A Self-Assembled Cage Binding Iodide Anions over Other Halide Ions in Water.

A triangular-prism shaped cage was self-assembled by the formation of a dynamic covalent bond, namely a hydrazone, in acidic aqueous solution. The hexacationic host bears a number of relatively acidic protons pointing inside the cage cavity, which is able to accommodate an iodide anion selectively in water over other halide anions such as F- , Cl- , and Br- , which are more hydrated. As a comparison, a macrocycle analogue bearing fewer positive charges and fewer hydrogen bond donors shows no anion binding ability. As inferred from the single-crystal structure and theoretical calculations, the ability of the cage to selectively recognize iodide anions results from the combination of electrostatic forces, C-H⋅⋅⋅I- hydrogen bonds, and the hydrophobic effect.

A π-Electron Rich Cage via the Friedel-Crafts Reaction.

A prism-shaped cage was obtained via the Friedel-Crafts reaction in a 2:3 mixture of trisfuryl and bis-isopropenyl precursors, in a remarkable yield of 40% considering six C-C bonds formed in a one-pot manner. The cage contains two π-electron rich trisfuryl platforms bridged in a face-to-face manner with three p-xylylene linkers. Therefore, it enables accommodation of π-electron poor guests with complementary size, including biscationic viologen.

Water-Soluble Cyclophanes Synthesized via the Zincke Reaction.

By taking advantage of the Zincke reaction, we successfully synthesized three macrocycles, each of which contains two bipyridinium units as the electron acceptors. Two of them contain sp2-hybridized atoms exclusively in the ring frameworks, while the third contains two methylene units. The third macrocycle is able to form 1:1 inclusion complexes with guests of complementary sizes. A pair of isomers, namely, phenanthrene and anthracene, could be separated by the third macrocycle.

A cylinder-shaped macrocycle formed via Friedel-Crafts reaction.

By performing Friedel-Crafts reaction with a mixture of 1,3,5-tri(furan-2-yl) benzene (TFB) and acetone, we successfully synthesized a cylinder-shaped macrocycle. The isolated yield of 36% is relatively high, considering that twelve C-C bonds are formed simultaneously. The structure of this macrocycle was confirmed using 1H NMR spectroscopy, mass spectrometry and X-ray crystallography. This macrocycle is able to recognize a variety of cationic guests driven by cation-dipole and CH-π interactions.

A water-soluble naphthalenediimide-containing hexacationic cage.

A water-soluble cage containing three naphthalenediimide (NDI) units was synthesized in a one-pot manner without chromatographic purification, during which six irreversible C-N bonds formed simultaneously via an SN2 reaction. The cage was observed to be capable of accommodating a variety π-electron rich guests in a peripheral manner in water. However, for linear guests including I3- and I2, the cage is able to form an inclusion complex. Besides, in the solid state, the cage can absorb vapor of I2.

Copper-Catalyzed C-H Difluoroalkylations and Perfluoroalkylations of Alkenes and (Hetero)arenes.

A general and facile synthetic method for C(sp2)-H difluoroalkylations and perfluoroalkylations of alkenes and (hetero)arenes with commercially available fluoroalkyl halides has been developed with a copper-amine catalyst system. This method is characterized by high yields, mild reaction conditions, low-cost catalyst, broad substrate scope, and excellent functional group compatibility, therefore providing a convenient synthetic strategy toward various difluoroalkyl- and perfluoroalkyl-substituted alkenes and (hetero)arenes.