How Adsorption Onto TiO₂ Modifies the Properties of Multiswitchable DTE Systems: Theoretical Insights

Abstract

In order to best employ multiphotochromes as complex molecular gates, each isomer should ideally have a distinct optical profile to be selectively addressable. In this ab initio DFT and TD-DFT study, we have modeled the electronic and optical properties of a series of dithienylethene (DTE) dimers grafted onto an anatase (101) surface. We seek to investigate how grafting onto a TiO₂ surface modifies the energy levels and UV–visible spectra of the dimers and enhances the asymmetry of the isomers. By extracting information from the density of states, we have qualified the distinct degrees of interaction between the substrate and each isomeric configuration as CO > CC > OC > OO in order of decreasing electronic coupling. We subsequently use this information to interpret the UV–vis spectra computed for the isomers. The results show that the grafted systems present new peaks and shifted <i>S</i>₁ energies compared with the isolated photochrome, suggesting that adsorption onto a TiO₂ surface may induce an asymmetric character in the DTE dyad