Mechanistic appraisal of the charge-transfer complexes of promethazine with chloranil: A modelling approach

Various mechanisms are often used to explain the interaction between electr on donors and accepters, Commonly proposed mechanisms are those in which th e acceptor interacts with the aromatic pi -systems in the donor molecule or the acceptor forms a weak interaction of the Lewis acid with Lewis base ty pe. In this study, the above mechanisms were examined as well as other poss ible mechanisms. Promethazine was chosen as the model drug containing aroma tic systems capable of pi-pi interaction as well as,V-methyl group capable of forming a complex with the weak Lewis acid, p-chloranil. Our modelling s tudies revealed that the situation where the p-chloranil interacts with a p rotonated N-methyl group is the most significant mechanism of interaction, based on the calculated energies for the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), the Tripes force held energy terms and also the stability of the complexes during molecular dynamics simulations.