2003/01/22 by Junwu Chen, Zhiliang Xie, Jacky W. Y. Lam +3
Chemistry · Materials Science · #Synthesis and Properties of Aromatic Compounds #Synthesis and characterization of novel inorganic/organometallic compounds #Luminescence and Fluorescent Materials
paper · doi:10.1021/ma0213504
We synthesized three substituted polyacetylenes carrying 1,2,3,4,5-pentaphenylsilolyl (PS) pendants, i.e., −[HC C(PS)] n − ( 1 ), −HC C[(CH 2 ) 9 OPS] n − ( 2 ) and −(C 6 H 5 )C C[(CH 2 ) 9 OPS] n − ( 3 ), and succeeded in turning polymers 2 and 3 from weak luminophors into strong emitters by external stimuli of aggregation and cooling. The silolylacetylene monomers HC⋮CPS ( 10 ), HC⋮C(CH 2 ) 9 OPS ( 11 ), and C 6 H 5 C⋮C(CH 2 ) 9 OPS ( 12 ) were polymerized by NbCl 5 − and WCl 6 −Ph 4 Sn catalysts, which gave high molecular weight polymers in high yields ( M w up to ∼70 × 10 3 Da and yield up to ∼80%). The structures and properties of the polymers were characterized and evaluated by IR, UV, NMR, DSC, TGA, PL, EL, and nanoparticle size analyses. The polymers were thermally stable and lost little weights when heated to ∼350 °C. Whereas all the polymers were practically nonluminescent when molecularly dissolved, polymers 2 and 3 became emissive when aggregated in poor solvents or when cooled to low temperatures. Restricted intramolecular rotation or twisting of the silole chromophores in the solid nanoaggregates or at the low temperatures may be responsible for the aggregation- or cooling-induced emission. A multilayer electroluminescence device using 3 as an active layer emitted a blue light of 496 nm with maximum brightness, current efficiency, and external quantum yield of 1118 cd/m 2, 1.45 cd/A, and 0.55%, respectively.