Photophysical properties of porphyrins and their applications to polariton chemistry (a review)

Abstract

Porphyrins are a fundamental class of molecules involved in a multitude of biological and chemical functions ranging from photosynthesis in plants to biomarkers in medicine to optoelectronic devises. Despite the porphyrin molecule being such an important class of molecules known for centuries, its photophysics are surprisingly complex and models describing the spectroscopic behavior of porphyrins did not emerge until the 1950s. This review aims to distil the basics of porphyrin photophysics, describing how the Soret band and the Q band of the molecule are formed. In particular, a discussion of the four orbital theory and Hertzberg-Teller coupling will be conducted, both of which are necessary to understand the spectral properties of the porphyrin molecule. The review further aims to complement previous work discussing the chemical applications of hybrid light-matter states by discussing how the spectroscopic behavior of porphyrins is particularly useful in polariton chemistry.