A multi-responsive regenerable water-stable two-dimensional cadmium (II) fluorescent probe for highly selective, sensitive and real-time sensing of nitrofurazone and cupric ion

Abstract

In recent years, luminescent metal organic frameworks (MOFs) materials have attracted widespread attention in the field of fluorescence sensing. In this work, a novel two-dimensional (2D) micro-porous water-stable coordination material {[Cd(μ3-HL)2(H2O)]⋅2.3H2O}n (1, H2L = 4,4′-(1H-1,2,4-triazol-1-yl)methylene-bis (benzonic acid)) has been prepared through the powerful solvo-thermal approaches, which has been characterized by single crystal X-ray diffraction analysis, PXRD, scanning electron microscope (SEM) and Transmission electron microscopy (TEM) characterization. Crystal structural analysis also reveals the partly de-pronated μ3-coordinated HL− adopted tri-dentate bridging mode, which link these cadmium (II) centers, eventually forming the two-dimensional (2D) micro-porous coordination framework of 1. 1D channel with diemsionality of 12.216(3) Å × 8.578(11) Å that can be observed along the crystallographic a axis. It is noted that 1 has good chemical stability and maintains structural integrity not only in various solvents, but also in aqueous solutions with pH values varying from 2 to 12. Additionally, 1 has the unique advantages such as high detection sensitivity for Nitrofurazone (NZF) and Cupric ion (Cu2+) (Ksv quenching efficiency for NZF: 5.0 × 106 M−1 and Cu2+ 5.6 × 106 M−1) and low detection limits (NZF: 1.21 μM and Cu2+: 1.07 μM), good selectivity and good real-time performance. The result of photo-luminescent experiment demonstrates that 1 can realize high sensitivity and real-time chemical discrimination of antibiotics and ions, and has good reusability. To the best of our knowledge, 1 is the first example of the ultra-stable 2D cadmium (II) micro-porous coordination material as a renewable chemical sensor for NZF and Cu2+.