Novel Anthracene-Appended Calix[4]triazacrown-5 as an Effective Fluorescence Probe for Co2+ and Hazardous Cr2O7 2- Ions.

Abstract

A new calix[4]triazacrown-5-derived fluorescence chemosensor (AntUr-AzClx) at cone conformation was synthesized to afford an effective fluorescent probe, which enables an enhancement in the fluorescence intensity specifically in the presence of Co2+ metal ions as well as a turnoff response for hazardous dichromate anions. 1H-NMR, 13C-NMR, ESI-MS, and elemental analysis techniques were used to characterize the structure of the anthracene-appended calix[4]triazacrown-5 (AntUr-AzClx). The metal ion-binding ability of AntUr-AzClx was evaluated against Co2+, Ba2+, Ni2+, Pb2+, and Zn2+ ions. On the basis of various metal ion recognition phenomena, AntUr-AzClx exhibited outstanding selectivity for only the Co2+ ion among other metal ions. Also, the calix[4]triazacrown-5-derived fluorescence chemosensor showed high sensitivity towards the Co2+ ion with a very low limit of detection (LOD) 0.142 μmol L-1. In addition, anion binding abilities of AntUr-AzClx against various anions such Cr2O7 2-, HCO3 -, CO3 2-, NO3 -, SO3 2-, SO4 2-, N3 -, F-, and I- demonstrated that AntUr-AzClx enables selective and highly sensitive detection of the Cr2O7 2- anion with an excellent LOD of 4.182 nmol L-1 in DMF/PBS (1/1, v/v; pH: 7.05). Furthermore, the calix[4]triazacrown-5-derived fluorescence chemosensor displayed a significant sensing behavior to detect the presence of dichromate anions even in real samples.