Selected theoretical methods, basis sets and solvation models have been tested in their ability to predict (31)P NMR chemical shifts of large phosphorous-containing molecular systems in solution. The most efficient strategy was found to involve NMR shift calculations at the GIAO-MPW1K/6-311++G(2d,2p)//MPW1K/6-31G(d) level in combination with a dual solvation model including the explicit conside...

This paper reports the (1)H, (13)C and (15)N NMR experimental study of five benzimidazoles in solution and in the solid state ((13)C and (15)N CPMAS NMR) as well as the theoretically calculated (GIAO/DFT) chemical shifts. We have assigned unambiguously the "tautomeric positions" (C3a/C7a, C4/C7 and C5/C6) of NH-benzimidazoles that, in some solvents and in the solid state, appear different (bloc...

the molecular geometry of complex of adenine with 8 water molecules was calculated with hartree-fock (hf). the standard 6-31g(d) basis set has been employed. the existence of c-h…o hydrogen bonds between the water molecules and the hydrophobic part of nucleobase is stablished. we optimized structures and computed interaction energies of all complexes of adenine with water molecules step by step...

In this paper, we report the anisochrony of the fluorine atoms of a CHF₂ group when linked to a pyrazole ring. The pyrazole is part of (4S,7R)-7,8,8-trimethyl-4,5,6,7-tetrahydro-4,7-methano-2H-indazole also known as (4S,7R)-campho[2,3-c]pyrazole, which has two stereogenic centers. Gauge-Independent Atomic Orbital (GIAO)/Becke, 3-parameter, Lee-Yang-Parr (B3LYP)/6-311++G(d,f) calculated 19F chem...

Selected theoretical methods, basis sets and solvation models have been tested in their ability to predict P NMR chemical shifts of large phosphorous-containing molecular systems in solution. The most efficient strategy was found to involve NMR shift calculations at the GIAO-MPW1K/ 6-311++G(2d,2p)//MPW1K/6-31G(d) level in combination with a dual solvation model including the explicit considerat...

The NMR methodology based on spectral aliasing developed at the University of Geneva is reviewed. Different approaches aimed at increasing the resolution in the indirect carbon dimension of 2D heteronuclear experiments are presented with their respective advantages. Applications to HSQC, HMBC and other 2D heteronuclear experiments to the study of natural products and synthesis intermediates are...

N,N-dioctyl-azepanium, -piperidinium and -pyrrolidinium bromides 1-3, have been obtained and characterized by FTIR and NMR spectroscopy. DFT calculations have also been carried out. The optimized bond lengths, bond angles and torsion angles calculated by B3LYP/6-31G(d,p) approach have been presented. Both FTIR and Raman spectra of 1-3 are consistent with the calculated structures in the gas pha...

A generalization of the Moving-Domain Quantum Mechanics/Molecular Mechanics (MoD-QM/MM) hybrid method [Gascon, J. A.; Leung, S. S. F.; Batista, E. R.; Batista, V. S. J. Chem. Theory Comput. 2006, 2, 175-186] is introduced to provide a self-consistent computational protocol for structural refinement of extended systems. The method partitions the system into molecular domains that are iteratively...