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The syntheses of several norbornene block copolymers containing oligonucleotide and ferrocenyl side chains and their use in the electrochemical detection of DNA are described. Two kinds of DNA-containing block copolymers with either ferrocenyl or dibromoferrocenyl groups were prepared via ring-opening metathesis polymerization (ROMP). Based on these two distinct ferrocene derivatives, a triblock copolymer labeling strategy was developed. With this strategy, the identity of DNA target can be determined by the E1/2s of the ferrocenyl moieties and the ratio of peak currents. These polymers exhibit predictable and tailorable electrochemical properties, high DNA duplex stability, and unusually sharp melting transitions, which are highly desirable characteristics for DNA detection applications. Significantly, single-base mismatches could be easily detected using two distinct block copolymers as dual-channel detection probes in an electrochemical DNA detection format.

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A series of monodisperse amphiphilic diblock copolymers containing a high-density of covalently linked indomethacin as the hydrophobic block and pendant hexaethylene glycol monomethyl ether as the hydrophilic block have been synthesized from ring-opening metathesis polymerization (ROMP) using Cl 2(PCy3)2RudCHPh. Dynamic light scattering (DLS), transmission electron microscopy (TEM), and 1 H NMR spectroscopy have been used to investigate the directed-assembly of these polynorbornenebased copolymers into polymeric nanoparticles in aqueous media as a function of copolymer composition, concentration, and degree of polymerization. The block copolymers formed micelle-like aggregates in the aqueous phase with mean diameters ranging from 993 ( 270 nm to 94 ( 14 nm by TEM. In general, the aggregate size decreased as the overall copolymer length decreased. After incubation in an acidic environment (pH ) 3) at 37 °C for 48 h, 20% of the indomethacin was released from the nanoparticles.

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The in situ rhodium-catalyzed addition of catecholborane (HBcat, cat = 1,2-O2C6H4) and pinacolborane (HBpin, pin = 1,2-O2C2Me4) to allylamine, allylimine, 2- and 4-vinylpyridines, and a thienyl imine has been examined using multinuclear NMR spectroscopy. Although reactions of allylamine (H2NCH2CH=CH2) and HBcat gave complex product distributions arising from competing dehydrogenative borylation pathways, addition of HBpin to allylamine using a rhodium catalyst afforded only products arising from hydroboration (RN(Bpin)CH2CH2CH2Bpin, where R = H, Bpin) and hydrogenation (RN(Bpin)CH2CH2CH3). Hydroboration of allylimines (RHC=NCH2CH=CH2, R = Ar) with HBcat occurs initially at the more reactive imine functionality to give unsaturated borylamines (RCH2N(Bcat)CH2CH=CH2). Further reaction with HBcat gives varying amounts of hydroboration products RCH2N(Bcat)CH2CH2CH2Bcat and RCH2N(Bcat)CH2CH(Bcat)CH3 as well as the diboration product RCH2N(Bcat)CH2CH2CH(Bcat)2, depending on the choice of catalyst. Reactions with related unsaturated pyridine derivatives are complicated by extensive degradation, which can be avoided by coordination of the pyridine nitrogen to a Lewis acid. The first examples of metal-catalyzed hydroboration of imines using HBpin are also reported.Key words: catalysis, hydroboration, boronate esters, dehydrogenative borylation, allylimines.

The synthesis and polymerization of norbornenyl-substituted thiophenes (2 and 4) and terthiophenes (3 and 5) are reported. All monomers readily undergo ring-opening metathesis polymerization (ROMP) using the ruthenium catalyst, Cl2(PPCy3)2 RudCHPh (1). The terthienyl monomers 3 and 5 were directly polymerized onto the surface of a gold electrode via electrochemical oxidation of the capping terthienyl units, while the direct electrochemical homopolymerization of 2 was not achievable, which is consistent with previous literature reports for similarly substituted thiophenes. Chemical polymerization of the terthienyl segments of 3 and 5 using FeCl3 yielded insoluble materials. Finally, polymers obtained from the ROMP procedure were further cross-linked using the oxidative techniques described above, yielding highly networked materials which displayed an increase in thermal stability and electrical conductivity relative to their single-chain polymeric precursors.

Ring-opening metathesis polymerization was used to modify organic soluble gold nanoparticles with redox-active polymers. A gel-permeation chromatography study revealed that each nanoparticle is modified with approximately 11 polymer chains. Electrochemical studies of nanoparticles modified with block copolymers of two different redox-active groups revealed that each monomer is electrochemically accessible, while no current rectification was observed.