Phosphorescence of Cyclophanes and Cyclophane/Ag+ Complexes

Abstract

Phosphorescence in ethanol at 77 K of the cyclophanes 1-14 has been investigated. It is shown that the phosphorescence characteristics are strongly determined by transannular interaction between the benzene rings. This interaction does not occur in cyclophanes 9 and 14. Phosphorescence quenching by silver Perchlorate of paracyclophanes and benzene derivatives 15-20 is due to the formation of arene/Ag+ ground state complexes. From the quenching data it is concluded that the complexes of paracyclophanes with Ag+ ions are more stable than the corresponding complexes of the benzene derivatives by approximately two orders of magnitude. Various factors are discussed regarding this marked difference in complex stability.