Boron-containing pi-conjugated polymers built with transition metal cage complexes and C3-symmetric pi-conjugation: Modular synthesis of oligomers and polymers

π-Conjugated systems are widely used as electronic materials and chemical sensors. We have successfully synthesized polymers built with transition metal cage monomers. The structural features including the bulky ligand as the insulated sheath, and caged metal center embedded in the polymeric networks, allow outer-sphere electron transfer. Such unique molecular structures profoundly influence the electrochemical properties. Another project is targeted to the synthesis of C3-symmetric π-conjugated oligomers and the corresponding polymers. C3-symmteric structural platforms widely exist in nature, and in recent decades they have been applied in novel electronic materials as well. We have successfully synthesized a series of C3-symmetric π-conjugated oligomers and corresponding polymers with electron-deficient core, tristriazolobenzene (TTAB) and electron-rich peripheral substituents. We have shown that the efficient intramolecular charge transfer and relatively high quantum yield emission was achieved upon photo-excitation. A detailed characterization of TTAB-based materials has been conducted, including photophysical and electrochemical studies by cyclic voltammetry, UV-Vis spectroscopy and fluorescence spectroscopy. All results indicated that the charge redistribution is closely related to the π-conjugation "length" and the nature of donor/acceptor groups.