Encapsulation of a Cr^III Single‐Ion Magnet within an Fe^II Spin‐Crossover Supramolecular Host

Abstract

Single functional molecules are regarded as future components of nanoscale spintronic devices. Supramolecular coordination chemistry provides unlimited resources to implement multiple functions to individual molecules. A novel coordination [Fe ] helicate exhibiting spin-crossover is demonstrated to be ideally suited to encapsulate a [Cr(ox) ] complex anion (ox=oxalate), unveiling for the first-time single ion slow relaxation of the magnetization for this metal. A possibility of tuning the dynamics of this relaxation as well as the performance of the Cr center as qubit arises from the observation that metastable high spin Fe centers from the host can be generated by irradiation with green light at low temperature.

Tuning spin-crossover transition temperatures in non-symmetrical homoleptic meridional/facial [Fe(didentate)3]2+complexes: what for and who cares about it?

“…Since precise chemical programming of spin state transitions are not accessible in solution, there is much less chance to propose some reliable design in solids, and major interest in the SCO community moved toward the systematic structural exploration of classes of ligands and complexes for designing addressable (via temperature, pressure, light) switches implemented in various materials (solids, films, nanoparticles, liquid crystals, etc.). 37,[48][49][50][51][52][53] The deliberate combination of SCO properties with other physical or chemical properties in a synergetic fashion in molecular entities, summarized under the term of multifunctionality, [54][55][56] remains in its infancy despite remarkable efforts focused on the modulation of magnetic communication 57,58 and luminescence. 59 For instance, the modulation of an emissive lanthanide by an adjacent SCO Fe II metallic site in an isolated dimetallic complex has been recently attempted ( Fig.…”

Bistable Hofmann-Type FeII Spin-Crossover Two-Dimensional Polymers of 4-Alkyldisulfanylpyridine for Prospective Grafting of Monolayers on Metallic Surfaces

“…This requires a rational design of the synthesis at macroscopic scale and precise control of essential elusive SCO parameters, such as critical temperature ( T 1/2 ), abruptness, hysteresis width, and completeness. Relevant achievements of this strategy include the combination of SCO and nonlinear optical properties, 4 electronic conduction, 5 electroluminescence, 6 fluorescence, 7 liquid-crystalline properties, 8 porosity, 2d , 2g molecular recognition, 9 photoswitchable magnets, 10 chirality, 11 room-temperature photoisomers and reactions, 12 etc. The ultimate goal is the construction of sensing materials capable of acting as switchers in response to changes of ambient conditions (temperature, humidity, chemical contaminants, etc.).…”

Heterolepticmer-[Cr(N∩N∩N)(CN)3] complexes: synthetic challenge, structural characterization and photophysical properties

“…Moreover, the energy of the metal-centered excited states Cr ( 2 E), Cr( 2 T 1 ) and Cr( 4 T 2 ), which control the optical properties, can be easily tuned by the primary coordination sphere around the chromium center via the ligand field (Δ) and Racah (B, C) parameters (Scheme 1 and Table S1 †). [6][7][8][9][10][11][12][13] Whereas the design of inert heteroleptic trivalent chromium complexes has been systematically exploited within the frame of the 'complexas-ligand and complex-as-metal' strategy for producing heteropolymetallic paramagnetic assemblies and clusters working as ferromagnets or single-molecule magnets (SMMs), 3,[14][15][16][17][18][19] the alternative building of optical devices using the same strategy remained scarce. [20][21][22][23] Under weak ligand field conditions, as found in [CrX 6 ] 3− (X = F, Cl) and in [CrO 6 ] chromophores possessing Δ/B < 30 (Scheme 1a, Table S1 †), the excited Cr( 4 T 2 ) and Cr( 2 E, 2 T 1 ) levels are close in energy and involved in backintersystem crossing (BISC) processes.…”