Poly , branched metal complexes

This article surveys the research work on the synthesis and modification reactions of poly(ethyleneimine) as well as its applications to metal complexation processes. Poly-(ethyleneimine), one of the most simple heterochain polymers exists in the form of two different chemical structures one of them is branched, which is a commercially available and the other one linear which is synthesized by cationic polymerization of oxazoline monomers and subsequent hydrolysis of polyf(/V acylimino)cthylcne]. The most salient feature of poly(ethyleneimine) is the simultaneous presence of primary, secondary, and tertiary amino groups in the polymer chain which explains its basic properties and gives access to various modification reactions. A great number of synthetic routes to branched and linear poly(ethyleneimine)s and polymer-analogous reactions are described. In addition, the complexation of polyfethyleneimine) and its derivatives with metal ions is investigated. Homogeneous and heterogeneous metal separation and enrichment processes are reviewed. 

Readily soluble poly(2,9-o-phenanthroline-(2, 5 -dihexyl)-4,4"-p-ter-phenylene)s with a degree of polymerization up to 39 have been prepared via a Pd-catalyzed polycondensation reaction of 2,9-bis-(p-bromophenyl)-o-phenanthroline and 2,5-dihexylbenzene-l,4-diboronic acid [50]. Some cyclic oligomers could be separated from the polymer. Diamagnetic transition metal complexes of well-defined constitution as shown in 26 were obtained with Cu(I) and Ag(I) without branching and cross-linking. 

Further investigations into the effect of the size of the side chains on polymer properties as well as the ability of these branched poly(oxyethylenes) to complex other metal ions is currently in progress. 

The general patterns of structures and bonding in metal poly-olefin complexes are similar to those in olefin complexes. Linear, branched and cyclic polyolefin complexes are known. The bonding is delocalized over the carbon atoms and the metal(s). These species also play important roles in organic syntheses. 

Crude petroleum contains complex mixtures of hydrocarbons as well as relatively small amounts of nitrogen-, sulfur-, and oxygen-containing organic compounds, asphaltenes, and various trace metals (uncomplexed and complexed forms). The hydrocarbons can be divided into two classes related to their chemical structure the alkanes (normal, branched, and cyclo) and aromatic compounds (mono-, di-, and poly-, i.e., PAH). 

Tsuchida and co-workers (97) tried similar crosslinking with branched and linear poly(ethylene imin ) and W th poly(vinylimidazole) in the presence of Cu or Co ion templates, but no enhancement of selectivity towards the same metal ions was achieved. The same was true when they prepared a polymer from a monomeric complex (98). In this case the metal-1-vinylimidazole complex (from Ni, Co or Zn as the template) was copolymerized and crosslinked... 

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