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The optical and physical properties of five ladder indolo[3,2-b]carbazoles, M1,M2,M3, M4 and M5 were studied. It was found that the side chains were twisted in the equilibrium geometry of the molecules, with relatively high rotational energy barriers against planarity and in their lowest states, the five compounds investigated become more quinoid like.

The synthesis, characterization, and field-effect transistor (FET) properties of new indolo[3,2-b]carbazoles are described. Best result are obtained with phenyl-substituted indolo[3,2-b]carbazoles since the presence of phenyl substituents seems to allow efficient overlap between the oligomeric molecules.

We report the synthesis and properties of three novelacetylenicmaterials based on the new electron-rich building block, 2,2′-ethyne-1,2-diylbis[3-(alk-1-yn-1-yl)thiophene](EBT). The synthesis of this new nonacene core is efficient and straightforward,and variation among n-hexyl, n-tetradecyl,and 2-ethylhexyl substituents substantially impacts the materialsproperties. Appending 2-ethylhexyl substituted diketopyrrolopyrrole(DPP) units to either terminus of the EBT core yields a series oflow band gap molecules that are characterized in detail by a rangeof experimental microstructure and electronic structure probes andby density functional theory (DFT) computation. Detailed morphology/microstructurecharacterization of spin-cast films by X-ray diffraction and AFM revealsinstructive microstructure and electronic/photovoltaic response relationshipsin both organic field-effect transistors and bulk-heterojunction organicphotovoltaic cells. Thus, the former devices exhibit hole mobilities(μh) as large as ∼0.2 cm2/(V s)which fall as thermal annealing increases long-range order. The latterdevices using PC61BM as the electron acceptor exhibit powerconversion efficiencies as high as ∼2%, which appear to fallas the materials become less ordered. These results are in accordwith a model where evolving grain boundaries and crystallinity impedeshole transport and excitonic charge generation. [ABSTRACT FROM AUTHOR]

The synthesis, characterization, and field-effect transistor (FET) properties of new indolo[3,2-b]carbazoles are described. In particular, an extensive characterization of their crystal structures has revealed the importance of the nature of the side chains (alkyl, phenyl, thienyl substituents) on their solid-state organization. These organic materials have exhibited p-type FET behavior with hole mobilities as high as 0.2 cm² V-1 s-1 with an on/off current ratio higher than 106. Best results were obtained with phenyl-substituted indolo[3,2-b]carbazoles since the presence of phenyl substituents seems to allow efficient overlap between the oligomeric molecules. More importantly, FET properties were kept constant during several months in air. [ABSTRACT FROM AUTHOR]

1-Phenyl-3-(1-phenyl-1-(pyridin-2-yl)ethyl)isoquinoline (H 2 MeL) has been prepared by Pd( N -XantPhos)-catalyzed " deprotonative cross-coupling processes " to synthesize new phosphorescent red iridium(III) emitters (601-732 nm), including the carbonyl derivative Ir(κ 4 - cis - C , C '- cis - N , N '-MeL)Cl(CO) and the acetylacetonate compound Ir(κ 4 - cis - C , C '- cis - N , N '-MeL)(acac). The tetradentate 6e-donor ligand (6tt') of these complexes is formed by two different bidentate units, namely, an orthometalated 2-phenylisoquinoline and an orthometalated 2-benzylpyridine. The link between the bidentate units reduces the number of possible stereoisomers of the structures [6tt' + 3b] (3b = bidentate 3e-donor ligand), with respect to a [3b + 3b' + 3b″] emitter containing three free bidentate units, and it permits a noticeable stereocontrol. Thus, the isomers fac -Ir(κ 4 - cis - C , C '- cis - N , N '-MeL){κ 2 - C , N -(C 6 H 4 -py)}, mer -Ir(κ 4 - cis - C , C '- cis - N , N '-MeL){κ 2 - C , N -(C 6 H 3 R-py)}, and mer -Ir(κ 4 - trans - C , C '- cis - N , N '-MeL){κ 2 - C , N -(C 6 HR-py)} (R = H, Me) have also been selectively obtained. The new emitters display short lifetimes (0.7-4.6 μs) and quantum yields in a doped poly(methyl methacrylate) film at 5 wt % and 2-methyltetrahydrofuran at room temperature between 0.08 and 0.58. The acetylacetonate complex Ir(κ 4 - cis - C , C '- cis - N , N '-MeL)(acac) has been used as a dopant for a red PhOLED device with an electroluminescence λ max of 672 nm and an external quantum efficiency of 3.4% at 10 mA/cm 2 .

The way to prepare molecular emitters [5t + 4t'] of iridium(III) with a 5t ligand derived from the abstraction of the hydrogen atom at position 2 of the aryl group of 1,3-di(2-pyridyl)benzene (dpybH) is shown. In addition, the photophysical properties of the new emitters are compared with those of their counterparts resulting from the deprotonation of 1,3-di(2-pyridyl)-4,6-dimethylbenzene (dpyMebH), at the same position, which are also synthesized. Treatment of 0.5 equiv of the dimer [Ir(μ-Cl)(η 2 -COE) 2 ] 2 (COE = cyclooctene) with 1.0 equiv of Hg(dpyb)Cl leads to the iridium(III) derivative IrCl 2 {κ 3 - N , C , N -(dpyb)}(η 2 -COE) ( 3 ), which reacts with 2-(1 H -imidazol-2-yl)-6-phenylpyridine (HNImpyC 6 H 5 ) and 2-(1 H -benzimidazol-2-yl)-6-phenylpyridine (HNBzimpyC 6 H 5 ) in the presence of Na 2 CO 3 to give Ir{κ 3 - C , N , N -(NImpyC 6 H 4 )}{κ 3 - N , C , N -(dpyb)} ( 4 ) and Ir{κ 3 - C , N , N -(NBzimpyC 6 H 4 )}{κ 3 - N , C , N -(dpyb)} ( 5 ), respectively. Similar reactions of the Williams's dimer [IrCl(μ-Cl){κ 3 - N , C , N -(dpyMeb)}] 2 with HNImpyC 6 H 5 and HNBzimpyC 6 H 5 in the presence of Na 2 CO 3 afford the dimethylated counterparts Ir{κ 3 - C , N , N -(NImpyC 6 H 4 )}{κ 3 - N , C , N -(dpyMeb)} ( 6 ) and Ir{κ 3 - C , N , N -(NBzimpyC 6 H 4 )}{κ 3 - N , C , N -(dpyMeb)} ( 7 ), whereas 2-(6-phenylpyridine-2-yl)-1 H -indole (HIndpyC 6 H 5 ) initially gives IrH{κ 2 - N , N -(IndpyC 6 H 5 )}{κ 3 - N , C , N -(dpyMeb)} ( 8 ) and subsequently Ir{κ 3 - C , N , N -(IndpyC 6 H 4 )}{κ 3 - N , C , N -(dpyMeb)} ( 9 ). Complexes 4 - 7 are phosphorescent green emitters (λ em 490-550 nm), whereas 9 is greenish yellow emissive (λ em 547-624 nm). They display lifetimes in the range 0.5-9.7 μs and quantum yields in both doped poly(methyl)methacrylate films and in 2-methyltetrahydrofuran at room temperature depending upon the ligands: 0.5-0.7 for 6 and 7 , about 0.4 for 4 and 5 , and 0.3-0.2 for 9 .