A Synthetic and Stereochemical Study of 2,6-Diaroyl-3,5-Diaryl-4-Ethyltetrahydro-1,4-Thiazine-1,1-Dioxides

Double aza-Michael addition of ethylamine over 2,2'-sulfonylbis(1,3-diarylprop-2-en-1-ones) gave the previously unknown title compounds in moderate yields. The decreased yields of the title compounds compared to 2,6-diaroyl-3,5-diaryltetrahydro-1,4-thiazine-1,1-dioxides or the corresponding 4-methyl derivatives is explained on the basis of steric size of the nucleophile. The structure and stereochemistry of the thianes have been deduced from elemental analyses and spectroscopic data.     

A Diastereoselective Synthesis of Novel Multifunctional Thianes

The reaction of 2,2′-thiobis(1,3-diarylprop-2-en-1-ones) with malononitrile in the presence of sodium ethoxide under both thermal and solvent-free microwave conditions afforded a series of hitherto unknown 2e,6e-diaroyl-3e,5e-diaryl-4,4-dicyanothianes diastereoselectively in good yields via a double Michael addition. The structures of all the compounds have been elucidated by IR, ¹H NMR, ¹³C NMR, and elemental analysis.     

The synthesis of spirophanes from a pentaerythrityl core

Various thia- and oxa-spirobicyclic cyclophanes were synthesized from a pentaerythrityl building block and appropriate dithiols/bisphenols.     

A novel four-component tandem protocol for the stereoselective synthesis of highly functionalised thiazoles

The reaction of bis(aroylmethyl) sulfides with aromatic aldehydes and ammonium acetate in 1:2:1 molar ratio under solvent-free microwave irradiation afforded predominantly a series of thiazoles, viz., 1-aryl-2-[5(Z)-5-arylmethylidene-2,4-diaryl-2,5-dihydrothiazol-2-yl]ethanones stereoselectively. This reaction presumably occurs via a Knoevenagel condensation-Michael addition-cyclocondensation-ring opening-ring closing Michael addition sequence. The intermediacy of (Z,Z)-2,2′-thiobis(1,3-diarylprop-2-en-1-ones) in the above transformation is demonstrated by their conversion to the thiazoles upon reaction with ammonium acetate under solvent-free microwave irradiation.     

SERS studies of 1-butylaminoanthraquinone in silver sol

SERS studies of 1-butylaminoanthraquinone in silver sol have been made to understand the nature of adsorption. The enhancement mechanism is explained on the basis of charge transfer process. The molecule is adsorbed through the binding sites but not flat on to the surface.     

Dioxastilbenophanes—synthesis and charge transfer complexation studies

Intramolecular McMurry coupling of dialdehydes derived from xylenyl dibromide and 4-hydroxy benzaldehyde afforded cis-stilbenophanes along with cyclophane diols. Stilbenophanes with a large cavity were also synthesized. Charge transfer complexations of the stilbenophanes with TCNE, TCNQ and PQT were studied. Some stilbenophanes form a relatively stronger complex with PQT rather than with TCNE and TCNQ.     

Diastereoselective synthesis of cis-fused pyrano and furanobenzopyrans catalyzed by indium trichloride or triphenyl phosphonium perchlorate

Indium trichloride (InCl₃) and triphenyl phosphonium perchlorate (TPP) are found to be effective catalysts for the cyclization of o-hydroxyaldimines with 3,4-dihydro-2H-pyran and 2,3-dihydrofuran at ambient temperature to afford novel pyrano and furanobenzopyran derivatives in excellent yields with high diastereoselectivity. One pot syntheses of pyrano and furanobenzopyrans from o-hydroxybenzaldehyde, aromatic amines and an enol ether under identical conditions is reported for the first time. Similarly, o-hydroxyaldimine reacted with ethyl vinyl ether to give 2-ethoxy-4-N-aryl aminobenzopyran in good yields.     

Binding interaction of bioactive imidazole with bovine serum albumin--a mechanistic investigation

A novel Y-shaped imidazole derivative 4-((E)-2-(4,5-diphenyl-1-p-tolyl-1H-imidazol-2-yl)vinyl)phenol has been synthesized and characterised by IR, UV-vis, mass and NMR spectral techniques. The mutual interaction of this imidazole derivative (DPTIV) with bovine serum albumin (BSA) was investigated using photoluminescent studies. The fluorescence quenching mechanism of BSA by DPTIV was analyzed and the binding constant has been calculated. The binding distance between DPTIV and BSA was obtained based on the theory of Forester's non-radiation energy transfer. The effect of some common ions on the binding constant between DPTIV and BSA was also examined.     

An inorganic-organic diblock copolymer photoresist for direct mesoporous SiCN ceramic patterns via photolithography

A high resolution negative-tone-type of inorganic-organic diblock copolymer photoresist was synthesized as a novel precursor for simple and direct fabrication of SiCN ceramic mesoporous patterns with ordered nanoscale pores by using a "top-down" photolithographic technique and the subsequent sacrificial processes of a "bottom-up" self-assembled nanostructure.     

A physiochemical study of azo dyes: DFT based ESIPT process

Azo linked dye derivatives were synthesized and characterized by NMR, mass and elemental analysis. An excited state intramolecular proton transfer (ESIPT) in hydroxy Schiff base has been analyzed, and found that two distinct ground state isomers of I and II are responsible for the observed dual emission. DFT calculation on energy, dipole moment, charge distribution of the rotamers in the ground and excited states support the ESIPT process. PES calculation indicates that the energy barrier for the interconversion of two rotamers is too high in the excited state than the ground state. By varying the addition of base concentration to hydroxy Schiff base, two isobestic points were found which confirm the equilibrium among the trans enol form, anion and the cis enol form. Fluorescence quenching with metal ions reveal that hydroxy Schiff base can be used as a new fluorescence sensor to detect the Cu(2+) ion.