Synergic Bistability between Spin Transition and Fluorescence in Polyfluorene Composites with Spin Crossover Polymers

Abstract

In recent years, several examples of materials combining the molecular bistability of spin crossover (SC) and fluorescent moieties have flourished in the literature. Fluorescence is a sensitive probe, and SC may provide modulation of the signal, thus affording systems in which physicochemical changes in the environment of the SC centers could be effectively detected. On the contrary, organic semiconductor polymers are of great interest and, furthermore, have been successfully applied in different optoelectronic devices, such as transistors, solar cells, and light-emitting devices. Herein, we report on the fabrication of composites comprising a fluorescent, organic semiconductor polymer (polyfluorene) and a spin crossover compound, an Fe­(II)-triazole coordination polymer. A strong synergy was observed between the spin transition of the Fe­(II) compound and variations in the fluorescence of the organic polymer. The fluorescence modulation was shown to be reversible, with an increase of ≤20% with respect to the original value.

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

“…Modifying SCO materials with fluorescent species can be realized by physical mixing or doping SCO materials with fluorescent molecules, or simply modifying SCO (nano)materials with fluorescent groups. This strategy is advantageous for technical applications, and to date a lot of SCO-fluorescent bifunctional materials obtained from this strategy have been reported, including SCO complexes mixed or doped with luminescent guest molecules, 60,61 counter ions, 62,63 co-crystallization molecules, 64 fluorophore-modified thin films, [65][66][67][68][69][70] nanoparticles, [71][72][73][74][75][76] and core-shell nanomaterials. [77][78][79][80][81][82] Mixing or doping SCO materials with fluorescent guest molecules, counter ions, or cocrystallization molecules is usually adopted in the process of crystal growth or device fabrication.…”

Memory effect in ferroelectric polyvinylidene fluoride (PVDF) films via spin crossover probes

“…This same strategy conferred bistability on composites of organic fluorescent polymers. 28 This synergy between the phase transition of SCOs with the mechanically responsive nature of the conducting organic polymers may be general. If so, spin crossover probes may bring memory effects to a variety of organic polymer-based materials and devices.…”

Manipulating fluorescence by photo-switched spin-state conversions in an iron(ii)-based SCO-MOF

“…[27][28][29][30][31] Recent studies have proven that the uorescence intensity of SCO complexes can be effectively modulated by spin-state conversions. [32][33][34][35][36][37][38][39] The uorophore acts as a photosensitizer responsible for absorbing photons and emitting uorescence, while the SCO unit is a better energy acceptor. When a coupling path is built between them, the energy transfer efficiency from the uorophores to metal ions will be different for the HS and LS states due to the varied overlaps of emission bands of the ligand and absorption bands of the metal ion.…”