Cyclodextrins with Multiple Pyrenyl Groups: An Approach to Organic Molecules Exhibiting Bright Excimer Circularly Polarized Luminescence.

We report a simple and effective approach to organic molecules exhibiting bright circularly polarized luminescence (CPL) by combining a chiral cyclic molecular scaffold and multiple excimer-enabling moieties. An α-cyclodextrin (CyD) scaffold was modified with six pyrenyl groups to obtain pyrene-cyclodextrins (PCDs) in a one-step synthesis from commercially available compounds. The PCDs exhibited high molar extinction coefficients (ϵ≈10  M  cm ), polarized emission with a good dissymmetry factor (|g |≈10 ), and quantum yield (Φ ≈0.

Bipyridine-Type Bidentate Auxiliary-Enabled Copper-Mediated C-H/C-H Biaryl Coupling of Phenols and 1,3-Azoles.

A copper-mediated dehydrogenative C-H/C-H biaryl coupling of phenols and 1,3-azoles has been developed. The key to its success is the introduction of a bipyridine-type bidentate auxiliary, 4,4'-di(-butyl)-2,2'-bipyridine, on the phenol oxygen, which is readily prepared and easily attachable, detachable, and recyclable. The reaction proceeds smoothly in the presence of copper salt alone to form the corresponding phenol-azole heterobiaryls, which are prevalent motifs in functional molecules such as excited-state intramolecular proton transfer materials.

Copper-Mediated Regioselective C-H Sulfenylation and Selenation of Phenols with Phenanthroline Bidentate Auxiliary.

A copper-mediated, phenanthroline-directed highly ortho-selective C-H sulfenylation of phenols with diaryl disulfides proceeds to form the corresponding unsymmetrical diaryl sulfides in good yield. The key to success is the introduction of a phenanthroline directing group of the bidentate-chelating nature, which is easily attachable, detachable, and even recyclable. Moreover, the same strategy is applicable to the C-H selenation, giving the diaryl selenides with high efficiency and regioselectivity.