01884nas a2200253 4500008004100000022001400041245011800055210006900173260007300242300001200315490000800327520094000335653002301275653002301298653002701321653002301348653002101371653002401392100001501416700001901431700002401450700002801474856012801502 2006 eng d a0926-860X00aTransesterification of cyclic carbonates with methanol at ambient conditions over tungstate-based solid catalysts0 aTransesterification of cyclic carbonates with methanol at ambien aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcSEP a108-1140 v3123 a

Dimethyl carbonate synthesis with 80 mol% yield is achieved through transesterification of ethylene carbonate with methanol at ambient conditions (RT and atmospheric pressure) using alkali and alkaline-earth tungstates as solid catalysts. The catalysts are efficient even at the sub-ambient temperatures. Reactions under CO2 pressure indicate that CO2 atmosphere retards the transesterification reaction completely below 100 degrees C. Experimental conditions of 150 degrees C and 3.4 MPa CO2 pressure are required to obtain maximum DMC yield of 71 mol%. Synthesis of DMC by one-pot synthesis using epoxide, CO2 and methanol is not as effective as that by two-step method with the present catalyst system. Raman and IR spectra of methanol-interacting tungstates indicate the formation of a methoxide ion species adsorbed at the catalyst surface as one possible reaction intermediates. (C) 2006 Elsevier B.V. All rights reserved.

10aDimethyl carbonate10aethylene carbonate10aheterogeneous catalyst10aRaman spectroscopy10asodium tungstate10atransesterification1 aSankar, M.1 aNair, Madhavan1 aMurty, K., V. G. K.1 aManikandan, Palanichamy uhttps://library.ncl.res.in/content/transesterification-cyclic-carbonates-methanol-ambient-conditions-over-tungstate-based-001826nas a2200217 4500008004100000022001400041245016400055210006900219260007100288300001600359490000800375520093400383100002301317700001901340700001501359700002101374700002801395700002401423700003201447856012901479 2009 eng d a1932-744700aImmobilization of phosphotungstic acid (PTA) on imidazole functionalized silica: evidence for the nature of PTA binding by solid state NMR and reaction studies0 aImmobilization of phosphotungstic acid PTA on imidazole function a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcDEC a21114-211220 v1133 a

Phosphotungstic acid (PTA) immobilized onto imidazole functionalized fumed silica and was used its an efficient catalyst for epoxidation of a variety of olefins using aqueous H(2)O(2) as all oxidant. Negligible leaching of PTA under the reaction conditions employed indicates a strong interaction between PTA and imidazole The immobilized catalysts Could be separated and reused after the catalytic cycle Evidence for the heterogenization of PTA oil the imidazole functionalized fumed silica has been inferred from different spectroscopic techniques like IR, UV-vis, and NMR. Importantly, the nature of binding of PTA oil the support has been studied in detail by solid state NMR spectroscopy using (15)N labeled imidazole Support. It is clear from the NMR Studies that the effective heterogenization of PTA is mainly due to imidazolium ion Formation oil the support by the acidic protons of PTA and the resultant ion pair

1 aSofia, L., T. Aany1 aKrishnan, Asha1 aSankar, M.1 aRaj, N., K. Kala1 aManikandan, Palanichamy1 aRajamohanan, P., R.1 aAjithkumar, Thalasseril, G. uhttps://library.ncl.res.in/content/immobilization-phosphotungstic-acid-pta-imidazole-functionalized-silica-evidence-nature-002343nas a2200277 4500008004100000245009800041210007000139260000800209300001000217490000800227520145200235653002001687653002101707653002101728653001701749653001701766653001901783653001901802100001601821700001801837700001701855700001501872700001501887700002301902856014001925 2017 eng d00aFacile synthesis of β-functionalized “push-pull” Zn(II) porphyrins for DSSC applications0 aFacile synthesis of βfunctionalized pushpull ZnII porphyrins for cDEC a56-660 v1473 a

Three new β-substituted “push-pull” Zn(II) porphyrin dyes with various electron donors at meso-positions and cyanoacetic acid as acceptor at β-position have been designed and synthesized. These porphyrins have been characterized by UV-Vis, Fluorescence, 1H NMR and 13C NMR spectroscopic techniques and cyclic voltammetric studies. The Soret and Q band of Zn(II) porphyrin dyes were found to be red-shifted (30–35 nm) as compared to ZnTPP. The fluorescence quenching and the decrement in quantum yield and lifetime suggest intramolecular charge transfer from donor to acceptor. Zn porphyrins exhibited anodic shift in their first redox potentials (0.03–0.11 V) as compared to ZnTPP. The HOMO-LUMO energy levels of Zn porphyrin dyes were compared with the conduction band of TiO2 and the electrolyte I−/I3 −. The HOMO levels of all the dyes are sufficiently higher than the energy level of electrolyte I−/I3 − and LUMO levels significantly lower than the conduction band of TiO2 which reflect the feasibility of facile electron-transfer. ZnT(Mes)P(CN-COOH) has been co-sensitized with N719 dye to further improve the PCE efficiency. These dyes displayed power conversion efficiency (PCE) of η = 1.72–3.13% where co-sensitized ZnT(Mes)P(CN-COOH) (N719) dye demonstrated maximum PCE efficiency up to 5.35%, with a Jsc of 11.8 mA cm−2, a Voc of 630 mV and a fill factor (FF) of 72% due to better light harvesting capacity.

10acharge transfer10aConduction Bands10aCyanoacetic Acid10aElectrolytes10aFloorescence10aRedox Reaction10azinc compounds1 aPrakash, K.1 aManchanda, S.1 aSudhakar, V.1 aSharma, N.1 aSankar, M.1 aKrishnamoorthy, K. uhttps://library.ncl.res.in/content/facile-synthesis-%CE%B2-functionalized-%E2%80%9Cpush-pull%E2%80%9D-znii-porphyrins-dssc-applications