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•Acetonitrile adsorption on thePt(111)surface was studied by PM-IRRAS at 80–150 K.•Adsorption and desorption of acetonitrile on platinum occurred in molecular form.•Configuration of ...adsorption with coordination through the nitrogen atom was proposed.•DFT calculations confirmed the formation of ice-like multilayers of acetonitrile.
The extensive use of acetonitrile in various fields of organic synthesis and electrochemistry has provided widespread interest in studying the processes of acetonitrile adsorption on metal surfaces. In this work, the adsorption of acetonitrile and deuterated acetonitrile on thePt(111)surface was studied by polarization–modulation infrared reflection-absorption spectroscopy in the temperature range of 80–150 K. It was found that the adsorption and desorption of acetonitrile on platinum occurred in the molecular form. The possible configuration of adsorption with coordination through the nitrogen atom was proposed. To support the interpretation of obtained experimental data, density functional theory calculations were performed for acetonitrile adsorption considering 2 types of possible adsorption configurations: “bridge” with both N and C atoms bonded to the surface (η2(C,N) mode) and “top” with coordination through the nitrogen atom (N-top mode). Adsorption energies and frequency shifts of acetonitrile were calculated for different coverages ofPt(111)surface, including the second molecular layer. A joint experimental-theoretical study confirmed the formation of ice-like multilayers of acetonitrile onPt(111)under the considered conditions when C≡N bond is kept.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Ca3Ln2W2O12 (Ln = La, Sm) ceramics were prepared and their microwave dielectric properties were reported.•The crystal structure, Raman, and infrared reflectivity spectra of ...Ca3Ln2W2O12 ceramics were systematically investigated together with their effects on the microwave dielectric properties.•The optimum microwave dielectric properties (εr = 18.7, Qf = 50,500 GHz, τf =–90 ppm/oC) were achieved in Ca3La2W2O12 ceramics.
Two novel tungstate ceramics with a nominal composition of Ca3Ln2W2O12 (Ln = La, Sm) were prepared via standard solid-state reaction methods. According to X-ray diffraction patterns, both ceramics crystallized in hexagonal crystal systems with a space group of R3¯m (No. 166). The vibrational modes of the Raman spectra were identified, and the evolutions of the wavenumber and the full width at half maximum (FWHM) were analyzed. The optimum microwave dielectric properties with εr = 18.7, Qf = 50,500 GHz, andτf =–90 ppm/oC were realized in Ca3La2W2O12 ceramics, while moderate Qf values were obtained in the Sm composition (εr = 19.5, Qf = 15,700 GHz, andτf =–95 ppm/oC). The discrepancy in theQf values was associated with the broader FWHM of Raman spectra and smaller grain sizes. Infrared reflectivity (IR) spectra were also used to determine the intrinsic dielectric loss, where more damped phonon parameters were also identified in Ca3Sm2W2O12 ceramics.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Vibrational spectroscopy (IR and Raman) are powerful techniques to detect and evaluate speciation of uranium in both solid-state compounds and solutions.
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•Overview of vibrational ...bands associated with U(IV), U(V), and U(VI).•Discussion and analysis of Raman-active vibrational bands within U(IV) and U(VI) solid state materials.•Use of Raman spectroscopy to analyze U(VI) speciation in water, ionic liquids, and polar organic solvents.•Determination of U(VI) surface species using IR spectroscopy.
The purpose of this review is to provide an overview of uranium speciation using vibrational spectroscopy methods including Raman and IR. Uranium is a naturally occurring, radioactive element that is utilized in the nuclear energy and national security sectors. Fundamental uranium chemistry is also an active area of investigation due to ongoing questions regarding the participation of 5f orbitals in bonding, variation in oxidation states and coordination environments, and unique chemical and physical properties. Importantly, uranium speciation affects fate and transportation in the environment, influences bioavailability and toxicity to human health, controls separation processes for nuclear waste, and impacts isotopic partitioning and geochronological dating. This review article provides a thorough discussion of the vibrational modes for U(IV), U(V), and U(VI) and applications of infrared absorption and Raman scattering spectroscopies in the identification and detection of both naturally occurring and synthetic uranium species in solid and solution states. The vibrational frequencies of the uranyl moiety, including both symmetric and asymmetric stretches are sensitive to the coordinating ligands and used to identify individual species in water, organic solvents, and ionic liquids or on the surface of materials. Additionally, vibrational spectroscopy allows for the in situ detection and real-time monitoring of chemical reactions involving uranium. Finally, techniques to enhance uranium species signals with vibrational modes are discussed to expand the application of vibrational spectroscopy to biological, environmental, inorganic, and materials scientists and engineers.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Food adulteration, commonplace throughout human history, remains a concern today, with several notable instances involving the agro-food industry.
