Photoluminescence, Electroluminescence, and Complex Formation of Novel N-7-Azaindolyl- and 2,2‘-Dipyridylamino-Functionalized Siloles

New silole compounds based on the 7-azaindolyl and 2,2‘-dipyridylamino groups, 1,1-dimethyl-2,5-bis(4-N-7-azaindolylphenyl)-3,4-diphenylsilole (1), 1,1-dimethyl-2,5-bis(4‘-N-7-azaindoylbiphenylyl)-3,4-diphenylsilole (2), 1,1-dimethyl-2,5-bis(p-2,2‘-dipyridylaminophenyl)-3,4-diphenylsilole (3), and 1,1-dimethyl-2,5-bis(p-2,2‘-dipyridylaminobiphenylyl)-3,4-diphenylsilole (4), have been synthesized and structurally characterized. These new silole compounds are capable of binding to metal ions as demonstrated by the zinc(II) complex 5 obtained from the reaction of 3 with Zn(O2CCF3)2(H2O)3, where 3 functions as a bridging-chelating ligand to zinc(II) ions. The structure of siloles 1 and 3, and complex 5 were determined by single-crystal X-ray diffraction analyses. Compound 5 displays an extended 1D polymer structure in the solid state with alternating molecules of 3 and a dinuclear unit of Zn2(O2CCF3)4(H2O). Compounds 14 are bright green emitters in solution and in the solid state with emission λmax at 506, 511, 519, and 516 nm, respectively. In contrast, the emission maximum of complex 5 is blue-shifted (λmax = 488 nm), which is attributed to the disruption of the conjugation of the functionalized phenyl rings with the central silole ring by zinc(II) coordination, as revealed by X-ray diffraction analysis. Electroluminescent devices using compounds 1 and 3 as the emitting layer and the electron-transporting layer have been fabricated successfully.