Stepwise Assembly of Turn‐on Fluorescence Sensors in Multicomponent Metal–Organic Frameworks for in Vitro Cyanide Detection

Abstract

The controlled synthesis of multicomponent metal–organic frameworks (MOFs) allows for the precise placement of multiple cooperative functional groups within a framework, leading to emergent synergistic effects. Herein, we demonstrate that turn‐on fluorescence sensors can be assembled by combining a fluorophore and a recognition moiety within a complex cavity of a multicomponent MOF. An anthracene‐based fluorescent linker and a hemicyanine‐containing CN−‐responsive linker were sequentially installed into the lattice of PCN‐700. The selective binding of CN− to hemicyanine inhibited the energy transfer between the two moieties, resulting in a fluorescence turn‐on effect. Taking advantage of the high tunability of the MOF platform, the ratio between anthracene and the hemicyanine moiety could be fine‐tuned in order to maximize the sensitivity of the overall framework. The optimized MOF‐sensor had a CN−‐detection limit of 0.05 μm, which is much lower than traditional CN− fluorescent sensors (about 0.2 μm).

Homochiral MOF as Chiroptical Sensor for Determination of Absolute Configuration and Enantiomeric Ratio of Chiral Tryptophan

“…[ 58 ] Structural diversity and tenability, specific electronic, and photoluminescent properties, as well as good water stabilities make MOFs suitable materials for fluorescent sensing. [ 58–68 ] Several enantioselective fluorescent chiral MOFs have shown ability to recognize amino acids; [ 67,68 ] however, none of the existing fluorescent methods enable quantitative enantioselective sensing of chiral amino acids. A small number of studies reported chiral MOF sensors exhibiting initial CD signals, which could be applied for the recognition of specific enantiomers of chiral compounds by analyzing the difference in CD signal intensities.…”

A Comprehensive Overview on Advanced Sensing Applications of Functional Metal Organic Frameworks (MOFs)

“…The CN À will selectively bound to hemicyanine, which will lead to the inhibition of transfer of energy among the two moieties, and that results in a turn-on effect of fluorescence. [54] Khan et al solvothermally synthesised a highly stable, luminescent and 3D Zn-MOF having a [Zn 4 (μ 3 -OH) 2 ] 6 + core using a rare benz-bis(imidazole)-based ligand (BBI4PY), without utilising any external base, as the characteristic basicity of BBI4PY filled the need. The electron-rich nature and exceptional fluorescence of Zn-MOF have been further used for the specific detection of Reproduced with permission from Ref.…”

“…Effective transfer of energy among the two linkers causes fluorescence quenching. The CN − will selectively bound to hemicyanine, which will lead to the inhibition of transfer of energy among the two moieties, and that results in a turn‐on effect of fluorescence [54] . Khan et al.…”

The Decisive Role of Spin States and Spin Coupling in Dictating Selective O2 Adsorption in Chromium(II) Metal–Organic Frameworks**

“…Owing to their fascinating properties such as structural and functional diversity, tunable pore size, and enormous surface area, metal-organic frameworks (MOFs), have tremendous applications in gas storage, [1][2][3][4] molecular separation, [5][6][7][8][9][10] sensors, [11][12][13][14][15] and catalysis. [16][17][18][19][20][21][22] Though zeolites, covalent organic frameworks, and complex hydrides are available for gas separation applications, [23,24] MOF-based separative systems have attracted wide attention due to their high selectivity as a result of their extensive chemical diversity and porous nature in comparison to other classical adsorbate systems.…”