Poly stilbene-4-formate

Stimulated by extensive research activities on donor/acceptor substituted stilbenes, Mullen and Klarner have reported a donor/acceptor substituted poly(4,4 -biphenyl-diylvinylene) derivative (85) in which the NR2 donor and CN acceptor substituents are located on the vinylene unit [111]. The synthesis is based on a C-C-coupling reaction of in situ generated carbanion functions with a (pseudo)cation function, followed by a subsequent elimination of MeSH with formation of the olefinic double bond. 

Capillaries packed with poly-A-acryloyl-L-phenylalanine ethyl ester (Chiraspher) modified silica were used for electrochromatographic enantiomer separation of ben-droflumethiazide. To suppress bubble formation, the inlet buffer vial was pressurized to 12 bar and the outlet buffer vial to 4 bar [42], Acetonitrile or methanol were used as organic modifier whereby acetonitrile was superior to methanol. Non-aqueous p-CEC was performed on helical poly(diphenyl-2-pyridylmethylmethacrylate) coated on wide-pore aminopropyl silica [56]. With this chiral stationary phase, the enantiomer separation of Trogers base, benzoin acetate, methylbenzoin and trans-stilbene oxide was achieved by pressure-supported CEC, applying a higher pressure to the inlet than to the outlet buffer vial. 

Polyester. The most common polyester in use is derived from the homopolymer poly (ethylene terephthalate). Many types of this fiber contain a delustrant, usually titanium dioxide. Optically brightened polymers are quite common. The optical brightener, such as specially stabilized derivatives of either stilbenes or phenylcoumarins, can be added to the polyester before formation of the fiber (107). Some commercial fibers contain minor amounts of copolymerized modifier to confer such properties as basic dyeability. A wide range of polyester fibers is used for consumer end-uses. Both staple fiber and filament yarn are available. Filament yarns with noncircular cross-sections are made (107). 

Because of the versatility of the polyurethane system it is possible to introduce comonomers which can affect the physical properties of the derived polymers. For example, photo cross-linkable polyurethanes are formulated using 2,5-dimethoxy-2,4 -diisocyanato stilbene as a monomer (76). Comonomers, having an azoaromatic chromophore, are used in optical bleaching applications (77), or in the formation of photorefractive polymers (78). The latter random poljnners have second-order nonlinear optical (NLO) properties. Linear poljnners are also obtained from HDI/PTMG and diacetylenic diols. These polymers can be cross-linked through the acetylenic linkages producing a network polymer with properties similar to poly(diacetylenes) (79). 

Three new mainchain chromophoric polymers were synthesized and characterized. The physical properites of these polymers were compared to those of poly((4-N-ethylene-N-ethylamino)-a-cyanocinnamate). Films of the polymers can be made by either solution or melt casting of films. It was possible to obtain an oriented fibw of a polymer, namely poly(4 -[N-ethylene-N-(2-hydroxyethyl)amino] stilbene-4-formate, most likely because it has a melt transition temperature at around 210°C. Nonlinear optical studies of these polymers are in progress. 

A stilbene-cored poly(glutamate) dendrimer in benzene underwent intermolecular photochemical [2 + 2] cycloaddition. The bisignate circular dichroism signal of the resulting cycloadduct indicated the formation of chiral aggregates with through-space electronic interactions between the two stilbene cores. 

Excimer formation has been found to be most prominent for small organic aromatic molecules such as benzene [13],p-xylene [14], naphthalene [15], anthracene [16], pyrene [17], perylene [18], stilbene [19], and others [20]. Some polymers that contain aromatic groups, such as polystyrene [21] and poly (ethylene terephthalate) (PET) [22], and polynucleotides such as cytosine and thymine [23] have also been shown to exhibit excimer emission. Excimer emission is, in fact, widely observed in aromatic hydrocarbons [20]. 

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