Chirogenesis in Zinc Porphyrins: Theoretical Evaluation of Electronic Transitions, Controlling Structural Factors and Axial Ligation.

Abstract

In the present work, sixteen different zinc porphyrins (possessing different meso substituents) with and without a chiral guest were modelled using DFT and TD‐DFT approaches in order to understand the influence of various controlling factors on electronic circular dichroism (ECD) spectra. Two major aspects are influenced by these factors: excitation energy of the electronic transitions and their intensity. In the case of excitation energy, the influence increases in the following order: orientation of the peripheral substituents<substituent's nature<axial ligation. However, the deformation of the porphyrin plane does not affect the excitation energies. In the case of intensity, the influence increases as follows: substituent's nature<conrotatory orientation of the peripheral substituents<deformation of the porphyrin plane<disrotatory orientation of the peripheral substituents<axial ligation.