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Okur S, Hashem T, Bogdanova E, Hodapp P, Heinke L, Bräse S, Wöll C. Optimized Detection of Volatile Organic Compounds Utilizing Durable and Selective Arrays of Tailored UiO-66-X SURMOF Sensors. ACS Sens 2024; 9:622-630. [PMID: 38320750 PMCID: PMC10898453 DOI: 10.1021/acssensors.3c01575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 12/27/2023] [Accepted: 01/05/2024] [Indexed: 02/24/2024]
Abstract
Metal-organic frameworks (MOFs), with their well-defined and highly flexible nanoporous architectures, provide a material platform ideal for fabricating sensors. We demonstrate that the efficacy and specificity of detecting and differentiating volatile organic compounds (VOCs) can be significantly enhanced using a range of slightly varied MOFs. These variations are obtained via postsynthetic modification (PSM) of a primary framework. We alter the original MOF's guest adsorption affinities by incorporating functional groups into the MOF linkers, which yields subtle changes in responses. These responses are subsequently evaluated by using machine learning (ML) techniques. Under severe conditions, such as high humidity and acidic environments, sensor stability and lifespan are of utmost importance. The UiO-66-X MOFs demonstrate the necessary durability in acidic, neutral, and basic environments with pH values ranging from 2 to 11, thus surpassing most other similar materials. The UiO-66-NH2 thin films were deposited on quartz-crystal microbalance (QCM) sensors in a high-temperature QCM liquid cell using a layer-by-layer pump method. Three different, highly stable surface-anchored MOFs (SURMOFs) of UiO-66-X obtained via the PSM approach (X: NH2, Cl, and N3) were employed to fabricate arrays suitable for electronic nose applications. These fabricated sensors were tested for their capability to distinguish between eight VOCs. Data from the sensor array were processed using three distinct ML techniques: linear discriminant (LDA), nearest neighbor (k-NN), and neural network analysis methods. The discrimination accuracies achieved were nearly 100% at high concentrations and over 95% at lower concentrations (50-100 ppm).
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Affiliation(s)
- Salih Okur
- Karlsruhe
Institute of Technology (KIT), Institute of Functional Interfaces, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Tawheed Hashem
- Karlsruhe
Institute of Technology (KIT), Institute of Functional Interfaces, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Evgenia Bogdanova
- Karlsruhe
Institute of Technology (KIT), Institute of Functional Interfaces, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Patrick Hodapp
- Karlsruhe
Institute of Technology (KIT), Institute for Biological Interfaces
3–Soft Matter Synthesis Laboratory (IBG3–SML), Kaiserstrasse 12, 76131 Karlsruhe, Germany
| | - Lars Heinke
- Karlsruhe
Institute of Technology (KIT), Institute of Functional Interfaces, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Stefan Bräse
- Karlsruhe
Institute of Technology (KIT), Institute of Organic Chemistry (IOC), Kaiserstrasse 12,, 76131 Karlsruhe, Germany
- Karlsruhe
Institute of Technology (KIT), Institute of Biological and Chemical
Systems–Functional Molecular Systems (IBCS–FMS), Kaiserstrasse 12, 76131 Karlsruhe, Germany
| | - Christof Wöll
- Karlsruhe
Institute of Technology (KIT), Institute of Functional Interfaces, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
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2
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Rehman TU, Agnello S, Gelardi FM, Calvino MM, Lazzara G, Buscarino G, Cannas M. Unveiling the MIL-53(Al) MOF: Tuning Photoluminescence and Structural Properties via Volatile Organic Compounds Interactions. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:388. [PMID: 38470719 PMCID: PMC10935077 DOI: 10.3390/nano14050388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 02/17/2024] [Accepted: 02/18/2024] [Indexed: 03/14/2024]
Abstract
MIL-53(Al) is a metal-organic framework (MOF) with unique properties, including structural flexibility, thermal stability, and luminescence. Its ability to adsorb volatile organic compounds (VOCs) and water vapor makes it a promising platform for sensing applications. This study investigated the adsorption mechanism of MIL-53(Al) with different VOCs, including ketones, alcohols, aromatics, and water molecules, focusing on structural transformations due to pore size variation and photoluminescence properties. The reported results assess MIL-53(Al) selectivity towards different VOCs and provide insights into their fundamental properties and potential applications in sensing.
