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Five new 2-(2'-pyridyl)benzimidazole derivative ligands, 1,4-bis[2-(2'-pyridyl)benzimidazolyl]benzene (1,4-bmb), 4,4'-bis[2-(2'-pyridyl)benzimidazolyl]biphenyl (bmbp), 1-bromo-4-[2-(2'-pyridyl)benzimidazolyl]benzene (Brmb), 1,3-bis[2-(2'-pyridyl)benzimidazolyl]benzene (1,3-bmb), and 1,3,5-tris[2-(2'-pyridyl)benzimidazolyl]benzene (tmb), have been synthesized by Ullmann condensation methods. The corresponding mononuclear and polynuclear PtII complexes, Pt2(1,4-bmb)Ph4 (1), Pt2(bmbp)Ph4 (2), Pt(Brmb)Ph2 (3), Pt2(1,3-bmb)Ph4 (4), and Pt3(tmb)Ph6 (5), have been obtained by the reaction of the appropriate ligand with [PtPh2(SMe2)]n. The structures of the free ligands 1,4-bmb, bmbp, and tmb, as well as the complexes 1-3, were determined by single-crystal X-ray diffraction. All ligands display fluorescent emissions in the purple/blue region of the spectrum at ambient temperature and phosphorescent emissions in the blue/green region at 77 K, which are attributable to ligand-centered pi --pi* transition. No ligand-based emission was observed for the PtII complexes 1-5. All PtII complexes display orange/red emissions at 77 K in a frozen solution or in the solid state, attributable to metal-to-ligand charge transfers (MLCT). Variable-temperature 1H NMR experiments establish that complexes 1, 4, and 5 exist in isomeric forms in solution at ambient temperature due to the hindered rotation of the square PtC2N2 planes in the complexes.

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.

A series of lanthanide–copper coordination polymers with nitrilotriacetic acid (H3NTA) were synthesized as [LnCuCl(NTA)(H2O)6]ClO4·H2O [LnLa (1), Ce (2), Pr (3), Gd (4, 4′), Tb (5) and Dy (6)] and [LnCuCl(NTA)(H2O)6]ClO4·3H2O [LnHo (7), Er (8), Tm(9), Lu (10) and Y (11)] in aqueous solution. The crystal structures of 1, 4, 4′, 8, 11 were determined and isomorphous relationships of the others identified. They turned out to be diverse, ranging from a two-dimensional (2D) array for 1 to one-dimensional (1D) chains of three different types (2–4, 4′–6, and 7–11), as controlled by lanthanide contraction and mixed anions Cl− and ClO4 −, which were found to play a crucial role in the formation and stabilization of this series of LnCu polymers. Temperature-dependent magnetic susceptibilities for 1, 3, 4, 5 and 8 were studied. 1 shows a weak ferromagnetic-like behavior, whereas the others exhibit an overall antiferromagnetic feature.

Novel 3D Ln–Cu heteronuclear complexes [Ln2Cu3(μ2-H2O)(DGA)6(H2O)3]·3H2O (Ln = La, Ce) containing unusual μ2-H2O bridges were formed by linking mononuclear units of [Ln(DGA)3] (H2DGA = diglycolic acid) by copper ions, to produce an open framework containing large amount of spacious hexagon channels with stable skeletons as demonstrated by thermogravimetric analysis (TGA) and X-ray diffraction (XRD) analysis.

The new heteronuclear iminodiacetic acid (H2L) complexes [LnCu6(μ3-OH)3(HL)2(L)4](ClO4)2·25H2O with Ln = La (1) and Tb (2) have been prepared in aqueous solution and characterized by single-crystal X-ray diffraction to be isomorphous (crystallographic data for 1 and 2: hexagonal, P63/m; a = b = 12.6425(14) A, c = 24.541(5) A, Z = 2 (1); a = b = 12.5802(9) A, c = 24.285(4) A, Z = 2 (2)). Ln3+ was found to be located in the center of the trigonal prismatic cage formed by six Cu2+ ions, with a tricapped trigonal prismatic coordination environment of nine O atoms. The magnetic properties of complexes 1 and 2 have been studied. The results indicate the presence of ferromagnetic couplings between Tb3+ and Cu2+ in compound 2.

