Cryoelastic and cryochromic organic crystals.
Jiechang Wang1, Linfeng Lan1, Hongyu Zhang2,3
1State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, P. R. China.
Nature Communications
|June 10, 2026
Summary
Flexible organic crystals change color with temperature due to structural changes. This discovery enables new optical encryption and low-temperature sensing technologies using luminescent materials.
Area of Science:
- Materials Science
- Crystallography
- Photonic Technologies
Background:
- Cryoelastic and cryochromic luminescent organic crystals are promising for adaptive photonics and sensing.
- The structural basis for their temperature-dependent color changes is not well understood.
Purpose of the Study:
- To investigate the structural origins of thermofluorochromism in flexible naphthalene-based Schiff base single crystals.
- To establish a structure-property correlation for predicting temperature-dependent optical behavior.
Main Methods:
- Single-crystal X-ray diffraction at variable temperatures (298–77 K).
- Analysis of crystal lattice dynamics, π⋯π interactions, and exciton coupling.
- Characterization of thermofluorochromic responses and excited-state lifetimes.
Main Results:
- Flexible single crystals maintained reversible elasticity and crystallinity across a wide temperature range.
- Observed distinct thermofluorochromic responses, including significant red shifts (up to ~92 nm) and blue shifts.
- Identified a correlation between emission shift direction and changes in π⋯π contact area, influencing exciton coupling.
Conclusions:
- Reversible lattice contraction without disorder was observed.
- Enhanced π⋯π overlap correlates with red shifts due to stronger exciton coupling.
- Geometric descriptors can predict low-temperature color changes, enabling applications in optical encryption and sensing.
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