Three boric acid-functionalized two-dimensional metal-organic frameworks (2D MOFs) nanosheets, namely, 2D Tb-bop, Eu-bop and Tb/Eu-bop nanosheets, were synthesized through simple mixing of a reaction mixture of Tb/Eu salts and 5-boronoisophthalic acid (5-bop) in the presence of triethylamine (TEA) at room temperature. The product had excellent mercury ions (Hg²⁺) sensing properties. The highly exposed boric acid sites on the surface of the 2D structure can undergo a transmetalation reaction with Hg²⁺ to promote the energy transfer between the ligand and the lanthanide ions, thus enhancing the emission of 2D Tb-bop and Eu-bop nanosheets and resulting in high sensitivity for Hg²⁺ sensing. Significantly, the Hg²⁺-induced transmetalation reaction in 2D binary Tb/Eu-bop nanosheets also enhanced the energy transfer between Tb³⁺ and Eu³⁺ nodes, showing a ratiometric fluorescence response toward Hg²⁺, and further improving the sensitivity. This novel 2D ratiometric fluorescence probe showed good linearity from 0.1 to 40 μM for Hg²⁺ with a detection limit of 4.83 nM. This work not only provided a simple and efficient strategy for synthesizing 2D MOFs but also yielded new insights for designing fluorescence probes with excellent sensing properties.

通过简单混合 Tb/Eu 盐的反应混合物，合成了三种硼酸功能化的二维金属有机骨架 (2D MOF) 纳米片，即 2D Tb-bop、Eu-bop 和 Tb/Eu-bop 纳米片和 5-硼代间苯二甲酸 (5-bop) 在三乙胺 (TEA) 存在下，室温。该产品具有优异的汞离子 (Hg ²⁺ ) 传感特性。二维结构表面高度暴露的硼酸位点可以与 Hg ²⁺发生金属转移反应，促进配体和镧系元素之间的能量转移，从而增强二维 Tb-bop 和 Eu-bop 纳米片的发射和导致 Hg ²⁺感应的高灵敏度。值得注意的是，Hg ²⁺二维二元Tb/Eu-bop 纳米片中的-诱导的金属转移反应也增强了Tb ³⁺和Eu ³⁺节点之间的能量转移，显示出对Hg ²⁺的比率荧光响应，并进一步提高了灵敏度。这种新型二维比率荧光探针对 Hg ²⁺在 0.1 至 40 μM 范围内显示出良好的线性，检测限为 4.83 nM。这项工作不仅为合成二维 MOF 提供了一种简单有效的策略，而且还为设计具有优异传感特性的荧光探针提供了新的见解。