WATER-SOLUBLE PHOTOLUMINESCENT AND ELECTROLUMINESCENT ALKOXY-SULFONATED POLY(P-PHENYLENES) SYNTHESIZED VIA PALLADIUM CATALYSIS

Water soluble poly(p-phenylene) derivatives, sulfonatopropoxy)-1,6-phe nylene-abt-1,4-phenylene] sodium salt (PPP-OPSO3) and fonatopropoxy)-1 ,4-phenylene-alt-4,4'-biphenylene] sodium salt (PPBP-OPSO3), have been synthesized through a Suzuki coupling reaction of 1,4-dibromo-2,5-bis (3-sulfonatopropoxy)benzene sodium salt with 1,4-phenylenediboronic ac id or 4,4'-biphenyldiyldiboronic acid 2,2'-dimethylpropyl diester usin g a water soluble Pd(0) catalyst or Pd(OAc)(2). The pH dependence of t he coupling reaction was investigated and resulted in pH independence at pH levels greater than 10.0. End group analysis of PPP-OPSO3 via H- 1 NMR of tert-butyl end-capped polymers indicates degrees of polymeriz ation in excess of 40 (ca. 80 rings per chain). Viscometric analysis o f PPP-OPSO3 in water shows a behavior comparable to sodium poly(styren esulfonate) !PSS) of molecular weight 8000. In addition, the polyelect rolyte effect is observed at low polymer concentrations. The lambda(ma x) of the pi --> pi absorption for PPP-OPSO3 is found at 339-342 nm, while that of PPBP-OPSO3 shows a bathochromic shift to 349-352 nm. All of the water soluble PPP oligomers and polymers feature strong blue f luorescence. The fluorescence has been characterized by quantum yield and lifetime studies. Nanosecond-microsecond laser flash photolysis ex periments indicate that direct excitation of the polymers in the near- UV leads to triplet state formation, albeit with comparatively low eff iciency. Multilayered films of PPP-OPSO3 were fabricated with poly(eth yleneimine) (PEI) using layer-by-layer self-assembly and incorporated into blue-light-emitting devices.