Two-dimensional emission quenching and charge separation using a Ru(II)-photosensitizer assembled with membrane-bound acceptors

Leif Hammarström, Thomas Norrby, Gunnar Stenhagen, Jerker Mårtensson, Björn Åkermark, Mats Almgren

Research output: Contribution to journalArticle

40 Citations (Scopus)

Abstract

Novel syntheses of the bipyridine ligand 1, dcHb (dcHb = 4,4′-dicarboxy-2,2′-bipyridine), by anionic oxidation of 4,4′-dimethyl-2′,2-bipyridine (dmb) using molecular oxygen (4 atm), and of the sensitizer precursor 4, tris(4,4′-diethoxycarbonyl-2,2′-bipyridine)ruthenium(II) bis(triflate), from a chloride-free Ru(II) precursor 3b, RuII(DMSO)4(triflate)2-n(EtOH)n (n = 0-2, DMSO = dimethyl sulfoxide, triflate = OSO2CF3) are reported. The anionic sensitizer Ru(dcb)3 4- (5) was shown to bind to vesicles of lecithin when these were made positively charged by cationic bipyridinium electron acceptors. With cetylmethylviologen (CMV2+) as quencher, the time-resolved decay of the Ru(dcb)3 4- emission followed a model for diffusion-controlled quenching in two dimensions. However, the diffusion coefficient obtained from a fit to the data was very small, (6 ± 2) x 10-11 m2 s-1, comparable to values for amphiphiles in bilayers, even though Ru(dcb)3 4- diffuses in the water region at the vesicle surface. The quantum yield of primary charge separation was 0.06 ± 0.02, which is significant, if not high, despite the large elecrostatic attraction between the reactants. Attempts were made to increase the charge separation yield by the use of a monocationic acceptor. Possible extensions of the system are discussed, such as charge separation across the vesicle membrane and the covalent linking of a donor to the sensitizer.

Original languageEnglish
Pages (from-to)7494-7504
Number of pages11
JournalJournal of Physical Chemistry B
Volume101
Issue number38
Publication statusPublished - Sep 18 1997

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Photosensitizing Agents
Photosensitizers
polarization (charge separation)
Dimethyl Sulfoxide
Quenching
quenching
membranes
Membranes
Lecithin
Amphiphiles
Ruthenium
Dimethyl sulfoxide
Lecithins
Molecular oxygen
Quantum yield
ruthenium
attraction
Chlorides
diffusion coefficient
chlorides

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Engineering(all)

Cite this

Two-dimensional emission quenching and charge separation using a Ru(II)-photosensitizer assembled with membrane-bound acceptors. / Hammarström, Leif; Norrby, Thomas; Stenhagen, Gunnar; Mårtensson, Jerker; Åkermark, Björn; Almgren, Mats.

In: Journal of Physical Chemistry B, Vol. 101, No. 38, 18.09.1997, p. 7494-7504.

Research output: Contribution to journalArticle

Hammarström, Leif ; Norrby, Thomas ; Stenhagen, Gunnar ; Mårtensson, Jerker ; Åkermark, Björn ; Almgren, Mats. / Two-dimensional emission quenching and charge separation using a Ru(II)-photosensitizer assembled with membrane-bound acceptors. In: Journal of Physical Chemistry B. 1997 ; Vol. 101, No. 38. pp. 7494-7504.
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