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.

Radical pathway in catecholase activity with zinc-based model complexes of compartmental ligands.

Abstract: Four dinuclear and three mononuclear ZnII complexes of phenol-based compartmental ligands (HL1–HL7) have been synthesized with the aim to investigate the viability of a radical pathway in catecholase activity. The complexes have been characterized by routine physicochemical studies as well as X-ray single-crystal structure analysis: [Zn2(H2L1)(OH)(H2O)(NO3)](NO3)3 (1), [Zn2L2Cl3] (2), [Zn2L3Cl3] (3), [Zn2(L4)2(CH3COO)2] (4), [Zn(HL5)Cl2] (5), [Zn(HL6)Cl2] (6), and [Zn(HL7)Cl2] (7) [L1–L3 and L5–L7 = 2,6-bis(R-iminomethyl)-4-methylphenolato, where R= N-ethylpiperazine for L1, R = 2-(N-ethyl)pyridine for L2, R = N-ethylpyrrolidine for L3, R = N-methylbenzene for L5, R = 2-(N-methyl)thiophene for L6, R = 2-(N-ethyl)thiophene for L7, and L4 = 2-formyl-4-methyl-6-N-methylbenzene-iminomethyl-phenolato]. Catecholase-like activity of the complexes has been investigated in methanol medium by UV–vis spectrophotometric study using 3,5-di-tert-butylcatechol as model substrate. All complexes are highly active in catal...

Synthesis, Characterization, and Biofuel Application of Mesoporous Zirconium Oxophosphates

Abstract: Mesoporous zirconium oxophosphates have been synthesized through the evaporation-induced self-assembly (EISA) method in the presence of an amphiphilic block copolymer, pluronic F127 as template under strongly acidic conditions. The mesophases of the materials were analyzed by using small-angle powder X-ray diffractions and transmission electron microscopic (TEM) image analysis. N2 adsorption−desorption studies showed high surface area (260−312 m2 g−1) and narrow pore size distribution (4.5−5.5 nm) for the materials. NH3-TPD and pyridine-IR analyses suggested the presence of strong Lewis and Bronsted acid sites. These mesoporous materials showed excellent catalytic activity in biodiesel reaction for the effective conversion of the long chain fatty acids to their respective methyl esters. The maximum biodiesel yield was about 91% under optimal reaction conditions. High catalytic activity could be attributed to the large surface area and the presence of large number of acidic sites located at the surface of ...

Water gelation of an amino acid-based amphiphile

Abstract: The water immobilization by a simple amino acid-containing cationic surfactant was investigated. A variety of techniques, such as (1)H NMR spectroscopy, circular dichroism (CD), steady-state fluorescence spectroscopy, and field-emission scanning electron microscopy (FESEM) were applied to determine the formation and architecture of the hydrogel. The new gelator with a minimum gelation concentration (MGC) of 0.3 % w/v shows prolonged stability and a low melting temperature (39 degrees C). (1)H NMR experiments revealed that intermolecular hydrogen bonding between the amide groups and pi-pi stacking of the indole rings are the two regulating parameters for gelation. Furthermore, fluorescence studies with 8-anilino-1-naphthalenesulfonic acid (ANS) as the probe indicate the participation of hydrophobicity during gelation. The luminescence study using both ANS and pyrene, along with FESEM results, indicate a critical concentration, well below the MGC, at which fibres begin to form. These cross-link further to give thicker fibers, leading to the formation of a hydrogel (0.3 % w/v). This new hydrogelator expresses high supramolecular chirality, as evidenced by the CD spectra. In addition, the gelator molecule was found to be nontoxic up to a concentration of 4 mM (0.2 % w/v). The high supramolecular chirality, prolonged stability, low melting point, and biocompatibility of the molecule make it a focus of chemical and biological interest.

Solvation dynamics of DCM in human serum albumin

Abstract: Solvation dynamics of 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl) 4H-pyran (DCM) in aqueous solution of a protein, human serum albumin (HSA), is studied using picosecond time-resolved emission spectroscopy. The solvation dynamics of DCM bound to HSA is found to be biexponential with one component of 600 ± 100 ps (25%) and a very long component of 10 ± 1 ns (75%). This indicates that the motion of the water molecules in the vicinity of the protein is highly constrained.

Dinuclear zinc(II) complexes of tetraiminodiphenol macrocycles and their interactions with carboxylate anions and amino acids. Photoluminescence, equilibria, and structure.

Abstract: The reaction equilibria [H4L]2+ + Zn(OAc)2 ⇌ [Zn(H2L)]2+ + 2HOAc (K1) and [Zn(H2L)]2+ + Zn(OAc)2 ⇌ [Zn2L]2+ + 2HOAc (K2), involving zinc acetate and the perchlorate salts of the tetraiminodiphenol macrocycles [H4L1-3](ClO4)2, the lateral (CH2)n chains of which vary between n = 2 and n = 4, have been studied by spectrophotometric and spectrofluorimetric titrations in acetonitrile. The photoluminescence behavior of the complexes [Zn2L1](ClO4)2, [Zn2L2(H2O)2](ClO4)2, [Zn2L2(μ-O2CR)](ClO4) (R = CH3, C6H5, p-CH3C6H4, p-OCH3C6H4, p-ClC6H4, p-NO2C6H4), and [Zn2L3(μ-OAc)](ClO4) have been investigated. The X-ray crystal structures of the complexes [Zn2L2(H2O)2](ClO4)2, [Zn2L3(μ-OAc)](ClO4), and [Zn2L2(μ-OBz)(OBz)(H3O)](ClO4) have been determined. The complex [Zn2L2(μ-OBz)(OBz)(H3O)](ClO4) in which the coordinated water molecule is present as the hydronium ion (H3O+) on deprotonation gives rise to the neutral dibenzoate-bridged compound [Zn2L2(μ-OBz)2]·H2O. The equilibrium constants (K) for the reaction [Zn2L2(H2O)...