A new Hg ~(2+) fluorescent sensors based on 1,3-alternate thiacalix[4]arene (L) and the complex of [L+Hg ~(2+)] as turn-on sensor for cysteine

摘要

A new thiacalix[4]arene derivative in a 1,3-alternate conformation bearing four naphthalene groups through crown-3 chains has been synthesized, which exhibits high selectivity toward Hg ~(2+) by forming a 1:2 complex, among other metal ions (Na ~+, K ~+, Mg ~(2+), Ba ~(2+), Ca ~(2+), Sr ~(2+), Cs ~+, Mn ~(2+), Fe ~(2+), Cd ~(2+), Co ~(2+), Ni ~(2+), Cu ~(2+), Li ~+, and Zn ~(2+)) with a low detection limit (3.30×10 ~(-7) M). The metal ion-binding properties were studied by fluorescence, AFM, and ~1H NMR spectroscopy. The in situ prepared [Hg ~(2+)+L] complex shows well recognition ability for cysteine with a low detection limit (2.23×10 -7 M) through fluorescence turning on. The mechanism of fluorescence turning on is the host L releasing from [L+Hg ~(2+)] for [Cys+Hg ~(2+)] complex formed. Thus the paper reports secondary-sensor design: Hg ~(2+) as a first sensor for [L+Hg ~(2+)] form, cysteine as a second sensor for Hg ~(2+) releasing from the [L+Hg ~(2+)] complex after cysteine adding in.