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(O 2 CCF 3 ) 2 (H 2 O) 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 Zn 2 (O 2 CCF 3 ) 4 (H 2 O). Compounds 1 − 4 are bright green emitters in solution and in the solid state with emission λ max at 506, 511, 519, and 516 nm, respectively. In contrast, the emission maximum of complex 5 is blue-shifted (λ max = 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.