I-V Curves of an Apigenin Dye and Their Analysis by a New Parabolic Function.

A new parabolic function for I-V curves' analysis has been proposed. The new "analytical tool" provides a simple way to describe photophysical processes at an approximately monolayer surface of a dye-sensitized solar cell. It may now be possible to estimate factors such as hole-electron recombination, surface defects, and electron diffusion at the semiconductor layer. The theoretical approach that was previously reported by our group for predicting the photovoltaic performance of potential dye sensitizers has also been validated. The experimental photovoltaic and DFT/TD-DFT data of apigenin and those of the highly rated black dyes were used for the validation.

Tryptanthrin from microwave-assisted reduction of isatin using solid-state-supported sodium borohydride: DFT calculations, molecular docking and evaluation of its analgesic and anti-inflammatory activity.

Tryptanthrin is a potent natural alkaloid with good in vitro pharmacological properties. Herein, we report the synthesis of the compound via a new method involving the reduction of isatin with solid-state-supported sodium borohydride under microwave irradiation. The title compound has been tested for its analgesic and anti-inflammatory activity. The results showed that tryptanthrin dose dependently inhibits oedema and pain formation in all the models used. The agent also exhibited significant higher effects in its anti-inflammatory and analgesic activities better than positive drugs (aspirin and indomethacin) being currently used in the treatment and in the management of acute and chronic forms of pain and inflammatory disorders. The inhibitory potential of the compound was investigated by molecular docking using the software AutoDock Vina. The docking results were used to better rationalize the action and prediction of the binding affinity of tryptanthrin. Density Functional Theory (DFT) calculations at the B3LYP/6-311++G (2df, 2pd) level of theory showed that compared to ascorbic acid, tryptanthrin shows higher antioxidant activity which may be improved upon by functionalizing the aromatic core to enhance its solubility in polar solvents. The calculated electronic and thermodynamic properties obtained for tryptanthrin compete well with the standard ascorbic acid.

Supramolecular architecture in 1:1 cocrystal of N-carbamothioylacetamide and N,N'-thiocarbonyldiacetamide from the attempted synthesis of 1,3-diacetyl-2-thioxoimidazolidine-4,5-dione (a thioparabanic acid derivative).

An attempt to synthesize thioparabanic acid as precursor to other fused heterocyclic compounds, by a microwave assisted multistep one-pot reaction yielded a co-crystal of N-carbamothioylacetamide (NCTA) and N,N'-thiocarbonyldiacetamide (NNTCA) which is being reported in this paper. The structure of N-carbamothioylacetamide and N,N'-thiocarbonyldiacetamide from the attempted synthesis of 1,3-diacetyl-2-thioxoimidazolidine-4,5-dione, C5H8N2O2S.C3H6N2OS, has triclinic (P-1) symmetry. It is of interest with respect to biological application. The structure displays inter- and intra-molecular hydrogen bonding through -C=O···H interactions. Similarly, -C=S···H hydrogen bonding interactions are present, providing additional intermolecular stability to the co-crystal. For application as a potential drug candidate, a density functional theory (DFT) simulation of the antioxidant activities of the co-crystal and its individual components (NCTA and NNTCA) has been performed. The computed redox potentials indicate that the study compounds show comparable antioxidant activities with ascorbic acid (AA) for a one electron transfer process. Meanwhile, for a two-electron process, AA showed significant antioxidant advantage over the titled compound.

Thiol-thione tautomeric analysis, spectroscopic (FT-IR, Laser-Raman, NMR and UV-vis) properties and DFT computations of 5-(3-pyridyl)-4H-1,2,4-triazole-3-thiol molecule.

In this study, the 5-(3-pyridyl)-4H-1,2,4-triazole-3-thiol molecule (C7H6N4S) molecule has been characterized by using FT-IR, Laser-Raman, NMR and UV-vis spectroscopies. Quantum chemical calculations have been performed to investigate the molecular structure (thione-thiol tautomerism), vibrational wavenumbers, electronic transition absorption wavelengths in DMSO solvent and vacuum, proton and carbon-13 NMR chemical shifts and HOMOs-LUMOs energies at DFT/B3LYP/6-311++G(d,p) level for all five tautomers of the title molecule. The obtained results show that the calculated vibrational wavenumbers, NMR chemical shifts and UV-vis wavelengths are in a good agreement with experimental data.

The EPR study of Mn(2+) ion doped KBr and VO(2+) ion doped KH2PO4 under high pressure.

