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 (E1/21=-0.074V vs Ag/AgCl) than the former process (E1/22=0.498V). 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.