New Ruthenium Bis(terpyridine) Methanofullerene and Pyrrolidinofullerene Complexes: Synthesis and Electrochemical and Photophysical Properties

Abstract

A series of terpyridine (tpy) methanofullerene and pyrrolidinofullerene dyads linked via p-phenylene or p-phenyleneethynylenephenylene (PEP) units is presented. The coordination to ruthenium(II) yields donor-bridge-acceptor assemblies with different lengths. Cyclic voltammetry and UV-vis and luminescence spectroscopy are applied to study the electronic interactions between the active moieties. It is shown that, upon light excitation of the ruthenium(II)-based (1)MLCT transition, the formed (3)MLCT state is readily quenched in the presence of C60. The photoinduced dynamics have been studied by transient absorption spectroscopy, which reveals fast depopulation of the (3)MLCT (73-406 ps). As a consequence, energy transfer occurs, populating a long-lived triplet state, which could be assigned to the (3)C60* state.

Dyads and Triads Based on Phenothiazine, Bis(terpyridine)ruthenium(II) Complexes, and Fullerene

“…Recently, we reported the synthesis of the C 60 -Sp-tpy ligands 5b and 5c (Sp = spacer). [11] In a repetition of the reported synthesis we could increase the yield to 60 and 81 % for 5b and 5c, respectively. Accordingly, the shorter C 60 -Sp-tpy ligand 5a and the longer ligand 5d were synthesized.…”

“…All ruthenium coordination reactions with a second tpy-based ligand were performed in DMF at 130°C for 1 h, as described previously. [11] The first route represents the coordination of PTZ-tpy ligand 7 with [Ru(tpy)(MeCN) 3 ](PF 6 ) 2 [19] and afforded complex 2 in 70 % yield. However, this procedure is not applicable for the triad preparation, since the corresponding C 60 -Sp-tpy ruthenium precursors are not available.…”

“…A similar behavior was also ob-served in a related complex missing the PTZ moiety. [11] Two reversible C 60 -based reduction processes were recorded in the cathodic region for 1c at -1.13 and -1.51 V in dichloromethane. The signal of the second C 60 -based reduction is overlapping with that of the first tpy-based reduction in the CV spectrum, while two clearly separated peaks occurred in the DPV spectrum.…”

“…[10] We recently reported the photodynamic processes in dyads based on a bis(tpy)ruthenium(II) complex [Ru(tpy) 2 ] 2+ , a π-conjugated bridge, and a methano-or pyrrolidino-functionalized C 60 . [11] [Ru(tpy) 2 ] 2+ was chosen as photosensitizer and electron donor because of its intense absorption at ca. 500 nm and the reversible ruthenium-based redox potential (i.e.…”

Photophysics of BODIPY Dyes as Readily-Designable Photosensitisers in Light-Driven Proton Reduction

“…To determine excited state lifetimes of long-lived triplet states transient absorption spectroscopy with ns time-resolution was performed in setup with 90 • pump-probe geometry, which has been described previously [43]. The pump pulses were delivered by a Continuum OPO Plus pumped by a Continuum Surelite Nd:YAG laser (pulse duration 5 ns, pulse-to-pulse repetition rate 10 Hz), and a 75 W Xenon arc lamp served as source for the probe light.…”