New Insights into the Physicochemical and Electrochemical Characterization of Gold Phthalocyanine-Based Materials

---

Résumé

Gold phthalocyanine-based materials can allow to combine the unique physical properties of the metallophthalocyanine with gold for numerous applications such as (photo)-electrochemistry or the so-called single atom catalysts (SACs), which require very small amounts of metal. However, there is currently a lack of physico-chemical and electrochemical knowledge to consider such applications. We report the synthesis and the physical characterization of three types of materials, the unsubstituted and the octosubstituted gold phthalocyanines AuPc, AuPc(CN)8 and AuPc(COOH)8, which were successfully synthesized. To interrogate the
physicochemical and electrochemical properties of the as-synthesized materials, we have performed a multi-variant study by integrating different methods (UV–vis, FTIRS, TGA-TDA, HR-ESI-MS, SEM-EDX, XRD, XPS, CV). UV–vis confirms the shift towards high wavelengths (bathochromic effect) for the transition Q-band (charge transfer from pyrrolic carbons to neighboring atoms in the macrocycle) of AuPc(CN)8 and AuPc(COOH)8 compared to AuPc. CV in both aqueous and non-aqueous provides the first electrochemical insights into the phthalocyanine ring reduction and oxidation, AuPc/[AuPc]−, [AuPc]−/[AuPc]2− and [AuPc]2−/[AuPc]3−. The results delineate a possible rational pathway for AuPc-based materials or alternatively, their transformation into SACs, where a single Au atom is embedded in a nanostructured carbon-nitrogen scaffold.

Mots-clés

Gold Phthalocyanine, Materials, Physicochemical, Electrochemical, Characterization