title: cis-trans photoisomerization in [Ru(DIP)2(MeOH)2][OTf]2: synthesis, NMR, X-ray structure of the trans-isomer and photophysical properties.
abstract: The first trans-ruthenium complex trans-[Ru(DIP)2(MeOH)2][OTf]2 (1b, where DIP = 4,7-diphenyl-1,10-phenanthroline) incorporating a pi-extended ligand was prepared via two methods: either photolysis of cis-[Ru(DIP)2(OTf)2] in MeOH-Et(2)O or via crystallization from MeOH-Et(2)O in direct sunlight. The X-ray molecular structure of is reported and confirmed the trans geometry of the title compound. The cis-trans isomerization process was monitored by 1H-NMR and showed that 1b reverts back to cis-[Ru(DIP)2(MeOH)2][OTf]2 (1a) in methanol-d4 after 15 h at 55 degrees C or several days at room temperature. The absorption spectra recorded in MeOH showed a bathochromic shift of the MLCT band of the trans-isomer 1b relative to that of the cis complex 1a. Interestingly at 77 K the emission spectrum of 1b is red shifted compared to the cis analog 1a. A rational explanation in terms of the energy of the excited states in the cis- and trans-isomers is proposed to explain this behavior.
authors.affiliation: Laboratoire de Chimie Inorganique et Matériaux Moléculaires, UMR CNRS 7071, Université Pierre et Marie Curie-Paris 6, 4 place Jussieu, case 42, 75252, Paris Cedex 05, France. amouri@ccr.jussieu.fr
authors.forename: Hani
authors.initials: H
authors.lastname: Amouri
authors.forename: Jenny B
authors.initials: JB
authors.lastname: Waern
authors.forename: Regis
authors.initials: R
authors.lastname: Caspar
authors.forename: Andrea
authors.initials: A
authors.lastname: Barbieri
authors.forename: Cristiana
authors.initials: C
authors.lastname: Sabatini
authors.forename: Alberto
authors.initials: A
authors.lastname: Zanelli
authors.forename: Francesco
authors.initials: F
authors.lastname: Barigelletti