Ultra-Stable Metal–Organic Framework with Concurrent High Proton Conductivity and Fluorescence Sensing for Nitrobenzene

Abstract

Luminescent metal−organic frameworks (MOFs) coupled with proton conduction offer wide applications in clean energy and luminescence sensors. High stability and remarkable proton conductivity and sensing are requisites for practical applications. Specifically, high thermal and chemical stabilities under harsh conditions are important but challenging to achieve. Herein, an ultra-stable Cu(I)-tetrazolate MOF, NaCu 3 (mtz) 4 (1, mtz = 5-methyltetrazolate), was prepared. It possesses a 3D framework with 1D channels and exhibits outstanding thermal and chemical stabilities under various conditions, including water, organic solvents, and acidic and basic solutions of wide pH range. The compound exhibits strong green emissions, which can be ascribed to metal-toligand charge transfer, and selective fluorescence sensing for pollutant nitrobenzene. Moreover, compound 1 presents a high proton conductivity of over 10 −2 S cm −1 at 70 °C and 100% relative humidity. In 1, abundant uncoordinated nitrogen atoms on the pore walls act as H-bonding acceptors to achieve its high proton conductivity under waterassisted conditions. The compound is an unprecedented water-dependent proton conductor of the tetrazole-based MOF, providing a new avenue to design robust and high-performance proton-conductive MOFs.

Construction of Water-Stable Rare-Earth Organic Frameworks with Ambient High Proton Conductivity Based on Zirconium Sandwiched Heteropolytungstate

“…Good thermal and water stabilities are extremely important for the practical application of proton-conducting materials . The thermal stability and the existing experiments of guest water molecules in the channels of 1 – 3 were corroborated by TG.…”

“…Good thermal and water stabilities are extremely important for the practical application of protonconducting materials. 37 The thermal stability and the existing experiments of guest water molecules in the channels of 1−3 were corroborated by TG. As shown in Figure S7 for 3, the result suggests that the fast weight loss in the range of 30−180 °C is 7.67%, corresponding to the content of 15 lattice water molecules and partially coordinated water molecules (4.27%, calculated lattice water molecules).…”

Stable Lanthanide Metal–Organic Frameworks with Ratiometric Fluorescence Sensing for Amino Acids and Tunable Proton Conduction and Magnetic Properties

“…The proton transfer in the Grotthuss mechanism mainly includes two processes: proton hopping and reorientation . Protons first hop from one proton carrier to another proton acceptor along the hydrogen bond network in MOFs, and then, the protons are redirected on the carrier to the next proton acceptor . The abundant coordinated H 2 O molecules in Ln-MOFs 1 – 4 form a 1D H-bond network, and the H-bonds between coordinated H 2 O molecules with guest H 2 O molecules effectively increase the proton conductivity.…”

“…45 Protons first hop from one proton carrier to another proton acceptor along the hydrogen bond network in MOFs, and then, the protons are redirected on the carrier to the next proton acceptor. 46 The abundant coordinated S7, Supporting Information), indicating the presence of weak ferromagnetic interaction in 2. For 3 and 4, the χ M T values decrease with decreasing temperature because of the weak antiferromagnetic interaction and magnetic anisotropy and/or thermal depopulation of the Stark sublevels.…”

Fluorescence analysis for characterizing the alkali stability of metal–organic frameworks: an informative complement to X-ray diffraction

“…Metal-organic frameworks (MOFs), an emerging kind of porous material built from metal nodes and organic links, [1][2][3] have aroused great scientific interest. Their structural designability, diversity, tunability, and porosity endow MOFs with potential applications in gas adsorption and separation, [4][5][6][7] chemical sensing, [8][9][10][11][12][13][14] photonics, 15,16 heterogeneous catalysis, [17][18][19][20][21] proton conduction, [22][23][24][25] etc. The functional performance of MOFs is highly dependent on their crystalline porous structures, and the structural lability to humidity, acids, bases and other external stimuli often limits their practical applications.…”