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.

Novel Nitrogen and Sulfur Rich Hyper-Cross-Linked Microporous Poly-Triazine-Thiophene Copolymer for Superior CO2 Capture

Abstract: A novel synthetic strategy has been developed for the preparation of hyper-cross-linked microporous copolymers, HMC-1, HMC-2, and HMC-3, by using 2,4,6-tri(thiophen-2-yl)-1,3,5-triazine and thiophene monomers in their different molar ratios in the presence of anhydrous FeCl3 in chloroform under solvothermal conditions at 150 °C. These polymers are highly porous and robust materials, exhibiting very high BET surface areas and supermicroporosity. The presence of triazine and thiophene moieties within the copolymer network increases the electron donating basic N and S sites in the porous frameworks. Thus, these porous polymers displayed efficient adsorption of Lewis acidic CO2 molecules and showed good CO2/N2 adsorption selectivity. The maximum CO2 uptake of 14.2 mmol g–1 at 273 K under 3 bar pressure has been observed.

A triazine-based porous organic polymer: a novel heterogeneous basic organocatalyst for facile one-pot synthesis of 2-amino-4H-chromenes

Abstract: A new triazine-based porous organic polymer TPOP-2 has been synthesized through the reaction between cyanuric chloride and tris(2-aminoethyl)amine in anhydrous 1,4-dioxane under N2 atmosphere. The porous polymer has been characterized by powder X-ray diffraction, N2 sorption, HR TEM, FE SEM, 13C CPMAS NMR, CO2-TPD, TG-DTA and FT IR spectroscopic tools. Due to the high density of amine and triazine functional groups, this porous polymer is N-rich and possesses excellent surface basicity, and is utilized as a heterogeneous metal-free basic organocatalyst for the one-pot three-component condensation reaction of aromatic aldehyde, activated phenols (resorcinol and 2-naphthol) and malononitrile for the synthesis of 2-amino-chromenes under solvent-free or aqueous conditions. The ease of catalyst synthesis and its efficient use for five consecutive cycles without noticeable loss in catalytic activity suggest significant future potential of this new N-rich porous organic polymer material for a wide range of base catalyzed reactions.

Doping Iron in CsPbBr3 Perovskite Nanocrystals for Efficient and Product Selective CO2 Reduction.

Abstract: Lead halide perovskite nanocrystals have recently emerged as an efficient optical material for light harvesting. While these have been extensively studied for obtaining bright emissions, their use as catalysts for enhancing the rate of chemical reactions has been explored little. Considering their importance in catalysis, herein, Fe(II)-doped CsPbBr3 perovskite nanocrystals have been explored for photocatalytic reduction of CO2. In comparison to undoped CsPbBr3, doped nanocrystals showed enhanced catalytic activity and also predominantly led to evolution of CH4 instead of CO. The observation of a reverse trend of predominated CH4 evolution in doped nanocrystals rather than CO observed for undoped nanocrystals was correlated to the adsorption/desorption energy of respective products established theoretically earlier. This selective evolution of major products on doping remained unique and also a step forward for understanding more regarding light to chemical energy conversions using perovskite nanocrystals.

Syntheses, Structural Analyses, and Magneto-Structural Correlations of Three Polymeric Fe(II) Complexes with Azide Ligand

Abstract: Three new metal-organic polymeric complexes, [Fe(N(3))(2)(bpp)(2)] (1), [Fe(N(3))(2)(bpe)] (2), and [Fe(N(3))(2)(phen)] (3) [bpp = (1,3-bis(4-pyridyl)-propane), bpe = (1,2-bis(4-pyridyl)-ethane), phen = 1,10-phenanthroline], have been synthesized and characterized by single-crystal X-ray diffraction studies and low-temperature magnetic measurements in the range 300-2 K. Complexes 1 and 2 crystallize in the monoclinic system, space group C2/c, with the following cell parameters: a = 19.355(4) A, b = 7.076(2) A, c = 22.549(4) A, beta = 119.50(3) degrees, Z = 4, and a = 10.007(14) A, b = 13.789(18) A, c = 10.377(14) A, beta = 103.50(1) degrees, Z = 4, respectively. Complex 3 crystallizes in the triclinic system, space group P(-)1, with a = 7.155(12) A, b = 10.066(14) A, c = 10.508(14) A, alpha = 109.57(1) degrees, beta = 104.57(1) degrees, gamma = 105.10(1) degrees, and Z = 2. All coordination polymers exhibit octahedral Fe(II) nodes. The structural determination of 1 reveals a parallel interpenetrated structure of 2D layers of (4,4) topology, formed by Fe(II) nodes linked through bpp ligands, while mono-coordinated azide anions are pendant from the corrugated sheet. Complex 2 has a 2D arrangement constructed through 1D double end-to-end azide bridged iron(II) chains interconnected through bpe ligands. Complex 3 shows a polymeric arrangement where the metal ions are interlinked through pairs of end-on and end-to-end azide ligands exhibiting a zigzag arrangement of metals (Fe-Fe-Fe angle of 111.18 degrees) and an intermetallic separation of 3.347 A (through the EO azide) and of 5.229 A (EE azide). Variable-temperature magnetic susceptibility data suggest that there is no magnetic interaction between the metal centers in 1, whereas in 2 there is an antiferromagnetic interaction through the end-to-end azide bridge. Complex 3 shows ferro- as well as anti-ferromagnetic interactions between the metal centers generated through the alternating end-on and end-to-end azide bridges. Complex 1 has been modeled using the D parameter (considering distorted octahedral Fe(II) geometry and with any possible J value equal to zero) and complex 2 has been modeled as a one-dimensional system with classical and/or quantum spin where we have used two possible full diagonalization processes: without and with the D parameter, considering the important distortions of the Fe(II) ions. For complex 3, the alternating coupling model impedes a mathematical solution for the modeling as classical spins. With quantum spin, the modeling has been made as in 2.

Nanoparticle-Induced Controlled Biodegradation and Its Mechanism in Poly(ε-caprolactone)

Abstract: Poly(e-caprolactone) (PCL)/layered silicate nanocomposites have been prepared via solution route. Two different organically modified nanoclays were used to compare the variation in properties based on organic modifications. The nanostructures, as observed from wide-angle X-ray diffraction and transmission electron microscopy, indicate intercalated and partially exfoliated hybrids depending on the nature of organic modification in nanoclay. The nanohybrids exhibit significant improvement in thermal and mechanical properties of the matrix as compared to neat polymer. The nanoclays act as nucleating agent for the crystallization of PCL. The biodegradability of pure PCL and its nanocomposites have been studied under controlled conditions in enzyme, pure microorganism (fungi), compost, Ganges water, and alkaline buffer solution. The rate of biodegradation of PCL has enhanced dramatically in nanohybrids and depends strongly on the media used. Scanning confocal, electron, and atomic force microscopes have used t...