Metallopolymers conjugated

More recently, there has been growing interest in a new type of redox polymer that is a hybrid of materials from PTs and will be referred to as conjugated metallopolymers. The key feature of this class of material is that the metal is coordinated directly to the conjugated backbone of the polymer, or forms a link in the backbone, such that there is an electronic interaction between the electroactive metal centers and the electroactive polymer backbone. This can enhance electron transport in the polymer, enhance its electrocatalytic activity, and lead to novel electronic and electrochemical properties <1999JMC1641>. 

Characterization of conjugated metallopolymers can be difficult. When the metals are paramagnetic, very broad NMR spectra are obtained. Also, many metal complexes, particularly porphyrins and phthalocyanines, aggregate in solution. This leads to broad NMR spectra and can lower solubility. Some researchers have used bulky substituents to disrupt cofacial stacking, but this can add several synthetic steps to the polymer preparation. It is often difficult to obtain clear, unequivocal characterization of the structures of metallopolymers. 

Strong electronic communication between the metal centers is indicated by the presence of IVCT bands and the M(II)2/M(II)M(III) and Mai)M(m)/M(ffl)2 redox waves with large separations [44-47]. Note that a recent review of conjugated metallopolymers is available [48] and there is also an earlier review by Pickup [49]. 

Smith RC, Tennyson AG et al (2006) Conjugated metallopolymers for fluorescent tum-on detection of nitric oxide. Inorg Chem 45 9367-9373... 

Do L, Smith RC et al (2006) Luminescent properties of water-soluble conjugated metallopolymers and their application to fluorescent nitric oxide detection. Inorg Chem 45 8998-9005... 

Kean, C.L. and RG. Pickup. 2001. A low band gap conjugated metallopolymer with nickel foisjdithiolene) crosslinks. Chem Commun 815. 

Pickup, PG. 1999. Conjugated metallopolymers. Redox polymers with interacting metal based redox sites. / Mater Chem 9 1641-1653. 

In polymers which have an electron-conducting backbone with pendant or built-in redox groups (e.g., conjugated metallopolymers), three electron transfer pathways may be operative [114] (see Fig. 6.13). 

C. Pozo-Gonzalo, R. Berridge, P. J. Skabara, E. Cerrada, M. Laguna, S. J. Coles and M. B. Hursthouse, A new family of conjugated metallopolymers from electropolymerised bis[(terthiophene)dithiolene] complexes, Chem. Commun., 2408-2409 (2002). 

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