EXTENDED p-QUINODIMETHANES WITH DIRADICAL CHARACTER

Abstract

Open-shell quinoidal molecules with diradical character are highly reactive and inherently unstable yet show unique properties which are not present in closed-shell molecules. Such properties render them attractive candidates for material sciences applications such as organic semiconductors. Therefore, our motivation is to stabilize such highly reactive molecules to take advantage of their unique properties. In this work, the syntheses of a series of extended quinoidal π-conjugated molecules 3-A, 4-T, and 5-P are reported. The three molecules contain the 2,6-anthraquinodimethane, 2,8-tetracenequinodimethane and 2,9-pentacenequinodimethane quinoidal units respectively and are predicted to show distinctive open-shell diradical character. DFT calculations confirm the increase in diradical character upon lengthening of the quinoidal unit length. Crude compound 3-A was obtained in trace amounts (< 1mg) and characterized via UV-vis-NIR spectroscopy, while the synthesis of 4-T and 5-P are currently ongoing in our laboratory. 3-A show good stability in solution under ambient conditions.