Reversible Phase Transition of 1,4-Diazoniabicyclo[2.2.2]octane-1-acetate-4-acetic Acid Chloride Trihydrate

Abstract

1,4-Diazoniabicyclo[2.2.2]octane-1-acetate-4-acetic acid forms a complex (1) with chloride ion and water molecule in the ratio 1:1:3. Differential scanning calorimetry (DSC) measurement shows a pair of reversible peaks at 210.7 K (heating) and 180.3 K (cooling) with a large heat hysteresis about 30.4 K, indicating this compound undergoes a reversible structural phase transition. Dielectric measurement further confirms the phase transition. The DSC and dielectric measurements results of its deuterated compound (2) exhibit obvious change compared to those of 1. The crystal structures of these two compounds, determined at 153 and 298 K, are all monoclinic in P2 1 /n, suggesting the phase transition is isosymmetric. Structural analysis reveals that the changes of the relative location of water molecules and chloride ions affect the formation of different modes of hydrogen-bonded anionic chains, leading to the reversible structural phase transition.

An Alkaline-Stable, Metal Hydroxide Mimicking Metal–Organic Framework for Efficient Electrocatalytic Oxygen Evolution

“…The IR stretching vibration of OD − of MAF-X27-OD at 2672 cm −1 almost disappeared after an OER testing time of 15 min, accompanied with the appearance of the stretching vibration of OH − at 3617 cm −1 ( Figure S12). 43,44 In contrast, the stretching vibration of OD − was almost unchanged for 60 min without application of an electric field. These observations demonstrated the direct participation of the μ-OH − ligand or the intraframework coupling pathway in the OER process.…”

Anomalous Dielectric Features and Structural Implications in Gallic Acid–Isoniazid Cocrystal Mediated by Lattice Water

“…It is of interest to note that above 389 K, the dielectric constant drops to about 5.5 and remains invariant on the cooling cycle due to the loss of the water of hydration(Figure 2 inset). Further, loss of water molecule and irreversibility of transition was also captured by in situ powder X-ray diffraction (Figure S4; Supporting Information).Thus, even though this material does not exhibit switchable dielectric phenomenon[5][6][7][8][9][10][11][12] , the appearance of a step like behavior brings out the role of lattice water initially in augmenting the value of the dielectric constant.…”

“…2 In this context, some of the physical properties like dielectric and ferroelectric behaviour [3][4][5][6][7][8][9][10][11][12] of such materials have been correlated with their structural features. In particular, considerable attention has been placed on switchable dielectric materials for data storage and data dissemination applications, resulting from the transition between dynamic/disordered phases in molecular solids.…”

Temperature-induced first-order displacive phase transition of isonicotinamide-4-methoxybenzoic acid co-crystal

“…crystal structure), whereby second-order phase transitions show continuous changes in thermodynamic quantities when their first derivatives are discontinuous. The temperature-or pressure-induced phase transitions are accompanied with different types of structural changes such as displacive (Zhang et al, 2013;Rybarczyk-Pirek et al, 2014), order-disorder (Wu & Jin, 2013;Suzuki et al, 2014;Brandel et al, 2015), reconstructive (Johnston et al, 2014;Maloney et al, 2014) etc. The high-temperature phase of an enantiotropic phase transition in a crystal is commonly of higher symmetry than its low-temperature phase; however, an isosymmetry transition with the same space-group symmetry at both phases does exist (Swainson et al, 2002 Quah et al, 2012;Ellena et al, 2014).…”