Key Laboratory of Macromolecular Science of Shaanxi Province, Shaanxi Key Laboratory for Advanced Energy Devices, Shaanxi Engineering Laboratory for Advanced Energy Technology, School of Chemistry & Chemical Engineering, Shaanxi Normal University, Xi'an 710062, Shaanxi Province, P. R. China.
Dalton Trans. 2021 Jan 7;50(1):143-150. doi: 10.1039/d0dt03626a. Epub 2020 Dec 7.
The detection of pH and water is of significance in natural and production processes. The ionothermal reactions of 4,4'-oxybisbenzoic acid (HOBA) with Eu and Tb produced [M(OBA)(HO)Cl] (M = Eu (1) and Tb (2)) and heteronuclear [EuTb(OBA)(HO)Cl] (3). 3 emits the combined characteristic transitions of Eu and Tb. Its energy transition processes can be disturbed by pH and water. The emission colors of 3 follow pH changes. It emits blue light when pH = 1-2, in which OBA turns into HOBA based on the acid-base equilibrium. When pH = 3-11, the emission colors change from green to orange and I/I exhibits a linearity of I/I = 6.7482-0.5971·pH; the emissions are quenched at pH = 12-13, due to OH destroying the delocalized conjugated system of 3. 3 shows a fluorescence response to water with a linearity of I/I = 0.30353 + 0.15042·V% within 0-0.8% V%. The green (G) and red (R) color intensities of the paper-based MOF sensor of 3 reveal a trinomial fitting equation of G/R = 4.16334 - 1.23014·pH + 0.14036·pH- 0.00551·pH when pH = 3-11. 3 can be used as a ratiometric fluorescent sensor to detect pH and water and the paper-based MOF sensor can also be used in on-site pH detection.
pH 值和水的检测在自然和生产过程中都具有重要意义。4,4'-氧双苯甲酸（HOBA）与 Eu 和 Tb 的离子热反应生成了[M（OBA）（HO）Cl]（M=Eu（1）和 Tb（2））和杂核[EuTb（OBA）（HO）Cl]（3）。3 发出 Eu 和 Tb 的特征组合跃迁。其能量跃迁过程可以被 pH 值和水干扰。3 的发射颜色随 pH 值变化而变化。当 pH=1-2 时，它发出蓝光，此时 OBA 根据酸碱平衡转化为 HOBA。当 pH=3-11 时，发射颜色从绿色变为橙色，I/I 呈现出 I/I=6.7482-0.5971·pH 的线性关系；当 pH=12-13 时，由于 OH 破坏了 3 的离域共轭体系，发射被猝灭。3 对水具有荧光响应，在 0-0.8% V%范围内的线性关系为 I/I=0.30353+0.15042·V%。基于 3 的纸基 MOF 传感器的绿色（G）和红色（R）颜色强度呈现出 G/R=4.16334-1.23014·pH+0.14036·pH-0.00551·pH 的三元拟合方程，当 pH=3-11 时。3 可作为比率荧光传感器用于检测 pH 值和水，纸基 MOF 传感器也可用于现场 pH 值检测。
