Yin Xue-Bo, Sun Yi-Qing, Yu Hua, Cheng Yue, Wen Cong
Shanghai Frontiers Science Research Center for Druggability of Cardiovascular Noncoding RNA and College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai 201620, China.
Tianjin Key Laboratory of Biosensing and Molecular Recognition, College of Chemistry, Nankai University, Tianjin 300071, China.
Anal Chem. 2022 Mar 29;94(12):4938-4947. doi: 10.1021/acs.analchem.1c02949. Epub 2022 Mar 14.
Herein, we revealed the factors that affect the emission in mixed-ligand metal-organic frameworks (MOFs) with the combination of terephthalic acid (BDC), 2-aminoterephthalic acid (BDC-NH), and 2,5-dihydroxylterephthalic acid [BDC-(OH)] as models. The -NH and -(OH) groups change the π-conjugation and luminescence behaviors than BDC, so the ligands show different optical behaviors. The Zn ion with a 3d full electronic structure shows little effect on the emission of the ligand and is selected as the metal node. We found that the emission of BDC is weak and incompatible to that of BDC-NH, so only the emission of BDC-NH was observed in the BDC/BDC-NH-MOF. Crosstalk occurs between the emissions from BDC and BDC-(OH) for the single emission from BDC/BDC-(OH)-MOFs, even different ratios are selected. The MOFs prepared with BDC-NH and BDC-(OH) show dual emission at 450 and 550 nm, while the relative intensity was easily tuned with the ligand ratio and excitation wavelength. Thus, abundant optical behaviors and extensive applications were realized, including but not limited to (1) dual emission from single MOFs, (2) tunable color from blue to yellow with the excitation from 290 to 370 nm for information encryption and decryption, (3) white emission obtained under an excitation of 330 nm, and (4) response of -NH groups to HCHO and Fe ions for ratiometric fluorescence sensing and visual detection. This work revealed the factors that affect the emission in mixed-ligand MOFs, studied their optical behaviors, and realized different applications with single MOFs.
在此，我们以对苯二甲酸（BDC）、2-氨基对苯二甲酸（BDC-NH）和2,5-二羟基对苯二甲酸[BDC-(OH)]组合而成的混合配体金属有机框架（MOF）为模型，揭示了影响其发光的因素。-NH和-(OH)基团相比于BDC改变了π共轭和发光行为，因此这些配体呈现出不同的光学行为。具有3d全电子结构的锌离子对配体的发光影响较小，故而被选为金属节点。我们发现BDC的发光较弱且与BDC-NH的发光不兼容，所以在BDC/BDC-NH-MOF中仅观察到BDC-NH的发光。对于BDC/BDC-(OH)-MOF的单一发光，BDC和BDC-(OH)的发光之间会发生串扰，即便选择了不同的比例也是如此。用BDC-NH和BDC-(OH)制备的MOF在450和550 nm处呈现双发射，而相对强度可通过配体比例和激发波长轻松调节。由此，实现了丰富的光学行为和广泛的应用，包括但不限于：（1）单一MOF的双发射；（2）在290至370 nm激发下从蓝色到黄色的可调颜色用于信息加密和解密；（3）在330 nm激发下获得白色发射；（4）-NH基团对HCHO和铁离子的响应用于比率荧光传感和视觉检测。这项工作揭示了影响混合配体MOF发光的因素，研究了它们的光学行为，并利用单一MOF实现了不同的应用。
