Thermal Strain and Microstrain in a Polymorphic Schiff Base: Routes to Thermosalience

Klaser, Teodoro; Jaklin, Marko; Popović, Jasminka; Grgičević, Ivan; Skoko, Željko (2025) Thermal Strain and Microstrain in a Polymorphic Schiff Base: Routes to Thermosalience. Molecules, 30 (12). ISSN 1420-3049

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Abstract

We present a comprehensive structural and thermomechanical investigation of N-salicylideneaniline, a Schiff base derivative that exhibits remarkable thermosalient phase transition behavior. By combining variable-temperature X-ray powder diffraction (VT-XRPD), differential scanning calorimetry (DSC), hot-stage microscopy, and Hirshfeld surface analysis, we reveal two distinct thermosalient mechanisms operating in different polymorphic forms. Form I displays pronounced anisotropic thermal expansion with negative strain along a principal axis, culminating in a sudden and explosive phase transition into Form IV. In contrast, Form III transforms more gradually through a microstrain accumulation mechanism. Fingerprint plots and contact evolution from Hirshfeld surface analysis further support this dual-mechanism model. These insights highlight the importance of integrating macro- and microscale structural descriptors to fully capture the mechanical behavior of responsive molecular solids. The findings not only enhance the fundamental understanding of thermosalience but also inform the rational design of functional materials for actuating and sensing applications.

Item Type:	Article
Uncontrolled Keywords:	thermomechanical actuation; negative thermal expansion (NTE); variable-temperature X-ray powder diffraction (VT-XRPD); principal axis strain analysis; polymorphic transition dynamics; crystallographic stress anisotropy
Subjects:	NATURAL SCIENCES > Physics
Divisions:	Division of Materials Physics
Depositing User:	Lorena Palameta
Date Deposited:	24 Jun 2025 07:30
URI:	http://fulir.irb.hr/id/eprint/9858
DOI:	10.3390/molecules30122567

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