In this review, we introduce four vibrational ...spectroscopic techniques (near-infrared, mid-infrared, Raman spectroscopy, and hyperspectral imaging) for the determination of food authenticity and adulteration. The characteristics and applications of these techniques, along with the major barriers and limitations, are discussed, with an emphasis on the treatment of spectral data using chemometrics.
Vibrational spectroscopic techniques have potential to fulfill the industrial need for food quality and authenticity analysis, however, still requires measurement accessories and dynamic chemomatric analytical methods for modern food inspection. We believe this review will be an effective guide for food industry researchers and engineers to aid in the selection of spectroscopic methods to analyze food quality and authenticity.
•Reviewed food quality and authenticity analysis with four spectroscopic techniques.•Increasing concern with existing analytical methods is considered.•Developments and fundamental concepts of spectroscopic techniques are discussed.•The limitations and constraints of the spectroscopic techniques are presented.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The plant cell wall is a dynamic network of several biopolymers and structural proteins including cellulose, pectin, hemicellulose and lignin. Cellulose is one of the main load bearing components of ...this complex, heterogeneous structure, and in this way, is an important regulator of cell wall growth and mechanics. Glucan chains of cellulose aggregate via hydrogen bonds and van der Waals forces to form long thread-like crystalline structures called cellulose microfibrils. The shape, size, and crystallinity of these microfibrils are important structural parameters that influence mechanical properties of the cell wall and these parameters are likely important determinants of cell wall digestibility for biofuel conversion. Cellulose-cellulose and cellulose-matrix interactions also contribute to the regulation of the mechanics and growth of the cell wall. As a consequence, much emphasis has been placed on extracting valuable structural details about cell wall components from several techniques, either individually or in combination, including diffraction/scattering, microscopy, and spectroscopy. In this review, we describe efforts to characterize the organization of cellulose in plant cell walls. X-ray scattering reveals the size and orientation of microfibrils; diffraction reveals unit lattice parameters and crystallinity. The presence of different cell wall components, their physical and chemical states, and their alignment and orientation have been identified by Infrared, Raman, Nuclear Magnetic Resonance, and Sum Frequency Generation spectroscopy. Direct visualization of cell wall components, their network-like structure, and interactions between different components has also been made possible through a host of microscopic imaging techniques including scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. This review highlights advantages and limitations of different analytical techniques for characterizing cellulose structure and its interaction with other wall polymers. We also delineate emerging opportunities for future developments of structural characterization tools and multi-modal analyses of cellulose and plant cell walls. Ultimately, elucidation of the structure of plant cell walls across multiple length scales will be imperative for establishing structure-property relationships to link cell wall structure to control of growth and mechanics.
The liquid binary system of aniline (ANL) and chloroform (CHL) was discovered to form aggregates at a nano-size level responsible for the peculiar trends of some physico-chemical properties, ...reflected in morphology. The density and viscosity were recorded in the temperature range from 273.15 K to 313.15 K at ten different molar fractions. While the correlation of viscosity and density with molar fraction indicated a modest deviation from ideality, the excess molar volume values derived from density values exhibited a large discrepancy from the directly measured results, suggesting the potential aggregation leading to local inhomogeneity of mixtures’ concentration. On the other hand, FT-IR and Raman spectra showed no significant frequency shift both for N-H stretching on ANL and C-H stretching vibration on CHL upon mixing, in agreement with quantum mechanical calculations, which revealed the presence of a few complexes with stoichiometry ANL:CHL = 1:2 and 2:2, formed through CH···π interactions. The nano-scale morphology was characterised using the dynamic light scattering (DLS) method and SEM imaging. The calculated molecular electrostatic potential (MEP) of complexes indicated the capability for further association among complexes or between complexes and ANL or CHL molecules to form larger aggregates. For the first time, nano-sized aggregates were spotted for a liquid binary system made of small-sized organic molecules (solvents) using the combination of thermodynamic measurement, vibrational spectroscopy, quantum mechanical calculations and SEM imaging.
