Bistable Molecular Switches Based on Linkage Isomerization in Ruthenium Polypyridyl Complexes with a Ligand-Bound Ambidentate Motif
2009 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 15, no 5, 1195-1204 p.Article in journal (Refereed) Published
Electron-transfer-induced linkage isomerization was investigated in a series of bis-tridentate Ru polypyridyl complexes [Ru(L-X-OH)(Y-tpy)](2+) with ambidentate ligand L-X-OH bpy-C(R)(OH)-py (bpy-2,2'-bipyridine py-pyridine; R-H, Me, Ph, or tBu) and spectator ligand Y-tpy (tpy 2.2':6',2 ''-terpyridine, Y-p-tolyl, p-PhCO2Me, Cl, OEt, N-pyrrolidine). The ligand-bound ambidentate motif switches reversibly between N and O coordination in the Ru-II and Ru-III state,respectively. The potentials of the Ru-III/II couple differ by about 0.5 V between the isomers, and this results in a bistable electrochemical response of the molecular switches. The effects of structural modifications in form of substituents on the linking carbon atom of the ambidentate ligand and on the central pyridine moiety of the spectator ligand were investigated by electrochemical and computational methods. Differences in isomerization behavior span six orders of magnitude in rate constants and two orders of magnitude in equilibrium constants. The results can be interpreted in terms of steric and electronic substituent effects and their influence on rotational barriers, ligation geometry, and electron deficiency of the metal center.
Place, publisher, year, edition, pages
2009. Vol. 15, no 5, 1195-1204 p.
ambidentate ligands, electrochemistry, isomerization, ruthenium, tridentate ligands
IdentifiersURN: urn:nbn:se:uu:diva-137346DOI: 10.1002/chem.200801208ISI: 000263093700017OAI: oai:DiVA.org:uu-137346DiVA: diva2:378205