Comparative study on tetrahedral and tripodal luminescent silane and methane compounds with a 2,2′-dipyridylamino group

A comparative study on methane and silane derivatives that contain either one or four 2,2'-dipyridylamino group (dpa) functionalized groups has been carried out. Six new compounds, (p-dpa-phenyl)triphenylsilane (1), (p-dpa-phenyl)triphenylmethane (2), tetra(p-dpa-phenyl)silane (3), tetra(p-dpa-phenyl)methane (4), tetra(p-dpa-biphenyl)silane (5), and tetra(p-dpa-biphenyl)methane (6), have been synthesized using Suzuki coupling, Ullmann condensation methods, or simple substitution reactions. The structures of 3 and 4 have been determined by X-ray diffraction analyses. Thermal and luminescent properties have been investigated, which revealed that these new compounds are luminescent in the violet-blue region and the methane derivatives in general have a higher thermal stability than the corresponding silane analogues. The electronic properties of the new compounds were investigated experimentally and theoretically by molecular orbital calculations, which revealed that there is a subtle difference between the methane derivatives and their silane analogues.