Photoinduced Energy and Electron-Transfer Reactions by Polypyridine Ruthenium(II) Complexes Containing a Derivatized Perylene Diimide

Author(s)

dos Santos, Edjane R. ; Pina, Joao ; Venancio, Tiago ; Serpa, Carlos ; Martinho, Jose M. G. ; Carlos, Rose Maria

• Document type: Journal article
• Source: Journal of Physical Chemistry C; v. 120, n. 40, p. 22831-22843, OCT 13 2016.
• Web of Science Citations: 9

Abstract

The {[}Ru(II) (phen)(2)(pPDIp)](2+) complex, where pPDIp is the symmetric bridging ligand phenanthroline-perylene-phenanthroline, shows strong electronic absorption bands attributed to the pPDIp and [Ru(phen)(2)](2+) moieties in acetonitrile. The charge-separated intermediate [Ru(III) (phen)(2)(pPDIp(-center dot))] was detected by transient absorption spectroscopy upon electronic excitation in either the pPDIp or the complex moieties. The charge-separated intermediate species decays to generate the triplet state (3){*}pPDIp-Ru(II) (tau(P) = 1.8 mu s) that sensitizes the formation of singlet molecular oxygen with quantum yield phi(Delta) = 0.57. The dyad in deaerated acetonitrile solutions is reduced by triethylamine (NEt3) to the {[}Ru(II) (phen)(2)(pPDIp(center dot-))] radical anion in the dark. The electron-transfer reaction is accelerated by light absorption. By photolysis of the radical anion, a second electron transfer reaction occurs to generate the {[}Ru(II)(phen)(2)(pPDIp(center dot-))] dianion. The changes of the color of solution indicate the redox states of complexes and offer a sensitive reporter of each stage of redox reaction from start to finish. The reduced complexes can be converted to the initial complex, using methyl viologen or molecular oxygen as an electron acceptor. The accumulation of electrons in two well-separated steps opens promising opportunities such as in catalysis. (AU)

• FAPESP's process: 13/23943-8 - Probing photoinduced charge transfer process and aggregation in excited State of mono- and bi-nuclear compounds
• Grantee: Edjane Rocha dos Santos
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• FAPESP's process: 11/10882-5 - Mimicking photosystem II reactions in artificial photosynthesis
• Grantee: Edjane Rocha dos Santos
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 14/12538-8 - Development of luminescent transition metal complexes to recognize and map in real time the aggregation processes of the B-amyloid peptide and of tau protein and to investigate the antioxidant and acetylcholinesterase enzyme inhibition activity
• Grantee: Rose Maria Carlos
• Support Opportunities: Regular Research Grants