title: Visible-light activation of the bimetallic chromophore-catalyst dyad: analysis of transient intermediates and reactivity toward organic sulfides.
abstract: In order to develop a new photocatalytic system, we designed a new redox-active module (5) to hold both a photosensitizer part, [Ru(II)(terpy)(bpy)X](n+) (where terpy = 2,2':6',2''-terpyridine and bpy = 2,2'-bipyridine), and a popular Jacobsen catalytic part, salen-Mn(III), covalently linked through a pyridine-based electron-relay moiety. On the basis of nanosecond laser flash photolysis studies, an intramolecular electron transfer mechanism from salen-Mn(III) to photooxidized Ru(III) chromophore yielding the catalytically active high-valent salen-Mn(IV) species was proposed. To examine the reactivity of such photogenerated salen-Mn(IV), we employed organic sulfide as substrate. Detection of the formation of a Mn(III)-phenoxyl radical and a sulfur radical cation during the course of reaction using time-resolved transient absorption spectroscopy confirms the electron transfer nature of the reaction. This is the first report for the electron transfer reaction of organic sulfide with the photochemically generated salen-Mn(IV) catalytic center.
authors.affiliation: Post Graduate and Research Department of Chemistry, Vivekananda College , Tiruvedakam West, Madurai 625 234, India.
authors.forename: Krishnan
authors.initials: K
authors.lastname: Senthil Murugan
authors.forename: Thangamuthu
authors.initials: T
authors.lastname: Rajendran
authors.forename: Gopalakrishnan
authors.initials: G
authors.lastname: Balakrishnan
authors.forename: Muniyandi
authors.initials: M
authors.lastname: Ganesan
authors.forename: Veluchamy Kamaraj
authors.initials: VK
authors.lastname: Sivasubramanian
authors.forename: Jeyaraman
authors.initials: J
authors.lastname: Sankar
authors.forename: Andivelu
authors.initials: A
authors.lastname: Ilangovan
authors.forename: Perumal
authors.initials: P
authors.lastname: Ramamurthy
authors.forename: Seenivasan
authors.initials: S
authors.lastname: Rajagopal