MP2 and DFT studies of beta-D-neocarrabiose and beta-D-neocarrabiose monohydrate

MP2 and density functional theory calculations have been carried out on beta-D-neocarrabiose and its mono hydrate in order to determine the conformational preferences of these molecules in the gas phase and in solvent. Relaxed iso-energetic maps were first obtained using B3LYP/6-31G(d). Then, the lower energy conformers were further fully optimized using B3LYP, B3PW91 and MP2 methods. Overall, it was demonstrated that a lower energy conformer corresponding to the couple of dihedral angles (Phi,Psi)= (69 degrees,-117 degrees) is detected either in the gas phase or in solvent provided that full optimizations are performed on the conformers corresponding to the minima detected from the iso-energetic maps. (C) 2016 Elsevier B.V. All rights reserved.