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The treatment of C-iso-butylpyrogallarene (PgC4) or C-ethylpyrogallarene (PgC2) with ferrocene (FcH) in a 2:1 molar ratio under different reaction conditions afforded the host–guest compounds FcH@(PgC4)2·CH3OH·3H2O (1) and FcH@(PgC2)2·3EtOH·2H2O (2), respectively. Complexes 1 and 2 are both pyrogallarene dimers providing capsule-type voids. Single crystal X-ray crystallography was used to investigate the role of hydrogen bonding networks in the assembly of the two host–guest systems. [ABSTRACT FROM AUTHOR]

1,8-Dioxyanthracene-based bisarylene crown ethers, composed of ethylene glycol chains and aromatic moieties, have been synthesized. Complexation studies revealed that these crown ethers could form 1:1 complexes with methyl viologen dication ( N, N′-dimethyl-4,4′-bipyridinium dication; MV2+) in a mixed solvent of CDCl3 and CD3CN (1:1 v/v) with association constants in a range of (1.2 ± 0.1) × 103 M-1 to (1.6 ± 0.2) × 104 M-1. The structure of the complex and the strength of the π-donor/π-acceptor interactions between the 1,8-dioxyanthracene planes and the pyridinium rings of MV2+ are highly dependent on the length of the polyether chains of the ethers. Structural analysis showed that the tetraethylene glycol-derived bis-1,8-dioxyanthracene-based crown ether 9 forms a U-shaped host-guest complex with MV2+ by inserting the coplanar pyridinium rings of MV2+ between the two parallel oriented 1,8-dioxyanthracene units of 9, which is driven predominantly by π-donor/π-acceptor interactions. The pentaethylene glycol-derived bis-1,8-dioxyanthracene-based crown ether 10, however, adopts a crescent-shaped conformation in complex 10⊃MV2+ with the MV2+ guest being encapsulated by the polyether chains, propelled mainly by the hydrogen-bonding interactions between the hydrogen atoms of MV2+ and the oxygen atoms of the polyether chains of 10. Similarly, the hexaethylene glycol-derived bis-1,8-dioxyanthracene-based crown ether 11 forms a complex with MV2+. However, only weak π-donor/π-acceptor interactions between the aromatic groups of the mixed bisarylene crown ethers 12 and 13, and MV2+ were observed, and construction of tetracationic cyclophane [CBPQT4+] and crown ether 13 based [2]catenane 15 was achieved through supramolecular interactions between the [CBPQT4+] ring and naphtho unit in the crown ether. [ABSTRACT FROM AUTHOR]