B22-Multimode InfraRed imaging And Microspectroscopy
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Diamond Proposal Number(s):
[30369]
Open Access
Abstract: Despite exhaled human breath having enabled noninvasive diabetes diagnosis, selective acetone vapor detection by fluorescence approach in the diabetic range (1.8–3.5 ppm) remains a long-standing challenge. A set of water-resistant luminescent metal-organic framework (MOF)-based composites have been reported for detecting acetone vapor in the diabetic range with a limit of detection of 200 ppb. The luminescent materials possess the ability to selectively detect acetone vapor from a mixture comprising nitrogen, oxygen, carbon dioxide, water vapor, and alcohol vapor, which are prevalent in exhaled breath. It is noteworthy that this is the first luminescent MOF material capable of selectively detecting acetone vapor in the diabetic range via a turn-on mechanism. The material can be reused within a matter of minutes under ambient conditions. Industrially pertinent electrospun luminescent fibers are likewise fabricated alongside various luminescent films for selective detection of ultratrace quantities of acetone vapor present in the air. Ab initio theoretical calculations combined with in situ synchrotron-based dosing studies uncovered the material's remarkable hypersensitivity toward acetone vapor. Finally, a freshly designed prototype fluorescence-based portable optical sensor is utilized as a proof-of-concept for the rapid detection of acetone vapor within the diabetic range.
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Nov 2023
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B22-Multimode InfraRed imaging And Microspectroscopy
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Diamond Proposal Number(s):
[22137, 30398]
Open Access
Abstract: Metal–organic framework (MOF) materials are attracting increasing interest in the field of electronics due to their structural diversity, intrinsic porosity, and designable host–guest interactions. Here, we report the dielectric properties of a series of robust materials, MFM-300(M) (M = Al, Sc, Cr, Fe, Ga, In), when exposed to different guest molecules. MFM-300(Fe) exhibits the most notable increase in dielectric constant to 35.3 ± 0.3 at 10 kHz upon adsorption of NH3. Structural analysis suggests that the electron delocalization induced by host–guest interactions between NH3 and the MOF host, as confirmed by neutron powder diffraction studies, leads to structural polarization, resulting in a high dielectric constant for NH3@MFM-300(Fe). This is further supported by ligand-to-metal charge-transfer transitions observed by solid-state UV/vis spectroscopy. The high detection sensitivity and stability to NH3 suggest that MFM-300(Fe) may act as a powerful dielectric-based sensor for NH3.
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Oct 2023
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B22-Multimode InfraRed imaging And Microspectroscopy
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Diamond Proposal Number(s):
[34009, 32463]
Open Access
Abstract: Metal-organic frameworks (MOFs) have emerged as a versatile material platform for a wide range of applications. However, the development of practical devices is constrained by their inherently low mechanical stability. The synthesis of MOFs in a monolithic morphology represents a viable way for the transition of these materials from laboratory research to real-world applications. For the design of MOF-based devices, the mechanical characterization of such materials cannot be overlooked. In this regard, stress-strain relationships represent the most valuable tool for assessing the mechanical response of materials. Here, we use flat punch nanoindentation, micropillar compression and Raman microspectroscopy to investigate the stress-strain behaviour of MOF monoliths. A pseudo-plastic flow is observed under indentation, where the confining pressure prevents unstable crack propagation. Material flow is accommodated by grain boundary sliding, with occasional stepwise cracking to accommodate excessive stress building up. Micropillar compression reveals a brittle failure of ZIF-8, while plastic flow is observed for MIL-68.
