Dibutylammonium Hydrogen Oxalate: An Above-Room-Temperature Order–Disorder Phase Transition Molecular Material Tariq Khan Yuanyuan Tang Zhihua Sun Shuquan Zhang Muhammad Adnan Asghar Tianliang Chen Sangen Zhao Junhua Luo 10.1021/acs.cgd.5b00758.s003 https://acs.figshare.com/articles/dataset/Dibutylammonium_Hydrogen_Oxalate_An_Above_Room_Temperature_Order_Disorder_Phase_Transition_Molecular_Material/2113528 An above-room-temperature new phase transition molecular material, dibutylammonium hydrogen oxalate (<b>1</b>), has been synthesized, which undergoes a reversible phase transition at 321.6 K. Differential scanning calorimetry (DSC) measurements confirm its reversible phase transition with a large heat hysteresis of ∼10 K. The dielectric constants of <b>1</b> exhibit an obvious step-like anomaly, showing the high and low dielectric constant states at high and room-temperature phases, respectively, which reveal that <b>1</b> might be considered a potential switchable dielectric material. Variable-temperature single crystal X-ray diffraction analyses disclose that the origin of this phase transition is greatly attributed to the coupling of the order–disorder change and reorientation of the dibutylammonium cation; that is, the frozen ordering of ethyl group in butyl moiety triggered by the decreasing temperature forces the reorientation of cation, thus resulting in the structural phase transition. 2015-11-04 00:00:00 phase transition DSC Dibutylammonium Hydrogen Oxalate Differential scanning calorimetry switchable dielectric material