Computational design of singlet fission biradicaloid chromophores

Abstract

We present three different computational designs of potential singlet fission chromophores. In the first two cases, we propose structural modifications of two biradicaloid compounds already known with regard to singlet fission, namely 1,3-diphenyl-isobenzofuran (DPBF) and 2,3-diamino-1,4-benzoquinone (DABQ). In the former case, the introduction of methylene bridges between the phenyl rings and the isobenzofuran core of DPBF leads to an improvement of the singlet fission energetics and confers a higher degree of rigidity to the resulting molecule. In the second case, structural modifications of DABQ are proposed in order to overcome its fast nonradiative excited state decay and to improve its singlet fission energetics. The resulting diamino-fluoroquinone compounds fulfill the desired energy criteria and represent new potential chromophores for singlet fission. Finally, in the third proposed design we exploit the captodative effect to tune the energy levels of small biradicaloid molecules, leading to propose several compounds presented for the first time as suitable chromophores for singlet fission.