Organometallic polymers dendrimers

Metal-acetylide complexes have been used as a unit of organometallic polymers that have metallic species in the main chain [20]. Representative examples are metal-poly(yne) polymers (19) of group 10 metals depicted in Scheme 5. These polymers are easily prepared from M(PR3)2Cl2 (M=Pt, Pd) and dialkynyl compounds catalyzed by Cu(I) salts in amine. Recently, this synthetic method was successfully applied to the construction of metal-acetylide dendrimers. 

A number of research groups have reported the preparation of a large number of star-shaped molecules and dendrimers containing ferrocenyl or arene cyclopentadienyliron complexes at the core or the peripheries.300-320 A number of these dendrimers were prepared via cyclopentadienyliron-mediated per-alkylation, -benzylation and -allylation reactions of cationic tri-, tetra- and hexamethylbenzene complexes. These dendrimers were multifunctional materials and have been used in the synthesis of branched organic and organometallic polymers. 

In summary, the Ion Evaporation Model is experimentally well supported for small ions of the kind that one encounters in inorganic and organic chemistry. However, when the ions become very large, such as polymers, dendrimers or biological supramolecular complexes like proteins and enzymes, the Charged Residue Model (CRM) becomes much more plausible, see Section 1.2.10. Because many applications of ESMS in analytical organometallic and physical organic chemistry involve small ions it is desirable to consider the expected relative sensitivities for these analytes when detected with ESMS. 

Dendritic polymers can be covalently functionalized with organometallic complexes to obtain a dendritic catalyst with molecularly defined catalytic sites [5-7]. Moreover, a considerable number of reports on the applicability of functionalized dendrimers in catalysis have led to the idea of a dendritic effect on the catalyst activity/selectivity, which can either be positive or... 

As a result of their ease of solubility, characterization of dendritic materials can be readily achieved by means of standard polymer characterization techniques, such as NMR and GPC. However, despite the excellent characterization that pervades the materials discussed in this chapter, it should be noted that with the widespread introduction of mass spectrometric techniques which can characterize such macromolecules, the structural perfection assumed in many depictions of dendrimers have been shown to be highly idealized. Indeed, spectrometric analysis of many samples has revealed that imperfections and defects are, in fact, very common. In this section, organometallic dendrimers, a subset of metallodendrimers, are discussed. 

Section 12.09.6 details recent advances toward the application of organometallic receptors as sensing devices, including their use in dendrimer, polymer, functionalized nanoparticle, and self-assembled monolayer systems. 

Phosphazene polymers comprise a class of several hundred different macromolecules with the general formula shown in Structure 1, where R represents organic, organometallic or inorganic side groups. Two structural factors can be varied for these polymers. First, the basic skeletal architecture varies from linear polymers or block copolymers to stars, dendrimers, combs, cyclolinear or cyclomatrix structures. Second, more than 250 different side groups have been linked to the various skeletons. Most of the polymers that have been studied in detail are linear macromolecules of type 1 or block copolymers formed between 1 and classical organic polymers. 

PGSE methods were introduced in 1965 by Stejskal and Tanner and, since then, have been widely used. In the 1970s this approach was used to determine diffusion coefficients of organic molecules. In the following decade, variants of the technique were applied to problems in polymer chemistry. "" Since then, diffusion data on dendrimers " and peptides, " as well as on molecules in various environments, e.g., in porous silica and zeolites,have been obtained. Recent applications of PGSE methods in coordination and/or organometallic chemistry have emerged. ... 

There has been considerable interest directed toward the synthesis of organometallic star polymers and dendrimers in recent years (see Dendronized Polymers). The production of highly ordered, highly branched organometallic materials is of importance due to their electronic, optical, and biomedical applications (224-232). 

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