Metal−Organic Frameworks as Sensors: A ZIF-8 Based Fabry−Pérot Device as a Selective Sensor for Chemical Vapors and Gases

Abstract

Permanently microporous metal-organic framework (MOF) materials 1 have attracted considerable attention on account of their large internal surface areas, uniform channels, (sub)nanometer-sized cavities, thermal stability, and chemical tailorability. 2 Among the potential applications for which proof-of-concept reports have proliferated are gas storage, 3 chemical catalysis, 4 and smallmolecule separations. 5 At first glance MOFs would also appear to be attractive for chemical sensing. Nevertheless, reports of MOFbased sensing are comparatively few. 6 The challenge is signal transduction: the cavities of MOFs are generally too small to tailor with reporter molecules, i.e. moieties that can readily signal analytebinding events via changes in color, redox potential, or other properties. In the handful of cases where sensing has been described, advantage has generally been taken of framework luminescence, 7 with signal transduction consisting of luminescence quenching. 6,8 Here we describe an alternative approach that circumvents the need for molecular-level reporters and instead relies upon a readout of changes in a macroscopic property of the sensing material, the refractive index. Specifically, we have configured the material as a transparent thin film on an appropriate support material (glass or silicon) and optically monitored the energies of Fabry-Pe ´rot interference peaks as a function of analyte exposure. 9 These peaks are observable when the thickness of a supported material is comparable to the wavelength of light (λ). Importantly, their energies also depend on the film's refractive index.

Highly sensitive volatile organic compounds vapour measurements using a long period grating optical fibre sensor coated with metal organic framework ZIF-8

“…An investigation of a ZIF-8 film demonstrated the adsorption of isopropanol in a selective manner versus water [36]. A ZIF-8 based Fabry-Perot interferometer exhibited a concentrationspecific reaction to a mixture of propane and nitrogen [37]. ZIF-8 film fabrication involves no substrate modification, works at room temperature and facilitates control over the thickness with one growth cycle that takes less than an hour [37,38].…”

“…A ZIF-8 based Fabry-Perot interferometer exhibited a concentrationspecific reaction to a mixture of propane and nitrogen [37]. ZIF-8 film fabrication involves no substrate modification, works at room temperature and facilitates control over the thickness with one growth cycle that takes less than an hour [37,38]. In addition to being sensitive to organic vapours [36,37], ZIF-8 has been selected over other MOFs (and ZIFs) due to simplicity in fabrication and deposition of the thin film.…”

“…ZIF-8 film fabrication involves no substrate modification, works at room temperature and facilitates control over the thickness with one growth cycle that takes less than an hour [37,38]. In addition to being sensitive to organic vapours [36,37], ZIF-8 has been selected over other MOFs (and ZIFs) due to simplicity in fabrication and deposition of the thin film. The procedure for ZIF-8 film fabrication involves no substrate modification [37], works at room temperature and facilitates control over the thickness with one growth cycle that takes less than an hour.…”

Reductive Electrosynthesis of Crystalline Metal–Organic Frameworks

“…Importantly, many of the anticipated applications require that MOFs be deposited on various surfaces as, for instance, in membranes for gas separation, 5 or thin films in luminescent sensing devices. 6 This requirement poses significant difficulties, however, because bulk MOFs are made as brittle crystals or insoluble powders that are not amenable to common surface processing techniques. 7 To address this, membrane or thin film growth techniques initially developed for zeolites and molecular materials, such as seeded and epitaxial growth, have also been adapted to MOFs recently.…”

Effect of Transition Metal Cations on Assembly of Highly Ordered 2D Multiporphyrin Arrays on Liquid and Solid Substrates

“…Для получения иммобилизованных на поверхности металлоорганических каркасов, ПОВМОК (Surface-Anchored Metal-Organic Frameworks, SURMOFs) используют несколько методов. [9][10][11][12][13][14] Простейший из них состоит в осаждении на подложку частиц МОК, предварительно сформированных в растворе традици-онным сольватотермальным способом. Как правило, перед этим подложка покрывается самоорганизо-ванным монослоем (СОМ) поверхностно-активного вещества, содержащего соответствующие данному МОК функциональные группы.…”