Reaction Monitoring Research Articles

Synthesis, Characterization, Anti-Inflammatory, and Antimicrobial Evaluation of New 2-Pyrazolines Derivatives Derived from Guaiacol

Abstract:
 Chalcones were used to synthesis series of 2-pyrazoline derivatives and evaluated their antimicrobial and anti-inflammatory activities
 (E)-1,3-diphenylprop-2-en-1-one (1-5) were synthesized by Claisen-Schmidt Condensation method through the reaction of acetophenone with five various para substituted benzaldehyde in presence of KOH, the reaction monitoring by TLC and the result intermediates were checked by melting point and FT-IR
 Various 2-Pyrazoline derivatives were prepared by one pot reaction that involved the refluxing of (E)-1,3-diphenylprop-2-en-1-one (1–5) and Hydrazine monohydrate in the presence of glacial acetic acid for 24 hours at a temperature of (45–50) °C for a duration 24 hrs. pyrazoline II (1-5) was formed, then antioxidant compound (guaiacol) was added reflex for 24-48 hours, monitoring by TLC to ensure the reaction was completed. The final mixture was cooled in ice-water bathe until the formation of crystals were completed, added to crushed ice, kept in refrigerator overnight, filter, recrystallized and then dried to get 2-pyrazoline derivatives, IIIa, IIIb, IIIc, IIId and, IIIe. based on the spectral data 2-pyrazoline derivatives structures have been confirmed. The synthesized compounds were screened for their antimicrobial activity and anti-inflammatory.

Acid-Catalyzed Etherification of Glycerol with Tert-Butanol: Reaction Monitoring through a Complete Identification of the Produced Alkyl Ethers

Higher tert-Butyl glycerol ethers (tBGEs) are interesting glycerol derivatives that can be produced from tert-butyl alcohol (TBA) and glycerol using an acid catalyst. Glycerol tert-butylation is a complex reaction that leads to the formation of five tBGEs (two monoethers, two diethers, and one triether). In order to gain insight into the reaction progress, the present work reports on the monitoring of glycerol etherification with TBA and p-toluensulfonic acid (PTSA) as homogeneous catalysts. Two analytical techniques were used: gas chromatography (GC), which constitutes the benchmark method, and 1H nuclear magnetic resonance (1H NMR), whose use for this purpose has not been reported to date. A method for the quantitative analysis of tBGEs and glycerol based on 1H NMR is presented that greatly reduced the analysis time and relative error compared with GC-based methods. The combined use of both techniques allowed for a complete quantitative and qualitative description of the glycerol tert-butylation progress. The set of experimental results collected showed the influence of the catalyst concentration and TBA/glycerol ratio on the etherification reaction and evidenced the intrinsic difficulties of this process to achieve high selectivities and yields to the triether.

RdRp activity test using CRISPR/Cas13a enzyme (RACE) for screening of SARS-CoV-2 inhibitors

The coronavirus disease 2019 pandemic has highlighted the need for efficient antiviral drug screening technologies, particularly for targeting RNA-dependent RNA polymerase (RdRp). Here, we present a novel RdRp activity assay using the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 13a (Cas13a) enzyme (RACE) for screening of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) inhibitors. This is the first application of the CRISPR/Cas complex for RdRp activity-based drug screening. The RACE system combines RdRp, RNA template, target inhibitor, CRISPR/Cas13a, and reporter probe, enabling accurate detection of the inhibitory effect on RdRp activity. This is demonstrated by the system's ability to provide half-maximal inhibitory concentration values of 7.5 ± 0.5 and 8.9 ± 0.6 μM for remdesivir triphosphate and C646, respectively. In addition, the RACE system requires a detection time of 5 min, making it more efficient than traditional endpoint assays. The real-time fluorometric output of the RACE system allows monitoring of reactions, providing insight into the kinetics of RdRp activity. Furthermore, the versatility of the RACE system extends to lateral flow assay formats, improving convenience. We anticipate that the RACE system has the potential to identify antiviral compounds that target RdRp, thereby accelerating the development of effective antiviral therapies.

Nonlinear multispectral tomographic absorption deflection spectroscopy based on Bayesian estimation for spatially resolved multiparameter measurement in methane flame exhaust

In aerospace propulsion systems with high temperature, pressure, and distortion, inhomogeneous thermophysical gradients can cause line-of-sight deflection and spectral integral deviation. This introduces nonlinearity and measurement error into spectral models, impacting multiparameter field measurements. To address this, we developed a nonlinear multispectral tomographic absorption deflection spectroscopy (MTADS) technique, based on Bayesian inference, for temperature and gas concentration prediction. Our forward model considers inhomogeneous refractive index gradient and laser deflection, synthesising multispectral laser absorption signal through a gas mixing equation and multipoint ray tracing. Simulation results reveal inhomogeneous parameter distribution can cause non-Gaussian and non-zero mean deviations of the spectral absorption signal. The inverse model increases spectral lines to expand measurement signals under sparse optical arrangements. Combining the measured laser absorption signal with Bayesian statistical information of the estimated parameter field improves measurement robustness and accuracy. The maximum a posteriori (MAP) estimation introduces priors such as experiment samples, computational fluid dynamics data, and diffusive transport-induced spatial smoothing. A proof-of-concept based on methane diffusion flame data demonstrates the effectiveness of MTADS, enabling quantitative flame topology and parameter distribution, more accurate 2D temperature, and concentration imaging. These measurements are crucial for revealing chemical reaction dynamics and monitoring combustion systems.