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•Nonideal surface tension, viscosity and density of aniline-chloroform binary mixtures.•CH•••π interactions and sigma-holes revealed by DFT calculations.•Concentration inhomogeniety was identified due to aggregation.•Nanosize aggregation was characterised using scanning electron microscope.
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Chemometric models for multicomponent mixture analysis are reliant upon representative and accurate training data. However, the required amount of training data can increase exponentially with the ...number of constituents. Shifting spectral baselines and changing process objectives may necessitate recurring calibration data collection. Furthermore, all possible constituents may not be known prior to analysis. Here, we introduce a preprocessing procedure that reduces the burden of collecting extensive calibration datasets by filtering out non-target species (species that are not part of the calibration data) in real-time. The method, nonnegatively constrained classical least squares (NCCLS), utilizes a spectral nonnegativity constraint on non-target species to remove them from mixture spectra. The preprocessing method is physically motivated, does not rely on time-series data, and can operate in real-time. NCCLS is compared to established methods using in silico data and an experimental dataset comprised of Raman spectra and attenuated total reflectance - Fourier transform infrared spectra.
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•Composition estimation from spectral data in a complex mixture is challenging.•A nonnegativity constraint on the spectral contribution from each species is used.•The spectral contribution of unknown species can be removed using this constraint.•This new method performs best for real-time estimation and overlapping peaks.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
New crystal, (E)-N’-(4-(dimethylamino)benzylidene)-5-methyl-1H-pyrazole-3-carbohydrazide (3) has been synthesized and characterized by FT-IR, NMR, ESI-MS and single crystal X-ray diffraction (XRD). ...The optimized molecular structures of free base and cationic species of (3) in gas phase and aqueous solution, vibrational frequencies and, corresponding vibrational assignments have been investigated experimentally and theoretically by using the B3LYP/6-31G∗ and B3LYP/6–311++G∗∗ methods. High solvation energy values are observed for both species of (3) in solution while the NBO and AIM studies support the higher stability of the cationic species in solution. The high energy values ΔEσ→σ∗ and ΔEσ→π∗ transitions, due to the planarity of both CH3 groups linked to N atom, could support the high reactivities of its free base and cationic species, as compared with naloxone, cocaine and scopolamine. Complete vibrational assignments of 105 and 108 vibration modes expected for free base and cationic species of (3) together with the corresponding harmonic force constants are here reported. In vitro antidiabetic and antioxidant activities were revealed for (3). The molecular docking studies of the title compound revealed that it may exhibit anti-diabetic activity via inhibition of α-glucosidase PDB:3A4A enzyme.
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•A new pyrazole derivative was synthesized and characterized by spectroscopic methods.•Two species of new derivative were studied theoretically in gas phase and aqueous solution.•NBO and AIM studies support the higher stability of the cationic species in solution.•Complete vibrational assignments for both species and the force constants are reported.•The anti-diabetic and antioxidant activities were tested, and Molecular docking studies were carried.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Dark orange and highly explosive: The cover figure displays the structure of cation‐poor BaAu‐(N3)42⋅4 H2O, containing tetraazidoaurate(III)anions with a novel geometry and gold in a square‐planar ...coordination of nitrogen. Depicted IR and Raman spectra confirm both the anion geometry and the existence of hydrogen bonds. More information can be found in the Research Article by S. Afyon, P. Höhn and co‐workers (DOI: 10.1002/chem.202203501).
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Vibrational circular dichroism (VCD) spectroscopy was used by Boris J. Nachtsheim, Christian Merten et al. in their Communication (e202204624) to verify DFT‐calculated chiral iodane structures. Based ...on a chiral triazole‐substituted iodoarene catalyst, a yet undescribed cationic chiral iodane was elucidated as the most populated intermediate under oxidative conditions with a significant intermolecular N–I interaction.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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