Solid-state photochromism and acidochromism multifunctional materials constructed by tetraphenylethene and spiropyran

Abstract

Solid-state stimuli-responsive materials are attracting increasing attention due to their broad prospects in the field of functional materials, but there are still some challenges. We design and synthesize two efficient solid-state stimuli-responsive materials SP-TPEm (m = 4, 6) based on TPE covalent connection with N-position of spiropyran through different lengths of alkyl spacers. Both of them show aggregation-induced emission behaviors. Efficient solid-state photoswitching between SP-TPEm and their photoisomer MC-TPEm is achieved. Both of the two films show great stimulus-responsive properties, and the characteristic emission peak is at around 460 nm for TPE and 601 nm for MC isomer. Therefore, SP-TPE4 is applied as an anticounterfeiting ink due to its great solid-state photochromic characteristics. In addition, the solid-state films of SP-TPEm are acidochromic responsive. Moreover, the surface wettability of the SP-TPEm films can be adjusted by UV light. Hence, we provide a new strategy for building solid-state multifunctional materials.