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Ternary catalytic systems consisting of cobalt salts, phosphine ligands and Grignard reagents which promote addition of arylpyridines and imines to unactivated internal alkynes with high regio- and stereoselectivities is presented. The reaction involves chelation-assisted oxidative addition of the aryl C-H bond to the cobalt center and insertion of the C-C triple bond into the Co-H bond, followed by reductive elimination of the resulting diorganocobalt species.

We designed and synthesized the DPPEZnP-TEH molecule, with a porphyrin ring linked to two diketopyrrolopyrrole units by ethynylene bridges. The resulting material exhibits a very low energy band gap of 1.37 eV and a broad light absorption to 907 nm. An open-circuit voltage of 0.78 V was obtained in bulk heterojunction (BHJ) organic solar cells, showing a low energy loss of only 0.59 eV, which is the first report that small molecule solar cells show energy losses <0.6 eV. The optimized solar cells show remarkable external quantum efficiency, short circuit current, and power conversion efficiency up to 65%, 16.76 mA/cm², and 8.08%, respectively, which are the best values for BHJ solar cells with very low energy losses. Additionally, the morphology of DPPEZnP-TEH neat and blend films with PC61BM was studied thoroughly by grazing incidence X-ray diffraction, resonant soft X-ray scattering, and transmission electron microscopy under different fabrication conditions. [ABSTRACT FROM AUTHOR]

We report here cobalt-N-heterocyclic carbene catalytic systems for the ortho alkylation of aromatic imines with alkyl chlorides and bromides, which allows the introduction of a variety of primary and secondary alkyl groups at room temperature. The stereochemical outcomes of the reaction of secondary alkyl halides suggest that the present reaction involves single-electron transfer from a cobalt species to the alkyl halide to generate the corresponding alkyl radical. A cycloalkylated product obtained by this method can be transformed into unique spirocycles through manipulation of the directing and cycloalkyl groups. [ABSTRACT FROM AUTHOR]

Cobalt-phosphine and cobalt-carbene catalysts have been developed for the hydroarylation of styrenes via chelation-assisted C-H bond activation, to afford branched and linear addition products, respectively, in a highly regioselective fashion. Deuterium-labeling experiments suggested a mechanism involving reversible C-H bond cleavage and olefin insertion steps and reductive elimination as the rate- and regioselectivity-determining step. [ABSTRACT FROM AUTHOR]