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.

Estimation of the van der Waals radii of the d-block elements using the concept of bond valence

Abstract: It is assumed that the valence v of the bond between a metal M and a non-metal X is negligibly small but not equal to zero when the distance between them is equal to the sum of their R values; the R value derived here for a d-block element with the Pauling RX values does not seem to depend on the oxidation state of M.

A Bottom-Up Approach toward Fabrication of Ultrathin PbS Sheets

Abstract: Two-dimensional (2D) sheets are currently in the spotlight of nanotechnology owing to high-performance device fabrication possibilities. Building a free-standing quantum sheet with controlled morphology is challenging when large planar geometry and ultranarrow thickness are simultaneously concerned. Coalescence of nanowires into large single-crystalline sheet is a promising approach leading to large, molecularly thick 2D sheets with controlled planar morphology. Here we report on a bottom-up approach to fabricate high-quality ultrathin 2D single crystalline sheets with well-defined rectangular morphology via collective coalescence of PbS nanowires. The ultrathin sheets are strictly rectangular with 1.8 nm thickness, 200–250 nm width, and 3–20 μm length. The sheets show high electrical conductivity at room and cryogenic temperatures upon device fabrication. Density functional theory (DFT) calculations reveal that a single row of delocalized orbitals of a nanowire is gradually converted into several paralle...

Polyurethane-Grafted Chitosan as New Biomaterials for Controlled Drug Delivery

Abstract: The present investigation focuses on the grafting of chitosan (CHT) with diisocyanate terminated polyurethane. Solid state 13C NMR spectroscopy confirms the grafting reaction and the degree of substitution (DS) was calculated from the deconvoluted area of the corresponding NMR peak. Solubility studies, swelling behavior and contact angle measurements support the hydrophobic chemical modification on CHT molecules and higher DS leads to the cross-linking of CHT molecules having polyurethane bridges resulting insolubility and regulated swelling in the graft copolymer. Molecular relaxations phenomena due to the constraint associated with the grafting have been revealed using spin–lattice relaxation tine (T1) and shifting of peak position in tan δ curve toward lower temperature in dynamic mechanical measurement at constant frequency indicating flexible nature of graft copolymers as compared to pure CHT. The sustained drug delivery has been achieved using graft copolymers vis-a-vis pure CHT following the Fickia...

Aerobic Radical‐Cascade Alkylation/Cyclization of α,β‐Unsaturated Amides: an Efficient Approach to Quaternary Oxindoles

Abstract: An efficient method for the aerobic radical-cascade alkylation/cyclization of α,β-unsaturated amides to afford functionalized oxindoles with a C3 quaternary stereocenter is described. The process is based on the generation of valuable alkyl radicals through sustainable aerobic C-H activation of aldehydes followed by decarbonylation using O2 as the sole oxidant. This method features a broad substrate scope, inexpensive alkyl radical precursors, and convenient reagents. Finally, the method was successfully applied to the synthesis of alkyl analogues of tetrahydrofuranoindoline and (±)-esermethole.

Perovskite Nanocrystal Heterostructures: Synthesis, Optical Properties, and Applications

Abstract: Bringing together two nanostructures of different materials in a single building block can create a new platform where both can share their electronic and optical characteristics. While these have ...