Switchable Dielectric Materials Based on a Diprotonated Organic Cation Containing Two Different Anions: (C5H16N2)BF4X (X = Cl, Br, NO3)

• Published in: Crystal growth & design 2023-04, Vol.23 (4), p.2916-2921
• Main Authors: Wang, Ze-Jie, Wu, Ling-Kun, Feng, Yan, Gu, Yong, Ye, Heng-Yun, Li, Jian-Rong
• Format: Article
• Language: English
• ISSN: 1528-7483; 1528-7505
• DOI: 10.1021/acs.cgd.3c00063

Three molecular-based phase transition compounds, namely, (C5H16N2)­BF4Cl (1, C5H16N2 = diprotonated 2,2-dimethyl-1,3-propanediamine), (C5H16N2)­BF4Br (2), and (C5H16N2)­BF4NO3 (3), were synthesized and characterized. Differential scanning calorimetry and the step-like anomaly of the real part (ε′) of the temperature-dependent dielectric constant revealed that the compounds underwent reversible first-order phase transition with high phase transition temperature under the stimulation of temperature. Variable-temperature X-ray diffraction analysis revealed that the microcosmic driving force of phase transition was the order–disordered change of the organic cation and spherical anion. Notably, the diprotonated organic cations were charge-balanced by two different anions of the combination BF4 – and Cl–, Br– and NO3 –. Our research paves a new avenue to construct molecular-based phase transition materials with temperature stimulus response.