A Density-Functional Study on the Change of Q/B-Band Intensity Ratio of Zinc Tetraphenylporphyrin in Solvents

Abstract

We study the Q/B-band intensity ratio (I Q/B ) of zinc tetraphenylporphyrin (ZnTPP) in various solvents from its electronic structure by utilizing the polarizable continuum model and density functional theory (DFT). The selected solvents are benzene, chloroform, dichloromethane, pyridine and methanol. The Q/B-band intensity ratio is simplified by dipole strength of HOMO ¼ LUMO and HOMO¹1 ¼ LUMO from a two-level system, or f Q/B . The results show the linear correlation between the calculated f Q/B and the experimental I Q/B . This suggests that I Q/B of ZnTPP in solvents can be studied from dipole strength ratio from a two-level system, where the orbitals are determined by DFT. The change of f Q/B is due to the change of frontier molecular orbital shape of ZnTPP which are dominantly constructed by p z -orbital. In the core part of ZnTPP, the change of p z -orbital shape is inversely proportional to the solvent dielectric constant, ¥.

The transition state conformational effect on the activation energy of ethyl acetate neutral hydrolysis

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