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Affiliation(s)
| | | | | | | | | | | | - Marco Cannas
- Dipartimento di Fisica e Chimica−Emilio Segrè, Università degli Studi di Palermo, 90123 Palermo, Italy; (T.U.R.); (S.A.); (F.M.G.); (M.M.C.); (G.L.); (G.B.)
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3
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Liu Y, Jiang Y, Heinke L. Photoswitchable Radical State in Nanoporous Metal-Organic Framework Films with Embedded Hexaarylbiimidazole. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:474-479. [PMID: 38149797 DOI: 10.1021/acs.langmuir.3c02734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2023]
Abstract
Photoresponsive materials enable dynamic remote control of their fundamental properties. The incorporation of photochromic molecules in nanoporous metal-organic frameworks (MOFs) provides a unique opportunity to tailor the material properties, including the interaction between the MOF host and guest molecules in the pores. Here, a MOF film of type HKUST-1 with embedded hexaarylbiimidazole (HABI), undergoing reversible light-induced reactions between the stable dimer state and the metastable radical state, is presented. The switching between the dimer and radical form is shown by infrared, UV-vis, and electron paramagnetic resonance (EPR) spectroscopy. By transient uptake experiments with ethanol and methanol as probe molecules, we show that the dimer-radical switching impacts the host-guest interaction and, in particular, modifies the uptake amount and diffusion coefficient of the guest molecules. For ethanol, the diffusion slows down by 75%. This research presents the first MOF material with photoswitchable (meta)stable dimer and radical molecules, and it contributes to the advancement of photoresponsive nanoporous materials.
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Affiliation(s)
- Yidong Liu
- Institute of Functional Interfaces (IFG), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Yunzhe Jiang
- Institute of Functional Interfaces (IFG), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Lars Heinke
- Institute of Functional Interfaces (IFG), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
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4
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Yang J, Ren C, Liu M, Li W, Gao D, Li H, Ning Z. A Novel Dye-Modified Metal-Organic Framework as a Bifunctional Fluorescent Probe for Visual Sensing for Styrene and Temperature. Molecules 2023; 28:4919. [PMID: 37446579 PMCID: PMC10343389 DOI: 10.3390/molecules28134919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 06/16/2023] [Accepted: 06/20/2023] [Indexed: 07/15/2023] Open
Abstract
A novel fluorescent probe (C460@Tb-MOFs) was designed and synthesized by encapsulating the fluorescent dye 7-diethylamino-4-methyl coumarin (C460) into a terbium-based metal-organic framework using a simple ultrasonic impregnation method. It is impressive that this dye-modified metal-organic framework can specifically detect styrene and temperature upon luminescence quenching. The sensing platform of this material exhibits great selectivity, fast response, and good cyclability toward styrene detection. It is worth mentioning that the sensing process undergoes a distinct color change from blue to colorless, providing conditions for the accurate visual detection of styrene liquid and gas. The significant fluorescence quenching mechanism of styrene toward C460@Tb-MOFs is explored in detail. Moreover, the dye-modified metal-organic framework can also achieve temperature sensing from 298 to 498 K with high relative sensitivity at 498 K. The preparation of functionalized MOF composites with fluorescent dyes provides an effective strategy for the construction of sensors for multifunctional applications.
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Affiliation(s)
- Jie Yang
- College of Chemistry and Materials Science, Sichuan Normal University, Chengdu 610068, China; (J.Y.); (M.L.); (W.L.); (D.G.)
| | - Chaojun Ren
- Beijing Aerospace Propulsion Institute, Beijing 100076, China;
| | - Min Liu
- College of Chemistry and Materials Science, Sichuan Normal University, Chengdu 610068, China; (J.Y.); (M.L.); (W.L.); (D.G.)
| | - Wenwei Li
- College of Chemistry and Materials Science, Sichuan Normal University, Chengdu 610068, China; (J.Y.); (M.L.); (W.L.); (D.G.)
| | - Daojiang Gao
- College of Chemistry and Materials Science, Sichuan Normal University, Chengdu 610068, China; (J.Y.); (M.L.); (W.L.); (D.G.)
| | - Hongda Li
- Liuzhou Key Laboratory for New Energy Vehicle Power Lithium Battery, School of Electronic Engineering, Guangxi University of Science and Technology, Liuzhou 545006, China;
| | - Zhanglei Ning
- College of Chemistry and Materials Science, Sichuan Normal University, Chengdu 610068, China; (J.Y.); (M.L.); (W.L.); (D.G.)
