Dalapati Rana, Biswas Shyam
Department of Chemistry, Indian Institute of Technology Guwahati, 781039, Assam, India.
Chem Asian J. 2019 Aug 16;14(16):2822-2830. doi: 10.1002/asia.201900546. Epub 2019 Jul 8.
A new Hf -based metal-organic framework with UiO-66 topology was synthesized via a one-step solvothermal method by using 3-methyl-4-phenylthieno[2,3-b]thiophene-2,5-dicarboxylic acid (H MPTDC) as a ligand. The MOF material showed a high stability in a broad pH range (from pH 2 to pH 12) in an aqueous medium. The presence of hydrophobic methyl and phenyl substituents in the carboxylic acid ligand and strong Hf-O bond play crucial roles in its stability. The new MOF material was systematically characterized by various techniques such as XRPD, N sorption, thermogravimetric analyses and FT-IR spectroscopy. The photophysical properties of the MOF material were also examined by steady-state and time-resolved fluorescence studies. It was observed that the blue fluorescence of the MOF material was selectively quenched in the presence of Fe ion in pure aqueous medium. A mechanistic study disclosed that quenching occurs via a strong inner filter effect (IFE) arising from Fe ion in aqueous medium. Interestingly, the fluorescence of the MOF material can be recovered by elimination of the IFE of Fe ion via reduction of Fe ion by ascorbic acid (AA). Based on the fluorescence recovery by AA, a MOF based on-off-on probe was developed for the sensing of Fe ion and AA in aqueous medium. Inspired by this reversible sensing event, we demonstrate basic (NOT, OR, YES, INHIBIT and IMP) and higher integrated logic operations utilizing this fluorescent MOF. This MOF-based logic systems could be potentially used for next-generation logic-gate based analytical applications as well as for the detection and discrimination of targeted molecules in various complex domains.
通过一步溶剂热法，以3-甲基-4-苯基噻吩并[2,3-b]噻吩-2,5-二羧酸（H MPTDC）为配体，合成了一种具有UiO-66拓扑结构的新型铪基金属有机框架材料。该金属有机框架材料在水介质中的宽pH范围（从pH 2到pH 12）内表现出高稳定性。羧酸配体中疏水甲基和苯基取代基的存在以及强铪-氧键在其稳定性中起关键作用。通过各种技术，如X射线粉末衍射（XRPD）、氮吸附、热重分析和傅里叶变换红外光谱（FT-IR），对新型金属有机框架材料进行了系统表征。还通过稳态和时间分辨荧光研究考察了该金属有机框架材料的光物理性质。观察到在纯水溶液介质中，铁离子存在时，该金属有机框架材料的蓝色荧光被选择性猝灭。机理研究表明，猝灭是通过水介质中铁离子产生的强内滤效应（IFE）发生的。有趣的是，通过抗坏血酸（AA）还原铁离子消除铁离子的IFE，可以恢复该金属有机框架材料的荧光。基于AA对荧光的恢复，开发了一种用于检测水介质中铁离子和AA的基于金属有机框架的开-关-开型探针。受这种可逆传感事件的启发，我们展示了利用这种荧光金属有机框架进行基本（非、或、是、抑制和禁止）和更高层次的集成逻辑运算。这种基于金属有机框架的逻辑系统可能潜在地用于下一代基于逻辑门的分析应用，以及用于检测和区分各种复杂领域中的目标分子。
