Polyynes backbone

Cobalt complexes among other metals such as iron and nickel are known to catalyze the growth of carbon nanotube (CNT) by chemical vapor deposition (CVD) [79-81]. Thanks to the thermal stability of the hyperbranched polyyne backbone, spin-coated films of the organometalhc polymer were successfully probed to function as catalyst and arrays of CNT bundles could be prepared (Figure 2.4). This preliminary result already suggests potential application in the field of paUemable tailor-made catalysts. 

The main distinction between the dehydrohalogenation approach and polycondensation processes is that in the former case the carbon backbone is formed first by polymerizing relevant monomers, and the task for synthesizing polyyne and/or polycumulene is reduced to the complete elimination of hydrogen halide with the retention of one-dimensional structure. 

Soluble platinum polyynes containing bithiazole units in the backbone were prepared by Wong et al.71 Polymer 22 was prepared via dehydrohalogenation reactions and contains... 

The synthesis of several high molecular-weight platinum polyyne polymers carrying chiral (R)-l,l -bi-2-naphthol bridge, P17, was described.48 These represent the first examples of metal acetylide polymer with an optically active backbone. They display much larger specific negative optical rotations than both the metal-free alkyne precursors and their corresponding dinuclear model compounds. These results support the fact that the main chain of P17 adopts a one-handed helical conformation and induces the helical chirality of the polymers. 

Raithby and co-workers further compared the photophysical properties of several platinum(II) polyynes P25, P27, and P29 with their organic copolyynes.59 Since the nonradiative decay rate for the triplet emission, (Lm)p, is equal or larger than the corresponding radiative decay rate, (Ljjp, the PL quantum efficiencies of the platinum polyynes are reduced from those for the organic polymers. Optical data reveal that the anchoring of octyl side chains on the fluorenyl spacer reduces interchain interaction in the polyynes, while a fluorenonyl spacer affords a donor-acceptor motif along the rodlike backbone. 

Recently, an extension of the dehydrohalogenation process to the synthesis of a new class of heterobimetallic polyyne materials 174 which contain mixed metals with alternating Ru(dppe)2 and Pd(P Bu3)2 moieties (dppe = bis(diphenylphosphino)ethane) in the polymer backbone has been reported (Equation (67)), with 71/ =14,000 (by GPC measurements). The incorporation of ferrocene units into the polymer main chain and alternation between either Ni(PBu3)2 175 or Pd(PBu3)2 1 6 moieties has also been achieved (Equation (68)) and the molecular weights of the resulting polymers were 71/ = 26,100 and 21,400, respectively. 

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