The title complex has been synthesized in aqueous solution and its crystal structure was determined by X-ray diffraction. It consists of a one-dimensional ladder-like chain. One carboxyl group bridges the adjacent Tm ions giving rise to the edge of the ladder, a second one links the Tm ions from the neighboring edge in zigzag form to act as the rung of the ladder, and a third one monodentately coordinates with Tm to serve as the pendant of the ladder. Each Tm ion is eight coordinated by one nitrogen atom, five oxygen atoms from three NTA molecules and two oxygen atoms from H 2 O.

Three phosphorescent dendrimers (IrC1, IrC3, and IrF2) with an iridium complex core and oligocarbazole or oligofluorene substituted ligands were synthesized and characterized. The structures of the oligocarbazole were designed to maintain high triplet energy of the ligands so that phosphorescence quenching in the resulting dendrimers can be prevented, while the oligofluorene in IrF2 resulted in undesired phosphorescence quenching. Best performance was obtained from an IrC3 based electro-phosphorescent light-emitting device with a maximum luminance of 13 060 cd m -2 at a driving voltage of 11.5 V and a peak current-efficiency of 4.3 cd. A -1 1 at a luminance of 3 400 cd. m -2 , owing to its high PL efficiency, and efficient energy transfer between the iridium complex core and the ligands.

Four new luminescent organoboron complexes have been synthesized and fully characterized. These compounds are four-coordinate boron chelated by either 8-hydroxyquinolato (q) or functionalized 8-hydroxylquinolato ligands, including BPh2(5-(1-naphthyl)-q) (1), BPh2(5-(2-benzothienyl)-q) (2), B(2-benzothienyl)2q (3), and B(2-benzothienyl)2(2-Me-q) (4). All four compounds have a tetrahedral geometry as established by X-ray diffraction analyses. In solution, compounds 1-4 have an emission maximum at 534, 565, 501, and 496 nm, respectively, at room temperature. They emit similar colors in the solid states without red shifts of the emission band due to the lack of significant intermolecular interactions in the crystal lattices. The substituent group at C5 or C2 position of the 8-hydroxyquinolato ligand has been observed to have a significant impact on the emission energy and the emission quantum efficiency of the boron complexes. Molecular orbital calculations (Gaussian 98) showed that the electronic transition of 1 and 2 is a pi-pi* transition centered on the functionalized 8-hydroxyquinolato group and the electronic transition of 3 and 4 is an interligand charge transfer from the 2-benzothienyl ligand to the hydroxyquinolato ring. A double-layer electroluminescent device using 3 as the emitter has been fabricated, which produced a broad emission band with a significant contribution of exciplex emission.

Six new diethynylsilane compounds with the general formula Si(C⋮C−R)2R‘2 (R = p-N-indolylphenyl, R‘ = Me, 1; R‘ = Ph, 2; R = p-N-7-azaindolylphenyl, R‘ = Me, 3; R‘ = Ph, 4; R = p-2,2‘-dipyridylaminophenyl, R‘ = Me, 5; R‘ = Ph, 6) have been synthesized and fully characterized. Compounds 1, 2, and 4 have been found to undergo intramolecular cyclization in the presence of Li-naphthyl to form the corresponding 2,5-dilithiosiloles, which after methylation by CH3I or undergoing Pd-catalyzed cross-coupling reactions with the appropriate arylbromide produced six new silole compounds: 1,1-diphenyl-2,5-dimethyl-3,4-bis(4-N-7-azaindoylphenyl)silole (7), 1,1-diphenyl-2,3,4,5-tetrakis(4-N-indoylphenyl)silole (8), 1,1-dimethyl-2,5-bis(4-N-7-azaindoylphenyl)-3,4-bis(4-N-indoylphenyl)silole (9), 1,1-dimethyl-2,5-bis(p-2,2‘-dipyridylaminophenyl)-3,4-(4-N-indoylphenyl)silole (10), 1,1-dimethyl-2,5-bis(4-(N-1-naphthylphenylamino)phenyl)-3,4-bis(4-N-indoylphenyl)silole (11), and 1,1-dimethyl-2,5-bis(4‘-(N-1-naphthylphenylam...