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

Abstract

A series of novel ferrocenylsubphthalocyanine dyads Y-BSubPc(H)₁₂ with ferrocenylcarboxylic acids Y-H = (FcCH₂CO₂-H), (Fc(CH₂)₃CO₂-H) or (FcCO(CH₂)₂CO₂-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)₃CO₂BSubPc(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)nCO₂BSubPc(H)₁₂ (n = 0–3), FcCO(CH₂)₂CO₂BSubPc(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.