Spin Transition Charted in a Fluorophore-Tagged Thermochromic Dinuclear Iron(II) Complex

Abstract

The first crystal structures of a dinuclear iron(II) complex with three N1,N2-1,2,4-triazole bridges in the high-spin and low-spin states are reported. Its sharp spin transition, which was probed using X-ray, calorimetric, magnetic, and (57)Fe Mossbauer analyses, is also delineated in the crystalline state by variable-temperature fluorimetry for the first time.

Iron(II) Complexes of Tridentate Indazolylpyridine Ligands: Enhanced Spin-Crossover Hysteresis and Ligand-Based Fluorescence

“…This observation has consequences for the design of fluorescent spin-crossover compounds, which have been pursued by several groups with mixed success. [40][41][42][43][44][45][46] The strongest coupling between spin-crossover and emission has been achieved using remote fluorophores tethered to iron complex centers, either in individual molecules 40,41 or more complex nanostructures. 42,43 This antenna effect may be a more promising approach towards multifunctional fluorescent switches, than compounds where the emissive group is directly ligated to the iron center as in this work.…”

Spin-state switches in molecular materials chemistry

“…Such spin-transitions inevitably lead to a change in magnetic moment which, in favourable cases, can correspond to "on-off" switchable diamagnetism/ paramagnetism. 4 In many cases the electronic rearrangement also changes the colour of a compound, 4 while bulk properties such as conductivity, 5,6 fluorescence, 7 magnetic ordering, 8 dielectric constant 9 and mechanical properties 10 are also affected by spin-state switching in the solid state. The stimulus is most commonly a change in temperature.…”

CdTe Quantum Dot Fluorescence Modulation by Spin Crossover

“…Depending on the spatial proximity of the luminescent and SCO centers, this energy transfer can be either radiative or resonant, but such mechanistic aspects have been scarcely investigated [2]. In a few cases, other mechanisms of luminescence modulation by SCO, related to structural instead of electronic changes, have been also proposed [14,22].…”