Polyacetylene analogues

Pochan et al. 585) have studied poly(l,6-heptadiyne), a polyacetylene analogue, which forms dense continuous films. They find oxygen doping follwed by degradation in a manner similar to polyacetylene, except that the rate of degradation is much larger. 

Both synthetic and naturally occurring polymers have been used as CSPs. Figure 3.2 shows typical CSPs prepared from optically active polymers (1-18) 1-15 are totally synthetic polymers, including vinyl polymers (1-7), polyamides (8-12), polyurethanes (13), polyacetylene (14), and polysaccharide analogue (15). The CSPs 16-18 are based on natural polymers, proteins (16), and polysaccharides (17, 18). 

Table I. Structural Parameters Used in Calculations for Polyacetylene and Its Halogenated and Silylated Analogues...

The above values were selected, in the case of polyacetylene, from averages taken from available experimental and theoretical structural data. For the halogenated chains, appropriate values were selected from the results of both ab initio and CNDO/2 molecular orbital calculations and from structural data available on small-molecule analogues. Due to the unavailability of structural data for the silylated analogues, values were taken from those used for polyacetylene (except, of course, for those bonds and angles associated with an X atom) so as to deduce the effect of the substitution alone without inclusion of concomitant structural modifications along the polymer backbone resulting from such substitutions. 

An interesting approach to conjugated materials was reported by Lee and co-workers. ROMP of the tetrasila-analogue of cyclooctadiene (COD) yields a hybrid polyacetylene—polyorganosilane copolymer where conjugation is based on a a—Ji network (Scheme 37) 349 ppv analogues. poly(1.4-naphthylenevmylenes)... 

The polythiophene (PT) derivative is one of the most useful conjugated polymers, with extensive electrical, optical and chiroptical properties [71-82]. Following LC polyacetylene derivatives, many efforts have been made to synthesize LC-PT derivatives [22-27, 31-34]. Here, we describe the synthesis and properties of PT derivatives and their analogues of LC or FLC nature. 

In 1969, Kern first reported that the Wilkinson catalyst, RhCl(PPh3)3, could be used to polymerize phenylacetylene monomer, and that the color of the resulting poly(phenylacetylene) was dependent on the polymerization conditions used." Recently, analogues of the Wilkinson catalyst such as [(2,5-norbornadiene)RhCl]2 (7, Figure 21.1) have been developed that selectively produce c/ -PPA even at room temperature. This is in contrast to the low temperature (—78 °C) required when using Ziegler-Natta catalysts to produce perfect c/ -polyacetylene." ... 

Figure 4.3 Band structure and electronic configuration for species implicated in conduction mechanisms in conjugated polymers, illustrated for polyacetylene. Negative analogues via electron addition.

Polyazines are simple, linear, conjugated polymers that are nitrogen-containing analogues of polyacetylene [1-7]. These materials can be viewed as head-to-head polymers of the imine repeat unit ... 

General photodegradation mechanisms of the most common classes of polymers were vastiy detailed by Rabek [5]. These mechanisms include polyketones, polyolefins, polycarboxylic acids and analogues, poly (vinyl alcohol), polyacrylates and polymethacrylates, polyvinylpyrrolidone, polyacrylonitrile, polystirenes, polydienes, and polyacetylenes. 

Guerriero, A., Debitus, C., Laurent, D., D Ambrosio, M., and Pietra, F. (1998) Aztdjuynol A, the first clearly defined, C-hranched polyacetylene and the analogue aztequynol B. Isolation from die tropical marine sponge Petrosia sp. Tetrahedron Lett., 39,6395—6398. 

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