# Size Reduction to Enhance Crystal-to-Liquid Phase Transition Induced by E-to-Z Photoisomerization Based on Molecular Crystals of Phenylbutadiene Ester

## TL;DR

This study shows that shrinking crystals of a specific compound increases their response to light-induced melting, offering a new way to control material transitions for smart devices.

## Contribution

The paper introduces a new photoactive molecular crystal and shows that size reduction enhances light-induced phase transitions.

## Key findings

- The compound (E)-PADM undergoes E-to-Z photoisomerization and crystal-to-liquid phase transition under UV light.
- Nanoscopic crystals melt faster and more completely than bulk crystals when exposed to UV light.
- Miniaturization enhances the photoinduced melting effect in molecular crystals.

## Abstract

Harnessing the photoinduced phase transitions in organic crystals, especially the changes in shape and structure across various dimensions, offers a fascinating avenue for exact spatiotemporal control, which is crucial for developing future smart devices. In our study, we report a new photoactive molecular crystal made from (E)-2-(3-phenyl-allylidene)malonate ((E)-PADM). When exposed to ultraviolet (UV) light at 365 nm, this compound experiences an E-to-Z photoisomerization in liquid solution and a crystal-to-liquid phase transition in solid crystals. Remarkably, nanoscopic crystalline rods boost their melting rate and degree compared to bulk crystals, indicating that miniaturization enhances the photoinduced melting effect. Our results demonstrate a simple approach to rapidly drive molecular crystals into liquids via photochemical reactions and phase transitions.