No abstract

The field of chemical and biological sensing is increasingly dependent on the availability of new functional materials that enhance the ability of the system to respond to chemical interactions. Organometallic bioconjugates derived from amino acids, peptides, proteins, peptide nucleic acids, and dendrimers have had a profound effect in this area and have endowed modern sensory systems with a superior performance. Owing to their fairly high stability, solubility in various solvents, and excellent redox properties, ferrocene and ferrocenyl conjugates have emerged as one of the most important classes of materials that enable direct observation of molecular interactions and as electron mediators. The low potential, reversible redox behavior of the ferrocene/ferrocenium couple is a unique property that finds widespread application in the design of sensory platforms. Currently, there is significant drive to exploit new organometallic systems, in which the presence of ferrocene acting as a redox center is critical and allows the design of highly sensitive electrochemical sensors for the sensing and recognition of a vast array of analytes.

The reaction of 4-(dibromoboryl)styrene with 2pyridylmagnesium chloride resulted in the formation of 4-styryltris(2-pyridyl)borate free acid (StTypb), a new polymerizable nonpyrazolyl "scorpionate" ligand. StTypb did not undergo selfinitiated polymerization under ambient conditions and proved to slowly polymerize through standard radical polymerization at 90 °C. Nitroxide-mediated polymerization (NMP) of StTypb at 135 °C proceeded with good control, resulting in a polymer of M n = 27400 and PDI = 1.21. The TEMPO-terminated homopolymer successfully initiated the polymerization of styrene, generating an amphiphilic block copolymer with DP n of 1200 and 78 for the PS and the StTypb block, respectively. A similar block copolymer with DP n of 29 and 20 for the PS and the StTypb block respectively was obtained in a reverse polymerization procedure from a PS macroinitiator. The self-assembly of these block copolymers was examined in selective solvents and preliminary metal complexation studies were performed.

Nucleophilic aromatic substitution reactions of chloroarene cyclopentadienyliron complexes were utilized to prepare new classes of oligomers and polymers containing both neutral and cationic organoiron complexes in their structures. Photolysis of these polymers resulted in the removal of the cationic cyclopentadienyliron moieties, while the neutral organoiron complexes remained intact within the polymer structures. The weight-average molecular weights of these polymers after photolysis ranged from 8700 to 56 200 with polydispersities from 1.1 to 3.1. Thermal analysis established that the cationic polymers possess higher glass transition temperatures, but lower thermal stability than the neutral ferrocene-based polymers. The glass transition temperatures of the cationic polymers ranged from 65 to 161 °C, while the T gs of the neutral polymers ranged from 10 to 92 °C. Electrochemical studies showed that the iron centers in the neutral complexes were oxidized, while the cationic complexes were reduced. Viscosity studies showed that the cationic polymers exhibited a polyelectrolyte effect.