Issue 11, 2011

Photosensitive azobispyridine gold(i) and silver(i) complexes

Abstract

The neutral and cationic dinuclear gold(I) compounds [(μ-N–N)(AuR)2] (N–N = 2,2′-azobispyridine (2-abpy), 4,4′-azobispyridine (4-abpy); R = C6F5, C6F4OC12H25p, C6F4OCH2C6H4OC12H25p) and [(μ-N–N){Au(PR3)}2](CF3SO3)2 (N–N = 2-abpy, 4-abpy, R = Ph, Me) have been obtained by displacement of a weakly coordinated ligand by an azobispyridine ligand. The corresponding silver(I) dinuclear [(μ-2-abpy){Ag(CF3SO3)(PPh3)}2] and polynuclear [{Ag(CF3SO3)(4-abpy)}n] compounds have been obtained. The molecular structures of [(μ-2-abpy){Au(PPh3)}2](CF3SO3)2 and [(μ-4-abpy){Au(PMe3)}2](CF3SO3)2 have been confirmed by X-ray diffraction studies and feature linear gold(I) centers coordinated by pyridyl groups, and non-coordinated azo groups. In contrast the X-ray structure of [(2-abpy){Ag(CF3SO3)(PPh3)}2] shows tetracoordinated silver(I) centers involving chelating N–N coordination by pyridyl and azo nitrogen atoms. The gold(I) compounds with a long alkoxy chain do not behave as liquid crystals, and decompose before their melting point. The soluble gold(I) derivatives are photosensitive in solution and isomerize to the cis azo isomer under UV irradiation, returning photochemically or thermally to the most stable initial trans isomer. The silver(I) derivative [(2-abpy){Ag(CF3SO3)(PPh3)}2] also photoisomerizes in solution under UV irradiation, showing that its solid state structure, which would block isomerization by azo coordination, is easily broken. These processes have been monitored by UV-vis absorption and 1H NMR spectroscopy. All these compounds are non-emissive in the solid state, even at 77 K.

Graphical abstract: Photosensitive azobispyridine gold(i) and silver(i) complexes

Supplementary files

Article information

Article type
Paper
Submitted
03 Sep 2010
Accepted
09 Dec 2010
First published
31 Jan 2011

Dalton Trans., 2011,40, 2570-2577

Photosensitive azobispyridine gold(I) and silver(I) complexes

M. Bardají, M. Barrio and P. Espinet, Dalton Trans., 2011, 40, 2570 DOI: 10.1039/C0DT01167C

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