Stimuli-Responsive Optical Materials Based on Hypervalent Antimony-Containing Conjugated Molecules

Stimuli-responsive materials have been applied for sensor devices because they can transform and amplify various target stimuli into observable signals. Much effort has been devoted to exploring effective molecular designs for obtaining stimuli-responsive behaviors by taking advantage of the unique optoelectronic properties of π-conjugated molecules involving various elements. This study focuses on the modulation of the electronic state of the π-conjugated scaffolds by the oxidation number change of the hypervalent antimony. This study demonstrate that the strength of the intramolecular interaction between hypervalent antimony and the π-conjugated framework can be tuned with ligand structure, substituent effect, and oxidation number shifts of hypervalent antimony. In particular, the color changes represented by hypsochromic and bathochromic wavelength shifts of optical bands are achieved by the oxidative reaction of hypervalent antimony in the solid state. Significantly, the direction of the color changes can be confidently predicted by quantum chemical calculations. The findings, based on the electronic interaction between π-conjugated scaffolds and hypervalent main-group elements, provide logical design strategies for advanced stimuli-responsive materials.