David R.P. Almeida

Density functional molecular computations on protonated serotonin in the gas phase and various solvent media

Abstract 5-Hydroxytryptamine (serotonin) was geometry optimized at the B3YP/6-31G(d) level of theory to determine the energetically most favourable conformations of the aromatic hydroxyl group and the protonated ethylamine side chain. The hydroxyl group was found to be most stable at anti for all conformations, and the two lowest energy gas phase conformers found were: χ 2 = g + , χ 3 = g − and χ 2 = g − , χ 3 = g + . The protonated amino group was found equally stable at g + , g − and anti . The transition structures linking each gas phase minimum were also computed. Minima found were subjected to solvation calculations in chloroform, DMSO, ethanol and water, which shifted their relative stabilities.

An ab initio and DFT conformational analysis of unsubstituted and ω-substituted ethyl-benzene: (Ph-CH2-CH2-Z; Z = -H, -F, -NH3+, -CH3)

Abstract A series of compounds of Ph–CH 2 –CH 2 –Z, with substituents Z=–H, –F, –NH 3 + , and –CH 3 , were subjected to conformational analysis. Conformational potential energy surfaces were generated and their minima were geometrically optimized at three levels of theory. The relative stabilities of the minima correlated with the electron withdrawing nature of the substituents (Z).