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Four novel five-coordinated Sn(IV) and Pb(IV) complexes of 2,6-bis(2‘-indolyl)pyridine (H2bip) and 2,6-bis[2‘-(7-azaindolyl)]pyridine (H2bap) were synthesized. These four complexes have the formulas Sn(bip)Ph2 (1), Sn(bap)Ph2 (2), Pb(bip)Ph2 (3), and Pb(bap)Ph2 (4), respectively. The structures were determined by single-crystal X-ray diffraction. In the complexes, the metal centers are tridentately chelated by the bip or the bap ligand and further coordinated by two phenyl groups, resulting in a distorted-trigonal-bipyramidal geometry. These complexes display interesting extended π−π stack structures in the solid state. Complexes 1 and 2 are luminescent at room temperature in solution and the solid state. At 77 K in THF solution, all four complexes display both blue-green fluorescent and orange-red phosphorescent emissions, which originate from ligand-centered π → π* transitions. The Sn(IV) and Pb(IV) centers play a key role in enhancing phosphorescent emission of the bip and bap ligands.

New binuclear and starburst trinuclear organoplatinum complexes based on 2,2‘-dipyridylamino (dpa) derivative ligands, Pt2Ph4(bab), bab = 1,4-bis(2,2‘-dipyridylamino)benzene, 1, Pt2Ph4(babp), babp = 4,4‘-bis(2,2‘-dipyridylamino)biphenyl, 2, Pt3Ph6(tab), tab = 1,3,5-tris(2,2‘-dipyridylamino)benzene, 3, Pt3Ph6(tat), tat = 2,4,6-tris(2,2‘-dipyridylamino)-1,3,5-triazine, 4, Pt3Ph6(tapb), tapb = 1,3,5-tris[p-(2,2‘-dipyridylamino)phenyl]benzene, 5, Pt3Ph6(tapt), tapt = 2,4,6-tris[p-(2,2‘-dipyridylamino)phenyl]-1,3,5-triazine, 6, Pt3Ph6(tabpb), tabpb = 1,3,5-tris{4‘-[4‘ ‘-(2,2‘-dipyridylamino)]biphenyl}benzene, 7, and Pt3Ph6(tabpt), tabpt = 1,3,5-tris{4‘-[4‘ ‘-(2,2‘-dipyridylamino)]biphenyl}benzene, 8, were synthesized by the reaction of [PtPh2(SMe2)]n with the corresponding chelate ligand. The structures of complexes 1−5 and 8 were determined by single-crystal X-ray diffraction. All eight complexes have phosphorescent emissions in the blue/green region at 77 K, attributed to ligand-centered π → π* transitions. ...

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'-biphenyldi-methylhydroxysilane (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 m a x 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.

To examine the effect of substituent groups on the luminescence of BPh2(X-2-PI) complexes, three new air-stable boron complexes BPh2(F-2-PI) (5a), BPh2(Cl-2-PI) (5b), and BPh2(CH3O-2-PI) (5c) were synthesized and characterized, where F-2-PI = 5-fluoro-2-(2‘-pyridyl)indole, Cl-2-PI = 5-chloro-2-(2‘-pyridyl)indole, and CH3O-2-PI = 5-methoxyl-2-(2‘-pyridyl)indole. In these complexes, the 5-substituted 2-PI ligand chelates in a tretrahedral fashion to the boron center. Compounds 5a−c are luminescent, with 5a having the highest emission efficiency. Compared with the emission maximum of BPh2(2-PI) (516 nm), the emission maximum of 5a and 5b is blue-shifted to 490 and 487 nm, respectively, while the emission of 5c is red-shifted to 532 nm, indicating the possibility of tuning the luminescence of these complexes by varying the substituent groups on the 2-PI ligand. An electroluminescent device using compound 5a as the emitter and the electron transport material has been fabricated.