Two bis-color excited luminescent sensors of two-dimensional Cd(II)-MOFs bearing mixed ligands for detection of ions and pesticides in aqueous solutions
Zhao-Di Zhou, Shiqi Li, Wenping Wang, Dongge Ma, Hanqing Zhao, Lin-Fang Jia, Yi Jia, Baoyi Yu
Abstract
Two metal organic framework were constructed from mix-ligands and Cd(II) ions: [Cd(NIP) 2 (DTP)(H 2 O) 2 ]·H 2 O ( Cd-1 ) (H 2 NIP = 5-nitro iso phthalic acid and DTP = 3,5-di(1,2,4-triazol-1-yl)pyridine) and [Cd(NTP) 2 (DTP)(Et)(H 2 O) 2 ]·(H 2 O) 0.5 ( Cd-2 ) (H 2 NTP = nitroterephthalic acid and Et = ethanol). The MOFs were determined and confirmed by single-crystal X-ray diffraction (XRD), elemental analysis, infrared spectroscopy (IR), powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA) and fluorescence analysis. The fluorescence sensing application of the sensors demonstrated the two sensors were extra sensitive and selective towards Fe 3+ and Cr 2 O 7 2- during the sensing of the ions under both 250 and 290 nm excitation wavelength; were extra effective and sensitive towards NTP (EX 250 nm) and MMT (EX 290 nm) in sensing of the pesticides for the two sensors. Mechanism investigation revealed both inner filter effect (IFE) and fluorescence resonance energy transfer (FRET) mechanisms played major roles during the sensing process of Fe 3+ , Cr 2 O 7 2− , NTP and MMT.