THEORETICAL STUDY ON THE ROTATION BARRIER AND ENERGY DIFFERENCE BETWEEN MALEALDEHYDE AND FUMARALDEHYDE AND THEIR ANALOGUES (Y = O, S, SE)‪.‬

Byline: Lim Kie Zen, Hassan Hadi Abdallah, Chong Shu Xian and Wong Zhi Xiang ABSTRACT: But-2-enedial consists of cis and trans isomers which are known as malealdehyde and fumaraldehyde, respectively. Density functional theory (DFT/B3LYP) and Moller-Plesset perturbation theory (MP2) are used for calculating the optimized structure for malealdehyde and fumaraldehyde conformers with sulphur and selenium analogues. The basis set 6-311++G(d,p) is applied for all calculations. Dipole moments, charges and vibrational frequencies were assigned and reported. The rotation barrier, B1 between malealdehyde and fumaraldehyde was investigated in both gas and solution phase. Nine solvents were used in optimizing molecules in solution phase by using Integral Equation Formalism Polarization Continuum Model with DFT method. The energy difference, DE of the cis and trans isomers were also calculated. Optimized malealdehyde, fumaraldehyde and transition state geometries have C2v, C2h and C1 point group respectively.