EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

The number of scientific communications commenting on the unique properties and the high potential for various applications of the compounds with diradical character grows constantly. It was demonstrated that molecules with low-to-intermediate diradical character are amidst the few prospective candidates for singlet fission chromophores [1], hence, are promising highly efficient photovoltaics. It was also observed that compounds with moderate diradical character feature remarkably high second hyperpolarizability values and are attractive as organic photonics materials [2].
All this makes it clear that the occurrence of diradical character enhances and even engenders certain desired optical properties and its assessment and modulation can be a modern molecular design strategy. What is the price, however, of the unique properties of the open-shell compounds? Alongside with all pros, the diradical character is usually associated with low stability and high reactivity – unwanted molecular qualities for practical purposes. Thus, from fundamental and applied point of view, it is important to investigate the correlation between diradical character and stability, as the literature does not offer exhaustive reports on the topic. Therefore, we carried out quantum-chemistry calculations of the diradical character and the reactivity indices of a series of o- and p-quinomethides, for the stability and reactivity of which experimental data have been published. The results give an answer to the question whether a compromise between diradical character and stability of a molecular material is feasible.
The study is supported by the National Research Program E+, grant D-01-214/2018, and Project ML4SF, grant КП-06-Н39/2/2019.
References:
[1] T. Minami and M. Nakano, J. Phys. Chem. Lett. 2012, 3, 145–150.
[2] M. Nakano, R. Kishi, S. Ohta, A. Takebe, H. Takahashi, S. Furukawa, T. Kubo, Y. Morita, K. Nakasuji, K. Yamaguchi, K. Kamada, K. Ohta, B. Champagne, and E. Botek, J. Chem. Phys. 2006, 125, 074113.