Dual Exciplex Formation and Photoinduced Electron Transfer in Pyrene End-Labeled Polynorbornenes

Abstract

Polynorbornenes substituted with 1-cyano-2-naphthyl and 2,5-dicyanophenyl groups as acceptors and terminated with pyrene as donor have been prepared by ring-opening metathesis polymerization. When excited with monochromatic light, pyrene transfers an electron, producing a radical ion pair with concurrent reduction of the acceptor. In the copolymers with one acceptor block, steady-state emission spectra reveal extensive pyrene fluorescence quenching and exciplex formation between the pyrene and the acceptor. In copolymers with two acceptor blocks, the steady-state emission spectra reveal two intramolecular exciplexes assigned to the cyanonaphthalene−pyrene and dicyanobenzene−pyrene excited-state complexes. Transient absorption spectra display an overlap of the pyrene triplet−triplet and radical cation spectra for all of the polymers. The lifetimes of the transient absorption maxima are dependent upon the identity of the acceptor and the length of the acceptor block.

Photoinduced Charge Separation in a Fluorophore−Gold Nanoassembly

“…The pyrene cation radical has been shown to absorb strongly in the 400−450 nm regions. Evidence in the literature suggests strong dependence of the maximum on the medium and substituent . Pyrene cation radical formed in polynorbornene end-labeled with pyrene has been shown in this study to exhibit absorption maximum at 400 nm.…”

“…Evidence in the literature suggests strong dependence of the maximum on the medium and substituent. 38 Pyrene cation radical formed in polynorbornene end-labeled with pyrene has been shown in this study to exhibit absorption maximum at 400 nm. Hence, we attribute the 400-nm absorption band to the formation of an oxidation product, viz., a radical cation formed by the interaction of excited pyrene with the gold nanocore.…”

A pyrene-containing fluorescent sensor with high selectivity for lead(II) ion in water with dual illustration of ground-state dimer

“…Pyrene derivatives are ubiquitous photophysical probes [12,13], and pyrene-containing molecular systems have been studied extensively because they demonstrate distinctive monomer and excimer emissions [14]. In a previous study, we have reported a pyrene-containing fluorescent chemosensor, N-[4(1-pyrene)-butyroyl]-l-tryptophan (PLT), for Pb 2+ , it possesses high sensitivity and selectivity to Pb 2+ in aqueous solutions.…”

Methionine–pyrene hybrid based fluorescent probe for trace level detection and estimation of Hg(II) in aqueous environmental samples: Experimental and computational studies

“…Various molecular systems have been reported that monitor Hg 2+ concentration by exploiting the mechanism of complexation-induced fluorescence quenching [19][20][21][22]. Because of its long fluorescence lifetime (up to 450 ns) [23], high fluorescence quantum yield [24] and its ability to act as a donor [25][26][27] as well as acceptor [28,29], pyrene has often been chosen as an ideal component in a fluorescent chemosensors for Hg(II) [30,31]. Amino acids are established metal ion receptors.…”