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5
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Monjezi BH, Okur S, Limbach R, Chandresh A, Sen K, Hashem T, Schwotzer M, Wondraczek L, Wöll C, Knebel A. Fast Dynamic Synthesis of MIL-68(In) Thin Films in High Optical Quality for Optical Cavity Sensing. ACS NANO 2023; 17:6121-6130. [PMID: 36877629 DOI: 10.1021/acsnano.3c01558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Fabrication of metal-organic framework (MOF) thin films rigidly anchored on suitable substrates is a crucial prerequisite for the integration of these porous hybrid materials into electronic and optical devices. Thus, far, the structural variety for MOF thin films available through layer-by-layer deposition was limited, as the preparation of those surface-anchored metal-organic frameworks (SURMOFs) has several requirements: mild conditions, low temperatures, day-long reaction times, and nonaggressive solvents. We herein present a fast method for the preparation of the MIL SURMOF on Au-surfaces under rather harsh conditions: Using a dynamic layer-by-layer synthesis for MIL-68(In), thin films of adjustable thickness between 50 and 2000 nm could be deposited within only 60 min. The MIL-68(In) thin film growth was monitored in situ using a quartz crystal microbalance. In-plane X-ray diffraction revealed oriented MIL-68(In) growth with the pore-channels of this interesting MOF aligned parallel to the support. Scanning electron microscopy data demonstrated an extraordinarily low roughness of the MIL-68(In) thin films. Mechanical properties and lateral homogeneity of the layer were probed through nanoindentation. These thin films showed extremely high optical quality. By applying a poly(methyl methacrylate) layer and further depositing an Au-mirror to the top, a MOF optical cavity was fabricated that can be used as a Fabry-Perot interferometer. The MIL-68(In)-based cavity showed a series of sharp resonances in the ultraviolet-visible regime. Changes in the refractive index of MIL-68(In) caused by exposure to volatile compounds led to pronounced position shifts of the resonances. Thus, these cavities are well suited to be used as optical read-out sensors.
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Affiliation(s)
- Bahram Hosseini Monjezi
- Institute of Functional Interfaces (IFG), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Salih Okur
- Institute of Functional Interfaces (IFG), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - René Limbach
- Otto Schott Institute of Materials Research, Friedrich Schiller University Jena, Fraunhoferstraße 6, 07743 Jena, Germany
| | - Abhinav Chandresh
- Institute of Functional Interfaces (IFG), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Kaushik Sen
- Institute of Functional Interfaces (IFG), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Tawheed Hashem
- Institute of Functional Interfaces (IFG), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Matthias Schwotzer
- Institute of Functional Interfaces (IFG), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Lothar Wondraczek
- Otto Schott Institute of Materials Research, Friedrich Schiller University Jena, Fraunhoferstraße 6, 07743 Jena, Germany
| | - Christof Wöll
- Institute of Functional Interfaces (IFG), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Alexander Knebel
- Otto Schott Institute of Materials Research, Friedrich Schiller University Jena, Fraunhoferstraße 6, 07743 Jena, Germany
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Greussing V, Kremer S, Ober I, Küssner K, Rödl M, Huppertz H, Schwartz HA. Mechanochemical Loading: An Alternative Route to form Spiropyran@MOF Composite Materials. Z Anorg Allg Chem 2023. [DOI: 10.1002/zaac.202200273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Affiliation(s)
- Victoria Greussing
- Institute of General, Inorganic and Theoretical Chemistry University of Innsbruck Innrain 80–82 A-6020 Innsbruck Austria
| | - Stephane Kremer
- Institute of General, Inorganic and Theoretical Chemistry University of Innsbruck Innrain 80–82 A-6020 Innsbruck Austria
| | - Isabell Ober
- Institute of General, Inorganic and Theoretical Chemistry University of Innsbruck Innrain 80–82 A-6020 Innsbruck Austria
| | - Kira Küssner
