An MS-CASPT2 Calculation of the Excited Electronic States of an Axial Difluoroborondipyrromethene (BODIPY) Dimer

0493068 - ÚOCHB 2019 RIV US eng J - Journal Article
Wen, Jin - Han, B. - Havlas, Zdeněk - Michl, Josef
An MS-CASPT2 Calculation of the Excited Electronic States of an Axial Difluoroborondipyrromethene (BODIPY) Dimer.
Journal of Chemical Theory and Computation. Roč. 14, č. 8 (2018), s. 4291-4297. ISSN 1549-9618. E-ISSN 1549-9626
R&D Projects: GA ČR GA15-19143S
Institutional support: RVO:61388963
Keywords : second-order perturbation theory * Gaussian basis sets * photodynamic therapy
OECD category: Physical chemistry
Impact factor: 5.313, year: 2018

The previously reported (Duman et al., J. Org. Chem. 2012, 77, 4516) calculated state energies of monomeric difluoroborondipyrromethene (BODIPY) and its axial dimer would suggest that these dyes are promising candidates for singlet fission, and the dimer was computed to have an unusual low-lying doubly excited state. We find that these results were affected by the use of an imbalanced active space in multireference calculations and are not correct. Multistate complete-active-space second-order perturbation theory (MS-CASPT2/cc-pVDZ) calculations using an [8,8] (8 electrons in 8 orbitals) active space for the monomer and a [16,16] active space for the dimer reproduce quite well the observed excitation energies of the S-1 states of both, and yield T-1 excitation energies well in excess of half of the S-1 excitation energies. We conclude that neither BODIPY monomer nor its axial dimer would permit exothermic singlet fission and are not worthy of investigation as potentially useful candidates, and that the unusual low-energy doubly excited states of the dimer were artifacts.
Permanent Link: http://hdl.handle.net/11104/0286526