Three blue‐light emitting dipyrenylbenzene derivatives, 1‐(4‐(1‐pyrenyl)phenyl)pyrene (PPP), 1‐(2,5‐dimethoxy‐4‐(1‐pyrenyl)phenyl)pyrene (DOPPP), and 1‐(2,5‐dimethyl‐4‐(1‐pyrenyl)phenyl)pyrene (DMPPP), have been prepared by the Suzuki coupling reaction of aryl dibromides with pyreneboronic acid in high yields. These compounds exhibit high glass‐transition temperatures of 97–137 °C and good film‐forming ability. As revealed from single‐crystal X‐ray analysis, these dipyrenylbenzenes adopt a twisted conformation with inter‐ring torsion angles of 44.5°–63.2° in the solid state. The twisted structure is responsible for the low degree of aggregation in the thin films that leads to fluorescence emission of the neat films at 446–463 nm, which is shorter than that of the typical pyrene excimer emission. The low degree of aggregation is also conducive for the observed high fluorescence quantum yields of 63–75%. In organic light‐emitting diode (OLED) applications, these dipyrenylbenzenes can be used as either the charge transporter or host emitter. The non‐doped blue OLEDs that employ these compounds as the emissive layer can achieve a very high external quantum efficiency (ηext) of 4.3–5.2%. In particular, the most efficient DMPPP‐based device can reach a maximum ηext of 5.2% and a very high luminescence of 40 400 cd m–2 in the deep‐blue region with Commission Internationale d'Énclairage (CIE) coordinates of (0.15, 0.11).

A new method for the synthesis of substituted 2-acylallylmetal reagents in a highly regio- and stereoselective fashion involving a three-component assembly of allenes, acyl chlorides, and bimetallic reagents (B-B, Si-Si, and Sn-Sn) catalyzed by phosphine-free palladium complexes is described. Treatment of various allenes (CR(2)R(3)=C=CH(2)) with acyl chlorides (R(1)COCl) and bispinacolatodiboron in the presence of PdCl(2)(CH(3)CN)(2) in toluene at 80 degrees C gave 2-acylallylboronates in moderate to good yields. The acylsilation of allenes with acid chlorides and hexamethyldisilane (5) proceeded successfully in the presence of Pd(dba)(2) in CH(3)CN affording the corresponding allylsilanes (CR(2)R(3)=C(COR(1))CH(2)SiMe(3)) in good to moderate yields. Several chloroformates (R(4)OCOCl) also react with 1,1-dimethylallene (2a) and 5 to afford allylsilanes (CR(2)R(3)=C(COOR(4))CH(2)SiMe(3)) in 66-70% yields. Acylstannation of allenes could also be achieved by slow addition of hexabutylditin (10) to the reaction mixture of acyl chloride (or chloroformate) and allene 2a in CH(3)CN in the presence of Pd(dba)(2) at 60 degrees C; the corresponding 2-substituted allylstannanes were isolated in moderate to good yields. The above catalytic reactions are completely regioselective and highly stereoselective. A mechanism is proposed to account for the catalytic reactions and the stereochemistry.

Two structurally simple Pt(II)-directed self-assembly loop complexes were prepared by reactions of cis-(PEt 3 ) 2 Pt(OTf ) 2 and the corresponding pyridylamide-functionalized pyridyl ligands. Both Pt(II)-based complexes exhibit singlet fluorescence, indicating that the platinum metal serves only as a structural, rather than a direct photophysical role within the loop framework. The crystal structure of complex 1 shows a distorted loop conformation with a hydrophobic pocket defined by the bridging ligands. The anion binding affinities of these two complexes were investigated with a range of anions. Such studies using UV-vis absorption, fluorescence, and 1 H NMR titrations showed that complex 1 exhibits excellent binding sensitivity and selectivity for benzoate over acetate in solution via a combination of electrostatic, hydrogen-bonding, and π-π interactions, whereas complex 2 shows comparable binding affinities toward acetate and benzoate due to the lack of favorable aromatic π-π interaction.

A series of anthracene and perylene bisimide derivatives with electron‐withdrawing benzimidazole substituents has been designed and prepared. Detailed studies on the electrochemical and photophysical properties as well as the field‐effect mobilities of these new compounds were explored. The incorporation of electron‐withdrawing benzimidazole groups lowered the LUMO levels in both anthracene and perylene bisimide derivatives compared to those of the parent compounds. Strong emission was observed for all anthracene derivatives, but only weak emission was observed for perylene bisimide derivatives. The anthracene derivatives showed typical p‐type semiconducting character, even when the derivatives were substituted with electron‐withdrawing benzimidazole groups at the 9‐ and 10‐positions, which apparently does not lower the LUMO levels to transform them into electron‐transporting molecules. Perylene bisimide derivatives displayed typical n‐channel semiconducting properties with low threshold voltages and electron mobilities of ca. 5.2 × 10–5 cm2 V–1 s–1.

Acylallylmetal Reagents. -For the first time, acyl chlorides or chloroformates are used as electrophiles in the three-component coupling reaction of allenes and bimetallic reagents (II), (IX), and (XV). A wide variety of 2-acylallylmetal reagents are obtained in good to moderate yields. The reaction is completely regioselective in which the acyl group and metal are added to the middle and unsubstituted terminal carbon of the allene moiety. No decarbonylative coupling products are observed in all reactions. In the case of monosubstituted allenes, the reaction is highly stereoselective except for one case. -(YANG, F.-Y.; SHANMUGASUNDARAM, M.; CHUANG, S.-Y.; KU, P.-J.; WU, M.-Y.; CHENG*, C.-H.; J.