1,8-Dioxyanthracene-Derived Crown Ethers: Synthesis, Complexation with Paraquat and Assembly of a Tetracationic Cyclophane-Crown Ether Based [2]Catenane

Enhanced molecular binding affinity toward aromatic dications by anthracene-derived crown ethers in water

The pursuit of high molecular binding affinity using conventional crown ethers in water remains a challenging task in the field of supramolecular chemistry and may hold great promise in the creation of advanced biocompatible nanoconstructs. In this work, the molecular binding strength toward a series of structurally relevant cationic guests has been greatly enhanced by tetrasulfonated 1,5-dianthracenyl-42-crown-10 and as investigated by means of ¹H NMR, UV-vis, and fluorescence spectroscopy, the host-guest association constants can reach up to 10⁸ M^-1 order of magnitude in aqueous solution. X-ray crystal diffraction analysis further demonstrates that the aromatic dication can be tightly encapsulated in the ring of anthracene-derived crown ether via multiple π-stacking and electrostatic interactions. Meanwhile, the obtained association constants are remarkably higher than the ones in the cases of the known benzene- and naphthalene-derived sulfonated crown ethers, substantiating that the appropriate extension of π-conjugation in the molecular skeleton of crown ether is a feasible method in attaining a highly affiliative host-guest complex. Taken together, our results indicate that the anthracene-based sulfonated crown ether can be developed as a new family of water-soluble macrocyclic receptors in the fabrication of functional nanoarchitectures.

Elucidation of naphthalene diimide metallomacrocycles and catenanes by solvent dependent excimer and exciplex emission

The formation of metallocatenanes, and their disruption by aromatic solvents, is followed by excimer and exciplex emission.

Multicavity macrocyclic hosts

Multicavity macrocyclic hosts are host molecules comprising more than one macrocyclic guest binding components connected through multipoint linkages.

High Sensitivity Viologen for a Facile and Versatile Sensor of Base and Solvent Polarity in Solution and Solid State in Air Atmosphere

Viologen cations are excellent electro- and photochromic materials. They generally have no response or very low sensitivity to bases. In this paper, three compounds, 1,1'-bis(2-oxo-2-phenylethyl)-4,4'-bipyridinium (viologen) with different substituents, including H (1), Cl (2), and OH (3), were synthesized. All three, especially 1 and 2, have very high sensitivity to base in both solution and solid state in air atmosphere. These viologens are responsive not only to bases but also to solvent polarity. NMR shows 1 became enolic and then a radical, whereas 3 is colored only in the radical form. These results are in agreement with EPR spectra. Crystal structures show that the C-C that links two pyridinium and N-C distances in coplanar pyridinium in the colored (radical) form is clearly longer than that of the pale-yellow form, indicating that the color is due to the viologen radical. Viologens containing an electron-withdrawing phenacetyl group are the most sensitive compounds for fast, naked eye detection of base and solvent polarity.

A [2]rota[2]catenane, constructed from a pillar[5]arene-crown ether fused double-cavity macrocycle: synthesis and structural characterization

A [2]rota[2]catenane, based on a pillar[5]arene-crown ether fused bicycle, was constructed and its structure was determined crystallographically.