02487nas a2200265   4500008004100000022001400041245020700055210006900262260007300331300001200404490000800416520142000424653002101844653003601865653002101901653001701922653002401939653002601963653002901989653001402018653001202032100002702044700001902071856013102090       2009                        eng d  a1387-181100aDependence of Si-29 NMR chemical shielding properties of precursor silicate species, Q(0) on its local structure at the pre-nucleation stages of zeolite synthesis - a DFT based computational correlation0 aDependence of Si29 NMR chemical shielding properties of precurso  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcJUN  a105-1130 v1223 a<p>The exploration for new zeolite structures with tailored framework architectures for enhanced catalytic applications requires the knowledge about their nucleation and crystallization at molecular level. Nuclear magnetic resonance (NMR) is one of the most widely tried techniques to understand this. However, by NMR, it is difficult to accurately assign the molecular level precursor silicate structures at the pre-nucleation stages of zeolite synthesis. Hence, understanding the chemical shielding of such precursor molecules using quantum mechanical (QM) computations is extremely useful. Alkali is a fundamental component in the alkali based hydrothermal zeolite synthesis and its nature plays a major role. In the present report, we attempt to understand the differences in the local structure of the primary building block such as Si(OH)(4) (Q(0) silicate species) due to the associated alkali and their influence on NMR chemical shielding properties. Present work reports the calculation of Si-29 NMIR isotropic chemical shifts of T species with different cations such as Na, K and Ca using density functional theory (DFT). Results of natural bonding orbital (NBO) analysis, Perturbation theory energy analysis and electron density iso-surfaces were employed to obtain a deeper insight about their influence on the chemical shielding and on zeolite synthesis. (C) 2009 Elsevier Inc. All rights reserved.</p>10aAb initio method10aDensity Functional Theory (DFT)10aElectron density10aNBO analysis10aPerturbation theory10aQ(0) silicate species10aSi-29 NMR chemical shift10asynthesis10azeolite1 aSelvaraj, Kaliaperumal1 aKurian, Reshmi  uhttp://library.ncl.res.in/content/dependence-si-29-nmr-chemical-shielding-properties-precursor-silicate-species-q0-its-local-002040nas a2200241   4500008004100000022001400041245009800055210006900153260014100222300001200363490000700375520108300382653002801465653002801493653001401521653001301535100002001548700002701568700002701595700003001622700002701652856011901679       2013                        eng d  a1516-143900aNovel vanadium n-propylamino phosphate catalyst: synthesis, characterization and applications0 aNovel vanadium npropylamino phosphate catalyst synthesis charact  aLABORATORIA DE MATERIAIS VITREOS, CAIXA POSTAL 676, SAO CARLOS, 13565-905SP, BRAZILbUNIV FED SAO CARLOS, DEPT ENGENHARIA MATERIALScJAN  a181-1890 v163 a<p>A novel, lamellar type Vanadium n-propylamino phosphate catalyst is synthesized and characterized by using various physicochemical techniques such as Powder X-ray diffraction, Scanning electron microscopy/Energy dispersive X-ray analysis, Thermogravimetry/Differential thermal analysis, Fourier transform Infrared analysis, Electron spin resonance spectroscopy, Ultraviolet - Visible Diffuse reflectance spectroscopy, X-ray Photoelectron spectroscopy, P-31 Magic angle spinning Nuclear Magnetic Resonance spectroscopy and Catalytic applications toward Octahydroquinazolinone synthesis. It is found that the n-propylamine is present as sandwich between Vanadyl phosphate layers. Most of the Vanadium is present as V4+ ions in tetrahedral co-ordination. Vanadium n-propylamino phosphate catalyses Octahydroquinazolinone synthesis more effeciently and the optimum conditions required for Octahydroquinazolinone synthesis are, Benzaldehyde (2 mmol), Dimedone (2 mmol), Urea (4 mmol), Methanol + Water (1:1, 5 mL) and Catalyst (0.05 g). A plausible mechanism is also proposed.</p>10an-propylamino phosphate10aoctahydroquinazolinones10asynthesis10aVanadium1 aAnumula, Rajini1 aNookaraju, Muralasetti1 aSelvaraj, Kaliaperumal1 aReddy, Ingala, Ajit Kumar1 aNarayanan, Venkatathri  uhttp://library.ncl.res.in/content/novel-vanadium-n-propylamino-phosphate-catalyst-synthesis-characterization-and-0