Synthesis, structure, and phase transition of a novel proton transfer in a supramolecular cation with 2-nitroanilinium based on 18-crown-6

Regulating Reversible Phase Transition Behaviors by Poly-H/F Substitution in Hybrid Perovskite-Like 2[CH2FCH2NH3]·[CdCl4]

The molecular design and regulation has shown bright future for constructing smart molecular materials such as ferroelectrics, dielectric switches, electro-optic effect, and so forth. Here, by poly-H/F substitution in a simple organic-inorganic hybrid 2[CH₂FCH₂NH₃]·[CdCl₄], 1 (CH₂FCH₂NH₃ = fluorine ethylamine cation), we obtained two novel hybrids, namely, 2[CHF₂CH₂NH₃]·[CdCl₄], 2 (CHF₂CH₂NH₃ = 2,2'-difluorine ethylamine cation) and 2[CF₃CH₂NH₃]·[CdCl₄], 3 (CF₃CH₂NH₃ = 2,2',2″-trifluorine ethylamine cation). Further investigations show that compounds 1, 2, and 3 experience solid reversible phase transitions with temperatures at 294, 319, and 329 K respectively. These unique phase transitions were confirmed by their remarkable dielectric and heat anomalies around the phase transition temperatures. X-ray single-crystal diffraction analyses before and after the phase transitions show that the order-disorder motions of F atoms and the twist motions from the 2D [CdCl₄]^2- framework lead to these solid reversible phase transitions. Also, the Hirshfeld surface calculation of compounds 1, 2, and 3 suggests that the increasing ratio of the F···F interaction from the intermolecular interaction makes a major contribution for the substantial increase of their phase transition temperatures.

Probing the supramolecular features via π–π interaction of a di-iminopyrene-di-benzo-18-crown-6-ether compound: experimental and theoretical study

Herein, we report the formation of a potential supramolecular arrangement mediated by inter- and intra-molecular interactions between di-iminopyrene-dibenzo-18-crown-6-ether molecules.

Conformational analysis and molecular dynamics of glass-forming aromatic thiacrown ethers

The dielectric properties, glass transition temperature and molecular dynamics of thiacrown ethers are strongly dependent on the thiacrown ring type.

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.

Unusual high-temperature reversible phase transition containing dielectric and nonlinear optical switches in host-guest supramolecular crown ether clathrates

A novel high-temperature dielectric and quadratic nonlinear optical switching material, 3,4-difluoroanilinium 18-crown-6 perchlorate, was synthesized. It exhibits two successive structural phase transitions at 347 K and 240 K, respectively. Gradually increased SHG-active characteristics are also identified.

An organometallic half-sandwich supramolecular complex {K(18-Crown-6)(ηn-C6H5B(C6H5)3)} (n = 1–6) exhibiting a reversible breaking-symmetry phase transition and switchable dielectric behaviour

An organometallic supramolecular crystal of {K(18-crown-6)(ηⁿ-C₆H₅B(C₆H₅)₃)} (n = 1–6) has a half-sandwich structure and exhibits a reversible breaking-symmetry phase transition and switchable dielectric behavior.

Reversible phase transition and switchable dielectric behaviors triggered by rotation and order-disorder motions of crowns

Compound 1 shows apparent step-like dielectric changes near the phase transition, which are triggered by the synergetic rotation motion of 18-C-6 crown ether cycles and hexafluorophosphate anions.