title: Nanometer length-dependent triplet-triplet energy transfers in zinc(II)porphyrin/trans-bis(ethynylbenzene)platinum(II) oligomers.
abstract: The synthesis and characterization of organometallic oligomers of the type [(p-C(6)H(4))C[triple bond]CPt(P(n-Bu)(3))(2)C identical withC(p-C(6)H(4))Zn(P)](n) with the corresponding models [(C(6)H(5)C[triple bond]C)Pt(P(n-Bu)(3))(2)C[triple bond]C(p-C(6)H(4))Zn(P)(p-C(6)H(4))C[triple bond]CPt(P(n-Bu)(3))(2)(C[triple bond]CC(6)H(5))], where Zn(P) is zinc(II)-10,20-di(mesityl)- (n = 4, 9) or zinc(II)-10,20-di-n-pentyl-porphyrin (n = 3, 6, 9), are reported. The electronic spectra (absorption, excitation, emission, and transient absorption) and the photophysical properties (emission lifetimes and quantum yields) of these species in 2-methyltetrahyrofuran at 298 and 77 K are presented. Rates for triplet (T(1)) energy transfer, k(ET), from the [(p-C(6)H(4)C[triple bond]C)Pt(P(n-Bu)(3))(2)(C[triple bond]C-p-C(6)H(4))] spacer to Zn(P) vary from 2.4 x 10(4) to 1.3 x 10(6) s(-1). For the n-pentyl case, a rate dependence of oligomer size is noted as k(ET) increases with the number of units, n. This phenomenon is interpreted by the presence of an excitonic process (i.e., delocalization of the energy along the Zn(P) array).
authors.affiliation: Département de Chimie, Université de Sherbrooke, PQ, Canada J1K 2R1.
authors.forename: Li
authors.initials: L
authors.lastname: Liu
authors.forename: Daniel
authors.initials: D
authors.lastname: Fortin
authors.forename: Pierre D
authors.initials: PD
authors.lastname: Harvey