Halogen Bonding in a Crystalline Sponge

Host–guest interactions are the key to the supramolecular chemistry and the further application of the receptors to study the structural details of the small guest molecules. Crystalline sponges as a kind of supramolecular receptor need to be investigated in terms of the binding ability with the guests. We found in this work that one guest with σ-hole donors and another with electron-donating species were separately entrapped in two distinct channels of the host framework via the crystalline sponge method. Halogen bonding and weak hydrogen bonding were detected between the host and the two guests, respectively. The ability of the crystalline sponge to absorb and sort guests of different types was unambiguously confirmed by X-ray crystallography

“Useless Channels” in a Molecular Crystal Formed via F···F and F···π Halogen Bonds

Tris­(pentafluorophenyl)­phosphine molecules in a new phase pack to form hourglass-shaped one-dimensional channels, whose inner surface is occupied by only fluorine. The channels show an effective diameter of 3.80 Å at the belly and only 2.68 Å at the neck, neither being possible for the encapsulation of any solvent molecules or for the permeability of air (N2 and O2), thus demonstrating an absolute vacuum. Such “vacuum” channels in the crystals have never been reported and would be of great significance in photo- and electrophysics. In addition, the structural analysis indicated that F···F contacts and F···π interactions are mainly responsible for the specific packing in the new phase, and a σ-hole-type attraction is found in both F···F and F···π forces according to the DFT computations