Sonochemical synthesis of novel blue-emissive, water-soluble, cationic polysilanes as fluorescent sensors

The design, synthesis, and characterization of novel blue-emissive, cationic, water-soluble, conjugated polymers based on polysilanes with amino-terminal groups are described. Water solubility was realized through the quaternization of the amino group to control the cationic degree, which in turn determined the solubility of the polymers in organic solvents and water. The sonochemical synthesis and 2,2′-azobisisobutyronitrile assistant hydrosilylation reaction well maintained the polysilane molecular weights and polydispersities. A redshift of the absorption and photoluminescence spectra in solutions was distinctly observed with increasing solvent polarity. The water-soluble polysilanes had better thermal and UV light stability. Before and after quaternization, the polymers showed acceptable photoluminescence quantum yields in solutions. The flexible main chains of the polysilanes, increasing the conformational freedom, adhered tightly to the secondary structure of the analyte, resulting in improved Förster-resonance-energy-transfer efficiencies. These polymers could be highly sensitive and selective materials for chemo- and biosensors.