Synthesis and characterization of ferrocenylgalvinol, a novel d–π redox system

A novel d–π redox molecule bearing ferrocene (Fc) and galvinoxyl (GalO) units as reversible redox active sites has been synthesized and characterized. The molecule shows solvatochromic behavior and changes from a red color in n-hexane (λmax = 388, 541 nm) to a greenish brown (λmax = 413, 582 nm) in MeOH. A cyclic voltammogram of 1 under neutral conditions shows a redox process corresponding to Fc/Fc+ but not one for GalOH (or GalO−)/GalO. Under basic conditions the latter process was observed and it occurred at a lower oxidative potential ( E 1 / 2 1 = - 0.074 V vs Ag/AgCl) than the former process ( E 1 / 2 2 = 0.498 V ) . Thus 1 shows potential as a bilateral multi-redox molecule with pH dependence. Chemical oxidation of 1 under basic conditions (aq KOH, K3Fe(CN)6) gives an EPR spectrum with an hfc of 1.2 G attributable to Fc–GalO.