title: Luminescence quenching of Re(I) molecular rectangles by quinones.
abstract: The rhenium-based rectangles [{Re(CO)(3)(mu-bpy)Br}{Re(CO)(3)(mu-L)Br}](2) (I, L = 4,4'-dipyridylacetylene (dpa); II, L = 4,4'-dipyridylbutadiyne (dpb); III, L = 1,4-bis(4'-pyridylethynyl)benzene (bpeb); bpy = 4,4'-bipyridine) are emissive in solution at room temperature. The presence of extended pi conjugation leads to an increase in electron delocalization, which, in turn, results in improved luminescence and lower nuclear reorganization energy. These rectangles, upon electronic excitation, undergo facile electron transfer (ET) reactions with quinones and both the dynamic and static quenching contribute to the reaction. Spectral and electrochemical measurements show that quinone 7,7,8,8-tetracyanoquinodimethane (TCNQ) binds strongly to rectangle I. The driving force dependence of k(et), deduced from the luminescence quenching of rectangles with quinones, can be well accounted for within the context of the Marcus theory of electron transfer.
authors.affiliation: Institute of Chemistry, Academia Sinica, Taipei, 115, Taiwan.
authors.forename: Thangamuthu
authors.initials: T
authors.lastname: Rajendran
authors.forename: Balasubramanian
authors.initials: B
authors.lastname: Manimaran
authors.forename: Rong-Tang
authors.initials: RT
authors.lastname: Liao
authors.forename: Yen-Hsiang
authors.initials: YH
authors.lastname: Liu
authors.forename: Pounraj
authors.initials: P
authors.lastname: Thanasekaran
authors.forename: Ren-Jay
authors.initials: RJ
authors.lastname: Lin
authors.forename: I-Jy
authors.initials: IJ
authors.lastname: Chang
authors.forename: Pi-Tai
authors.initials: PT
authors.lastname: Chou
authors.forename: Ramasamy
authors.initials: R
authors.lastname: Ramaraj
authors.forename: Seenivasan
authors.initials: S
authors.lastname: Rajagopal
authors.forename: Kuang-Lieh
authors.initials: KL
authors.lastname: Lu