Pyrenyl group

On the other hand, there are other series of polyaers having sc-electronic chroaophore such as N-carbazolyl and 1-pyrenyl groups, whose photophysical properties are quite different fron the above polyaers and whose laser cheaistry is studied in detail. A relation aaong interchronophoric interaction, spectral shape and geonetrical structure in the excited singlet, triplet, cationic and anionic... 

Polymer 7 with pyrenyl group is less effective than 6. The 0MVt for 7 is about half of that of 6. This is the same trend as for the polyester-bonded sensitizers used in photo-oxidation of LCV. Efficient excimer formation by pyrenyl groups accounts for the results. 

Copolymers of 3-(l -PyrenyDpropyl Methacrylate. The pyrene-containing methacrylate was copolymerized with vinylbenzyltriethylammonium chloride or sodium p-styrenesulfonate. These copolymers were expected to behave very differently from each other as electron transfer sensitizers. Photoreduction of MV2+ sensitized by the copolymers in the presence of EDTA is shown in Figure 5. The photoabsorbing species is exclusively pyrenyl groups. It is noteworthy that polycations which repel MV2+ are more effective sensitizers... 

Figure 9. Broadening of absorption spectra of pyrenyl groups bonded to polymers. Film 1 ( ), Film 2 (o). "Reproduced with permission from Ref. 17. Copyright 1983, John Wiley Sons, Inc.

Photo-oxidation of LCV by the Pyrene-Bonded Film. The surface properties and structure of these systems should be related to the sensitizer efficiency of pyrenyl groups. Pyrene is a good sensitizer for the oxidative color formation of LCV. The singlet excited state of Py acts as an electron acceptor bringing about one electron oxidation of LCV+. The unit processes are considered as... 

An interesting system for study the mechanism of electron tunneling in proteins was synthesized in Ref. [286]. In this work donor, p-dimethylanilino group, and photosensitizer, pyrenyl group were attached to a specially synthesized protein molecule. Electron transfer at the edge-to-edge distance 9.6 A was observed upon electronic excitation of the sensitizer fragment. 

The DNA bases most easily reduced are T and C, the reduction potentials of which are very similar [26]. It is therefore expected that excess electron migration through DNA occurs via a hopping mechanism involving all base pairs (C-G and T-A) and the radical anions C and T as stepping stones. We focused our work on 5-pyrenyl-2 -deoxyuridine (Py-dU) and 5-pyrenyl-2 -deoxycytidine (Py-dC) as nucleoside models for ET in DNA. Photoexcitation of the pyrenyl group results in... 

The positive charge of solvent radical-cations transfers to solute molecules in halogenated hydrocarbons such as chloroform and dichloroethane. However, only few studies have been made on the radical cations of polymers in solution. Tanaka et al. observed the dimer cation of the biphenyl group or the pyrenyl group of the polymers in the pulse radiolysis of PVB and PVP in 1,2-dichloroethane [49]. The absence of the monomeric cation is due to the rapid intramolecular dimerization of the radical cations of the side groups of the polymers. Irie et al. observed two kinds of intramolecular dimer cations in the... 

Fig. 9. Transient absorption spectra observed at ambient temperature on pulse radiolysis of MTHF solution containing 5 base-m mol dm " 3 poly(4-vinylbiphenyl-co-l-vinylpyrene). The content of pyrenyl group is 0.15% against the total number of the side groups. (O) pulse end ( ) 0.2 ps after a pulse (T1) 1.4 ps after a pulse [60]...

Where, A is a constant with the dimension [L]2[T] -1 which is equivalent to a one-dimensional diffusion coefficient of the electrons. The total existence probability in the section 0 < x < a at time t is obtained by the integration of w(x, f). The distance a of two pyrenyl groups must have a certain distribution as a result of random-copolymerization Tanaka et al. assumed the most probable distribution for it [61],... 

Fluorescent hydrophobes (naphthyl and pyrenyl groups) incorporated into the polysulfobetaines are a powerful tool for studying the formation of intra-and interpolymer aggregates in aqueous and aqueous salt solutions [85,229-231]. Intermacromolecular hydrophobic association is observed as an increase in the excimer emission relative to that of the monomer emission, where h/Iu is the ratio of intensities of excimer and monomer fluorescence which reflects the extent of inter/intra macromolecular interactions. Intramolecular micellization is easily monitored by the quenching efficiency of the thallium ions. The decrease of h/Iu reflects the breaking of the intra- and interchain associations in aqueous salt solutions, leading to chain expansion. 

The fluorescence decay of the locally excited state at temperatures were the excimer does not disociate back could be analysed as a sum of two exponentials. That this is not due to roational isomerism of the 1-pyrenyl group could be proven by the analysis of 2b which showed analogous behavior.The analysis of the fluorescence decay according to scheme 4 permits the determination of the ratio of Cy/Cg. 

Exciton couplet was also observed in the Ba absorption band (around 240 nm) of poly(pyrAla) in TMP. Conformational analysis based on the ECEPP potential functions and the theoretical CD computation suggested a left-handed a-helical main chain along which the side-chain pyrenyl groups are regularly arranged. 

Sequential Polypeptides Carrying Pyrenyl Groups, Ground-State Conformations Sequential polypeptides carrying pyrenyl chromophores (V) were also prepared (15). 

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