Poly , long lived

The dissociation of 7 (Scheme 5) from poly[(G-C)] showed three relaxation times and the amplitude corresponded to the total signal, while the dissociation of 7 from poly[(A-T)] was faster and only two relaxation times, corresponding to 70% of the total signal were observed in the stopped-flow experiment. The biological activity of this class of molecules was correlated to the presence of four relaxation times when the dissociation process is measured with DNA, in particular the presence of the long-lived component of hundreds of milliseconds.86,104 105,132 143 The difference in the dissociation kinetics observed with the two polydeoxynucleotides indicates that intercalation into G-C sites is responsible for the biological activity. The dissociation of 7 from ct-DNA led to four relaxation times, a result that is in line with the relaxation times observed with poly[(G-C)] and poly[(A-T)]. 

Other mechanistic ideas The most obvious problem with the colloidal crystal model is that it is hard to reconcile with the tracer diffusion experiments on poly (lysine) (15.) that do not detect any long-lived, slowly diffusing aggregates. While this type of experiment has not yet been done with DNA, it is reasonable to expect that the same result would be found. 

Long-lived photoluminescence, at 826 nm, is reported (t 15 (is) for thin films of the processable, -conjugated polymer, poly(3-hexylthio-phene) (93JA8447). Excitation of the n—n transition with 518 nm light (So >S ) yields only very weak luminescence of 826-nm light, even at 18 K. The emission is enhanced, to point where it can be observed at room temperature, when the excitation wavelength is 250 nm, but it is completely quenched by oxygen. Prompt fluorescence decays within... 

In the polyvinylimidazole-catalyzed solvolysis of NDBA, retardation behavior was noted for [NDBA] > [PVIm] and acceleration behavior for [PVIm] > [NDBA]. These results were related to the formation of the long-lived intermediate, dodecanoyi-poly-4-vinylimidazole 14 (55). 

The intense and long-lived luminescence of these complexes has been utilized in the development of the oxygen sensor. Four mononuclear and dinuclear cyclometalated iridium(III) diimine complexes were immobilized in polymerized poly(ethylene glycol) ethyl ether methacrylate matrices, and the oxygen quenching on the luminescence of the films was studied. Tinear Stem-Vohner plots were obtained. Despite the difference in the luminescence energy and lifetimes of the complexes, similar Stem-Volmer slopes were observed. The size and charge of the complexes played an important role in the sensitivity of the systems. 

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