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Synthesis, photophysical, photochemical, and redox properties of nitrospiropyrans substituted with Ru or Os tris(bipyridine) complexes

Jukes, R.T.F., Bozic, B., Hartl, F., Belser, P. and De Cola, L. (2006) Synthesis, photophysical, photochemical, and redox properties of nitrospiropyrans substituted with Ru or Os tris(bipyridine) complexes. Inorganic Chemistry, 45 (20). pp. 8326-8341. ISSN 0020-1669

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To link to this article DOI: 10.1021/ic0606680

Abstract/Summary

Photochromic nitrospiropyrans substituted with 2,2'-bipyridine (bpy), [Ru(bpy)(3)](2+), and [Os(bpy)(3)](2+) groups were synthesized, and their photophysical, photochemical, and redox properties investigated. Substitution of the spiropyran with the metal complex moiety results in strongly decreased efficiency of the ring-opening process as a result of energy transfer from the excited spiropyran to the metal center. The lowest excited triplet state of the spiropyran in its open merocyanine form is lower in energy than the excited triplet MLCT level of the [Ru(bpy)(3)](2+) moiety but higher in energy than for [Os(bpy)(3)](2+), resulting in energy transfer from the excited ruthenium center to the spiropyran but inversely in the osmium case. The open merocyanine form reduces and oxidizes electrochemically more easily than the closed nitrospiropyran. Like photoexcitation, electrochemical activation also causes opening of the spiropyran ring by first reducing the closed form and subsequently reoxidizing the corresponding radical anion in two well-resolved anodic steps. Interestingly, the substitution of the spiropyran with a Ru or Os metal center does not affect the efficiency of this electrochemically induced ring-opening process, different from the photochemical path.

Item Type:Article
Refereed:Yes
Divisions:Faculty of Life Sciences > School of Chemistry, Food and Pharmacy > Department of Chemistry
ID Code:17265
Publisher:ACS Publications

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