Hybrid DFT study on non-covalent interactions and their influence on pK's of magnesium-carboxylate complexes.

The electronic structure, stability, acidity, topological properties and charge transfer of octahedral magnesium-carboxylate complexes have been investigated at M05-2X/6-311G** level of theory. The interaction energy studies confirm the stability of the pentahydrated magnesium compounds. The calculated pK values using SMD solvation model through the deprotonation of metal-ion bound water molecule vary from 15.

Spectroscopic investigations and hydrogen bond interactions of 8-aza analogues of xanthine, theophylline and caffeine: a theoretical study.

The structure, spectral properties and the hydrogen bond interactions of 8-aza analogues of xanthine, theophylline and caffeine have been studied by using quantum chemical methods. The time-dependent density functional theory (TD-DFT) and the singly excited configuration interaction (CIS) methods are employed to optimize the excited state geometries of isolated 8-azaxanthine, 8-azatheophylline tautomers and 8-azacaffeine in both the gas and solvent phases. The solvent phase calculations are performed using the polarizable continuum model (PCM).