Blue–Green–Yellow Thermochromic Fluorescence and Bubble‐Propelled Crystal Motion Driven by Molecular Gear Rotations

Abstract

Abstract Guest‐release induced responsive behaviors in nonporous organic solvate crystals remain elusive due to the lack of well‐defined diffusion pathways and the rarity of crystal‐to‐crystal transitions. Here, we report a pentiptycene‐derived nonporous organic solvate ( 1B ) that exhibits a striking blue → green → yellow thermochromic fluorescence sequence through a two‐stage crystal‐to‐crystal transformation. In the first stage, subtle gear‐like rotations transiently open a zigzag diffusion pathway, releasing dichloromethane (DCM) and generating a green‐emissive phase ( 1G ). In silicone oil, asymmetric bubble evolution during DCM release drives directional crystal propulsion. A second heating step triggers a ∼90° correlated gear rotation that reconfigures alkyl conformation and anthracene packing, producing excimer‐based yellow emission ( 1Y ). These coupled sequential optical, mechanical, and structural responses reveal a unique paradigm of guest‐driven dynamics in nonporous solvate crystals.