Dissolution nature of the lithium hydroxide by water molecules.

The structures, stabilities, thermodynamic quantities, dissociation energies, infrared spectra, and electronic properties of LiOH hydrated by up to seven water molecules are investigated by using the density-functional theory and the Møller-Plesset second-order perturbation theory (MP2). Further accurate analysis based on the coupled-cluster theory with singles, doubles, and perturbative triples excitations agrees with the MP2 results. The Li-OH stretch mode significantly shifts with the increase of water molecules, and it eventually disappears upon dissociation.

Quantitative structure-activity relationship studies on some series of calcium channel blockers.

A quantitative structure-activity relationship (QSAR) study has been made on four different series of dihydropyrimidine analogs that mimic the most widely studied class of calcium channel blockers (CCBs)-the 1,4-dihydropyridine (DHP) class. The results show that almost all those characteristics that are essential for the activity of 1,4-DHPs are also essential for the activity of dihydropyrimidine analogs. The important characterstics indicated by the present study for dihydropyrimidine analogs are conformation of the molecule, the relative orientation of the aryl ring with respect to the pyrimidine ring, and some substituents capable of forming the hydrogen bonds with the receptor but less bulky in nature, and high molar refractivity of the molecule.