Thermal and protonation-induced electron transfer coupled spin transition in a discrete [FeCo] Prussian blue analogue

Multi-stimuli responsive switchable molecules have garnered interest for their potential applications in the field of magnetic materials. However, the persistent challenge lies in isolating these properties within the same material. Herein, we report a discrete [Fe 2 Co 3 ] pentanuclear cyanide bridged complex, [Co(L) 2 ] 3 [Fe(CN) 6 ] 2 ·20H 2 O, ( 1 ) (L = ( Z )- N ′-(4-(trifluoromethyl)phenyl)picolinimidamide) which undergoes electron transfer coupled spin transition (ETCST) from [Fe II 2 Co II HS Co III 2 ] to [Fe III 2 Co II 3 ] configurations through thermal activation and upon protonation. The work presents a rationally designed cyanide bridged [Fe 2 Co 3 ] pentanuclear complex integrated with protonation sites, where the electronic states can be triggered by both thermal and chemical stimuli. This provides a promising approach for multi-stimuli responsive switchable molecular materials.