Dehydropolymerization of 1,1-dihydrotetraphenylsilole and 1,1-dihydrotetraphenylgermole to optoelectronic copolymers catalyzed by colloidal silver nanoparticles.

The co-dehydrocoupling at ambient air atmosphere of 1,1-dihydrotetraphenylsilole 1 and 1,1-dihydrotetraphenylgermole 2 (9:1 mole ratio) with 2 mol% of AgNO3 in toluene at 90 degrees C produces optoelectronic poly(silole-co-germole)s 3 in high yield. The copolymer mainly has Si-Si bonds (and Si-Ge/Ge-Ge bonds in minor) along with the small portion of Si-O/Ge-O bonds in the polymer backbone chain. While Ag2SO4 is also a good catalyst as AgNO3 for the co-dehydrocoupling, AgI is a moderate catalyst. However, CP2Co, Cp2Ni, Cp2ZrCl2/Red-Al, AgX (X = F, Cl, Br) and AgI@MWCNT do not show appreciable catalytic activity. The silver complexes (AgNO3, Ag2SO4, AgI) transformed to colloidal silver nanoparticles during the catalytic reaction. The co-dehydrocoupling of 1 and 2 with AgNO3 even at dry nitrogen atmosphere is occurred, supporting that the oxidation of NO3- ion to NO2 is only the possible oxygen source, but not from the adventitious moisture in air. All cyclodextrins (sigma, beta, and gamma forms) considerably deteriorated the co-dehydrocoupling of 1 and 2 probably by forming toluene-insoluble inclusion complexes and by encapsulating SiH2 moiety. The resulting copolymer emits green light at 521 nm and is electroluminescent at 523 nm, which is similar to the polysilole.