In this study, we have investigated the relationship between aromaticity and photophysical properties of trifluoromethyl-substituted /π porphycenes by using theoretical calculations and various spectroscopic methodologies. Interestingly, we have found that the HOMO-LUMO gap of π porphycene is larger than that of π porphycene, which is in a sharp contrast with those of typical [4n]/[4n+2]π porphyrinoids. Based on our observations, we demonstrate that the origin of this contrasting feature of π porphycene arises from the uniquely large energy splitting between LUMO and LUMO+1 of π porphycene compared with other aromatic [4n+2]π porphyrinoids with nearly degenerate LUMO/LUMO+1. Consequently, we can propose that the energy difference between LUMO and LUMO+1 levels of aromatic [4n+2]π porphyrinoids is an important factor in determining the electronic nature of their corresponding antiaromatic [4n]π porphyrinoids. Moreover, to the best of our knowledge, this is the first study to illustrate the photophysical properties of porphycenes with [4n]π electronic circuits. Mind the gap: Photophysical properties of trifluoromethyl-substituted π porphycenes were investigated theoretically and spectroscopically. Compared with other [4n]π porphyrinoids, the π porphycene molecule exhibits quite unique photophysical behaviors that originate from a large HOMO-LUMO gap (see image).
All Science Journal Classification (ASJC) codes
- Organic Chemistry