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Oct 2023
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B22-Multimode InfraRed imaging And Microspectroscopy
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Diamond Proposal Number(s):
[25407]
Open Access
Abstract: Organic photoswitchable molecules have struggled in solid-state form to fulfill their remarkable potential, in terms of photoswitching performance and long-term stability when compared to their inorganic counterparts. We report the concept of non-electron deficient host’s surface with optimal porosity and hydrophobicity, as a priori strategy to design photoefficient organic solid-state photochromic materials with outstanding mechanical robustness. It is realized by the nanoconfinement of photochromes in a host matrix possessing optimal porosity and hydrophobicity. The resulting photochromic nanocomposites can be prepared in multigram scale employing a one-pot reaction under ambient conditions. When exposed to a light stimulus including natural sunlight, the photoswitchable nanocomposite powder changes color promptly and reversibly, in a matter of seconds (5 s and 30 s under UV irradiation and sunlight, respectively) along with excellent photo-fatigue resistance, which are on a par with inorganic photochromes. Exemplars of commercially viable prototypes that are optically clear, comprising smart windows, complex photochromic sculptures, and self-erasing rewritable devices, were engineered by direct blending with resilient polymers. Notably, the use of high-stiffness polymers (Young’s modulus > 2 GPa) is no longer considered an insurmountable challenge. Finally, photochromic films with anticounterfeiting features could be manufactured through precision printing of nanocrystals by drop-on-demand inkjet printing technology.
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Oct 2023
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B22-Multimode InfraRed imaging And Microspectroscopy
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Diamond Proposal Number(s):
[27504]
Open Access
Abstract: Triboelectric nanogenerator (TENG), a device that can convert mechanical energy into electricity based on the principle of triboelectrification, has gained tremendous attention since its first discovery in 2012. Although TENG has versatile applications in energy harvesting and self-powered sensing, its commercialization is still limited by the low power output. Recently, metal-organic frameworks (MOFs), with their large surface area and excellent tunability, have been explored to enhance the electrical performance of TENG. Herein, we synthesized nanoparticles of hydrophobic zeolitic imidazolate framework ZIF-71 (RHO topology) and its non-porous counterpart ZIF-72 (LCS topology), which were subsequently incorporated in a polydimethylsiloxane (PDMS) matrix as filler materials. By modifying the topology of ZIF nanofillers, we found the dielectric constant and surface adhesion of composites are both enhanced, thereby generating significantly higher triboelectric output. Moreover, we show the resultant ZIF/PDMS nanocomposite films exhibit enhanced triboelectric properties and long-term stability under cyclic mechanical loading. After integrating the prepared nanocomposite films into TENG devices, we accomplished the peak output voltage and current of 578 V and 19 μA for thin films (3 ×3 cm2, thickness ∼0.33 mm), respectively, by embedding 1 wt % of ZIF-72 nanoparticles into PDMS matrix, with an instantaneous maximum power density of ∼5 W m−2. In this study, the mechanism of improved TENG performance by incorporating MOF nanoparticles has, for the first time, been revealed through nanoscale-resolved mechanical and chemical studies. Furthermore, the practicality of MOF-based TENG was demonstrated by harvesting energy from oscillatory motions, for powering up commercial microelectronics, transmitting electrical signals remotely, and functioning as a self-powered Morse code generator.
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Sep 2023
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B22-Multimode InfraRed imaging And Microspectroscopy
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Diamond Proposal Number(s):
[27504]
Abstract: First fabricated in 2012, triboelectric nanogenerators (TENGs) are a new power-generation technology that can scavenge mechanical energy from the environment and convert it into electricity. Although they offer considerable promise for powering smart sensors and wearable devices, their current low power output limits commercial development. Recent research suggests that the large surface area and excellent tunability of metal-organic frameworks (MOFs) could be exploited to enhance the electrical performance of TENGs. In work recently published in Nano Energy, scientists from the University of Oxford used synchrotron far infrared (THz) probe to reveal how incorporating MOF nanoparticles improves TENG performance. They also demonstrated harvesting energy from oscillatory motions to power commercial microelectronics such as light emitting diodes (LEDs) and a Morse code generator.
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Sep 2023
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B22-Multimode InfraRed imaging And Microspectroscopy
I04-1-Macromolecular Crystallography (fixed wavelength)
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Rhiannon M.
Evans
,
Stephen E.
Beaton
,
Patricia
Rodriguez Macia
,
Yunjie
Pang
,
Kin Long
Wong
,
Leonie
Kertess
,
William K.
Myers
,
Ragnar
Bjornsson
,
Philip A.
Ash
,
Kylie A.
Vincent
,
Stephen B.
Carr
,
Fraser A.
