A High‐Temperature Order–Disorder Phase Transition Coupled With Conformational Change in the Hybrid Material [C6H13NH]2⋅ZnBr4. Issue 20 (14th September 2016)

• Record Type: Journal Article
• Authors: Khan, Tariq; Asghar, Muhammad Adnan; Sun, Zhihua; Zeb, Aurang; Li, Lina; Sijie, Liu; Zhao, Sangen; Ji, Chengmin; Luo, Junhua
• Is Part Of: Chemistry, an Asian journal. Volume 11:Issue 20(2016)
• Page Start: 2876
• Page End: 2881
• Publication Date: 2016-09-14
• Subjects: conformational changes -- dielectric properties -- disorder -- organic–inorganic hybrid composites -- phase transitions; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/asia.201600831
• Languages: English
• ISSNs: 1861-4728

Abstract

Abstract: A new high‐temperature, hybrid, phase‐transition material, 1‐methylpiperidinium tetrabromozincate (1 ), that shows a reversible transition at 345 K was synthesized. Differential scanning calorimetry and specific heat capacity measurements confirmed this reversible transformation with a large heat hysteresis of 25 K, which describes a typical first‐order phase transition in1 . The dielectric constant exhibited a steplike anomaly and showed high and low dielectric states in the high‐ and room‐temperature phases, respectively, and therefore, this hybrid might be considered as a potential switchable dielectric material. The variable‐temperature powder X‐ray diffraction patterns displayed remarkable shifts between the experimental patterns at the two different phases. Single‐crystal X‐ray diffraction analyses at various temperatures revealed that the origin of this transformation could be attributed to disordering of the bromine atoms in the anion and the nitrogen atom of the cation. The cation also assumed a conformational change, which was likely induced by the disordered nitrogen atom. The conformational onset of the transformation of the cation from a planar conformer into a relaxed chair also occurred upon decreasing the temperature below transition point; thus, the combined order–disorder and conformational change induced the structural transformation and the change in symmetry. Abstract : Transitioning through : A high‐temperature phase‐transition material that undergoes first‐order phase transition induced by order–disorder transformation of the anion and cation coupled with the conformational orientation of the cation is synthesized. This finding offers a new route for the design of phase‐transition materials.