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This Article describes the synthesis and physical properties of two bipolar starburst monomers: 1,3,5-tris{5-(7-(carbazol-9-yl)-(9,9′-spirobifluoren-2-yl)-1,3,4-oxadiazol-2-yl}benzene (OXD-CBZ) and 1,3,5tris[7-diphenyl-(9,9′-spirobifluorene)-1,3,4-oxadiazoyl]benzene (OXD-DPA) featuring an electron-deficient tris(1,3,4oxadiazole)phenylene ring as an interior core bridged by rigid spirobifluorene units to terminal electroactive carbazole (CBZ) and diphenylamino (DPA) groups. The electronic absorption spectra of OXD-CBZ and OXD-DPA depend only slightly on the solvent polarity, revealing that weak electronic coupling existed between the donor (CBZ and diphenylamino groups) and acceptor (1,3,4-oxadiazole) moieties in the ground state. In contrast, the emission spectra of these starburst bipolar molecules were strongly dependent on the solvent polarity, a phenomenon that we attribute to the polarized excited states generated through intramolecular charge transfer. The starburst monomer OXD-CBZ exhibited a redox gradient, where the peripheral CBZ moieties exhibited lower oxidation potentials than those of the fluorene units in the interior, allowing us to obtain a new electropolymerized macromolecule. The polymer films derived from OXD-CBZ exhibited good conductivity, reversible electrochemical processes, and stable color changes (from transparent to green to light blue) with high coloration efficiency upon electro-oxidation. The radical cations of OXD-CBZ were localized within the CBZ rings; the lack of substituents at the C3 and C6 positions of the CBZ unit led to the effective electrochemical cross-linking process. In contrast, electro-oxidation of OXD-DPA, which was end-capped with DPA groups, produced stable radical cations that did not undergo associated electrochemical reactions. The higher stability of the OXD-DPA radical cations through resonance stabilization with the fluorene ring impeded the progress of typical triphenylamine dimerization reactions.

Carbohydrates are detected by constant potential amperometric detection at a modi®ed electrode consisting of poly-1-naphthylamine coated glassy carbon with copper ions incorporated into the polymeric matrix. The polymer is electrodeposited onto the glassy carbon surface by cyclic voltammetric experiments, and copper ions incorporated by immersion of the modi®ed electrode in a 0.10 M cupric ions solution. The amount of copper incorporated into the polymeric matrix is regulated by controlling the immersion time. Cyclic voltammetric experiments showed that glucose was oxidized at the modi®ed electrode surface. The catalytic current for glucose oxidation was dependent on the amount of copper incorporated. Flow injection experiments allowed the determination of the working electrode potential at which maximum signal-to-noise ratios were obtained. The electrode was successfully used in the high performance liquid chromatographic analysis of various carbohydrates.