Tessymol Mathew

Catalytic properties of cobalt(II) porphyrins supported on styrene-divinylbenzene copolymer

Polymeric pyridinium chloride was synthesized by treating pyridine with 2% divinylbenzene (DVB)-crosslinked chloromethyl polystyrene. Sodium 5,10,15,20-tetrakis(4-sulfophenyl)porphyrin was synthesized and appended on the above polymer through an ionic linkage. Cobalt(II) complex of the polymeric porphyrin was synthesized and characterized chemically and spectroscopically. This complex was employed as catalyst for the oxidation of dithiocarbamates to thiuram disulfide. Electronic and ESR spectra of the complex were analyzed before and after catalysis. pH dependence of catalytic reactions was also studied. These studies provide evidence for the catalytic ability of the polymeric cobalt(II) porphyrin system. A mechanism for the catalytic reaction is suggested on the basis of the above results.

Antifungal activity of silver nanoparticle-encapsulated β-cyclodextrin against human opportunistic pathogens

Silver nanoparticles were synthesised by reducing silver acetate with a long-chain aliphatic amine. β-Cyclodextrin (CD)-stabilised silver nanoparticles were successfully synthesised and characterised by the UV–vis spectroscopy and scanning electron microscopy analysis. This system was examined for their antifungal activity against opportunistic human pathogens such as Aspergillus fumigatus, Mucor ramosissimus and Chrysosporium species. This study clearly demonstrates that the present system is a powerful antifungal agent against human opportunistic pathogenic fungi.

Synthesis, characterisation and antibacterial applications of water-soluble, silver nanoparticle-encapsulated β-cyclodextrin

This paper describes a simple method for the synthesis of water-soluble, silver nanoparticle-encapsulated β-cyclodextrin by phase transfer of silver nanoparticles from organic to aqueous phase using β-cyclodextrin as a capping agent. β-Cyclodextrin–silver nanoparticle inclusion complex was purified, characterised by spectroscopic and microscopic analyses and tested in vitro against Pseudomonas aeruginosa, Staphylococcus aureus, Serratia marcescens, Escherichia coli and Klebsiella pneumoniae. The silver nanoparticle-encapsulated β-cyclodextrin inclusion complex displayed considerable antimicrobial activity and stability.

Cobalt(II) Porphyrins Supported on Crosslinked Polymer Matrix as Model Compounds

Polymer-bound cobalt(II) porphyrins were studied for their dioxygen—binding capacity. Tetra—aminoporphyrins were anchored on a divinylbenzene (DVB)-crosslinked chloromethyl polystyrene network. The crosslinked, solid polymers were swelled in chloroform and the swollen polymers were used for the entire studies. Ortho-, meta- and para-substituted porphyrin systems were developed by adjusting the bonding position with the help of suitably substituted aminoporphyrins. The products were characterized by chemical and spectroscopic methods. Cobalt(II) complexes of polymeric porphyrins were synthesized and characterized by electronic and ESR spectral methods. The spectra gave evidence for the systematic variation of electronic properties in ortho, meta and para compounds and for the dioxygen-binding capacity of cobalt complexes. These results are discussed.

Copper (II) and silver (II) complexes of polymer‐bound porphyrins with Schiff base linkage

Two percent divinylbenzene (DVB)–crosslinked polystyrene was prepared and functionalized to obtain its aldehyde analog. Amino porphyrins were anchored on this polymer support by Schiff base condensation. The anchoring positions were adjusted so as to obtain ortho-, meta-, and para-isomeric systems. The polymer-bound free-base porphyrins were metallated to obtain the corresponding Cu(II) and Ag(II) complexes by treating them with the corresponding metal salt solutions. The products were characterized chemically and spectroscopically. Electronic and ESR spectral analysis shows the microenvironmental participation of the polymer network on the electronic levels of the porphyrin system. The extents of steric and electronic participation were evaluated and are presented.

Thermal and Photoresponsive Studies of Starch Modified with 2-(5-(4-Dimethylamino-benzylidine)-4-oxo- 2-thioxo-thiazolidin-3-yl)acetic Acid

The present study describes the synthesis of a chromophoric system 2-(5-(4-dimethylamino-benzylidin)-4-oxo-2-thioxo-thiazolidin-3-yl)acetic acid and its incorporation into starch through esterification of the hydroxyl group by the free carboxyl function of the chromophoric system by DCC coupling. The products were characterized by UV-visible, fluorescence, FT-IR, and NMR spectroscopic methods. The newly developed system was subjected to photoresponsive studies such as light absorption, light stabilization and fluorescence emission. The free chromophoric system and the coupled product were also subjected to thermal analysis. The results show that modification enhances the light absorption and light fastening properties of the chromophoric system. Thermal stability of the polymeric system greatly enhances on attaching the chromophoric system. In view of these results the newly developed system is proposed as a nature friendly, green, and photoactive product which could find application in dyes, inks, paints, and so forth.