Photomagnetic Studies of Spin‐Crossover‐ and Photochromic‐Based Complexes

Abstract

This work reports on the combination between photochromic complexes (Na2[Fe(CN)5(NO)]·2H2O and K2[RuCl5(NO)]) with spin‐crossover compounds derived from FeIII complexes {[Fe(qsal)2]+ and [Fe(salEen)2]+; Hqsal = N‐(8‐quinolyl)salicylaldimine; HsalEen = N‐[(2‐ethylamino)ethyl]salicylaldimine}. These associations have resulted in the synthesis of new materials that contain a spin‐crossover unit and a photochromic unit, as evidenced by their X‐ray structure. Spectroscopic, magnetic and photomagnetic properties of these complexes were studied, with or without light irradiation, to evaluate the possible influence of the photochromic group on the spin transition. [Fe(qsal)2]2[Fe(CN)5(NO)]·solvent, [Fe(salEen)2]2[Fe(CN)5(NO)] and [Fe(qsal)2]2[Ru(CN)5(NO)]·2.5H2O all exhibit a spin transition. The light‐induced excited spin‐state trapping (LIESST) effect was detected in the (Fe‐qsal)‐based complexes. [Fe(qsal)2]2[Ru(CN)5(NO)]·2.5H2O also exhibits a reverse‐LIESST effect. Regardless of the complex, no photochromic effect from the nitroprusside units was detected.

High-Temperature Cooperative Spin Crossover Transitions and Single-Crystal Reflection Spectra of [FeIII(qsal)2](CH3OSO3) and Related Compounds

“…We focused on the [Fe(qsal) 2 ] compounds showing a cooperative SCO transition probably due to strong π-stacking interactions and developed SCO conductors and magnets by combining the [Fe(qsal) 2 ] cation with redox active functional anions [22,23]. A number of multifunctional materials from the [Fe(qsal) 2 ] cation have been reported to date [24][25][26][27][28][29][30][31][32][33]. Recently, heteroleptic Fe(III) compounds [34][35][36][37] as well as Fe(II) compounds [38][39][40][41][42][43][44] from the qsal and its derivatives, were also reported.…”

Correlation between Supramolecular Connectivity and Magnetic Behaviour of [FeIII(5-X-qsal)2]+-Based Salts Prone to Exhibit SCO Transition

“…A large number of these salts are essentially HS at room temperature 1. [Fe(CN) 5 NO].MeOH [11,12], 1.I 3 [13], 1.SCN [14,15], 1.SeCN [15], 3.SCN.MeOH [16], 4.NO 3 .2MeOH [17], 5.CF 3 SO 3 .nPrOH [18] 5.CF 3 SO 3 .EtOH [18], 5.CF 3 SO 3 .iPOH [18], 5.CF 3 SO 3 .MeOH [19], 5.N(SO 2 CF 3 ) 2 [20] [21] and 7.NO 3 [21]. In a few cases both LS and HS states coexist at room temperature 1.…”

“…In a few cases both LS and HS states coexist at room temperature 1. [Fe(CN) 5 NO].2MeCN [12], 2.PF 6 [22], 2.SCN.MeOH [16], 4.SCN.MeOH [16], 6.PF 6 [23] or the [Fe(5-X-qsal) 2 ] + cations present essentially a LS configuration 1.I [24], 1.SCN.DCM [15], 1.SeCN.DCM [25], 2.ClO 4 [22], 2.BF 4 [22], 2.NO 3 [22], 2.SO 2 CF 3 [22], 5.CF 3 SO 3 .Me 2 CO [18], 5.CF 3 SO 3 .MeCN [18], 6.BF4.MeOH [23] and 6.SCN.DCM [23].…”

“…Apart from the six salts with gradual SCO processes or blocked HS cations (1. [Fe(CN) 5 NO].2MeCN [12], 5.CF 3 SO 3 .nPrOH [18], 5.CF 3 SO 3 .iPOH [18], 7.Cl.4MeOH.H 2 O, 7.ClO 4 .MeOH and 7.NO 3 [21]) and those with irreversible SCO behaviours (5.CF 3 SO 3 .EtOH [18] and 6.SCN.DCM [23]), the salts based on essentially HS [Fe(5-X-qsal) 2 ] + cations at 295K (1.I 3 [13], 1.SCN [14,15], 1.SeCN [15], 3.SCN.MeOH [16], 4.NO 3 .2MeOH [17], 5.CF 3 SO 3 .MeOH [19], 5.N(SO 2 CF 3 ) 2 [20] and 6.Cl•MeCN.H 2 O [10]) display cooperative SCO processes (Table S6). These salts exhibit the Chain Layers type of supramolecular configuration with crystal packings roughly similar to that described for 3.PF 6 .MeCN, 4.PF 6 .H 2 O and 5.PF 6 .1.5H 2 O, also with strong interchain DD interactions (Qn .…”

Synthesis, characterization and magnetic study of two new octahedral iron(III) complexes with pendant zwitterionic Schiff bases

“…Variable temperature magnetic susceptibility measurements identified the presence of SCO points in some of the complexes [34,35]. On the other hand, N 2 O donor Schiff bases, prepared by 1:1 condensation of any N-substituted diamine with suitable salicylaldehyde derivative have also been used to prepare various iron(III) complexes [36][37][38][39][40][41][42][43][44] of which mononuclear octahedral bis-ligand complexes constitute a unique class, as most of them show SCO behavior [36][37][38][39].…”