- Institute of General, Inorganic and Theoretical Chemistry University of Innsbruck Innrain 80–82 A-6020 Innsbruck Austria
| | - Markus Rödl
- Institute of General, Inorganic and Theoretical Chemistry University of Innsbruck Innrain 80–82 A-6020 Innsbruck Austria
| | - Hubert Huppertz
- Institute of General, Inorganic and Theoretical Chemistry University of Innsbruck Innrain 80–82 A-6020 Innsbruck Austria
| | - Heidi A. Schwartz
- Institute of General, Inorganic and Theoretical Chemistry University of Innsbruck Innrain 80–82 A-6020 Innsbruck Austria
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7
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Jiang Y, Danowski W, Feringa BL, Heinke L. Nanoporous Films with Oriented Arrays of Molecular Motors for Photoswitching the Guest Adsorption and Diffusion. Angew Chem Int Ed Engl 2023; 62:e202214202. [PMID: 36367076 PMCID: PMC10107543 DOI: 10.1002/anie.202214202] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 11/10/2022] [Accepted: 11/10/2022] [Indexed: 11/13/2022]
Abstract
Molecular motors are fascinating nanomachines. However, constructing smart materials from such functional molecules presents a severe challenge in material science. Here, we present a bottom-up layer-by-layer assembly of oriented overcrowded-alkene molecular motors forming a crystalline metal-organic framework thin film. While all stator parts of the overcrowded-alkene motors are oriented perpendicular to the substrate, the rotors point into the pores, which are large enough allowing for the light-induced molecular rotation. Taking advantage of the thin film's transparency, the motor rotation and its activation energy are determined by UV/Vis spectroscopy. As shown by gravimetric uptake experiments, molecular motors in crystalline porous materials are used, for the first time, to control the adsorption and diffusion properties of guest molecules in the pores, here, by switching with light between the (meta-)stable states. The work demonstrates the potential of designed materials with molecular motors and indicates a path for the future development of smart materials.
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Affiliation(s)
- Yunzhe Jiang
- Institute of Functional Interfaces (IFG), Karlsruhe Institute of Technology (KIT), 76344, Eggenstein-Leopoldshafen, Germany
| | - Wojciech Danowski
- Centre for Systems Chemistry, Stratingh Institute for Chemistry, University of Groningen, 9747, Nijenborgh 4, Groningen, AG, The Netherlands.,University of Strasbourg CNRS, ISIS UMR 7006, 8 Allée Gaspard Monge, 67000, Strasbourg, France
| | - Ben L Feringa
- Centre for Systems Chemistry, Stratingh Institute for Chemistry, University of Groningen, 9747, Nijenborgh 4, Groningen, AG, The Netherlands
| | - Lars Heinke
- Institute of Functional Interfaces (IFG), Karlsruhe Institute of Technology (KIT), 76344, Eggenstein-Leopoldshafen, Germany
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8
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Shen Y, Tissot A, Serre C. Recent progress on MOF-based optical sensors for VOC sensing. Chem Sci 2022; 13:13978-14007. [PMID: 36540831 PMCID: PMC9728564 DOI: 10.1039/d2sc04314a] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 10/04/2022] [Indexed: 08/16/2023] Open
Abstract
The raising apprehension of volatile organic compound (VOC) exposures urges the exploration of advanced monitoring platforms. Metal-organic frameworks (MOFs) provide many attractive features including tailorable porosity, high surface areas, good chemical/thermal stability, and various host-guest interactions, making them appealing candidates for VOC capture and sensing. To comprehensively exploit the potential of MOFs as sensing materials, great efforts have been dedicated to the shaping and patterning of MOFs for next-level device integration. Among different types of sensors (chemiresistive sensors, gravimetric sensors, optical sensors, etc.), MOFs coupled with optical sensors feature distinctive strength. This review summarized the latest advancements in MOF-based optical sensors with a particular focus on VOC sensing. The subject is discussed by different mechanisms: colorimetry, luminescence, and sensors based on optical index modulations. Critical analysis for each system highlighting practical aspects was also deliberated.
