Synthesis, Spectroscopy, Electrochemistry and DFT of Electron-Rich Ferrocenylsubphthalocyanines

A series of novel ferrocenylsubphthalocyanine dyads Y-BSubPc(H)(12) with ferrocenyl-carboxylic acids Y-H = (FcCH(2)CO(2)-H), (Fc(CH2)(3)CO2-H) or (FcCO(CH2)(2)CO2-H) in the axial position were synthesized from the parent Cl-BSubPc(H)(12) via an activated triflate-SubPc intermediate. UV/Vis data revealed that the axial ferrocenyl-containing ligand did not influence the Q-band maxima compared to Cl-BSubPc(H)(12). A combined electrochemical and density functional theory (DFT) study showed that Fe group of the ferrocenyl-containing axial ligand is involved in the first reversible oxidation process, followed by a second oxidation localized on the macrocycle of the subphthalocyanine. Both observed reductions were ring-based. It was found that the novel Fc(CH2)(3)CO(2)BSubPc(H)(12) exhibited the lowest first macrocycle-based reduction potential (-1.871 V vs. Fc/Fc(+)) reported for SubPcs till date. The oxidation and reduction values of Fc(CH2)(n)CO(2)BSubPc(H)(12) (n = 0-3), FcCO(CH2)(2)CO(2)BSubPc(H)(12), and Cl-BSubPc(H)(12) illustrated the electronic influence of the carboxyl group, the different alkyl chains and the ferrocenyl group in the axial ligand on the ring-based oxidation and reduction values of the SubPcs.