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Preligands of quinolyl-substitutedsecondary phosphine oxides (SPOs, 2a–d) were prepared and characterized.The unique palladium complex 3, having a distorted-square-pyramidalstructure, was obtained from the reaction of 2 equiv of 2cwith Pd(COD)Cl2or [Pd(μ2-Cl)(η3-allyl)]2. In the crystal structure of 3, an apical chloride ligand and a supramolecular tetradentate ligandcomposed of a deprotonated 2c′ and a neutral 2c′ were resolved (2c′: PA formof 2c). Intriguingly, the gas-phase optimized geometryof 3converged to a distorted-square-planar structure,which was predicted by density functional calculations. The solid-statedistorted-square-pyramidal structure of 3can only beexplained with the consideration of environmental effects (i.e., theelectrostatic interactions between the surrounding molecules). Asalso evidenced by 31P NMR experiments performed in differentdeuterated solvents, the crystal structure of 3is retainedin solution. In the crystal structure of 3, a long Pd–Clbond was analyzed by energy decomposition analysis, showing that thebond is dominated by electrostatic character. Furthermore, applicationof these SPOs using the Heck reaction shows good reactivity towardcommon aryl bromides. The hemilabile preligand 2calsotautomerizes to the competent ligand 2c′ for palladium-catalyzedthree-component reactions. [ABSTRACT FROM AUTHOR]

The synthesis, characterization, and application of two angular-shaped naphthalene bis(1,5-diamide-2,6-diylidene)malononitriles (NBAMs) as high-performance air-stable n-type organic field effect transistor (OFET) materials are reported. NBAM derivatives exhibit deep lowest-unoccupied molecular orbital (LUMO) levels, suitable for air-stable n-type OFETs. The OFET device based on NBAM-EH fabricated by vapor deposition exhibits a maximum electron mobility of 0.63 cm 2 V -1 s -1 in air with an on/off current ratio ( I on / I off ) of 10 5 .

5,7,12,14-Tetrachloro-6,13-diaza-6,13-dihydropentacene (TCDAHP) and 5,7,12,14-tetrachloro-6,13-diazapentacene (TCDAP) were synthesized and assessed as the active channel materials for thin-film transistor applications. Analyses of the crystal structures of these molecules revealed that both exhibited slipped pi-pi stacking of the long and fused aromatic moiety. Although the packing features of the two compounds are basically identical, their highest occupied molecular orbitals, which are relevant to hole transport, are very different. Better mobility was predicted for TCDAHP over TCDAP based on the dimeric structure in the X-ray coordinates. The morphologies of thin films of TCDAHP and TCDAP prepared by thermal evaporation depend critically on the substrate on which the molecules were deposited: from the amorphous state on a SiO(2)/Si surface to the crystalline state on a pentacene buffer layer surface. The performance of thin-film transistors prepared on various substrate surfaces was studied. While no field-effect mobility was observed for these films deposited on SiO(2)/Si, a high mobility of 1.4 cm(2)/(V s) for the TCDAHP film was achieved when deposited on a pentacene buffer layer prepared on a rubbed monolayer of n-nonyltrichlorosilane on a SiO(2)/Si surface. A similar device prepared from TCDAP gave a mobility of 0.13 cm(2)/(V s).

New dipolar compounds containing alternating electron-rich thieno[3,2-b]thiophene units and electron deficient units have been synthesized. Compounds with 5-pyrimidinyl (compound 2) or benzothiazole (compound 5) as the electron-deficient unit were structurally characterized by the single-crystal X-ray diffraction method. The arrangement of the molecules is found to be one-dimensional slipped-pi-stack for 2. That of 5 is of slipped-pi-stack, albeit with a tilt angle between neighboring pi-stacks. The pi-pi interfacial distances of the molecules in the crystal lattice are 3.47 and 3.59 A for 2 and 5, respectively. On the basis of the crystal structure, compound 2, with negligible pi-pi slip along the short axis of the molecules, has a calculated electronic coupling value (0.153 eV) twice as large as that of the largest coupling of pentacene. Accordingly, the theoretically estimated hole mobility (mu(+)) for 2 (2.32 cm(2) s(-1) V(-1)) compares favorably with that of pentacene (1.93-5.43 cm(2) s(-1) V(-1)), despite of the larger reorganization energy for hole transport in 2. The symmetric intrastack S...C contacts found between the thieno[3,2-b]thiophene and pyrimidinyl units explain the unique features of the crystal structure of 2 and the resulting large electronic coupling.