Flexible cis ‐Cyclohexane‐1,4‐diammonium Ion in Magnetic [Ni(dmit) 2 ] Crystals

Red/green-light emission in continuous dielectric phase transition materials: [Me3NVinyl]2[MnX4] (X = Cl, Br)

The luminescence of dielectric phase transition materials is one important property for technological applications, such as low-energy electron excitation. The combination of dielectric phase transitions and luminescence within organic–inorganic hybrids would lead to a new type of luminescent dielectric phase transition multifunctional material. Here, we report two novel A₂BX₄ organic–inorganic hybrid complexes [Me₃NVinyl]₂[MnCl₄] 1 and [Me₃NVinyl]₂[MnBr₄] 2, ([Me₃NVinyl] = trimethylvinyl ammonium cation). The complexes 1 and 2 were found to undergo continuous reversible phase transitions as well as switch dielectric phase transitions. Strikingly, intensive red luminescence and green luminescence were obtained under UV excitation respectively to reveal potential application of the two complexes in multi-functional materials along with dielectric switches and so on.

The luminescence of dielectric phase transition materials is one important property for technological applications, such as low-energy electron excitation.

Phase transition and switchable dielectric behaviours in an organic-inorganic hybrid compound: (3-nitroanilinium)2(18-crown-6)2(H2PO4)2(H3PO4)3(H2O)

An organic-inorganic hybrid compound with an extensive three-dimensional (3D) crystal structure, (3-nitroanilinium)₂(18-crown-6)₂(H₂PO₄)₂(H₃PO₄)₃(H₂O) (1), was synthesized under slow evaporation conditions. Differential scanning calorimetry measurements indicated that 1 underwent a reversible phase transition at ca 231 K with a hysteresis width of 10 K. Variable-temperature X-ray single-crystal diffraction revealed that the phase transition of 1 can be ascribed to coupling of pendulum-like motions of its nitro group with proton transfer in O-H···O hydrogen bonds of the 3D framework. The temperature dependence of its dielectric permittivity demonstrated a step-like change in the range of 150-280 K with remarkable dielectric anisotropy, making 1 a promising switchable dielectric material. Potential energy calculations further supported the possibility of dynamic motion of the cationic nitro group. Overall, our findings may inspire the development of other switchable dielectric phase transition materials by introducing inorganic anions into organic-inorganic hybrid systems.

Crystal Structure and Phase Transition of the C–H···F–H-Bonded Supramolecular Compound with 4-Nitroanilinium Based on 18-Crown-6

A novel inorganic-organic hybrid supramolecular macrocyclic compound, (4-nitroanilinium)(18-crown-6)(PF6)(1), was synthesized and characterized by infrared spectroscopy, thermogravimetric analysis, elemental analysis, differential scanning calorimetry (DSC), and single-crystal X-ray diffraction. Crystal 1 is found to comprise 1D C–H···F–P hydrogen-bonded chains of (4-nitroanilinium+)(18-crown-6) supramolecular cations and PF6− anions. DSC measurements confirm that 1 undergoes a reversible phase transition at 255 K with a hysteresis width of 6 K. A strong dielectric response is observed above 250 K at a low frequency (500 Hz), suggesting the occurrence of proton transfer in the C–H···F–P hydrogen bonds. A precise analysis on the main packing and structural differences, as well as the changes in the intermolecular interaction between the low- and high-temperature phases, reveals that C–H···F–P hydrogen bonds are the main factors affecting phase transition and dielectric behavior.

A spiro-type ammonium based switchable dielectric material with two sequential reversible phase transitions above room temperature

A novel spiro-type hybrid undergoes two phase transitions at 336 and 357 K, accompanied by remarkable changes of H-bond interactions.

Crystal structures, phase transitions, and switchable dielectric behaviors: comparison of a series of N-heterocyclic ammonium perchlorates

1-Propyl-1-methylpiperidinium, 1-cyanomethyl-1-methylpiperidinium and 1-cyanomethyl-1-methylmorpholinium perchlorates display switchable dielectric responses accompanied by phase transitions at around 199, 387 and 416 K, respectively.