Metal-/carboxylate-directed four d10 piperazine-amide-based coordination polymers for the fluorescent detection of nitrophenol and nitroaniline in various water environments

Abstract

Four piperazine-amide-bridged d10 metal-organic coordination polymers, namely, [Zn(L)0.5(1,3-BDC)∙H2O]∙H2O (1), [Cd(L)(1,3-BDC)] (2), [Zn(L)0.5(5-MIP) ∙H2O]·H2O (3), [Cd(L)(5-MIP)] (4) were synthesized by the L ligand [N, N'-bis[(3-pyridin)acrylophenone] piperazine (L)] and two carboxylic acids with Zn/Cd(II) chloride under hydrothermal conditions. The title complexes were characterized by IR spectroscopy, powder X-ray diffraction and single-crystal X-ray diffraction. Complex 1 is a 1D ladder-like structure. Complex 2 is a 3D NaCl type framework. Complexes 3 and 4 are 63 and 44 connected 2D structures. The different structural details of the title complexes directed by caroxylates and the central metals were compared. The complexes 1–4 can be used as excellent fluorescent sensors toward nitrophenol (NOP) and nitroaniline (NA) with a low limit of detection and a high quenching constant, and have good anti-interference and recyclable characteristics. The feasibility of actual sample detection was verified by tap water, river water and wastewater samples. Taking complex 3 as an example, the mechanism was also explored by fluorescence lifetime experiment and the UV-visible absorption spectroscopy. The 3-modified visual detection cloth and test paper were also prepared by solid phase deposition method.