mechanistic and spectroscopic investigations of molecular organophosphorus and organoarsenic compounds
This proposal aims at the development of low valent and low coordinated arsenic and phosphorus compounds and their application in organic electronics. The electronic properties of known building blocks for organic electronics are greatly influenced by the replacement of a carbon fragment in the conjugated backbone with an isolobal pnictogen (group 15 element, e.g. P-R or As-R) fragment. By the heteroelement incorporation we aim to achieve a stabilization of the LUMO levels, without affecting the energies of the occupied orbitals. By doing so the "band gap" of resulting materials should significantly decrease and gives rise to low band gap materials for applications within organic semi-conductors or as active components in bulk heterojunction solar cells. Currently we are investigating the photophysical properties of two molecular systems and their derived polymerica materials using time-resolved UV/vis spectroscopic methods. Deeper knowledge on the excited state properties of our systems will help us to a) understand the experimentally observed processes (decay behavior of excited states, electrochromic behavior ,etc) and b) to design novel building blocks based on performed calculations. We are particularly interested in understanding the excited states of these systems, i.e. looking at charge transfer states, which can be utilized in light harvesting and energy conversion systems to achive a charge seperation and injection of holes and electrons. We try in our approach to design low band gap materials by introducing acceptor sites which are built from low valent phosphorus and arsenic sites combined with conventional pi conjugated systems. In our group we combine experimental and theoretic chemistry to understand and predict the properties of interesting main group systems. Recently, we have published a few studies which are based on (or supplememented by) calculations that have been performed on earlier projects (SNIC being acknowledged): Svyaschenko, Y. V.; Orthaber, A.; Ott, S., Tuning the Electronic Properties of Acetylenic Fluorenes by Phosphaalkene Incorporation. Chem. Eur. J. 2016, 22 (12), 4247–4255. Nauroozi, D.; Orthaber, A., The Heavier Analogues of Alkenes: A Theoretical Comparison of Unsaturated Group 15/14 Systems. Eur. J. Inorg. Chem. 2016, 2016 (5), 709-717. and several other publications resulting from eperimental work related to these projects.