N-(4-amino-7-nitrobenzaoxa-1,3-diazole)-substituted aza crown ethers: complexation with alkali, alkaline earth metal ions and ammonium.

Three novel aza-crown ether derivatives incorporating 4-amino-7-nitrobenzaoxa-1,3-diazole (NBD) chromophore were synthesized and their structure confirmed by (1)H-NMR, IR and elemental analysis. The influence of the solvent polarity and protonation on the photophysical properties of NBD-15-crown-5 was studied by UV/Vis and fluorescence methods. The influence of the investigated cations on the absorption spectra of the ligands was negligible, however emission was strongly affected.