A hybrid magnet with coexistence of ferromagnetism and photoinduced Fe(iii) spin-crossover

Computational approach to the study of thermal spin crossover phenomena

“…3 However, the interest in SCO materials increased when it was discovered that conversion between the two spin states can be controlled by light irradiation, thus opening the possibility of using such materials as optically switchable devices. [4][5][6] This phenomenon, called Light-Induced Excited Spin State Trapping (LIESST), initially found in Fe(II) complexes [7][8][9][10][11] and later also observed in systems containing Fe(III), [12][13][14][15] and Ni(II) [16][17][18] has been intensively studied in the last years in order to unravel its mechanism both with experimental techniques 11,[19][20][21][22][23][24][25] and by means of theoretical calculations. [26][27][28][29][30][31][32][33] The most numerous and most studied family of SCO systems involves octahedral Fe(II) complexes in the solid state or in solution.…”

Recent Advances on Anilato-Based Molecular Materials with Magnetic and/or Conducting Properties

“…These molecular complexes, which represent one of the best examples of molecular bistability, change their spin state from low-spin (LS) to high-spin (HS) configurations and thus their molecular size, under an external stimulus such as temperature, light irradiation, or pressure [161,162]. Two-dimensional (2D) and three-dimensional (3D) bimetallic oxalate-based magnets with Fe(II) and Fe(III) spin-crossover cationic complexes have been obtained, where changes in size of the inserted cations influence the magnetic properties of the resulting materials [89,90,92,93]. By combining [Fe III (sal 2 -trien)] + (sal 2 -trien = N,N -disalicylidene triethylenetetramine) cations with the 2D Mn II Cr III oxalate-based network, a photoinduced spin-crossover transition of the inserted complex (LIESST effect), has been observed unexpectedely; this property infact is very unusual for Fe(III) complexes.…”

“…In the last 20 years many efforts have been addressed to add in these materials a further physical property by playing with the functionality of the A + cations located between the bimetallic layers. This strategy produced a large series of multifunctional molecular materials where the magnetic ordering of the bimetallic layers coexists or even interacts with other properties arising from the cationic layers, such as paramagnetism [2,[76][77][78][79][80], non-linear optical properties [2,81,82], metal-like conductivity [83,84], photochromism [2,81,85,86], photoisomerism [87], spin crossover [88][89][90][91][92][93], chirality [94][95][96][97], or proton conductivity [2,98,99]. Moreover, it is well-established that the ordering temperatures of these layered magnets are not sensitive to the separation determined by the cations incorporated between the layers, which slightly affects the magnetic properties of the resulting hybrid material, by emphasizing its 2D magnetic character [2,[75][76][77][78][79][80]95,100,101].…”

A spin crossover ferrous complex with ordered magnetic ferric anions

“…Fe(II) systems have so far eluded such success, likely because of a combination of inadequate charge, easier oxidation and greater sensitivity to environmental changes of the conditions favouring SCO. On the other hand, Fe(II) SCO 30 complexes were successfully integrated into materials with lower dimensionality, as cations 7 6 ] coordination core (tz = substituted tetrazole) probably represents the most-widely studied type of SCO compounds, while providing the highest probability of occurrence of SCO. On the other hand, tetrahaloferrate(III) ions have been widely used in molecular conductors 10 and can interact ferromagnetically depending on their stacking, 11 potentially resulting in ferromagnetic order.…”

“…4 An elegant synthetic strategy towards multifunctional materials is to build 20 two-network hybrid crystalline solids, and this has been particularly efficient with one of the networks having a 2D layered structure thus allowing intercalation of molecular, 1D or 2D species. 5 SCO complexes were only recently successfully integrated into 2D and 3D ferromagnetic magnetic oxalate 25 anionic networks, 6 using mononuclear Fe(III) complexes bearing chelating ligands. Fe(II) systems have so far eluded such success, likely because of a combination of inadequate charge, easier oxidation and greater sensitivity to environmental changes of the conditions favouring SCO.…”