A Ferroelectric Metallomesogen Exhibiting Field‐Induced Slow Magnetic Relaxation

Abstract

Magnetoelectric (ME) materials exhibiting coupled electric and magnetic properties are of significant interest because of their potential use in memory storage devices, new sensors, or low‐consumption devices. Herein, we report a new category of ME material that shows liquid crystal (LC), ferroelectric (FE), and field‐induced single molecule magnet (SMM) behaviors. Co(II) complex incorporating alkyl chains of type [Co(3C16‐bzimpy)2](BF4)2 (1; 3C16‐bzimpy=2,2’‐(4‐hexadecyloxy‐2,6‐diyl)bis(1‐hexadecyl‐1H‐benzo[d]imidazole)) displayed a chiral smectic C mesophase in the temperature range 321 K–458 K, in which distinct FE behavior was observed, with a remnant polarization (88.3 nC cm−2). Complex 1 also exhibited field‐induced slow magnetic relaxation behavior that reflects the large magnetic anisotropy of the Co(II) center. Furthermore, the dielectric property of 1 was able to be tuned by an external magnetic field occurring from both spin‐lattice coupling and molecular orientational variation. Clearly, this multifunctional compound, combining LC, FE, and SMM properties, represents an entry to the development of a range of next‐generation ME materials.

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

“…When the magnetic field was applied along the crystallographic a axis of the single crystal, a small positive MD effect was observed in the LT phase at 200 and 250 K, but a much larger negative MD effect (−1.3%) was observed in the HT phase at 300 K. The magnitude of this value is smaller than the triethylmethylammonium tetrabromoferrate, the liquid crystal of a Co II compound, the trinuclear iron cluster, the Ni II chain, DyMnO 3 and DyMn 2 O 5 inorganic oxides, [39,49,51‐53,56] but is larger than the chiral Dy III SMM, the [(CH 3 ) 2 NH 2 ][Fe(HCOO) 3 ], the [C 6 H 5 CH 2 CH 2 NH 3 ] 2 [MCl 4 ], the TbFe 3 (BO 3 ) 4 and the Mn 3 O 4 inorganic oxides [47‐48,50,54‐55] . It is worth noting that most of the reported coordination compounds show a positive MD effect, [50‐57] while 1 displays the opposite by contrast. This suggests that the crystal lattice in 1 expands on increasing magnetic field while shrinks on demagnetizing.…”

“…[40][41][42] In recent years, most single-phase magnetodielectric materials are inorganics, [43][44][45][46][47][48][49] only a few of which are molecular magnets. [50][51][52][53][54][55][56][57] Nevertheless, as far as we know, the singlecrystal MD effect has not yet been explored in switchable molecular magnetic coordination compounds, let alone their synergistic changes of magnetic anisotropy and magnetodielectric effect.…”

Ferroelectric coordination metal complexes based on structural and electron dynamics

“…We have reported the occurrence of ME coupling in an FLC of type [Co(3C 16 -bzimpy) 2 ](BF 4 ) 2 . 99 This complex is an analogue of [Fe(3C 16 -bzimpy) 2 ](BF 4 ) 2 Á2H 2 O and is isostructural with it (Fig. 11a).…”

Effects of Counterions, Coordination Anions, and Coordination Solvent Molecules on Single-Molecule Magnetic Behaviors and Nonlinear Optical Properties of Chiral Zn2Dy Schiff Base Complexes

“…Single-molecule magnets (SMMs) are nanomagnets composed of single molecules that exhibit magnetic bistability at the magnetic blocking temperature. , Although much difficult to synthesize than achiral SMMs, chiral SMMs have attracted more and more attention in recent years as a special class of multifunctional molecular materials. − They not only have advantages in high-density information storage but also perform well in chirality-induced properties such as ferroelectrics, − second-order nonlinear optics, , magnetochiral dichroism (MChD), , magneto-optical Faraday effect, , and circularly polarized luminescence. , Except for very few examples obtained by spontaneous chiral resolution after assembly with achiral ligands, ,,− most chiral SMMs derive their chirality directly from bonded chiral ligands − or even from the chiral organic molecules participating in the cocrystal . However, it is still difficult to obtain chiral SMMs through the coordination of chiral ligands due to the tendency of chiral molecules to spontaneously form racemates in solution .…”