Electronic structural studies of newly synthesized sterically hindered analogues of meta-benziporphodimethene and its metal complexes

Abstract

The presence of syn and anti-conformers in tetramethyl substituted meta-benziporphodimethenes has been well studied. Herein, we report a new sterically hindered hexaaryl-m-benziporphodimethene (m-BPDM) using benzaldehyde and its Zn(II) and Cd(II) complexes. The UV-Vis, mass, and NMR characterized data confirmed the synthesis of these m-BPDM analogues. Time-dependent DFT analysis has been performed to visualize the distribution of electron density at the HUMO and LUMO. The present work primarily focuses on the comparative study of the syn,anti-conformers of metallated meta-benziporphodimethenes upon increasing the bulkiness at the sp³meso carbon atoms. The placement of –H, –CH₃, and –Ph groups at the C6- and C21-positions of m-BPDM greatly impacts the stability of these conformers, which has been explored. Along with this, a comparison has also been drawn between the reported X-ray crystallographic geometry and B3LYP/LANL2DZ optimized structures for free-base tetramethyl-m-BPDM and its Zn(II) and Cd(II) complexes. The article sums up the much-anticipated results from the tetramethylene analogue of m-BPDM, which were contrary to that of tetraphenylene analogues.