Hg2+-selective fluoroionophore of p-tert-butylcalix[4]arene-diaza-crown ether having pyrenylacetamide subunits

A new ionophore having two pyrenylacetamide moieties based on the p-tert-butylcalix[4]arene-diaza-crown ether has been prepared and its fluoroionophoric properties were investigated. Bis(pyrenyl) derivative was found to exhibit selective ON–OFF type sensing behavior toward Hg2+ ions over other representative transition and heavy metal ions. The fluorescence quenching efficiency of larger than 20-fold was observed with 100 equiv of Hg2+ ions and the association constant was found to be 4.5 × 104 M−1 in methanol. The ionophore also exhibited a very efficient quenching of excimer fluorescence selectively upon treatment with Hg2+ ions in 50% aqueous methanol solution. The observed Hg2+-selective ON–OFF type fluorescence behavior could be utilized as efficient sensing and switching devices for the design of other supramolecular systems.