02206nas a2200265 4500008004100000022001400041245009500055210006900150260010600219300001400325490000700339520123800346653001901584653001801603653001601621653002001637653002201657100002801679700001701707700002201724700002601746700001801772700002401790856012601814 2010 eng d a0360-319900aInfluence of zeolitic structure on photoreduction property and hydrogen evolution reaction0 aInfluence of zeolitic structure on photoreduction property and h aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLANDbPERGAMON-ELSEVIER SCIENCE LTDcMAR a1911-19200 v353 a

A new photocatalytic material developed by supporting TiO(2) in combination with transition metal ion like cobalt and heteropolyacid (HPA) on the surface is facilitating enhanced photoreduction of water and methyl orange Zeolites being a solid acid play an important role in the electron transfer reaction, facilitated by the Lewis acid sites in the form of aluminium ions In the present work, four different zeolite matrices namely, NaY zeolite, ultrastable zeolite Y, beta zeolite and titanium silicate-1 have been used for the synthesis of new photocatalytic materials These materials have been evaluated for water splitting by an initial screening procedure using methyl orange photoreduction The photocatalyst containing Na Y has emerged as a potential photocatalyst with hydrogen evolution rate of 2730 mu mol/h/g of TiO(2) Hydrogen evolution was not observed for the composite photocatalysts synthesized using the other zeolite matrices It has been observed that physicochemical properties like Si/Al ratio, acidity and basicity of the zeolite support have a tremendous influence on the photoreduction property of these zeolite matrices (C) 2010 Professor T Nejat Veziroglu Published by Elsevier Ltd All rights reserved

10aH(2) evolution10aLewis acidity10aSi/Al ratio10awater splitting10aZeolite structure1 aChatti, Ravikrishna, V.1 aDubey, Nidhi1 aJoshi, Meenal, V.1 aLabhsetwar, Nitin, K.1 aJoshi, P., N.1 aRayalu, Sadhana, S. uhttps://library.ncl.res.in/content/influence-zeolitic-structure-photoreduction-property-and-hydrogen-evolution-reaction-002926nas a2200229 4500008004100000022001400041245014300055210006900198260007300267300001000340490000800350520203500358653001702393653001802410653002702428653001702455653002702472100002502499700002602524700001602550856013002566 2010 eng d a1381-116900aProbing lewis acidity and reactivity of Sn- and Ti-beta zeolite using industrially important moieties: a periodic density functional study0 aProbing lewis acidity and reactivity of Sn and Tibeta zeolite us aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcAUG a36-430 v3293 a

The Lewis acidic nature and reactivity of two industrially important catalysts, viz.. Sn and Ti substituted beta zeolite (T-BEA) are analyzed using a unique combination of structural parameters, energetics and reactivity descriptors. To achieve this purpose, we adsorb the industrially important moieties (L) namely NH(3), H(2)O, CH(3)OH, CH(3)CN on the active sites of T-BEA. The calculations were performed using a periodic density functional method where the valence electrons are described using a plane wave basis set in conjunction with pseudo-potentials for the core electrons. The analysis of the structural properties of these complexes reveals that TO(4) shows typical characteristic splitting 120 degrees/90 degrees, close to bipyramidal geometry as compared to tetrahedral symmetry observed in the bare T-BEA. This is associated with small variations in the framework bond lengths (>= 0.08 angstrom) and a substantially large variation of bond angles (<= 10 degrees) in all the ligand-zeolite complexes. Further in both cases of Sn and Ti substituted beta zeolite, ligand interacts at optimum inter-atomic bond distance. Our interaction energies show that adsorption of all ligand moieties is stronger at Sn center than that of Ti. In general, the order of stability of the different T-BEA adducts is NH(3) > H(2)O > CH(3)OH > CH(3)CN. The ligand interaction is associated with the corresponding bond elongation and bond reduction of the adsorbed molecules on catalyst active site, which can be taken as measure of red or blue shifted frequencies. Finally, the global descriptors of reactivity justify the fact that soft acid, Sn-BEA, interacts strongly with soft bases following the Pearson's HSAB principle. However, hard acid, Ti-BEA interacts with soft bases to form a stable Lewis adduct. Furthermore, the HOMO-LUMO gap of all Sn-BEA-L adducts is lower than that of Ti-BEA-L adducts indicating to its higher Lewis acidic nature compared to Ti-BEA. (C) 2010 Elsevier B.V. All rights reserved.

