Stimuli Responsive Hybrid Magnets: Tuning the Photoinduced Spin-Crossover in Fe(III) Complexes Inserted into Layered Magnets

Abstract

The insertion of a [Fe(sal2-trien)](+) complex cation into a 2D oxalate network in the presence of different solvents results in a family of hybrid magnets with coexistence of magnetic ordering and photoinduced spin-crossover (LIESST effect) in compounds [Fe(III)(sal2-trien)][Mn(II)Cr(III)(ox)3]·CHCl3 (1·CHCl3), [Fe(III)(sal2-trien)][Mn(II)Cr(III)(ox)3]·CHBr3 (1·CHBr3), and [Fe(III)(sal2-trien)][Mn(II)Cr(III)(ox)3]·CH2Br2 (1·CH2Br2). The three compounds crystallize in a 2D honeycomb anionic layer formed by Mn(II) and Cr(III) ions linked through oxalate ligands and a layer of [Fe(sal2-trien)](+) complexes and solvent molecules (CHCl3, CHBr3, or CH2Br2) intercalated between the 2D oxalate network. The magnetic properties and Mössbauer spectroscopy indicate that they undergo long-range ferromagnetic ordering at 5.6 K and a spin crossover of the intercalated [Fe(sal2-trien)](+) complexes at different temperatures T1/2. The three compounds present a LIESST effect with a relaxation temperature TLIESST inversely proportional to T1/2. The isostructural paramagnetic compound, [Fe(III)(sal2-trien)][Zn(II)Cr(III)(ox)3]·CH2Cl2 (2·CH2Cl2) was also prepared. This compound presents a partial spin crossover of the inserted Fe(III) complex as well as a LIESST effect. Finally, spectroscopic characterization of the Fe(III) doped compound [Ga0.99Fe0.01(sal2trien)][Mn(II)Cr(III)(ox)3]·CH2Cl2 (3·CH2Cl2) shows a gradual and complete thermal spin crossover and a LIESST effect on the isolated Fe(III) complexes. This result confirms that cooperativity is not a necessary condition to observe the LIESST effect in an Fe(III) compound.

Magnetic functionalities in MOFs: from the framework to the pore

“…109 The synthetic approach to obtain these hybrid materials involves a self-assembly method that consists in growing the extended network from its molecu- 2 Cl 2 ) which, apart from ferromagnetism and spincrossover, also exhibit a photo-induced spin transition (i.e., a light-induced excited spin trapping (LIEEST) effect). 112,113 Another approach that has also been successfully used to incorporate spin-crossover complexes within a magnetic MOF involves the so-called post-synthetic method (already pointed out in Section 2.3). À .…”

Versatile nano-platforms for hybrid systems: expressing spin-transition behavior on nanoparticles

“…Within the field of data storage, this has been realized through the development of a series of molecular switches based on redox compounds [4][5][6][7][8][9] or spin states. 12,[18][19][20] Nevertheless, the consistency of the magnetic properties in these kinds of complexes once integrated into hybrid architectures relies on whether the final structure allows for cooperativity between the molecular switching units. 12,[18][19][20] Nevertheless, the consistency of the magnetic properties in these kinds of complexes once integrated into hybrid architectures relies on whether the final structure allows for cooperativity between the molecular switching units.…”

Spin-Singlet Transition in the Magnetic Hybrid Compound from a Spin-Crossover Fe(III) Cation and π-Radical Anion

“…Thus the utilization of electronic and structural transformation accompanying SCO can lead to potential applications of display, memory, sensing and electronic devices [3,4]. One of the emergent fields of SCO research in the last decade is the development of multifunctional compounds between SCO and other solid-state electronic properties such as conductivity [5][6][7][8][9][10][11][12], magnetism [13][14][15][16][17][18][19][20][21][22][23], and optical properties [24,25]. The goal of this research is that one can design and synthesize a molecular solid whose electronic property can be controlled by external stimuli.…”