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. Controllable photochromic molecules both in solutions and solid states (amorphous, films, and crystals) are valuable nascent optical materials.