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Affiliation(s)
- Yuwei Shen
- Institut des Matériaux Poreux de Paris, Ecole Normale Supérieure, ESPCI Paris, CNRS, PSL University 75005 Paris France
| | - Antoine Tissot
- Institut des Matériaux Poreux de Paris, Ecole Normale Supérieure, ESPCI Paris, CNRS, PSL University 75005 Paris France
| | - Christian Serre
- Institut des Matériaux Poreux de Paris, Ecole Normale Supérieure, ESPCI Paris, CNRS, PSL University 75005 Paris France
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9
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Vapor sorption behavior in heptazine-based MOF featuring a brick-shaped framework. J SOLID STATE CHEM 2022. [DOI: 10.1016/j.jssc.2022.123735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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10
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Qin P, Day BA, Okur S, Li C, Chandresh A, Wilmer CE, Heinke L. VOC Mixture Sensing with a MOF Film Sensor Array: Detection and Discrimination of Xylene Isomers and Their Ternary Blends. ACS Sens 2022; 7:1666-1675. [PMID: 35674347 DOI: 10.1021/acssensors.2c00301] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Detection and recognition of volatile organic compounds (VOCs) are crucial in many applications. While pure VOCs can be detected by various sensors, the discrimination of VOCs in mixtures, especially of similar molecules, is hindered by cross-sensitivities. Isomer identification in mixtures is even harder. Metal-organic frameworks (MOFs) with their well-defined, nanoporous, and versatile structures have the potential to improve the VOC sensing performance by tailoring the adsorption affinities. Here, we detect and identify ternary xylene isomer mixtures by using an array of six gravimetric, quartz crystal microbalance (QCM)-based sensors coated with selected MOF films with different isomer affinities. We use classical molecular simulations to provide insights into the sensing mechanism. In addition to the attractive interaction between the analytes and the MOF film, the isomer discrimination is caused by the rigid crystalline framework sterically controlling the access of the isomers to different adsorption sites in the MOFs. The sensor array has a very low limit of detection of 1 ppm for each pure isomer and allows the isomer discrimination in mixtures. At 100 ppm, 16 different ternary o-p-m-xylene mixtures were identified with high classification accuracy (96.5%). This work shows the unprecedented performance of MOF-sensor arrays, also referred to as MOF-electronic nose (MOF-e-nose), for sensing VOC mixtures. Based on the study, guidelines for detecting and discriminating complex mixtures of volatile molecules are also provided.
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Affiliation(s)
- Peng Qin
- Karlsruhe Institute of Technology (KIT), Institute of Functional Interfaces (IFG), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Brian A Day
- Department of Chemical & Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, Unites States
| | - Salih Okur
- Karlsruhe Institute of Technology (KIT), Institute of Functional Interfaces (IFG), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Chun Li
- Karlsruhe Institute of Technology (KIT), Institute of Functional Interfaces (IFG), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Abhinav Chandresh
- Karlsruhe Institute of Technology (KIT), Institute of Functional Interfaces (IFG), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Christopher E Wilmer
- Department of Chemical & Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, Unites States.,Department of Electrical & Computer Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, Unites States
| | - Lars Heinke
- Karlsruhe Institute of Technology (KIT), Institute of Functional Interfaces (IFG), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
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Rödl M, Reka A, Panic M, Fischereder A, Oberlechner M, Mairegger T, Kopacka H, Huppertz H, Hofer TS, Schwartz HA. Fundamental Study of the Optical and Vibrational Properties of Fx-AZB@MOF systems as Functions of Dye Substitution and the Loading Amount. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:4295-4309. [PMID: 35344366 PMCID: PMC9009183 DOI: 10.1021/acs.langmuir.1c03482] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 03/22/2022] [Indexed: 06/14/2023]
Abstract
Controlling the switching efficiency of photoactive hybrid systems is an obligatory key prerequisite for systematically improving the design of functional materials. By modulating the degree of fluorination and the amount being embedded into porous hosts, the E/Z ratios of fluorinated azobenzenes were adjusted as both functions of substitution and the degree of loading. Octafluoroazobenzene (F8-AZB) and perfluoroazobenzene (F10-AZB) were inserted into porous DMOF-1. Especially for perfluoroazobenzene (F10-AZB), an immense stabilization of the E isomer was observed. In complementary molecular dynamics simulations performed at the DFTB (density functional tight binding) level, an in-depth characterization of the interactions of the different photoisomers and the host structure was carried out. On the basis of the resulting structural and energetic data, the experimentally observed increase in the amount of the Z conformer for F8-AZB can be explained, while the stabilization of E-F10-AZB can be directly related to a fundamentally different interaction motif compared to its tetra- and octafluorinated counterparts.
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