Synthesis and characterization of an unsymmetrical salen Schiff Base: Crystal structure and anticancer evaluation

Abstract

Salen Schiff bases with unsymmetrical substitution play an important role in the fields of organic synthesis, catalysis and material science. In the present work, a new salen type Schiff base (4) was synthesized by the reaction of an unsymmetrical ethylenediamine and 5-chlorosalicyaldehyde to study its anticancer activity through in silico and in vitro assay. The synthesized compound was characterized by UV, FT-IR, NMR and SC-XRD analysis to determine its structure. Spectral and X-ray diffraction studies reveal the existence of enol-enol tautomer in solution and solid states. The geometry-optimized structure of 4 in the gas phase, obtained through DFT studies using the B3LYP/6-311G++(d,p) basis set, also supports the aforementioned tautomer. HOMO-LUMO plots and molecular electrostatic potential (MEP) surface analysis offers valuable information about the electronic properties and reactive sites. Additionally, Hirshfeld surface and 2D fingerprint analysis provides essential insights into the intermolecular interactions that stabilize the crystal structure. Furthermore, the in silico docking analysis of 4 with 3ERT protein revealed a significant correlation with the in vitro findings obtained from MCF-7 cell line experiments.