Ferrocenes polymeric conjugates

The electropolymerization of ferrocene/thiophene conjugates [65] was conducted by oxidation on a Pt electrode and led to the deposition of a monolayer of poly (thiophene). The electropolymerization was performed from several solution systems, such as tetrabutylammonium hexafluorophosphate/acetonitrile and lithium perchlorate/acetonitrile, at a concentration of 0.1 M. Constant potential experiments (+ 2.0 V) for a definite time were used to effect polymerization. Polymerization was also attempted using cyclic voltammetry (repeatedly sweeping from 0.0 to + 2.5 V) and pulse potential (potential stepped from 0.0 to 2.0 V and back to 0.0 V). 

Ferrocene is an attractive and convenient organometallic species to incorporate into conjugated polymers—it is stable, easy to functionalize, has reversible electrochemistry, and its derivatives (both monomeric and polymeric) can be easily characterized [e.g., by nuclear magnetic resonance (NMR) spectroscopy]. Ferrocene has been incorporated into the backbone and side chains of polythiophene 45 In 1999, both Higgins and Wolf independently reported the synthesis of polythiophenes with ferrocene in the backbone.46,47 Electropolymerization of ferrocene substituted... 

The interesting redox chemistry of such conjugated polymeric metallocene systems has been reviewed [121]. For example, oligo(l,ll -dihexylferrocenylenes) 61 show an intervalence charge transfer band (IVCT) on oxidation. For the singly oxidized chains, the IVCT band zmax decreases as the number of ferrocene units increases, as expected. Also, as expected the energy of the IVCT band increases as the oxidation level increases. 

Polylithioferrocene was also derivatized with trimethylchlorosilane, yielding a mixture of polysilyl derivatives from which a crystalline tetrakis(trimethylsilyl) ferrocene was isolated and shown to be the 1,3,1, 3 derivative. Polylithioferrocene and the polylithioaromatics generally catalyze the polymerization of conjugated dienes leading to starshaped polymers. 

The dimeric complex 39 exhibits individual Fe(III)/ Fe(II) redox couples at +0.47 and +0.60 V v. SCE in CH2CI2. The averaged value (+0.54 V) is close to that of the corresponding monomeric complex 38 (+0.51 V). These results are explained by the electronic effect as reported in the literature. The trimer 40 exhibits two redox couples at +0.51 and +0.67 V in a similar condition. The positive peak suggests the presence of significant electronic interaction between two ferrocene units (center and C-terminus). This result indicates the possibility of constructing an expanded conjugation system of polymeric ferrocene amino acid and the development of the conductive devices by partial oxidation. 

The ruthenium oligothienylacetylide complexes 93 (Chart 5.30) [106] and the oligothienylferrocene complexes 94a and b were electrochemically polymerized [107]. The voltammetry of poly-94a and poly-94b films contains redox waves due to both the ferrocene and backbone redox couples. Low-energy absorption bands appear upon oxidation of both the Fe centers and the conjugated backbone in the UV-Vis-near-IR spectrum of the films, and these have been attributed to charge-transfer processes. The poor solubility of 94b prevents electropolymerization at room temperature however, polymer films can be prepared at elevated temperatures. Electropolymerization of 95, in which hexyl chains have been added to increase the monomer solubility, has also been reported [108]. 

Ring-opening metathesis polymerization (ROMP) of ferrocenophanes containing bridging olefinic groups (45, 46 48) has been examined in order to synthesize conjugated ferrocene-based polymers (93-95). The poljuners synthesized... 

SYNTHESIS, ELECTROCHEMISTRY AND CYTOTOXICITY OF FERROCENE-CONTAINING POLYASPARTAMIDES AS WATER-SOLUBLE POLYMERIC DRUG CARRIER/DRUG CONJUGATES Swarts J C... 

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