Recent developments in capillary and microchip electroseparations of peptides (2021-mid-2023).

This review article brings a comprehensive survey of developments and applications of high-performance capillary and microchip electromigration methods (zone electrophoresis in a free solution or in sieving media, isotachophoresis, isoelectric focusing, affinity electrophoresis, electrokinetic chromatography, and electrochromatography) for analysis, micropreparation, and physicochemical characterization of peptides in the period from 2021 up to ca. the middle of 2023. Progress in the study of electromigration properties of peptides and various aspects of their analysis, such as sample preparation, adsorption suppression, electroosmotic flow regulation, and detection, are presented. New developments in the particular capillary electromigration methods are demonstrated, and several types of their applications are reported. They cover qualitative and quantitative analysis of synthetic or isolated peptides and determination of peptides in complex biomatrices, peptide profiling of biofluids and tissues, and monitoring of chemical and enzymatic reactions and physicochemical changes of peptides. They include also amino acid and sequence analysis of peptides, peptide mapping of proteins, separation of stereoisomers of peptides, and their chiral analyses. In addition, micropreparative separations and physicochemical characterization of peptides and their interactions with other (bio)molecules by the above CE methods are described.

PRUNE1 (located on chromosome 1q21.3) promotes multiple myeloma with 1q21 Gain by enhancing the links between purine and mitochondrion.

Patients with multiple myeloma (MM) with chromosome 1q21 Gain (1q21+) are clinically and biologically heterogeneous. 1q21+ in the real world actually reflects the prognosis for gain/amplification of the CKS1B gene. In this study, we found that the copy number of prune exopolyphosphatase 1 (PRUNE1), located on chromosome 1q21.3, could further stratify the prognosis of MM patients with 1q21+. Using selected reaction monitoring/multiple reaction monitoring (SRM/MRM) analysis, liquid chromatography-tandem mass spectrometry (LC-MS/MS), transmission electron microscopy (TEM), confocal fluorescence microscopy, calculation of adenosine triphosphate (ATP), intracellular reactive oxygen species (ROS) and mitochondrial oxygen consumption rates (OCRs), we demonstrated for the first time that PRUNE1 promotes the proliferation and invasion of MM cells by stimulating purine metabolism, purine synthesis enzymes and mitochondrial functions, enhancing links between purinosomes and mitochondria. SOX11 was identified as a transcription factor for PRUNE1. Through integrated analysis of the transcriptome and proteome, CD73 was determined to be the downstream target of PRUNE1. Furthermore, it has been determined that dipyridamole can effectively suppress the proliferation of MM cells with high-expression levels of PRUNE1 in vitro and in vivo. These findings provide insights into disease-causing mechanisms and new therapeutic targets for MM patients with 1q21+.

Chemistry of Gold(III) with a Pyridine-Oxaziridine Ligand: Competition between C-O and N-O bond Activation.

The oxaziridine derivative 2-t-butyl-3-(2-pyridinyl)oxaziridine reacted with Na[AuCl4].2H2O to give, after recrystallization from a solvent mixture containing methanol, a mixture of gold(III) complexes which were characterized crystallographically as the amide complex [AuCl2{k2-N,N'-2-C5H4NC(=O)N(t-Bu)] and the aldolate complex [AuCl2{k2-N,O-2-C5H4NCH(OMe)O)]. It is suggested that these products arise after initial O-N or C-N bond cleavage respectively of the strained oxaziridine ring, after coordination to the gold(III) center. Monitoring of reactions by NMR spectroscopy showed that O-N bond cleavage of the oxaziridine ring was favoured in the presence of a protic solvent.

A plasmonic MOFs/Ag nanostructure for in-situ SERS monitoring of plasmon-mediated chemical reactions

Plasmon-mediated chemical reactions (PMCRs) are considered as promising methods for promoting photo-driven chemical reactions by using solar energy. In this work, metal–organic frameworks (MOFs; HKUST-1) /Ag NPs substrate was feasibly prepared by electrodeposition method and electrostatic adsorption, and it was applied for in-situ monitoring of PMCRs from 4-nitrobenzenethiol (4-NBT) to 4, 4′-dimercaptoazobenzene (DMAB). By conducting in-situ surface enhanced Raman spectroscopy (SERS), the HKUST-1/Ag NPs substrate was proved performing efficient localized surface plasmon resonance (LSPR) effect. Surprisingly, higher efficiency of plasmon catalytic reaction was observed comparing with traditional Ag substrate, which was benefited from the adsorption capacity and stabilization effect of HKUST-1. Thus, the reaction mechanism testified by using the high efficiency HKUST-1/Ag NPs substrate, and a novel route monitoring the plasmon catalytic reaction was further offered.

