A cooperative effect in sodium cation complexation by a macrocyclic bis (9,10) anthraceno-crown ether in the ground state and in the excited state

✍ Scribed by Damien Marquis; Jean-Pierre Desvergne

• Book ID: 103033208
• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 520 KB
• Volume: 230
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(94)01134-6

✦ Synopsis

The bisanthraceno-crown ether displays a dual fluorescence consisting of a 'monomer' and excimer emission. Its structural flexibility is demonstrated by the temperature dependence of the total fluorescence emission. The compound forms a 1: 1 complex with K+ in methanol (j?z IO M-' at +25"(Z), whereas a 1:2 complex is observed with Na+ in both methanol and acetonitrile with a positive cooperative effect. At + 25'C in acetonitrile the overall binding constant p deduced from UV measurements @=3.7X lo4 M-*) is lower than that obtained from fluorescence data (fiz lo5 M-*), indicating an enhancement of the complexation ability in the excited singlet state.

' KClO,, and CH,COONa were not found soluble enough in CHsOH and CHsCN; CH,COOK was unsufftciently soluble in CHsCN for our requirements.

For similar reasons of solubility, experiments in the presence of salts could not be carried out in methylcyclohexane.