Internal charge transfer based Hg-sensing Azocalix[4]arene Mono anthracenate derivatives

• In this study, azocalix[4]arene mono anthracenate derivatives were synthesized.
• Azocalix[4]arene derivatives have showed a good selectivity toward Hg2+ and Hg+ ions.
• These compounds could be applied for the selective extraction of Hg2+ ions from environmental waters.
• The sensor properties of anthracenate derivatives were investigated using spectroscopic techniques.

The present study describes the synthesis and characterization of mono anthracenate derivatives of azocalix[4]arene. The azocalix[4]arene anthracenates (6a-e) were performed by the esterification of the 2-bromoethyl antracenate (5) and azocalix[4]arene (3a-e) in dry acetonitrile. The prepared compounds were characterized by using the 1H NMR, IR, DTA/DTG techniques and elemental analysis. They were examined to observe their capabilities of recognizing various cations including K+, Ag+, Hg+, Hg2+, Co2+, Ni2+, Cu2+, Pb2+, Cr3+ and Al3+ with UV–vis spectroscopy. It was found that the extraction mechanisms of metal cations are highly effective with the azo (NN) groups and adjacent anthracenate electron density. The synthesized azocalix[4]arene ligands (6a-e) were obtained fluorescence emission with Na+, K+, Sr2+, Ag+, Hg2+, Co2+, Cu2+, Pb2+, Ba2+, Ca2+ and Mg2+ metal ions at a wavelength of 367 nm.

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