Blue Luminescent Organosilicon Compounds Based on 2,2‘-Dipyridylaminophenyl and 2,2‘-Dipyridylaminobiphenyl

Five new luminescent organosilicon compounds, bis[ p -(2,2‘-dipyridylamino)phenyl]dimethylsilane ( 1 ), bis[ p -(2,2‘-dipyridylamino)-4,4‘-biphenyl]dimethylsilane ( 2 ), p -(2,2‘-dipyridylamino)phenyldimethylhydroxysilane ( 3 ), p -(2,2‘-dipyridylamino)-4,4‘-biphenyldimethylhydroxysilane ( 4 ), and 1,1,3,3-tetramethyl-1,3-bis[ p -(2,2‘-dipyridylamino)phenyl]disiloxane ( 5 ), are synthesized. The structures of compounds 1 and 3 − 5 are determined by single-crystal X-ray diffraction. All five compounds have fluorescent emissions at 379−383 nm at room temperature. At 77 K, compounds 1 − 5 have phosphorescent emission bands with λ max ranging from 407 to 518 nm. Increasing the degree of conjugation of the ligand has no significant effect on the fluorescent emission energy of the complexes, but causes a substantial red shift of the phosphorescent emission energy. Both fluorescent and phosphorescent emission of these compounds originates from π* → π transitions centered on the p -(2,2‘-dipyridylamino)phenyl and p -(2,2‘-dipyridylamino)-4,4‘-biphenyl ligands.