In previous works under open atmosphere at various temperatures KBr host crystal never accepted paramagnetic Mn(2+) ion in its lattice, but KH2PO4 host crystal accepted VO(2+) ion in its lattice where K(+) ion substituted with VO(2+). In a series of works using high-pressure reactor at various pressures and temperatures under different gas atmospheres, Mn(2+) ion was inserted in KBr host, and VO(2+) ion was inserted in KH2PO4 host in sites different from those observed in previous works. The best results were obtained for Mn(2+) doped KBr at pressure of 100bars and 50°C under Argon atmosphere, and for VO(2+) doped KH2PO4 at pressure of 100bars and temperature of 50°C under oxygen atmosphere. The structural parameters of paramagnetic species formed were determined by EPR spectroscopy and optical transitions were determined by UV-Vis spectroscopy.

The EPR study of Mn(2+) ion doped DADT single crystal produced under high pressure and temperature.

An EPR study on Cu(2+) and VO(2+) doped di ammonium d-tartrate single crystals has been reported in previous papers, but the same host did not accept Mn(2+) ion at the same reaction conditions in previous trials. In this study EPR study of Mn(2+) ion doped di ammonium d tartrate single crystal, (DADT) [(NH4)2C4H4O6], produced in a reactor under high pressure and high temperature. The electronic transitions were determined by the optical absorption spectrum. Hyperfine splitting and g values of the Mn(2+) ion forming a complex in the lattice were measured from experimental spectra and spin-spin dipolar splitting parameters D and E were found by the spectrum simulation techniques.

Experimental and theoretical studies of (E)-2-(2-hydroxystyryl)-6-(4-methoxybenzoyl)-5-(4-methoxyphenyl)-1,2,4-triazin-3(2H)-one.

Crystal structure of the title compound, C26H21N3O5, has been synthesized and characterized by FT-IR, (1)H NMR, (13)C NMR and X-ray single crystal determination. The molecular geometry was also calculated by using Gaussian 03 software and structure was optimized by using HF and DFT/B3LYP method with the 6-31G(d) basis sets in ground state. The comparison of the theoretical and experimental geometries of the title compound indicated that the X-ray parameters agree with the theoretically obtained values. It was seen that R(2) value changes from 0.015 to 0.021 Å for bond length and angle. The calculated vibrational frequencies are also in good agreement with the experimental results. The (1)H and (13)C NMR chemical shifts values of (E)-2-(2-hydroxystyryl)-6-(4-methoxybenzoyl)-5-(4-methoxyphenyl)-1,2,4-triazin-3(2H)-one molecule have been calculated by the GIAO method. Besides, molecular electrostatic potential maps (MEP), Mulliken charges and Nonlinear Optical effects (NLO) analysis of the compound have been calculated by the HF and B3LYP/6-31G(d) methods.

(E)-4-Methyl-N-[(5-nitro-thio-phen-2-yl)methyl-idene]aniline.

In the crystal structure of the title compound, C(12)H(10)N(2)O(2)S, the benzene and the 2-nitro-thio-phene rings make a dihedral angle of 7.47 (12)°. The dihedral angle between the nitro group and the attached ring is 1.9 (6)°.

2-Ethyl-N-[(5-nitro-thio-phen-2-yl)methyl-idene]aniline.

In the title compound, C(13)H(12)N(2)O(2)S, the dihedral angle between the benzene and thio-phene rings is 36.72 (8)°. An inter-molecular C-H⋯π inter-action contributes to the stability of the crystal structure.

(2-Hy-droxy-eth-yl)triphenyl-phospho-nium chloride.

In the crystal structure of the title compound, C(20)H(20)OP(+)·Cl(-), the cations and anions are linked by inter-molecular C-H⋯Cl and O-H⋯Cl hydrogen bonds into chains running parallel to the b axis. In the cation, the hy-droxy-ethyl group is disordered over two orientations with site-occupancy factors of 0.554 (4) and 0.446 (4).

(E)-2-[(4-Iodo-phen-yl)imino-meth-yl]-6-methyl-phenol.

The title compound, C(14)H(12)INO, adopts the phenol-imine tautomeric form. The dihedral angle between the aromatic rings is 20.6 (3)°. The mol-ecular conformation is stabilized by an intra-molecular O-H⋯N hydrogen bond while in the crystal, weak inter-molecular C-H⋯O hydrogen bonds link the mol-ecules into a zigzag chain parallel to the b axis.