substituents at C(6) on irradiation are believed to undergo ring opening stereospecifically affording a mixture of two configurationally isomeric diene-ketenes (and descendents thereof)- Exceptions are generally found for those dienones with one C and one O substituent or even with two C substituents, if one of them carries a polar group at a site able to interact through space with the ring CO group. In these
types of bis(crownether) dyes bearing one or two azophenol units were synthesized, which may be expected to show different cation-complexing properties from the corresponding monocyclic crownether dyes. The extraction of alkali and alkaline-earth metal salts with the crownether dyes suggested that some cooperative action of the two adjacent crownether moieties of the bis(crownether)s occurs on