DFT Study on the Conformational Isomerism of Schiff baseN,N′-bis(3,3′-dichlorosalicylidene)-2,2′- ethylenedianiline

Dong Seon Shin, Kil Sik Min, Bong Gon Kim

In previous work, we have isolated and characterized two conformers, endo(syn) and exo(anti) as Schiff base, N,N′-bis(3,5-dichlorosalicylidene)-2,2′-ethylenedianiline (L) containing the salicylidene and dianiline moieties. In this paper we have identified the conformational behavior of the Schiff base by DFT calculation using various methods as B3LYP, PBE1PBE, M06-2X, and M11L/6-311G(d,p) levels. And also we were investigated the mechanism of isomerism from the endo type conformer to the exo isomer by DFT calculation. The equilibrium geometries computed by all methods were compared with X-ray diffraction results. The conformational isomerism of the ligand were computed both in gas and in ethanol solution using PBE1PBE/6-311G(d,p). In the results of theoretical calculations, the Schiff-base ligand can be exist several conformational isomers according to torsion angle of main skeleton. We have identified that the more stable conformers are two conformers as endo01 and exo02 conformer. it was identified that The inter-conversion between two conformers can be easily achieved by thermo-control.