Two-dimensional luminescence metal organic framework nanosheets (LMOF) named NH₂-CuMOFs were synthesized using Cu (II) nodes coordinated with negatively charged 2-aminoterephthalic acid (NH₂-BDC) via a bottom-up strategy, which were first used as the fluorescent probes for the detection of chromium Cr (VI). The nanosheets possess stable fluorescence with the maximum emission wavelength of 436 nm at excitation of 338 nm that can be effectively quenched by hexavalent chromium Cr (VI). The NH₂-CuMOFs nanosheets show superior advantage over the linker of NH₂-BDC for the excellent selectivity to Cr (Ⅵ) without the interferences of other metal ions. The mechanism investigation suggested that the sensitive detection of Cr (VI) was attributed to the chemical oxidation-reduction (redox) reaction and internal filtration effect (IFE) between Cr (VI) and NH₂-CuMOFs nanosheets. Based on this mechanism, the quantitation of Cr (VI) was realized in the linear range of 0.1–20 μM with a detection limit of 18 nM. Moreover, the detection of Cr (VI) in real samples was also conducted with good recovery. This work provides an optical sensing nanoplatform for heavy metal ions based on two-dimensional LMOFs via a novel mechanism integrating chemical redox reaction and IFE, which may promise broad application prospect for two-dimensional luminescence nanosheets.

使用与带负电荷的 2-氨基对苯二甲酸 (NH ₂ -BDC)配位的 Cu (II) 节点通过自下而上的策略合成了名为 NH ₂ -CuMOFs的二维发光金属有机骨架纳米片 (LMOF)，该纳米片首先用作用于检测铬 Cr (VI) 的荧光探针。纳米片具有稳定的荧光，最大发射波长为 436 nm，激发波长为 338 nm，可被六价铬 (VI) 有效淬灭。NH ₂ -CuMOFs 纳米片显示出优于 NH ₂连接体的优势-BDC 对 Cr (Ⅵ) 具有出色的选择性而不受其他金属离子的干扰。机理研究表明，Cr (VI) 的灵敏检测归因于Cr (VI) 和NH ₂ -CuMOFs 纳米片之间的化学氧化还原（氧化还原）反应和内部过滤效应（IFE）。基于这种机制，在 0.1-20 μM 的线性范围内实现了 Cr (VI) 的定量，检测限为 18 nM。此外，在实际样品中也进行了 Cr (VI) 的检测，回收率良好。这项工作通过结合化学氧化还原反应和 IFE 的新机制为基于二维 LMOF 的重金属离子光学传感纳米平台提供了一个光学传感纳米平台，有望为二维发光纳米片提供广阔的应用前景。