Armstrong
Diamond Proposal Number(s):
[12346, 21651]
Open Access
Abstract: The active site of [NiFe]-hydrogenases contains a strictly-conserved pendant arginine, the guanidine head group of which is suspended immediately above the Ni and Fe atoms. Replacement of this arginine (R479) in hydrogenase-2 from E. coli results in an enzyme that is isolated with a very tightly-bound diatomic ligand attached end-on to the Ni and stabilised by hydrogen bonding to the Nζ atom of the pendant lysine and one of the three additional water molecules located in the active site of the variant. The diatomic ligand is bound under oxidising conditions and is removed only after a prolonged period of reduction with H2 and reduced methyl viologen. Once freed of the diatomic ligand, the R479K variant catalyses both H2 oxidation and evolution but with greatly decreased rates compared to the native enzyme. Key kinetic characteristics are revealed by protein film electrochemistry: most importantly, a very low activation energy for H2 oxidation that is not linked to an increased H/D isotope effect. Native electrocatalytic reversibility is retained. The results show that the sluggish kinetics observed for the lysine variant arise most obviously because the advantage of a more favourable low-energy pathway is massively offset by an extremely unfavourable activation entropy. Extensive efforts to establish the identity of the diatomic ligand, the tight binding of which is an unexpected further consequence of replacing the pendant arginine, prove inconclusive.
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Jul 2023
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B22-Multimode InfraRed imaging And Microspectroscopy
I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[27504, 29415]
Open Access
Abstract: Luminescent metal-organic frameworks (LMOFs) are promising materials for nanophotonic applications due to their tuneable structure and programmability. Yet, the 3D nature of LMOFs creates challenges for stability, optical transparency, and device integration. Metal-organic nanosheets (MONs) potentially overcome these limitations by combining the benefits of metal-organic frameworks (MOFs) with an atomically thin morphology of large planar dimensions. Herein, the bottom-up synthesis of few-layer thin ZIF-7-III MONs via facile low-energy salt-templating is reported. Employing guest@MOF design, the fluorophores Rhodamine B and Fluorescein are intercalated into ZIF-7 nanosheets (Z7-NS) to form light emissive systems exhibiting intense and highly photostable fluorescence. Aggregation and Förster resonance energy transfer, enabled by the MON framework, are revealed as the mechanisms behind fluorescence. By varying guest concentration, these mechanisms provide predictable quantified control over emission chromaticity of a dual-guest Z7-NS material and the definition of an “emission chromaticity fingerprint” – a unique subset of the visible spectrum that a material can emit by fluorescence.
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Jun 2023
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B22-Multimode InfraRed imaging And Microspectroscopy
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Mar 2023
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B22-Multimode InfraRed imaging And Microspectroscopy
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Lixia
Guo
,
Joseph
Hurd
,
Meng
He
,
Wanpeng
Lu
,
Jiangnan
Li
,
Danielle
Crawshaw
,
Mengtian
Fan
,
Sergey A.
Sapchenko
,
Yinlin
Chen
,
Xiangdi
Zeng
,
Meredydd
Kippax-Jones
,
Wenyuan
Huang
,
Zhaodong
Zhu
,
Pascal
Manuel
,
Mark D.
Frogley
,
Daniel
Lee
,
Martin
Schroeder
,
Sihai
Yang
Diamond Proposal Number(s):
[30398]
Open Access
Abstract: The development of stable sorbent materials to deliver reversible adsorption of ammonia (NH3) is a challenging task. Here, we report the efficient capture and storage of NH3 in a series of robust microporous aluminium-based metal-organic framework materials, namely MIL-160, CAU-10-H, Al-fum, and MIL-53(Al). In particular, MIL-160 shows high uptakes of NH3 of 4.8 and 12.8 mmol g−1 at both low and high pressure (0.001 and 1.0 bar, respectively) at 298 K. The combination of in situ neutron powder diffraction, synchrotron infrared micro-spectroscopy and solid-state nuclear magnetic resonance spectroscopy reveals the preferred adsorption domains of NH3 molecules in MIL-160, with H/D site-exchange between the host and guest and an unusual distortion of the local structure of [AlO6] moieties being observed. Dynamic breakthrough experiments confirm the excellent ability of MIL-160 to capture of NH3 with a dynamic uptake of 4.2 mmol g−1 at 1000 ppm. The combination of high porosity, pore aperture size and multiple binding sites promotes the significant binding affinity and capacity for NH3, which makes it a promising candidate for practical applications.
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Mar 2023
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