Creation of Excitation‐Driven Hypervalent Tin(IV) Compounds For Aggregation‐Induced Emission and Application to Thermoresponsive Luminescent Films Below Freezing Point

Although many researchers have devoted their much effort to establish the strategy for developing a stimuli‐responsive molecule and tuning of their properties according to the preprogrammed design, it is still challenging to create desired molecules from the scratch. We recently demonstrated that the molecules with a large structural difference between the theoretically optimized structures in the ground and excited states have a potential to exhibit stimuli‐responsive luminescent properties. We defined these molecules as an excitation‐driven molecule and have shown that they are a versatile platform for designing stimuli‐responsive luminescent molecules. Herein, based on the concept of excitation‐driven molecules, we show that the hypervalent tin‐fused azomethine (TAm) compounds possessing aggregation‐induced emission (AIE) properties can be obtained by simple chemical modification with a methyl group although conventional TAm derivatives are well known to be highly luminescent compounds in solution. Furthermore, by combining the solid‐state luminescence property of AIE and the coordination number shifts of the hypervalent tin atom, the thermoresponsive films operating below the freezing point are fabricated with the polymer. In this study, we apply the concept of excitation‐driven molecules to the hypervalent compounds and demonstrate to obtain the novel functional materials. We designed and synthesized aggregation‐induced emission (AIE)‐active hypervalent tin‐fused azomethine (TAm) compounds from scratch by theoretical calculations based on the concept of excitation‐driven molecules. Furthermore, by using the excellent solid‐state luminescent properties from AIE and the coordination flexibility of the hypervalent tin, thermoresponsive luminescent polymer films operating below the freezing point were able to be fabricated.