Synthesis of new photosensitive H2BBQ2+[ZnCl4]2−/[(ZnCl)2(μ-BBH)] complexes, through selective oxidation of H2O to H2O2
Date
2017Author
Stylianou, MariosHadjiadamou, I.
Drouza, Chryssoula
Hayes, Sophia C.
Lariou, E.
Tantis, I.
Lianos, P.
Tsipis, Athanassios C.
Keramidas, Anastasios D.
ISSN
1477-9226Source
Dalton TransactionsVolume
46Issue
11Pages
3688-3699Google Scholar check
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A new two-electron photosensitizer, H2BBQ2+[ZnCl4]2−/[(ZnCl)2(μ-BBH)] (BBQ stands for 2,5-bis[bis(pyridin-2-ylmethyl)amino]-1,4-quinone and BBH stands for 2,5-bis[bis(pyridin-2-ylmethyl)amino]-1,4-hydroquinone), has been synthesized and the oxidation state of the ligand was determined by X-ray crystallography and NMR spectroscopy. Under light illumination the H2BBQ2+[ZnCl4]2− + ZnCl2 is reduced quantitatively to [(ZnCl)2(μ-BBH)] (pH ∼ 5) oxidizing H2O to H2O2 as is evident by trap experiments. Electrochemistry gave a reversible two-electron ligand-centered redox wave for [(ZnCl)2(μ-BBH)]. UV-Vis, luminescence and EPR spectroscopies reveal the slow formation of a stable quinone diradical, intermediate of the reaction. DFT calculations are in agreement with the proposed mechanism. Based on this property an aqueous {[(ZnCl)2(μ-BBH)] H2O2} solar rechargeable galvanic cell has been constructed. © The Royal Society of Chemistry.