A Computational Study on the Stability of Dapdiamide D Conformers

The conformational analysis of the organic compounds specially the biologically active natural products has attracted the consideration of different research groups. Therefore, in the present study the MP2/6-311+g(d,p)//B3LYP/6-311+g(d,p) level of theory was used to study the conformations of dapdiamide D. The identity of interactions in selected conformers was studied using atom in molecule approach. The energies of hydrogen bonding and Van der Waals interactions were calculated using the potential energy density V(r) at the bond critical point. An interaction between carbonyl and nitrogen of the amide functional group is evident, in most of the cases. This interaction creates a boat-like seven member-ring. The interaction between amine and hydrogen of the amide functional groups is important as well. This interaction forms a five-member ring. The results showed that the potential energy density V(r) and electron density at the bond critical points can be used as a criteria to determine the strength of the interactions.