An azido-bridged [FeII4] grid-like molecule showing spin crossover behaviour

Abstract

Supramolecular self-assembly synthetic strategy provides a valid tool to obtain polynuclear Fe(II) complexes containing effective communications between the metal centers and achieve distinct spin crossover behaviour. Despite great success in...

Recent developments in supramolecular complexes of azabenzenes containing one to four N atoms: synthetic strategies, structures, and magnetic properties

“…Again by using the same ligands L14 and L15 and by changing the metal ion to Fe II , same group had published two Fe II grids ([ L14 ) 4 Fe II 4 (N 3 ) 4 ][BPh 4 ] 4 ·sol ( FeL14 )and [( L15 ) 4 Fe II 4 (N 3 ) 4 ][BPh 4 ] 4 ·sol ( FeL15 )) in 2021. 77 Among these supramolecular self-assembled complexes, FeL14 showed spin crossover behavior at 230 K. At 300 K, χ m T values for both FeL14 and FeL15 was found to be 12.34 and 12.77 cm 3 mol −1 K respectively. Upon lowering the temperature a gradual decrease in the χ m T value was identified in FeL15 until 5 K, which was rapidly decreased to 6.66 cm 3 mol −1 K at 2 K. This behavior of FeL15 was the indication of ZFS or intermolecular antiferromagnetic coupling.…”

“…Both ligands L14 and L15 have huge potentials to show various magnetic behaviors as well as they were structurally suitable for many transition metal complexes to provide grid like structures. Again by using the same ligands L14 and L15 and by changing the metal ion to Fe II 77 Among these supramolecular self-assembled complexes, FeL14 showed spin crossover behavior at 230 K. At 300 K, c m T values for both FeL14 and FeL15 was found to be 12.34 and 12.77 cm 3 mol À1 K respectively. Upon lowering the temperature a gradual decrease in the c m T value was identied in FeL15 until 5 K, which was rapidly decreased to 6.66 cm 3 mol À1 K at 2 K. This behavior of FeL15 was the indication of ZFS or intermolecular antiferromagnetic coupling.…”

Synergistic strategies for the synthesis of Fe(ii)-based bifunctional fluorescent spin-crossover materials

“…In such bifunctional fluorescent SCO complexes, an explicit stoichiometric ratio of the two components is achieved, and chemical bonds are rationally used to control the distance between the fluorophore and the SCO-active center. Based on this strategy, a number of fluorescent SCO complexes including mononuclear complexes, [36][37][38][39][40][41][42][43][44][45][46] polynuclear complexes, [47][48][49][50][51] and coordination polymers [52][53][54][55][56][57] have been reported. Notably, besides thermally induced SCO that can initially control fluorescence emission, other stimuli such as light, 40 solvent, 41 pH, 45 and aggregation-induced emission (AIE) effects 58 affect the fluorescence emission and thus SCO-fluorescence coupling.…”

Self-assembly of Ni(ii) metallacycles (a square and a triangle) supported by tetrazine radical bridges

“…one 14 shows spin-crossover behaviour. Alternately, similar square complexes containing the tetrazine radical bridges were achieved when the related tetrazine derivatives were utilized instead.…”

“…With the incorporation of azide ions as secondary bridges, we recently prepared a series of [2 × 2] grid-like [M II 4 ] clusters based on 3,6-substituted pyridazine derivatives within cis -bridging modes as dictated by the end-on azido bridges. It should be mentioned that both the Co( ii ) analogues 13 exhibit typical single-molecule magnet (SMM) behaviour while the Fe( ii ) one 14 shows spin-crossover behaviour. Alternately, similar square complexes containing the tetrazine radical bridges were achieved when the related tetrazine derivatives were utilized instead.…”