Response of a benzoxainone derivative linked to monoaza-15-crown-5 with divalent heavy metals

The response of a monoaza-15-crown-5 with an optically active aminobenzoxazinone moiety to divalent cations was investigated. The crown ether was found to undergo a strong emission shift to the blue when complexed with specific divalent metals that have ionic diameters between 1.9-2.4 Angstrom. Consequently the photoactive macrocycle is responsive to Mg2+, Ca2+, Ba2+, Sr2+, Cd2+, and particularly responsive to Hg2+ and Pb2+. Macrocycle emission spectra are shown to be a function of cation concentration. Alkaline metal cations and smaller transition metals ions such as Ni2+, Co2+ and Zn2+ do not cause significant changes in the macrocycle emission spectra. Emission, absorption, and complex stability constants are determined. Mechanisms of cation selectivity and spectral emission shifts are discussed. Challenges involving immobilization of the macrocycle while preserving its spectral response to cations are explored. (C) 1998 Elsevier Science B.V. All rights reserved.