Density function theory conformational analysis

A review of the Journal of Physical Chemistry A, volume 110, issues 6 and 7, reveals that computational chemistry plays a major or supporting role in the majority of papers. Computational tools include use of large Gaussian basis sets and density functional theory, molecular mechanics, and molecular dynamics. There were quantum chemistry studies of complex reaction schemes to create detailed reaction potential energy surfaces/maps, molecular mechanics and molecular dynamics studies of larger chemical systems, and conformational analysis studies. Spectroscopic methods included photoelectron spectroscopy, microwave spectroscopy circular dichroism, IR, UV-vis, EPR, ENDOR, and ENDOR induced EPR. The kinetics papers focused on elucidation of complex mechanisms and potential energy reaction coordinate surfaces. 

Also in 2-substituted ethanesulphonates,35 the 33S chemical shift has a reverse substituent effect and correlates with both Taft substituent constants and the chemical shift of the carboxylic carbon in related carboxylic acids. It seems that the substituent effect does not depend on conformation, but prevailingly on intramolecular electronic effects. Density functional theory (DFT) calculations of 33S nuclear shielding constants and natural bond orbital (NBO) analysis made it possible to conclude that substituents cause a variation in the polarization of the S-C and S-O bonds and of the oxygen lone pairs of the C — S03 moiety. This affects the electron density in the surroundings of the sulphur nucleus and consequently the expansion or contraction of 3p sulphur orbitals. 

This book starts with seven chapters devoted to methods for the computation of molecular structure molecular mechanics, semiempirical methods, wave function-based quantum chemistry, density-functional theory methods, hybrid methods, an assessment of the accuracy and applicability of these methods, and finally 3D structure generation and conformational analysis. 

Sadlej J, Dobrowolski JCz, Rode JE, Jamroz MH (2007) Density functional theory study on vibrational circular dichroism as a tool for analysis of intermolecular systems (1 1) cysteine-water complex conformations. J Phys Chem A 111 10703-10711... 

Krishnamurty, S., Stefano, M., Mineva, T, Begu, S., Devoisselle, J. M., Goursot, A., Zhu, R., 8c Salahub, D. R. (2008b). Density functional theory-based conformational analysis of a phospholipid molecule (Dimyristoyl Phosphatidylcholine). Journal of Physical Chemistry B, 112, 13433. 

---