Reversible Switchability of Magnetic Anisotropy and Magnetodielectric Effect Induced by Intermolecular Motion

Abstract

Introducing magnetic switchability into artificial molecular machines is fascinating for precise control of magnetism via external stimuli. Herein, a field‐induced CoII single‐molecule magnet was found to exhibit the reversible switch of Jahn–Teller distortion near room temperature, along with thermal conformational motion of the 18‐crown‐6 rotor, which pulls the coordinated H2O to rotate through intermolecular hydrogen bonds and triggers a single‐crystal‐to‐single‐crystal phase transition with Twarm=282 K and Tcool=276 K. Interestingly, the molecular magnetic anisotropy probed by single‐crystal angular‐resolved magnetometry revealed the reorientation of easy axis by 14.6°. Moreover, ON/OFF negative magnetodielectric effects were respectively observed in the high‐/low‐temperature phase, which manifests the spin‐lattice interaction in the high‐temperature phase could be stronger, in accompanied by the hydrogen bonding between the rotating 18‐crown‐6 and the coordinated H2O.

Coupling Dielectric Functionality with Magnetic Properties in Coordination Metal Complexes

“…In another case, the flexible groups in a Co(II)-based SMM, [Co(NCS) 2 (H 2 O) 2 (4-amino-3-chloropyridine) 2 ] • (18-crown-6), were successfully isolated for dielectric property control using an external magnetic field. [54] A single-crystal sample of the target compound (Figure 3) with crystal face dependence, a Jahn-Teller-effect-active metal center, and a crown ether site for building supramolecular architecture exhibited interesting MD features. Two water molecules coordinating to the Co(II) center formed intermolecular hydrogen bonding with the 18-crown-6 unit.…”

A confinement-regulated (H3C–NH3)+ ion as a smallest dual-wheel rotator showing bisected rotation dynamics

“…Among various types of supramolecular rotors, crown-etherbased rotors are of particular interest, which have been intensively studied from time to time. [29][30][31][32][33][34][35][36][37][38][39][40] In confined space, the conformationally flexible crown ethers are capable of forming stable supramolecular complexes with primary ammonium (R-NH 3 ) + ions through multiple OÁ Á ÁH-N hydrogen bonds, which bind and/or semi-encapsulate the primary ammonium ions, providing a confined environment for their rotation. Following this strategy, a series of crown-ether-based supramolecular rotors had been prepared merely by a one pot self-assembly method, without intricate chemical processes.…”

Near‐Room‐Temperature Synergetic Response of Magnetism, Dielectricity and Luminescence Based on (C5NH13Cl)2MnBr4

“…A 2 MnX 4 is one kind of salt with organic ammonium cation A + and coordination anion [MnX 4 ] 2À , where X = halogen ion. [15,16] The lattice provides the big enough space for the rotation of groups in soft cation, leading to the SPT in solid and the change in physical properties. For example, (CH 6 N 3 ) 2 MnCl 4 reported by Sundaresan and co-workers shows the spin bistability at 166/195 K induced by SPT.…”

“…A 2 MnX 4 is one kind of salt with organic ammonium cation A + and coordination anion [MnX 4 ] 2− , where X=halogen ion [15,16] . The lattice provides the big enough space for the rotation of groups in soft cation, leading to the SPT in solid and the change in physical properties.…”