Ab Initio Investigation of the Electronic Properties of Coupled Dithienylethenes

The design of more efficient photochromes does not stand as the only challenge in the field of molecular switches; more complex and refined structures, allowing one to pave the way toward multiply addressable structures, are highly sought after. In this framework, compounds containing several dithienylethenes have been recently proposed. In the present Letter, we investigate the spectral properties of photochromes made of two dithienylethene units linked through conjugated bridges to form meta and para switches. All combinations of closed and open forms have been modeled by using (time-dependent) density functional theory. With this ab initio tool, the coupling between the photochromic centers could be assessed. Such calculations are a step necessary to understand the parameters guiding the formation of the fully closed forms.