Multi-state photochromism of bis-tetraarylethene luminogens modulated through oligosilane linkages.

Controllable photochromic molecules both in solutions and solid states (amorphous, films, and crystals) are valuable nascent optical materials. In this work, we report a facial route to design multi-state photochromic molecules by incorporating oligosilane chains into photoactive triphenylvinylthiophene (TPT) luminogens. The flexibility, bulkiness, and unique σ–π conjugation brought by silane chains enable different intramolecular interactions between two TPT units. A longer silicon chain bridge facilitates efficient electron delocalization and reduced structural constraint, thus resulting in reversible photochromism even in crystals with high-contrast color differences. This work provides a general method for developing novel multi-state photochromic materials for application in data encryption. [ABSTRACT FROM AUTHOR]