CuBDC MOFs can realize the sensitive and accurate colorimetric detection of S²⁻ in water based on two complementary mechanisms. As reactive metal centers in MOFs for S²⁻ responding, Cu²⁺ ions can be taken out from the MOF nodes by S²⁻, inducing the generation of sandy brown CuS. The ratio of blue CuBDC MOFs and sandy brown CuS in an aqueous solution is varied with the amount of S²⁻ added, leading to visual changes in the solution color according to the principle of pigment mixing. The presence of S²⁻ can be indirectly confirmed and quantitatively monitored through the UV-Vis spectrophotometry since the capture of Cu²⁺ by S²⁻ can induce the recovery of uncoordinated carboxyl groups in CuBDC MOFs accompanied by the increase in absorbance intensity. Moreover, CuBDC MOFs can be immobilized in polyvinyl alcohol (PVA) gels to form test strips that can realize S²⁻ detection in water samples with a linear range of 10–100 μM. Additionally, the PVA gels can be dried, accompanied by arbitrary bending deformations for the portable detection of S²⁻ in water. The design strategy based on two complementary mechanisms promises to provide an accurate, sensitive and portable colorimetric assay for S²⁻ detection in water.

中文翻译：

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通过两个互补机制进行S2-检测的精确便携式比色化学传感器

CuBDC MOF可以基于两个互补机制，实现水中S ^2-的灵敏，准确的比色检测。如在反应的MOF金属中心对于s ^2-响应，铜²⁺离子可以从由S中的MOF节点取出^2-，诱导沙褐色CuS的产生。水溶液中蓝色CuBDC MOF和沙棕色CuS的比例随S ^2-的添加量而变化，根据颜料混合原理，溶液颜色会发生视觉变化。由于S ^2-捕获Cu ²⁺，因此可以通过UV-Vis分光光度法间接确认和定量监测S ^{2-的存在。}可以诱导CuBDC MOF中未配位羧基的恢复，并伴随吸收强度的增加。此外，CuBDC MOF可以固定在聚乙烯醇（PVA）凝胶中以形成测试条，从而可以在线性范围为10–100μM的水样中实现S ^2-检测。此外，PVA凝胶可以干燥，并伴有任意弯曲变形，以便便携式检测水中的S ^2-。基于两种互补机制的设计策略有望为水中的S ^2-检测提供准确，灵敏和便携式的比色测定。