157202-47-6Relevant academic research and scientific papers
Photoinduced Electron Transfer and Hole Migration in Nanosized Helical Aromatic Oligoamide Foldamers
Li, Xuesong,Markandeya, Nagula,Jonusauskas, Gediminas,McClenaghan, Nathan D.,Maurizot, Victor,Denisov, Sergey A.,Huc, Ivan
, p. 13568 - 13578 (2016)
A series of photoactive triads have been synthesized and investigated in order to elucidate photoinduced electron transfer and hole migration mechanism across nanosized, rigid helical foldamers. The triads are comprised of a central helical oligoamide foldamer bridge with 9, 14, 18, 19, or 34 8-amino-2-quinolinecarboxylic acid repeat units, and of two chromophores, an N-terminal oligo(para-phenylenevinylene) electron donor and a C-terminal perylene bis-imide electron acceptor. Time-resolved fluorescence and transient absorption spectroscopic studies showed that, following photoexcitation of the electron acceptor, fast electron transfer occurs initially from the oligoquinoline bridge to the acceptor chromophore on the picosecond time scale. The oligo(para-phenylenevinylene) electron donor is oxidized after a time delay during which the hole migrates across the foldamer from the acceptor to the donor. The charge separated state that is finally generated was found to be remarkably long-lived (>80 μs). While the initial charge injection rate is largely invariant for all foldamer lengths (ca. 60 ps), the subsequent hole transfer to the donor varies from 1 × 109 s-1 for the longest sequence to 17 × 109 s-1 for the shortest. In all cases, charge transfer is very fast considering the foldamer length. Detailed analysis of the process in different media and at varying temperatures is consistent with a hopping mechanism of hole transport through the foldamer helix, with individual hops occurring on the subpicosecond time scale (kET = 2.5 × 1012 s-1 in CH2Cl2). This work demonstrates the possibility of fast long-range hole transfer over 300 ? (through bonds) across a synthetic modular bridge, an achievement that had been previously observed principally with DNA structures.
2,5-Dialkoxy Substituted Oligo- and Poly(1,4-phenyleneethenylene)s
Kretzschmann, H.,Meier, H.
, p. 247 - 254 (2007/10/02)
O-Alkylation and regioselective Rieche formylation of 2-methylhydroquinone (1) yields the 2,5-dialkoxy-4-methylbenzaldehydes 4a-j.The corresponding azomethines 5a-j enter in a strongly alkaline medium a selfcondensation reaction leading to the title compounds 6/7a-j.These conjugated oligomers and polymers possess highly regular structures with exclusively (E)-configurated double bonds.GPC, IR, 1H-, 13C-NMR and MS-FD measurements were used for their characterization.Somewhat different results were obtained for the similarly prepared Schiff base 5l which contains chlorine substituents in the side chains.Cleavage of hydrogen chloride leads not only to unsaturated alkoxy groups; additionally, cyclization reactions (5l8l) are observed.
