Bifunctional Zn Coordination Polymers for High-Performance Fluorescence Turn-On Detection of l-Glutamate and Adsorption of Malachite Green in Aqueous Medium

Abstract

Two time-induced Zn­(II) coordination polymers (CPs), namely {[Zn­(BIPA-TC)0.5(1,3-bimb)]·0.75DMF} n (1) and {[Zn­(BIPA-TC)0.5(1,3-bimb)]·0.5EtOH·DMF·H2O} n (2) were constructed based on 5,5′-(1,3,6,8-tetraoxybenzo­[3,8]­phenanthroline 2–7-substituent) bis-1,3-benzoic acid (H4BIPA-TC) and zinc salts. The structure analysis showed that 1 is 3D networks with the point symbol {62, 84} {64, 82}2 and 2 is 2D layered structures with the point symbol of {4, 64, 8}2 {42, 64}. Interestingly, the transformation from single crystal 1 to 2 is only due to the prolongation of reaction time, which can be confirmed by structural analysis and powder X-ray diffraction patterns. Meanwhile, the fluorescence sensing properties of 1 and 2 showed that both 1 and 2 had high sensitivity for l-glutamate with limits of detection of 0.10 (1) and 0.13 μM (2). The fluorescence mechanism analysis showed that the fluorescence enhancement of 1 and 2 is attributed to absorbance caused enhancement and photoinduced electron transfer. In addition, 1 and 2 can also be used as recyclable adsorbents to remove malachite green (MG) in aqueous medium. The adsorption isotherms and kinetics of both 1 and 2 follow the Freundlich model and the quasi-second-order kinetic model, respectively. The maximum equilibrium adsorption capacities of 1 and 2 for MG can reach 351.06 and 250.45 mg/g, respectively. The excellent adsorption properties of 1/2 for MG can be attributed to π–π interaction, hydrogen bonding, and electrostatic interaction between 1/2 and the MG molecule. Therefore, 1 and 2 have potential application prospects in fluorescence recognition and adsorption.

Lignin-Modified Metal–Organic Frameworks for Fluorescence Detection of Cr6+ and Adsorption of Congo Red

“…Besides heavy metal pollution, organic dyes also cause serious environmental pollution. For its simplicity and low cost, adsorption represents the most effective method of treating wastewater . MOFs exhibit excellent adsorption performance due to their characteristics.…”

“…For its simplicity and low cost, adsorption represents the most effective method of treating wastewater. 20 MOFs exhibit excellent adsorption performance due to their characteristics. However, they still have disadvantages such as monofunctionality and low efficiency.…”