A stable zinc(II)-organic framework as rapid and multi-responsive luminescent sensor for metal ions in water

Abstract

A very stable Zn^II-organic framework, {[Zn(Titpe)_0.5(bpodc)]·(H₂O)₃}_n (1, Titpe = 1,1,2,2-tetrakis(4-(imidazol-1-yl)phenyl)ethane, bpodc = benzophenone-4,4-dicarboxylic acid), has been synthesized under hydrothermal conditions. Single-crystal X-ray analysis reveals that 1 crystallizes in the monoclinic system and P₂1/c space group. Its overall structure is a 3-D stacking with a porosity of 20.95% and a 4-c type topological network; it shows good stability in many solvents. Studies of the solution-phase detection of metal cations show that Fe³⁺ and Cr³⁺ ions can quench luminescent emission of 1. Fluorescence titration experiments show that 1 is more selective to Fe³⁺ (K_sv = 2.8 × 10⁴ M⁻¹) than Cr³⁺ (K_sv = 1.4 × 10³ M⁻¹). The solution-phase detection for anions by 1 also show high selectivity and sensitivity for Cr₂O₇^2– anions (K_sv = 1.2 × 10⁴ M⁻¹). With water stability and strong blue luminescence, 1 can potentially apply as a reversible multi-responsive luminescence sensor for Fe³⁺, Cr³⁺, and Cr₂O₇^2– in aqueous solutions.

Graphical Abstract

Keywords:

• Hydrothermal reaction
• metal-organic frameworks
• luminescent
• sensor
• tetraphenyl ethylene

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by National Natural Science Foundation of China (Grant No. 21671084), a start-up grant from Jiangsu University of Science and Technology, and Jiangsu Innovation Program for Graduate Student (No. KYZZ15-0300) and Innovation Program for Graduate Student from Jiangsu University of Science and Technology, P. R. of China.