Supramolecular Control of Oligothienylenevinylene−Fullerene Interactions: Evidence for a Ground-State EDA Complex
摘要:
Complementary hydrogen-bonding interactions between a barbituric acid-substituted fullerene derivative (1) and corresponding receptor (2) bearing thienylenevinylene units are used to assemble a 1:1 supramolecular complex (K = 5500 M-1). Due to the close proximity of the redox-active moieties within the assembly, strong ground-state electron-donor-acceptor interactions are observed. Photoinduced electron transfer from electron-rich thienylenevinylene subunits to the fullerene is very fast (k(et) = 5.5 x 10(12) s(-1)), as determined by fs-time-resolved transient absorption spectroscopy.
Soluble thienylenevinylene oligomers based on 3,4-dihexylthiophene with chain length approaching 100 Angstrom (16-mer) have been synthesized, Optical data obtained in solution and on solution-processed thin films show that chain extension produces a narrowing of the HOMO-LUMO gap (Delta E) and band gap (E-g) which reach values significantly smaller than that of the parent polymer. Plots of Delta E and E-g vs the reciprocal number of carbons in the chain (1/Cn) reveal a deviation from Linearity beyond the 10-12-mer suggesting a limit of convergence around the 20-22-mer. Cyclic voltammetry shows that chain lengthening induces a negative shift of the first redox potential, an increase of the number of accessible redox states, and a decrease of the Coulombic repulsion in multicationic species. Thus, the 16-mer can be charged up to the hexacationic state within a 0.60-V potential window. A plot of the potential of the various redox steps vs 1/Cn suggests full coalescence into a single-step process for the 20-22-mar, A single process is indeed observed for solution cast films of 16-mer, and the respective contributions of the intra- and intermolecular mechanisms in the recombination process are discussed.
Jestin; Blanchard; Frere, Journal de Chimie Physique et de Physico-Chimie Biologique, 1998, vol. 95, # 6, p. 1266 - 1269
作者:Jestin、Blanchard、Frere、Roncali
DOI:——
日期:——
Extended Thienylenevinylene Oligomers as Highly Efficient Molecular Wires
A much smaller band gap than in the parent polymer is observed for the π-conjugated hexadecamer 1, which can be reversibly charged up to the hexacation in a small potential range.