A rigid linear bis-bidentate quaterpyridine undergoes metal directed self-assembly with iron(II) salts yielding M₄L₆ host–guest complexes; selective anion binding for PF₆ ⁻ over BF₄ ⁻ is observed.

A comparative investigation of the interaction of three dibenzo-substituted, mixed oxygen–nitrogen donor macrocycles with cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II), silver(I) and lead(II) has been carried out. The thermodynamic stabilities of the respective complexes in 95% methanol (I = 0.1; Et₄NClO₄, 25 °C) have been determined. All ligands form 1 ∶ 1 (metal ∶ ligand) species with the above metal ions. The results are compared with those obtained previously for related mixed-donor (cyclic) systems. Single crystal structures of six metal complexes of these 20-membered ring ligands have been determined by X-ray diffraction. All of the macrocyclic donor sites participate in binding to the metal ion in the copper(II) and cadmium(II) complexes. The copper complex is six-coordinate, while the cadmium complex is eight-coordinate with the addition of a bidentate nitrato ion. A tri-nuclear complex is formed on complexation with silver(I) in which two silver-containing macrocycles are linked by a bridging two-coordinate silver ion. The metal atoms in each of the cobalt(II), nickel(II) and zinc(II) complexes are six-coordinate, however, they are bound to the macrocycle only at the three secondary amine nitrogen sites. The coordination sphere is completed by two nitrato counterions in the zinc(II) complex, and by a nitrato ion and a methanol molecule in each of the cobalt(II) and nickel(II) complexes.

A unique example of incorporation of a tetrahalometalate anion in a small supramolecular cage is described in which a tetrahedral cage of type [Fe₄L₆]⁸⁺ selectively encapsulates a [Fe^IIICl₄]⁻ anion over a [Fe^IICl₄]^{2 −} anion in its central cavity to yield a discrete, mixed oxidation state, Fe(II)/Fe(III) supramolecular assembly. This unusual outcome has been achieved using two alternative synthetic strategies.

A large 4,4′-biphenylene-spaced bis-β-diketone ligand is demonstrated to form a neutral tetrahedral M₄L₆ metal–organic cage that encloses a volume of 844 ų and encapsulates four tetrahydrofuran guest molecules.