Issue 36, 2012

Ruthenium(ii) bis(terpyridine) electron transfer complexes with alkynyl–ferrocenyl bridges: synthesis, structures, and electrochemical and spectroscopic studies

Abstract

Two novel alkynyl-bridged symmetric bis-tridentate ligands 1,2-bis(1′-[4′-(2,2′:6′,2′′-terpyridinyl)]ferrocenyl)ethyne (3a; tpy–Fc–C[triple bond, length as m-dash]C–Fc–tpy; Fc = ferrocenyl; tpy = terpyridyl) and 1,4-bis(1′-[4′-(2,2′:6′,2′′-terpyridinyl)]ferrocenyl)-1,3-butadiyne (3b; tpy–Fc–C[triple bond, length as m-dash]C–C[triple bond, length as m-dash]C–Fc–tpy) and their Ru2+ complexes 6a and 6b have been synthesized and characterized by cyclic voltammetry, UV-vis and luminescence spectroscopy, and in the case of 3b by single-crystal X-ray diffraction. Cyclic voltammograms of both compounds, 3a and 3b, display two severely overlapping ferrocene-based oxidative peaks with only one reductive peak. The redox behavior of 6a and 6b is dominated by the Ru2+/Ru3+ redox couple (E1/2 from 1.33 to 1.34 V), the Fe2+/Fe3+ redox couples (E1/2 from 0.46 to 0.80 V), and the tpy/tpy/tpy2− redox couples (E1/2 from −1.19 to −1.48 V). The UV-vis spectra of 6a and 6b show absorption bands assigned to the 1[(d(π)Fe)6] → 1[(d(π)Fe)5(π*tpyRu)1] MMLCT transition at ∼555 nm. Complexes 6a and 6b are luminescent in H2O–CH3CN (4 : 1, v/v) solution at room temperature, and 6b exhibits the strongest luminescence intensity (λmaxem: 710 nm, Φem: 2.28 × 10−4, τ: 358 ns) relative to analogous ferrocene-based bis(terpyridine) Ru(II) complexes reported so far.

Graphical abstract: Ruthenium(ii) bis(terpyridine) electron transfer complexes with alkynyl–ferrocenyl bridges: synthesis, structures, and electrochemical and spectroscopic studies

Supplementary files

Article information

Article type
Paper
Submitted
21 May 2012
Accepted
23 Jun 2012
First published
27 Jun 2012

Dalton Trans., 2012,41, 11000-11008

Ruthenium(II) bis(terpyridine) electron transfer complexes with alkynyl–ferrocenyl bridges: synthesis, structures, and electrochemical and spectroscopic studies

K. Wu, J. Guo, J. Yan, L. Xie, F. Xu, S. Bai, P. Nockemann and Y. Yuan, Dalton Trans., 2012, 41, 11000 DOI: 10.1039/C2DT31091K

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