The project is directed towards aromaticity effects in electronically excited states. We will apply quantum chemical calculations using DFT and electron correlated wave function methods (primarily CASSCF and CASPT2, as well as coupled cluster methods), and the calculations are closely connected to on-going experimental studies in the group.
The topic concerns excited state aromaticity and is based on Baird's rule which tells that species with 4npi-electrons are aromatic and those with 4n+2 are antiaromatic in the lowest pipi* excited triplet and singlet states. A series of processes and properties can be examined and rationalized in terms of excited state aromaticity. In the next we will use calculations to (i) examine singlet state homoaromaticity, i.e., aromaticity where the aromatic cycle in part goes through space, (ii)
design of new compounds with low singlet-triplet energy gaps, (iii) explore novel high-spin molecules which could be used in molecular magnets (iv) investigate the influence of excited state aromaticity on photochemical reactivity.