Rapid energy transfer in bichromophoric tris-bipyridyl/cyclometallated ruthenium(ii) complexes

Sascha Ott, Magnus Borgström, Leif Hammarström, Olof Johansson

Research output: Contribution to journalArticle

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Abstract

The synthesis, characterization, and photophysical properties of the N6–N5C bichromophoric [(bpy)2Ru(I)Ru(ttpy)][PF6]3(bpy is 2,2′-bipyridine and ttpy is 4′-p-tolyl-2,2′:6′,2′-terpyridine) and [(bpy)2Ru(II)Ru(ttpy)][PF6]3(I and II are bpy-dipyridylbenzene ditopic ligands bridged by an ethynyl and phenyl unit, respectively) complexes are reported together with the model mononuclear complexes [(bpy)2Ru(I)][PF6]2, [(bpy)2Ru(II)][PF6]2, [Ru(VI)(ttpy)][PF6] (VI is 3,5-di(2-pyridyl)-biphenyl) and [Ru(dpb)(ttpy)][PF6] (Hdpb is 1,3-di(2-pyridyl)-benzene). The electrochemical data show that there is little ground state electronic communication between the metal centers in the bimetallic complexes. Selective excitation of the N5C unit in the bichromophoric systems leads to luminescence typical for a bis-tridentate cyclometallated ruthenium complex and is similar to the [Ru(VI)(ttpy)][PF6] model complex. In contrast, the luminescence from the tris-bidentate N6unit is efficiently quenched by energy transfer to the N5C unit. The energy transfer rate has been determined by femtosecond pump–probe measurements to 0.7 ps in the ethynyl-linked [(bpy)2Ru(I)Ru(ttpy)][PF6]3and to 1.5 ps in the phenyl-linked [(bpy)2Ru(II)Ru(ttpy)][PF6]3(in acetonitrilesolution at 298 K), and is inferred to occur via a Dexter mechanism.

Original languageEnglish
Pages (from-to)1434-1443
Number of pages10
JournalJournal of the Chemical Society. Dalton Transactions
Volume6
Issue number2
DOIs
Publication statusPublished - Nov 29 2005

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2,2'-Dipyridyl
Ruthenium
Energy transfer
Luminescence
Benzene
Ground state
Metals
Ligands
Communication
diphenyl

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Rapid energy transfer in bichromophoric tris-bipyridyl/cyclometallated ruthenium(ii) complexes. / Ott, Sascha; Borgström, Magnus; Hammarström, Leif; Johansson, Olof.

In: Journal of the Chemical Society. Dalton Transactions, Vol. 6, No. 2, 29.11.2005, p. 1434-1443.

Research output: Contribution to journalArticle

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title = "Rapid energy transfer in bichromophoric tris-bipyridyl/cyclometallated ruthenium(ii) complexes",
abstract = "The synthesis, characterization, and photophysical properties of the N6–N5C bichromophoric [(bpy)2Ru(I)Ru(ttpy)][PF6]3(bpy is 2,2′-bipyridine and ttpy is 4′-p-tolyl-2,2′:6′,2′-terpyridine) and [(bpy)2Ru(II)Ru(ttpy)][PF6]3(I and II are bpy-dipyridylbenzene ditopic ligands bridged by an ethynyl and phenyl unit, respectively) complexes are reported together with the model mononuclear complexes [(bpy)2Ru(I)][PF6]2, [(bpy)2Ru(II)][PF6]2, [Ru(VI)(ttpy)][PF6] (VI is 3,5-di(2-pyridyl)-biphenyl) and [Ru(dpb)(ttpy)][PF6] (Hdpb is 1,3-di(2-pyridyl)-benzene). The electrochemical data show that there is little ground state electronic communication between the metal centers in the bimetallic complexes. Selective excitation of the N5C unit in the bichromophoric systems leads to luminescence typical for a bis-tridentate cyclometallated ruthenium complex and is similar to the [Ru(VI)(ttpy)][PF6] model complex. In contrast, the luminescence from the tris-bidentate N6unit is efficiently quenched by energy transfer to the N5C unit. The energy transfer rate has been determined by femtosecond pump–probe measurements to 0.7 ps in the ethynyl-linked [(bpy)2Ru(I)Ru(ttpy)][PF6]3and to 1.5 ps in the phenyl-linked [(bpy)2Ru(II)Ru(ttpy)][PF6]3(in acetonitrilesolution at 298 K), and is inferred to occur via a Dexter mechanism.",
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AB - The synthesis, characterization, and photophysical properties of the N6–N5C bichromophoric [(bpy)2Ru(I)Ru(ttpy)][PF6]3(bpy is 2,2′-bipyridine and ttpy is 4′-p-tolyl-2,2′:6′,2′-terpyridine) and [(bpy)2Ru(II)Ru(ttpy)][PF6]3(I and II are bpy-dipyridylbenzene ditopic ligands bridged by an ethynyl and phenyl unit, respectively) complexes are reported together with the model mononuclear complexes [(bpy)2Ru(I)][PF6]2, [(bpy)2Ru(II)][PF6]2, [Ru(VI)(ttpy)][PF6] (VI is 3,5-di(2-pyridyl)-biphenyl) and [Ru(dpb)(ttpy)][PF6] (Hdpb is 1,3-di(2-pyridyl)-benzene). The electrochemical data show that there is little ground state electronic communication between the metal centers in the bimetallic complexes. Selective excitation of the N5C unit in the bichromophoric systems leads to luminescence typical for a bis-tridentate cyclometallated ruthenium complex and is similar to the [Ru(VI)(ttpy)][PF6] model complex. In contrast, the luminescence from the tris-bidentate N6unit is efficiently quenched by energy transfer to the N5C unit. The energy transfer rate has been determined by femtosecond pump–probe measurements to 0.7 ps in the ethynyl-linked [(bpy)2Ru(I)Ru(ttpy)][PF6]3and to 1.5 ps in the phenyl-linked [(bpy)2Ru(II)Ru(ttpy)][PF6]3(in acetonitrilesolution at 298 K), and is inferred to occur via a Dexter mechanism.

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