The physical and chemical properties of Pyrazole and Pyrazoline molecules were theoreticallystudied by Gaussian 03, software with NMR and Molecular orbital calculations at B3LYP/6-31G andB3LYP/6-31+G(d) levels, in gas phase and solution. In this study a comparison effect of threesolvents with different dielectric constants on Pyrazole and Pyrazoline molecules in aspect energyinteraction between...

in this paper, the hydrogen bonding (hb) effects on the nmr chemical shifts of selected atoms in serineand serine-nh2o complexes (from one to ten water molecules) have been investigated with quantummechanical calculations of the 15n and 13c tensors. interaction with water molecules causes importantchanges in geometry and electronic structure of serine.for the compound studied, the most importan...

the physical and chemical properties of pyrazole and pyrazoline molecules were theoreticallystudied by gaussian 03, software with nmr and molecular orbital calculations at b3lyp/6-31g andb3lyp/6-31+g(d) levels, in gas phase and solution. in this study a comparison effect of threesolvents with different dielectric constants on pyrazole and pyrazoline molecules in aspect energyinteraction between...

Ring currents can exert a large effect upon the chemical shielding of NMR resonances. The analytical expression developed by Waugh and Fessenden (Waugh, J. S.; Fessenden, R. W. J. Am. Chem. Soc. 1957, 79, 846) and Johnson and Bovey (Johnson, C. E.; Bovey, F. A. J. Chem. Phys. 1957, 29, 1012) only quantifies the contribution of ring currents to the isotropic component of the shielding tensor. In...

Ring formation in phosphate systems is expected to influence both the magnitude and orientation of the phosphorus (P) nuclear magnetic resonance (NMR) chemical shielding anisotropy (CSA) tensor. Ab initio calculations of the P CSA tensor in both cyclic and acyclic phosphate clusters were performed as a function of the number of phosphate tetrahedral in the system. The calculation of the P CSA t...

We have used ab initio quantum chemical techniques to compute the (13)C(alpha) and (13)C(beta) shielding surfaces for the 14 amino acids not previously investigated (R. H. Havlin et al., J. Am. Chem. Soc. 1997, 119, 11951-11958) in their most popular conformations. The spans (Omega = sigma(33) - sigma(11)) of all the tensors reported here are large ( approximately 34 ppm) and there are only ver...

A density functional method has been used to successfully predict the isotropic 59Co nuclear magnetic resonance (NMR) chemical shifts of the following anionic, cationic and neutral Co(III) complexes: [Co(CN)6], [Co(NH3)6], [Co(NO2)6], [Co(NH3)4CO3], Co(acac)3, and [Co(en)3]. Isotropic chemical shifts are wellreproduced by using Wachters’ cobalt basis set and uniform 6-31G* basis sets on the lig...

The nuclear magnetic shielding tensor is a sensitive probe of the local electronic environment, providing information about molecular structure and intermolecular interactions. The magnetic shielding tensor of the water proton has been determined in hexagonal ice, but in liquid water, where the tensor is isotropically averaged by rapid molecular tumbling, only the trace of the tensor has been m...

polycyclic aromatic hydrocarbons (pahs) are a class of compounds consisting of more than twobenzene rings fused in a linear, angular, or clustered arrangement and do not contain hetero atomsor carry subsistent. pahs originate from various sources. they are primarily formed byincomplete combustion of carbon-containing fuels such as wood, coal, diesel, fat, or tobacco. thepresent study reports an...

Title of Dissertation: Dynamics and Chemical Shielding in a Small Protein from NMR Spin Relaxation Experiments Jennifer Blake Hall, Doctor of Philosophy, 2006 Directed By: Prof. David Fushman Department of Chemistry and Biochemistry NMR spin relaxation spectroscopy is a proven method for characterization of the timescales and amplitudes of intramolecular motions in proteins. In a typical NMR re...