10aBeta zeolite10aLewis acidity10aLigand-zeolite complex10aPeriodic-DFT10aReactivity descriptors1 aKulkarni, Bhakti, S.1 aKrishnamurty, Sailaja1 aPal, Sourav uhttps://library.ncl.res.in/content/probing-lewis-acidity-and-reactivity-sn-and-ti-beta-zeolite-using-industrially-important-001572nas a2200229 4500008004100000022001400041245012400055210006900179260007300248300001200321490000800333520073000341653001801071653002701089653002601116653001101142653000801153100002201161700001801183700001801201856012301219 2011 eng d a1387-181100aCharacterization of surface acid sites in tin-silicalite-1 (Sn-MFI) molecular sieve by X-ray photoelectron spectroscopy0 aCharacterization of surface acid sites in tinsilicalite1 SnMFI m aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcMAY a236-2400 v1413 a

The nature, strength and density of surface acid sites in Sn-MFI molecular sieves with different Sn-content were characterized by N 1s high resolution photoelectron peak of chemisorbed pyridine in combination with pyridine-IR and TPAD. Two peaks emerged at 399.5 +/- 0.2 and 401.5 +/- 0.2 eV by deconvoluting composite N is peak were assigned to chemisorbed pyridine on weak and relatively strong Lewis acid sites, respectively. The relative percentage of strong Lewis acid sites was found to increase with the decrease of framework Sn content. A close agreement was observed between the ratios of weak Lewis acid sites to strong Lewis acid sites obtained from XPS and TPAD. (C) 2010 Elsevier Inc. All rights reserved.

10aLewis acidity10aPyridine chemisorption10aSiO2/SnO2 molar ratio10aSn-MFI10aXPS1 aNiphadkar, P., S.1 aPatil, K., R.1 aJoshi, P., N. uhttps://library.ncl.res.in/content/characterization-surface-acid-sites-tin-silicalite-1-sn-mfi-molecular-sieve-x-ray-002270nas a2200253 4500008004100000022001400041245017900055210006900234260000800303300001500311490000600326520131200332653004101644653002001685653001801705653001901723653000801742100002601750700002701776700002701803700002701830700002801857856013101885 2023 eng d a2365-654900aSelective one pot multicomponent green synthesis of 3-[(aryl)(arylthio)methyl]-1H-indole derivatives utilizing enhanced Lewis acidic sites of Surfactant-assisted ZnO catalyst0 aSelective one pot multicomponent green synthesis of 3arylarylthi cMAY ae2023007360 v83 a

Five different ZnO nanocrystallites (ZnO-1 to ZnO-5) were successfully synthesized by a surfactant-assisted hydrothermal technique using various surfactants. All the ZnO nanocrystallites are thoroughly characterized by XRD, IR, UV-DRS spectroscopy and FESEM-EDS analysis. Among the synthesized ZnO nanocrystallites, the CTAB-assisted synthesized ZnO-4 exhibited a fine disc-like morphology with a minimum crystallite size (23 nm). Subsequent to reaction optimization studies, the ZnO-4 is utilized as an efficient catalyst for one pot-three component green synthesis of 3-[(aryl)(arylthio)methyl]-1H-indoles (4a-4p) via. condensation of a variety of indoles, aromatic aldehydes and aromatic thiols at room temperature in water. The single-crystal X-ray structure of 3-[(phenyl)(phenylthio)methyl]-1H-indole (4a) is also been reported (CCDC 2170437). The Lewis acidic property of the catalyst-supported probable mechanism is well proposed subsequent to pyridine-IR studies of the ZnO catalysts. Indeed, CTAB-assisted synthesized ZnO-4 was found to be most effective and selective Lewis acid catalyst for the synthesis of a variety of 3-[(aryl)(arylthio)methyl]-1H-indole derivatives in water at ambient temperature with merits like higher yields, lower reaction time, catalyst recovery and reuse.

10a3-[(aryl)(arylthio)methyl]-1H-indole10agreen synthesis10aLewis acidity10aSingle crystal10aZnO1 aSangale, Vijay, B. B.1 aJagtap, Rohidas, M. M.1 aMali, Bhupendra, P. P.1 aGonnade, Rajesh, G. G.1 aPardeshi, Satish, K. K. uhttps://library.ncl.res.in/content/selective-one-pot-multicomponent-green-synthesis-3-arylarylthiomethyl-1h-indole-derivatives