Metallacyclophanes of 1,6-bis(diphenylphosphino)pyrene: excimeric emission and effect of oxygen on stability of the rings.

1,6-Bis(diphenylphosphino)pyrene (L) was reacted with Ag(I) and Cu(I) ions to form metallacyclophanes [Ag(2)L(2)(OTf)(2)] (1), [Cu(2)L(2)(MeCN)(4)](2+) (2), and [Cu(2)L(2)I(2)] (3) which consisted of two cofacial pyrenyl rings. 1 and 2 exhibited intramolecular excimeric emissions which along with the UV-vis absorption were invoked in understanding the solution dynamics of the metallocyclophanes. The metallacyclophanes were stable toward ring-opening dissociation at concentration as low as 10(-7) M. However, air oxidation of the dangling PPh(2) groups arising from metal-ligand bond dissociation drove the equilibrium toward dissociation and produced the oxidized phosphine 1,6-bis(diphenylphosphine oxide)pyrene.