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

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. Photomagnetic studies on materials containing spin‐crossover cations and photochromic anions led to materials that exhibit spin‐transition and photomagnetic properties. The influence of irradiation on the magnetic properties is reported.