A highly sensitive colorimetric and fluorogenic detection of copper(II) ion based on new picolylamine-armed calix[4]arene

In this study, two- and tetra-functionalized with bis(2-picolyl)amine calix[4]arene derivatives (2-PACX and 4-PACX) were synthesized, and their structures were confirmed by 1H NMR, 13C NMR, FT-IR and TOF-MS spectroscopies. Cation sensing behaviors of them were investigated towards several cations such as Fe2+, Al3+, Cr3+, Hg2+, Mn2+, Cu2+, Co2+, Cd2+, Zn2+, Ni2+, Ag+, Mg2+, Ca2+, Li+, Na+, and K+. The results showed that 4-PACX was an effective colorimetric sensor against Cu2+ ions. The binding constant (K) value of the complexation between 4-PACX and Cu2+ ion was calculated as 4.62x108 M−2 and the detection limit value of the sensor as 5.1 μM. Moreover, the fluorescence studies demonstrated that 4-PACX has great fluorogenic sensor potential with 0.16 μM of detection limit. As a result, good yield, large coupling constant with Cu2+ ion (Ka = 13.972), applicability to aqueous samples, low detection limit, and high sensitivity were some of the advantages of the obtained sensor.