Asim A. Balakit

Synthesis of New Thiophene Derivatives and Their Use as Photostabilizers for Rigid Poly(vinyl chloride)

Five new thiophenes, namely, N-[(3-bromo-2-methylthiophen-5-yl)methylene]-4-methoxyaniline (4a), N-[(3-bromo-2-methylthiophen-5-yl)methylene]-3,4-dimethoxyaniline (4b), N-[(3-bromo-2-methylthiophen-5-yl)methylene]-3,4-dimethylaniline (4c), 3-[(3-bromo-2-methylthiophen-5-yl)methyleneamino]-2-methylquinazolin-4(3H)-one (4d), and 3-[(3-bromo-2-methylthiophen-5-yl)methyleneamino]-2-isopropylquinazolin-4(3H)-one (4e), have been synthesized. All of these materials brought about a reduction in the level of photodegradation of poly(vinyl chloride) (PVC) films containing the synthesized thiophenes (0.5%; by weight). The results obtained showed that the extent of photostabilization of PVC in the presence of an additive was in the order 4e > 4d > 4b > 4a > 4c. For the most favorable additive (4e), the rate of appearance of infrared absorption bands of degradation products was reduced by around two-thirds, while the quantum yield of chain scission was calculated to be reduced by a factor of more than one thousand. It is suggested that the additives may help stabilize PVC by direct absorption of UV radiation and dissipation of the energy as heat or that electrostatic attraction between the additives and PVC may assist transfer of energy from excited state PVC to the additive, from where it can be dissipated.

New polymeric sulfide-borane complexes: convenient hydroborating and reducing reagents

New polymeric borane adducts have been synthesized from polymeric sulfides, which are solids with a minimal odour. The adducts contain a high concentration of borane, have significant stability and are soluble in THF. They act as hydroborating and reducing reagents with behaviour similar to that of borane-methyl sulfide, making them attractive borane sources.

Experimental (FT-IR, NMR and UV) and theoretical (M06-2X and DFT) investigation, and frequency estimation analyses on (E)-3-(4-bromo-5-methylthiophen-2-yl)acrylonitrile.

The spectroscopic properties of (E)-3-(4-bromo-5-methylthiophen-2-yl)acrylonitrile have been investigated by FT-IR, UV, (1)H and (13)C NMR techniques. The theoretical vibrational frequencies and optimized geometric parameters (bond lengths and angles) have been calculated using density functional theory (DFT/B3LYP: Becke, 3-parameter, Lee-Yang-Parr) and DFT/M06-2X (the highly parameterized, empirical exchange correlation function) quantum chemical methods with 6-311++G(d,p) basis set by Gaussian 03 software, for the first time. The assignments of the vibrational frequencies have been carried out by potential energy distribution (PED) analysis by using VEDA 4 software. The theoretical optimized geometric parameters and vibrational frequencies were in good agreement with the corresponding experimental data, and with the results in the literature. (1)H and (13)C NMR chemical shifts were calculated by using the gauge-invariant atomic orbital (GIAO) method. The electronic properties, such as excitation energies, oscillator strength wavelengths were performed by B3LYP methods. In addition, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies and the other related molecular energy values have been calculated and depicted.

2,2-Dimethyl-N-(4-methyl-pyridin-2-yl)propanamide.

In the title compound, C11H16N2O, the dihedral angle between the mean plane of the 4-methypyridine group and the plane of the amide link is 16.7 (1)°, and there is a short intramolecular C—H⋯O contact. Hydrogen bonding (N—H⋯O) between amide groups forms chains parallel to the b axis. Pairs of methylpyridine groups from molecules in adjacent chains are parallel but there is minimal π–π interaction.

Synthesis and characterization of a new photochromic alkylene sulfide derivative

ABSTRACT A process has been developed for the synthesis of a new photochromic alkylene sulfide derivative. The process involves the synthesis of an alkylene sulfide with terminal free amino groups and a novel unsymmetrical photochromic diarylperfluorocyclopentene containing an aldehyde group, which coupled together to produce the corresponding Schiff base. The structures of the products were confirmed by a range of spectroscopic techniques. GRAPHICAL ABSTRACT

4-(5-{2-[5-(4-Cyano­phen­yl)-3-methyl­thio­phen-2-yl]-3,3,4,4,5,5-hexa­fluoro­cyclo­pent-1-en-1-yl}-4-methyl­thio­phen-2-yl)benzo­nitrile chloro­form hemisolvate

The crystal structure of the title compound, C29H16F6N2S2·0.5CHCl3, consists of molecules with disordered perfluorocyclopentene rings [occupancy ratio 0.685 (3):0.315 (3)] and close F⋯F contacts (in the range 2.45–2.73 Å) between molecules. The short contacts are associated with the disorder. The dihedral angle between thiophene rings is 57.44 (8)°. The 5-(4-cyanophenyl)-3-methyl-2-thienyl groups of adjacent molecules are parallel, leading to zigzag chains of molecules along [101]. The dihedral angles between each thiophene ring and its adjacent cyanobenzene ring are 8.9 (2) and 7.15 (10)°.