Sumantra Paul

Polymer-Anchored Cu(II) Complex as an Efficient Catalyst for Selective and Mild Oxidation of Sulfides and Oxidative Bromination Reaction

A new polymer-anchored Cu(II) complex has been tested for the oxidation of sulfides and in oxidative bromination reaction with hydrogen peroxide as oxidant. Sulfides have been selectively oxidized to corresponding sulfoxides in excellent yields and in presence of KBr as bromine source, organic substrates have been selectively converted to mono bromo substituted compounds. The polymer-anchored Cu(II) catalyst could be easily recovered by simple filtration and reused more than six times without appreciable loss of its initial activity.Graphical Abstract

Olefin epoxidation with tert -butyl hydroperoxide catalyzed by functionalized polymer-supported copper(II) Schiff base complex

A new polymer-supported Cu(II) Schiff base complex has been synthesized and characterized by elemental (including metal) analysis, FT-IR spectroscopy, UV–Vis diffuse reflectance spectroscopy, thermogravimetric analysis, and scanning electron microscopy. The catalytic performance of this complex was evaluated in the epoxidation of styrene in acetonitrile/N,N-dimethylformamide (9:1) mixture with 70% tert-butyl hydroperoxide as an oxidizing agent under liquid phase reaction conditions for selective synthesis of styrene oxide. Suitable reaction conditions have been optimized by considering the effects of various reaction parameters such as temperature, reaction time, solvent, oxidant, catalyst amount, and styrene to hydroperoxide molar ratio for the maximum conversion of styrene as well as selectivity of styrene oxide. We have also investigated the epoxidation reaction of various olefins under the optimized reaction conditions. Comparison between catalytic activities of the polymer-supported Cu(II) Schiff base complex and its homogeneous analogue showed that the polymer-supported catalyst was more active. This heterogeneous complex was reused for five times. The selectivity of the heterogeneous catalyst does not change even after five times of reusing.Graphical Abstract

Catalytic activity of an iron(III) Schiff base complex bound in a polymer resin

An iron(III)–ferrocene complex and its heterogeneous analogue bound in a polymer resin have been prepared and employed as catalysts for the oxidation of various organic substrates. Characterization of the heterogeneous and homogeneous complexes was done by SEM, EDAX, TGA, FT-IR, DRS-UV, and spectroscopy. The catalyst’s activity, stability, and reusability were investigated through industrially relevant oxidation reactions. The solid iron(III)–ferrocene Schiff base complex gave more effective results than the solid-supported ferrocene Schiff base ligand. The antimicrobial activities of the molecular complex and free ligand were studied for Gram-positive and Gram-negative bacteria.

Synthesis, catalytic activity and phytotoxicity of a supported nickel(II) Schiff base complex

A supported Ni(II) complex has been synthesized and characterized by FTIR, UV–vis diffuse reflectance spectroscopy, thermogravimetric analysis and scanning electron microscopy. Its catalytic activity was evaluated for alkyne–azide coupling and benzothiazole synthesis. These reactions were found to require mild conditions, reaction times, and most importantly, could be carried out in aqueous medium. The catalyst could be easily recovered and reused five times without significant decrease in its activity. Leaching tests indicated that the catalyst is truly heterogeneous. The nickel complex was tested for its inhibition of germination of MTU 7029 seeds. Rice (MTU 7029, Oryza sativa) is a staple crop in southeast Asia.