An Increase in the Rigidity of the Environment Favors MLCT over the MC State in [Ru(bpy)(Nicotine)](Cl): A Case Study of Photolabile Ligands.

Ru(II)-complexes with photolabile ligands find a wide range of applications, e.g., in drug release and in the design of light-responsive interfaces.

Near room temperature stepwise spin state switching and photomagnetic effect in a mixed-valence molecular square.

A two-step thermo-induced spin-state switching was observed in a cyanide-bridged [FeFe] molecular square complex, {[Fe(pzTp)(CN)][Fe(L)]}[Fe(pzTp)(CN)]·4CHOH·2HO [1·4MeOH·2HO; pzTp = tetrakis(pyrazol-1-yl)borate and L = bis(1-ethylimidazol-2-yl)ketone (bik*)], which was characterized fully by single-crystal X-ray diffraction, (photo)magnetic measurements, and spectroscopic techniques. 1·4MeOH·2HO exhibited a two-step thermo-induced spin transition with (1) ↑ = 306 K and (2) ↑ = 370 K converting the low-temperature ground state, {[(FeIIILS)(FeIILS)](FeIIILS)} into the high-temperature state, {[(FeIIILS)(FeIIHS)](FeIIILS)} a stable intermediate phase. The desolvated phase, 1 also exhibited a gradual but reversible thermo-induced spin state change with a value of 190 K, significantly shifted to a lower temperature.

ON/OFF Photo(switching) along with Reversible Spin-State Change and Single-Crystal-to-Single-Crystal Transformation in a Mixed-Valence Fe(II)Fe(III) Molecular System.

A mixed-valence Fe(II)Fe(III) molecular system, {[Fe(pzTp)(CN)][Fe(bik)]}·[Fe(pzTp)(CN)]·4MeOH (·4MeOH) (bik = bis-(1-methylimidazolyl)-2-methanone, pzTp = tetrakis(pyrazolyl)borate), exhibits single-crystal-to-single-crystal (SC-SC) transformation while increasing the temperature and is converted into {[Fe(pzTp)(CN)][Fe(bik)]}·[Fe(pzTp)(CN)] (). Both complexes exhibit thermo-induced spin-state switching behavior along with reversible SC-SC transformation, where the low-temperature [FeFe] phase transforms into a high-temperature [FeFe] phase. ·4MeOH exhibits an abrupt spin-state switching with at 355 K, whereas undergoes a gradual and reversible spin-state switching with a lower at 338 K.