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: Excited state & Catalysis. The organization has 3867 authors who have published 10457 publications receiving 220098 citations.

Intramolecular Electron Transfer in (BzImH)[(LOV)2O] (H2L = S-Methyl 3-((2-Hydroxyphenyl)methyl)dithiocarbazate): A Novel μ-Oxo Dinuclear Oxovanadium(IV/V) Compound with a Trapped-Valence (V2O3)3+ Core

Abstract: The mononuclear oxovanadium complexes [VVOL(OR)] (R: Me, 1a; Et, 1b; Pri, 1c) and [VIVOLB] (B: Im, 2a; BzIm, 2b) of the tridentate ONS donor ligand S-methyl 3-((2-hydroxyphenyl)methyl)dithiocarbazate (H2L) are reported. The novel mixed-valence (μ-oxo)divanadium(IV,V) complex (BzImH)[(LVO)2O] (3) was synthesized using 1a and 2b as precursors. All of the complexes were characterized by various physical techniques, including 1H NMR, EPR, and cyclic voltammetry. The X-ray structures of 1a and 3 were determined. Crystals of 1a are triclinic, of space group P1, with a = 11.045(1) A, b = 13.429(4) A, c = 9.611(1) A, α = 100.00(1)°, β = 114.33(1)°, γ = 81.00(1)°, and Z = 4. The asymmetric unit of 1a contains two independent molecules with minor conformational differences. Crystals of 3 are monoclinic, of space group P21/n, with a = 10.10(1) A, b = 20.594(9) A, c = 14.679(8) A, β = 95.28(6)°, and Z = 4. 3 is a bent molecule, with a V−O−V bridge angle of 144.0(6)°. It has a trapped-valence structure in the solid...

Hierarchically porous titanium phosphate nanoparticles: an efficient solid acid catalyst for microwave assisted conversion of biomass and carbohydrates into 5-hydroxymethylfurfural

Abstract: A new hierarchical macro/mesoporous titanium phosphate MTiP-1 has been synthesized through a slow evaporation method by using titanium isopropoxide and orthophosphoric acid as inorganic sources and pluronic P123 as the structure directing agent. Powder X-ray diffraction, FT-IR and electron dispersive spectroscopy (EDS) were used to analyze the framework, structure and composition of the material. The N2 adsorption/desorption isotherm of this material is of type IV, which is characteristic of a mesoporous material and it shows a Brunauer–Emmett–Teller (BET) surface area of 193 m2 g−1 together with an average pore dimension of ca. 7 nm. From scanning electron microscopic (SEM) images it is seen that there is hierarchical porosity in MTiP-1 and the mesoporosity of this material arises due to self-aggregation of tiny spherical particles of dimension ca. 15–20 nm. Transmission electron microscopic (TEM) images show the existence of randomly distributed mesopores in the material. This MTiP-1 material shows very good catalytic activity in the microwave assisted conversion of biomass and carbohydrates into 5-hydroxymethylfurfural (HMF). The catalytic reactions are carried out in different solvents like water, water–methylisobutyl ketone (MIBK), MIBK and dimethylacetamide (DMA)–LiCl. MTiP-1 also catalyzes the direct conversion of cellulose substrates and lignocellulosic biomass, sugarcane bagasse, into HMF.

Self-sorted assembly in a mixture of donor and acceptor chromophores.

Abstract: A simple and novel supramolecular approach for orthogonal self-assembly of donor and acceptor chromophores has been demonstrated. Suitably designed 1,5-dialkoxynaphthalene (DAN) and naphthalene tetracarboxylic acid diimide (NDI) derivatives were used as the donor and acceptor systems, respectively. The molecular design for self-sorting relies upon the precise control over the placement of the self-complementary hydrogen-bonding units (amide functionality) with respect to the individual chromophore. By design, the distances between the two amide groups in the donor and acceptor chromophores are not identical, and consequently the effect of the hydrogen-bonding interaction cannot be maximised in the case of alternate donor-acceptor-type pi-stacking. Thus a relatively weak charge-transfer interaction is expected to be sacrificed, and segregated assembly among the individual chromophores should be enforced by virtue of the much stronger effects of hydrogen bonding and pi-pi stacking. Detailed spectroscopic studies were carried out to probe the mode of self-assembly in various derivatives of the DAN-NDI donor-acceptor pairs to establish the utility of the molecular design as a generalised one for orthogonal self-assembly.