Poly photoinduced reactions

From the viewpoint of photochemistry, fuiierenes are good electron acceptors and many photoinduced reactions have been reported by using these fuiierenes as acceptors [16-20]. The excellent acceptor ability of fullerene is a key feature of photoconductivity for fullerene-doped polymer films such as poly(Af-vinylcarbazole) and poly(p-phenylene vinylene) [4, 21]. Furthermore, many derivatives of the fuiierenes have been synthesized due to high reactivities of fuiierenes [22]. Fullerene oligomers and polymers are interesting materials as well as pristine fuiierenes [23, 24]. 

Photochromic changes and photoinduced reaction involving a flourene-based TPA chromophore given in Figure 39(a) are used for recording 3D data on a dye-doped poly(methyl methacrylate) film. The chromophore produces a... 

Meisel etal. [18-20] were the first to investigate how the addition of a polyelectrolyte affects photoinduced ET reactions. They found that charge separation was enhanced as a result of the retardation of the back ET when poly(vinyl sulfate) was added to an aqueous reaction system consisting of tris(2,2 -bipyridine)ruthenium(II) chloride (cationic photoactive chromophore) and neutral electron acceptors [21]. More recently, Sassoon and Rabani [22] observed that the addition of polybrene (a polycation) had a significant effect on separating the photoinduced ET products in an aqueous solution containing cir-dicyano-bis(2,2 -bipyridine)ruthenium(II) (photoactive donor) and potassium hexacyano-ferrate(III) (acceptor). These findings are ascribable to the electrostatic potential of the added polyelectrolytes. 

Sabbatini N, Dellonte S, Bonazzi A et al (1986) Photoinduced electron-transfer reactions of poly(pyridine)ruthenium(II) complexes with europium(III/II) cryptates. Inorg Chem 25 1738-1742... 

The ionic domain of polyelectrolytes also affects the photoinduced charge separation between the coexisting low molecular charged compounds38). The quenching of Ru(bpy)2 + by a zwitterion compound, dibenzylsulphonates viologen (18, BSV), was enhanced about 4 times by poly(vinylsulphate) (PVS)39), and the back reaction... 

When photoinduced electron transfer produces products of opposite charge, their physical separation will be enhanced by the presence of a charged poly-electrolyte, with the quantum yield for electron transfer increasing from zero to one in a particular dramatic example [159]. Similar effects will cause inhibition of back electron transfer as well, although the magnitude of these effects is often much smaller than in the photodriven reactions. 

The reductive photodehalogenation of aryl halides has been actively investigated in recent years. Special attention has been given to (poly)halobenzenes and (poly)halo-biphenyls. The reactions are of interest in view of their mechanisms, and because of the importance of chlorinated aromatic hydrocarbons as environmental pollutants and the possibility of their photoinduced degradation. The photochemistry of aryl halides and related compounds in general14 and the photochemistry of polyhaloarenes in particular18 have been reviewed. 

Assuming that the yield for gel fraction is proportional to the rate of crosslinking, it seemed that the observation on possibility of resolving the experimental results into terms proportional to I and Ia /2, points out the dual mechanism of photoinduced crosslinking of poly (vinyl butyral). The over all character of the equation (l) suggests that the main role in the discussed reaction plays the relation gel content connected possibly with direct coupling of... 

Recently, we (82) and others (82-84) have shown that similar hetero-structures can be prepared by using two-dimensional inorganic sheets (made by exfoliation of various lamellar solids) in place of the organic polyanion. This technique offers a potentially powerful alternative to the construction of multi-component electron transfer systems, because it can, in principle, be used to stack up an arbitrary number of redox-active polymers without interpenetration (85). This chapter describes the preparation and photochemistry of simple multilayer composites on high-surface-area silica. Specifically, the synthesis and electron transfer kinetics of systems containing a polycationic sensitizer, poly-[Ru(bpy)2(vbpy)(Cl)2] (1), (abbreviated [Ru(bpy)3 ]n bpy = 2,2 -bipytidine and vbpy = 4-vinyl-4 -methyl-2,2 -bipyridine), and an electron-acceptor polycation poly[(styrene-co-]V-vinylbenzyl-N -methyl-4,4 -bipyridine)(Cl)2] (2), (PS-MV ) are presented. Using a solution-phase electron donor, 3, as the third electroactive component, it was possible to prepare and study the photoinduced electron transfer reactions of several different diad and triad combinations. 

Photoinduced electron transfer-proton transfer reactions between the fullerene cage and polymeric secondary amine units serve as an efficient and selective buckyball fishing method for the preparation of pendant fullerene aminopolymers. As a novel approach to carry highly hydrophobic fullerene molecules into aqueous solution, pendant C6o-poly(propionylethyleneimine-co-ethyleneimine) polymer (17) has been prepared by the photochemical method [113,114]. The pendant polymer is highly water-soluble, with the equivalent aqueous solubility of the polymer-bound Cgo tmits (10-12 mg/mL) much higher... 

Scheme 6.3 Photoinduced cross-linking reactions of poly(vinyl cinnamate) by a-truxilic dimerization.

The photoinduced intramolecular electron transfer reactions of some poly-(ethylene glycol)-linked 9-aminoacridine-benzoate electron donor-acceptor systems have been described. Photosensitized oxidation of 5-methyl-2 -deoxy-cytidine using menadione (2-methylnaphthalene-l,4-dione) gives 5,6-dihydroxy-5,6-dihydro-5-methyl-2 -deoxycytidine in what is thought to be an electron... 

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