Double template effect in [4 + 4] Schiff base macrocycle formation; an ESI-MS study.

The mechanism of self-assembly of a polynuclear complex of a [4 + 4] Schiff base iminomethylenediphenolate macrocycle [BaCu(4)(4 + 4)](2+) via a non-macrocyclic dialdehyde intermediate has been followed using ESI-MS of the reaction solutions. Both assembly of the intermediate and Schiff-base condensation with diamine give rise to single products; formation of the intermediate metallacycle is fast but Schiff-base condensation is much slower. Both intermediate complex and macrocyclic product have been structurally characterised.