[(18‐Crown‐6)K][Fe(1)Cl(1)₄]_0.5[Fe(2)Cl(2)₄]_0.5: A Multifunctional Molecular Switch of Dielectric, Conductivity and Magnetic Properties

Abstract

Multifunctional materials that exhibit different physical properties in a single phase have potential for use in multifunctional devices. Herein, we reported an organic-inorganic hybrid compound [(18-crown-6)K][Fe(1)Cl(1) ] [Fe(2)Cl(2) ] (1) by incorporating KCl and FeCl into a 18-crown-6 molecule, which acts as a host of the six O atoms providing a lone pair of electrons to anchor the guest potassium cation, and [FeCl ] as a counterion for charge balance to construct a complex salt. This salt exhibited a one-step reversible structural transformation giving two separate high and low temperature phases at 373 K, which was confirmed by systematic characterizations including differential scanning calorimetry (DSC) measurements, variable-temperature structural analyses, and dielectric, impedance, variable-temperature magnetic susceptibility measurements. Interestingly, the structural transformation was coupled to both hysteretic dielectric phase transition, conductivity switch and magnetic-phase transition at 373 K. This result gives an idea for designing a new type of phase-transition materials harboring technologically important magnetic, conductivity and dielectric properties.

Monocycle‐like Molecular Rotor Induces a Dielectric Relaxation and Dielectric Phase Transformation in an Organic–Inorganic Hybrid Supermolecule

“…In our previous work, we reported an organic‐inorganic hybrid phase‐transition material, [(18‐crown‐6)K][FeCl 4 ], by incorporating flexible ring‐molecular 18‐crown‐6, alkali metal potassium ion, and FeCl 3 . The tetrahedral anions [FeCl 4 ] – in that structure is isolated and distribute in the void of lattice . And in that work, the dielectric, magnetic and conductivity switch is triggered by disorder motion of [FeCl 4 ] – anions.…”

Supramolecular crystals of Mn(15-crown-5)(MnCl4)(DMF) with dielectric phase transition, high quantum yield and phase transition-induced luminescence enhancement behavior

“…A thermotropic phase transition, linked to the rotational dynamics of the crown ether ring, is frequently observed in crystals containing crown ether or its supramolecular cation. [20][21][22][23][24][25][26][27] Furthermore, such supramolecular crystals demonstrate remarkable electric, [23][24][25] magnetic, 24 and optical 23,25 properties in the proximity of the phase transition, facilitated by phonon-assisted mechanisms, which manifest through frequencies observed within specific characteristic vibrational bands, both below and above the critical temperature of the phase transition. For practical applications, the coupling of multiple physical properties is crucial as it can offer various avenues for realizing the manipulation of specific functionalities.…”

2-Chloroethylamine·trifluoromethanesulfonate combined with 18-crown-6: a ferroelectric with excellent dielectric switching properties

“…19,20 In particular, 18-crown ether-6-based inclusions are often used as a platform for the construction of molecular ferroelectric and piezoelectric materials, as the host–guest inclusions may have ordered–disordered phase transitions. 21–24 Xiong et al have successfully designed a high-temperature multiaxial host–guest inclusion ferroelectric [(MeO-C 6 H 4 -NH 3 )(18-crown-6)][TFSA] (MeO-C 6 H 4 -NH 3 = 4-methoxyanilinium, TFSA = bis(trifluoromethanesulfonyl)ammonium) by adjusting the anion to control the “momentum matching” in the crystal structure. The internal environment of the crystal has changed and a new and distinct interaction between (MeO-C 6 H 4 -NH 3 ) + and the TFSA anion has taken place.…”