell cycle analyses also support the induced apoptosis. Cellular uptake studies revealed that the complex can go into the cytoplasm and accumulate in the cell nuclei. The complex induces EAC cell apoptosis through a ROS-mediated mitochondrial pathway by activating caspase 3 and caspase 7 and regulates the Bcl-2 family proteins. In vivo study of the complex was validated against the animal tumor growth (EAC) cell in Swiss albino mice.Graphical abstractThe bis(4′-(4-tolyl)-2,2′:6′,2″-terpyridine)copper(II) complex induces EAC cell apoptosis through a ROS-mediated mitochondrial pathway and significantly reduced the body weight and solid tumor volume in Swiss albino mice.

Theoretical, photophysical and biological investigations of an organic charge transfer compound 2-aminobenzimidazolium-2-oxyisoindolate-1,3-dione-2-hydroxyisoindoline-1,3-dione

An organic charge transfer compound, 2-aminobenzimidazolium-2-oxyisoindolate-1,3-dione-2-hydroxyisoindoline-1,3-dione (ABOH), was synthesized and fully characterized using elemental analysis, FT IR and UV-Vis spectroscopic techniques. The structure of the grown crystal was determined by single crystal X-ray diffraction analysis. Structural parameters from the crystallographic and DFT studies are in good agreement with each other. HOMO–LUMO energy levels were constructed and the corresponding theoretical frontier energy gaps are calculated to realise the charge transfer occurring in the molecule. The optical transmittance data was taken from the polished crystal of ABOH and cut-off wavelength was identified by UV-Vis spectral studies. The ABOH crystal exhibits negative optical non-linearity. The sample at 62% transmittance exhibited a non-linear refractive coefficient in the order of 10−8 cm2 W−1, a non-linear absorption coefficient in the order of 10−4 cm W−1 and non-linear susceptibility in the order of 10−6 esu. These results show that the ABOH crystal has potential applications in non-linear optics. A pharmacological study of ABOH shows excellent antibacterial activity, when compared with standard drugs. Molecular docking studies were carried out in order to find the binding affinity of ABOH with cyclin-dependent kinase 2 (CDK2).

Crystal structures of 2-[(4,6-di­amino­pyrimidin-2-yl)sulfan­yl]-N-(2,4-di­methyl­phen­yl)acetamide and 2-[(4,6-di­amino­pyrimidin-2-yl)sulfan­yl]-N-(3-meth­oxy­phen­yl)acetamide

Two 2-[(4,6-diaminopyrimidin-2-yl)sulfanyl]acetamide derivatives have folded conformations with the pyrimidine ring being inclined to the benzene ring by 58.64 (8) and 78.33 (9)°.

Crystal structures of 2-[(4,6-di­amino­pyrimidin-2-yl)sulfan­yl]-N-(naphthalen-1-yl)acetamide and 2-[(4,6-di­amino­pyrimidin-2-yl)sulfan­yl]-N-(4-fluoro­phen­yl)acetamide

The two title compounds are (diaminopyrimidin-2-yl)thioacetamide derivatives. In the first structure, the pyrimidine ring is inclined to the naphthalene ring system by 55.5 (1)°, while in the second, the pyrimidine ring is inclined to the benzene ring by 58.93 (8)°. In the crystals of both compounds, molecules are linked by pairs of N—H⋯N hydrogen bonds, forming inversion dimers with (8) ring motifs.

Crystal structures of N-(4-chloro­phen­yl)-2-[(4,6-di­amino­pyrimidin-2-yl)sulfan­yl]acetamide and N-(3-chloro­phen­yl)-2-[(4,6-di­amino­pyrimidin-2-yl)sulfan­yl]acetamide

The title compounds, (I) and (II), are 2-[(diaminopyrimidin-2-yl)sulfanyl]acetamides. The molecules have a folded conformation, with the pyrimidine ring being inclined to the benzene ring by 42.25 (14)° in (I), and by 59.70 (16) and 62.18 (15)° in the two independent molecules of compound (II).

Crystal structure of ethyl 6-chloro­methyl-2-oxo-4-(2,3,4-tri­meth­oxy­phen­yl)-1,2,3,4-tetra­hydro­pyrimidine-5-carboxyl­ate

The dihydropyrimidine ring in the title ester adopts a flattened envelope conformation. An intramolecular C—H⋯O hydrogen bond generates an S(6) ring. Molecules are linked via pairs of N—H⋯O hydrogen bonds, forming inversion dimers.

Crystal structure of (E)-4-{1-[2-(car­bamo­thio­yl)hydrazin-1-yl­idene]ethyl}phenyl 4-methyl­benzoate

The asymmetric unit of the title compound, C17H17N3O2S, consists of two independent molecules, A and B, with different conformations: in molecule A, the dihedral angles between the central benzene ring and the pendant tolyl and carbamothioylhydrazono groups are 71.12 (9) and 5.95 (8)°, respectively. The corresponding angles in molecule B are 50.56 (12) and 26.43 (11)°, respectively. Both molecules feature an intramolecular N—H⋯N hydrogen bond, which closes an S(5) ring. In the crystal, molecules are linked by N—H⋯O, N—H⋯S and C—H⋯O hydrogen bonds, generating a three-dimensional network.

Crystal structure of 15-(2-chloro-phen-yl)-6b-hy-droxy-17-methyl-6b,7,16,17-tetra-hydro-7,14a-methanona-phtho[1',8':1,2,3]pyrrolo-[3',2':8,8a]azuleno[5,6-b]quinolin-14(15H)-one.

In the title compound, C34H25ClN2O2, the fused pyrrolidine ring adopts an envelope conformation with the N atom as the flap. The two adjacent cyclopentane rings also adopt envelope conformations. The mean plane of the pyrrolidine ring makes dihedral angles of 40.53 (10) and 80.23 (10)° with the mean planes of the cyclopentane rings. The dihedral angle between the mean planes of the cyclopentane rings is 46.71 (9)°. An intramolecular O—H⋯N hydrogen bond is observed. In the crystal, molecules are linked by C—H⋯O, C—H⋯N and C—H⋯π interactions, forming a layer parallel to (10-2).