Indian Association for the Cultivation of Science

About: Indian Association for the Cultivation of Science is a education organization based out in Kolkata, India. It is known for research contribution in the topics: Catalysis & Excited state. The organization has 3867 authors who have published 10457 publications receiving 220098 citations.

Azo anion radical complexes of osmium and related nonradical species.

Abstract: The reaction of [Os(H)(Br)(CO)(PPh3)3], 5, with 2-(phenylazo)pyridine (pap) in boiling dry heptane has afforded the azo anion radical complex [Os(pap•-)(Br)(CO)(PPh3)2], 6a, as the major product and [Os(pap)(H)(CO)(PPh3)2]Br, 7, as a minor byproduct. Upon replacing pap by the better π-acceptor azo-2,2‘-bipyridine (abp) in the above synthesis, the radical complex [Os(abp•-)(Br)(CO)(PPh3)2], 6b, becomes the sole product. It is proposed that 6 is formed via homolytic cleavage of the Os−H bond in 5; in the formation of 7, the Os−Br bond of 5 is heterolytically cleaved. The X-ray structures of 6b and 7·CH2Cl2 have been determined. In 6b, the N−N length is 1.35(2) A, consistent with the anion radical description; in 7·CH2Cl2 the length is 1.27(1) A. The spin-bearing extended Huckel HOMO in a model of 6 is found to be ∼70% azo-π* in character associated with a small metal contribution. An electronic band observed in the range 600−700 nm in solutions of 6 is assigned to the HOMO → LUMO transition, the LUMO being ...

Surface-modified sulfur nanoparticles: an effective antifungal agent against Aspergillus niger and Fusarium oxysporum.

Abstract: Surface-modified sulfur nanoparticles (SNPs) of two different sizes were prepared via a modified liquid-phase precipitation method, using sodium polysulfide and ammonium polysulfide as starting material and polyethylene glycol-400 (PEG-400) as the surface stabilizing agent. Surface topology, size distribution, surface modification of SNPs with PEG-400, quantitative analysis for the presence of sulfur in nanoformulations, and thermal stability of SNPs were determined by atomic force microscopy (AFM), dynamic light scattering (DLS) plus high-resolution transmission electron microscopy (HR-TEM), fourier transform infrared (FT-IR) spectroscopy, energy dispersive X-ray (EDX) spectroscopy, and thermogravimetric analysis (TGA), respectively. A simultaneous study with micron-sized sulfur (S(0)) and SNPs was carried out to evaluate their fungicidal efficacy against Aspergillus niger and Fusarium oxysporum in terms of radial growth, sporulation, ultrastructural modifications, and phospholipid content of the fungal strains using a modified poisoned food technique, spore-germination slide bioassay, environmental scanning electron microscopy (ESEM), and spectrometry. SNPs expressed promising inhibitory effect on fungal growth and sporulation and also significantly reduced phospholipid content.

Novel Organic‐Inorganic Hybrid Mesoporous Silica Supported Oxo‐Vanadium Schiff Base for Selective Oxidation of Alcohols

Abstract: Novel organic-inorganic hybrid mesopo- rous materials containing diimine moieties inside the pore wall were used for the grafting of an oxo- vanadium Schiff base complex at the mesopore sur- face. The prepared catalyst was found to be highly active and selective for the oxidation of a variety of primary, secondary and a-hydroxy carbonyl com- pounds to the corresponding aldehydes, ketones and 1,2-dicarbonyl compounds using tert-butyl hy- droperoxide as oxidant under mild reaction condi- tions. After completion of the reaction, the catalyst could easily be recovered by simple filtration and could be reused several times without significant change in the catalytic efficiency. Importantly, the catalyst did not show any leaching during the reac- tion, confirming that the prepared catalyst was truly heterogeneous in nature.

Effect of headgroup on DNA-cationic surfactant interactions.

Abstract: The interaction behavior of DNA with different types of hydroxylated cationic surfactants has been studied. Attention was directed to how the introduction of hydroxyl substituents at the headgroup of the cationic surfactants affects the compaction of DNA. The DNA-cationic surfactant interaction was investigated at different charge ratios by several methods like UV melting, ethidium bromide exclusion, and gel electrophoresis. Studies show that there is a discrete transition in the DNA chain from extended coils (free chain) to a compact form and that this transition does not depend substantially on the architecture of the headgroup. However, the accessibility of DNA to ethidium bromide is preserved to a significantly larger extent for the more hydrophilic surfactants. This was discussed in terms of surfactant packing. Observations are interpreted to reflect that the surfactants with more substituents have a larger headgroup and therefore form smaller micellar aggregates; these higher curvature aggregates lead to a less efficient, "patch-like" coverage of DNA. The more hydrophilic surfactants also presented a significantly lower cytotoxicity, which is important for biotechnological applications.