Photoinduced Electron Transfer Reactions of Ruthenium(II)-Complexes Containing Amino Acid with Quinones

Abstract

With the aim of mimicking, at basic level the photoinduced electron transfer process in the reaction center of photosystem II, ruthenium(II)-polypyridyl complexes, carrying amino acids were synthesized and studied their photoinduced electron transfer reactions with quinones by steady state and time resolved measurements. The reaction of quinones with excited state of ruthenium(II)-complexes, I-V in acetonitrile has been studied by luminescence quenching technique and the rate constant, k(q), values are close to the diffusion controlled rate. The detection of the semiquinone anion radical in this system using time-resolved transient absorption spectroscopy confirms the electron transfer nature of the reaction. The semiclassical theory of electron transfer has been successfully applied to the photoluminescence quenching of Ru(II)-complexes with quinones.

Systematic Conversion of Photoinduced Intramolecular Electron Transfer in Trinuclear M-Ir-M (M = Re, Ir) Complexes to Intersystem Charge Transfer by Coupling to Gold Nanoclusters

“…Similar prominent signal for excited state absorption of light by the coordinate complexes due to PET has been reported earlier. 51,52 The corresponding decay time of the radicals due to the PIIET were 163 and 551 ps for the IrTRe and IrTIr, respectively (Figure 6b,d). The faster decay of the transient radicals for IrTRe compared to that from IrTIr is because of the difference in electronegativity of the metal, Ir being the more electronegative one.…”

“…It is well known that AuNCs are constructed through reduction of Au-salt, followed by the accumulation of the Au 0 atoms at the core and Au + ions at the surface to incur stability to the system. 52,53 The surrounding compounds or moieties help in this accumulation process through coordinate bond formation between the terminal functional groups and the AuNCs. 54−56 The acquired AuNCs were characterized by the traditional spectroscopic and microscopic techniques.…”

“…With this motivation, we used the cylcometalated coordination complexes, with free amine ends as reducing as well as protecting agents to synthesize ultrasmall AuNCs. It is well known that AuNCs are constructed through reduction of Au-salt, followed by the accumulation of the Au 0 atoms at the core and Au + ions at the surface to incur stability to the system. , The surrounding compounds or moieties help in this accumulation process through coordinate bond formation between the terminal functional groups and the AuNCs. − The acquired AuNCs were characterized by the traditional spectroscopic and microscopic techniques. The spherical jellium model for small NCs showed that the AuNCs contain nine Au atoms (see the Supporting Information).…”

Ruthenium polypyridyl complex-containing bioconjugates

“…4. [43] In this case, however, different quinones were selected as quenchers. The emission intensities of the complexes were quenched by the quinones following a trend: higher quenching was observed for quinones with higher reduction potentials.…”

Photoelectrochemically-assisted biofuel cell constructed by redox complex and g-C3N4 coated MWCNT bioanode

“…The quenching process is more efficient when the number of quinone subunits increase around the Ru(II) center and Ru3 is almost not emissive as a consequence of a very efficient quenching process. This quenching process is due to an electron transfer reaction from the Ru(II)* center to the quinone acceptor units (Eswaran et al, 2014;Opperman et al, 1994). However via the cascade of electron transfer processes initiate by the oxidation of glucose, the Ru(II) complexes play the role of a redox mediator and will accept an electron from the FADH 2 on the PLQ ligand.…”