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This paper describes the identification of specific host–guest interactions between basic gases (NH3, CD3CN, and pyridine) and four topologically similar 2-dimensional (2D) metal–organic frameworks (MOFs) comprising copper and nickel bis(diimine) and bis(dioxolene) linkages of triphenylene-based ligands using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance spectroscopy (EPR), and powder X-ray diffraction (PXRD). This contribution demonstrates that synthetic bottom-up control over surface chemistry of layered MOFs can be used to impart Lewis acidity or a mixture of Brønsted and Lewis acidities, through the choice of organic ligand and metal cation. This work also distinguishes differences in redox activity within this class of MOFs that contribute to their ability to promote electronic transduction of intermolecular interactions. Future design of structure–function relationships within multifunctional 2D MOFs will benefit from the insights this work provides. 

This paper describes the demonstration of a series of heterobimetallic, isoreticular 2D conductive metal–organic frameworks (MOFs) with metallophthalocyanine (MPc, M=Co and Ni) units interconnected by Cu nodes towards low-power chemiresistive sensing of ppm-levels of carbon monoxide (CO). Devices achieve sub-part-per-million (ppm) limits of detection (LOD) of 0.53 ppm toward CO at low driving voltages of 0.1 V. MPc-based Cu-linked MOFs can continuously detect CO at 50 ppm, the permissible exposure limit required by Occupational Health and Safety Assessment Series, for multiple exposures and realize CO detection in air and humid environment. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), density functional theory (DFT) calculations, and comparison experiments suggest the contribution of Cu nodes for CO binding and the essential role of MPc units in tuning and amplifying the sensing response. 

A set of dendrons and dendrimers is synthesized divergently using an orthogonal combination of kinetically-driven thiol-maleimide “click” chemistry and thermodynamically reversible furan-maleimide cycloaddition/retrocycloaddition reactions. Growth is controlled by taking advantage of the selective thiol–ene addition of thiols to the electron withdrawn alkene of maleimide in the presence of electron rich alkene of oxanorbornene. Subsequent activation of growing dendrons/dendrimers requires only heat to induce the dynamic covalent liberation of peripheral furan protecting groups. The methodology introduced provides a new route to multifunctional dendrimers that could, in principle, be synthesized by introducing different branched monomers at any stage of dendrimer growth, allowing dendrimer architectures and properties to be better tailored to their intended applications. 

This paper describes the first implementation of an array of two-dimensional (2D) layered conductive metal–organic frameworks (MOFs) as drop-casted film electrodes that facilitate voltammetric detection of redox active neurochemicals in a multi-analyte solution. The device configuration comprises a glassy carbon electrode modified with a film of conductive MOF (M3HXTP2; M = Ni, Cu; and X = NH, 2,3,6,7,10,11-hexaiminotriphenylene (HITP) or O, 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP)). The utility of 2D MOFs in voltammetric sensing is measured by the detection of ascorbic acid (AA), dopamine (DA), uric acid (UA), and serotonin (5-HT) in 0.1 M PBS (pH=7.4). In particular, Ni3HHTP2 MOF demonstrated nanomolar detection limits of 63 ± 11 nM for DA and 40 ± 17 nM for 5-HT through a wide concentration range (40 nM – 200 µM). The applicability in biologically-relevant detection was further demonstrated in simulated urine using Ni3HHTP2 MOFs for the detection of 5-HT with nanomolar detection limit of 63 ± 11 nM for 5-HT through a wide concentration range (63 nM – 200 µM) in the presence of constant background of DA. The implementation of conductive MOFs in voltammetric detection holds promise for further development of highly modular, sensitive, selective, and stable electroanalytical devices.