An Improved Synthesis of PN-adamantanoid Cages P4(NR)6 and a Mechanistic Study of their Fourfold Oxidation.

Phosphorus-nitrogen (PN) adamantanoid cages are valuable precursors for materials chemistry, but their syntheses are based on harsh methods that sometimes require access to restricted reagents. We report a new and scalable synthesis of PN adamantanoid compounds by chlorosilane elimination between bis-silylated amines and phosphorus trichloride. We further study the mechanism of the recently-reported four-fold oxidation of such cages with Me3SiN3 to yield tetravalent tetrahedral connectors for materials chemistry. Reaction monitoring and kinetic modelling revealed the key rate limiting step, but attempts to accelerate this using Lewis acid additives were unsuccessful. Nevertheless, a new four-fold oxidized PN-adamantanoid cage has been prepared and structurally characterized.

In-situ real-time monitoring of chemical kinetics by an automated micro-reaction device

Chemical kinetics plays an important role in the fields of chemical synthesis, pharmaceutical, environmental protection, and the study of related detection technology and devices is of great significance. This study presents an automated micro-reaction device capable of performing automated injection, reaction, and in-situ real-time monitoring of product concentration to analyze chemical kinetics. By designing microfluidic chips with micropore and microchannel structures, the device can precisely control the mixing of the reactants (µL scale) with one click and monitor the whole reaction process from time zero. Compared to traditional point-based detection methods, this device can obtain kinetic information of reaction rate, reaction order, and product concentration with micro samples under conditions where the equation of the chemical reaction is unknown, while avoiding errors caused by manual operation during the reaction process. The experimental results demonstrate that the device’s ability to accurately detect both spontaneous and excited fluorescence products, with a minimum detection unit of 0.0217 g/mL. This study realized the monitoring of chemical reactions with fast reaction rates, small reactant volumes, and complex reaction processes. It provides a feasible method and reliable equipment for tracing complex reactions in medicine, chemical industry, and environmental fields.

In Situ Electrical Detection of Methane Oxidation on Atomically Thin IrO2 Nanosheet Films Down to Room Temperature

AbstractActivation of the CH bond is the first step in converting methane into valuable chemicals. Herein, the successful induction and electrical detection of a methane oxidation reaction are reported at room temperature using IrO2 nanosheets, a 2D form of IrO2. A clear decrease in electrical resistance upon exposure to methane is observed by using atomically thin IrO2 nanosheet films. The resistance decrease disappears upon simultaneous exposure to oxygen, suggesting that methane is oxidized by consuming the lattice oxygen of the IrO2 nanosheets and that the oxygen vacancies generated are recovered by oxygen in the atmosphere. The resistance decrease is observed even at 300 K, indicating the high methane oxidation ability of the IrO2 nanosheets. These results are confirmed by a shift of the Ir 4f peaks in ambient pressure X‐ray photoelectron spectra. Furthermore, deposition of amorphous carbon, that is, methane oxidation products, on IrO2 nanosheets is also confirmed by Raman scattering spectroscopy after prolonged methane exposure at high temperatures in the absence of oxygen. This study demonstrates the ability of IrO2 nanosheets to oxidize methane at least down to 300 K and is an important example of the usefulness and simplicity of chemical reaction monitoring using electrical resistance changes.

ATR-FTIR and chemometric method for the detection of pig-based derivatives in food products - A review

The authentication of halal products is important, especially for Muslim communities. Based on the Islamic perspective, pig-based derivatives such as pork, lard, and gelatine are considered haram, which is an Arabic term for “forbidden”. Therefore, it is important to develop an analytical method for identifying and quantifying these compounds, which are sometimes found in some food products. The present work thus aimed to ascertain the potential of the attenuated total reflectance Fourier-transform infrared (ATR-FTIR) method for detecting pig-based derivatives in food products. ATR-FTIR spectrophotometry is recommended to be used to identify the presence of pig-based derivatives in some products, particularly processed food. In analytical chemistry, the method is generally used for the identification, characterisation, structure explanation, and monitoring of reactions. This analysis can be performed quickly, economically, easily, and does not require complicated sample preparation. ATR-FTIR can also be combined with principal component analysis (PCA), chemometric method, and multivariate partial least squares (PLS) calibration to accurately evaluate pig-based derivatives in beef meatballs. In combination with chemometric techniques, it can also provide the predictive and descriptive modelling in a combination with chemometric techniques by selecting the optimal frequency region. Furthermore, ATR-FTIR spectroscopy coupled with PLS and PCA chemometric regression models can be a potentially reliable, accurate, and precise method for determining pig-based derivatives in food.

Voltage Modulation of Nanoplasmonic Metal Luminescence from Nano-Optoelectrodes in Electrolytes.

Metallic nanostructures supporting surface plasmon modes can concentrate optical fields and enhance luminescence processes from the metal surface at plasmonic hotspots. Such nanoplasmonic metal luminescence contributes to the spectral background in surface-enhanced Raman spectroscopy (SERS) measurements and is helpful in bioimaging, nanothermometry and chemical reaction monitoring applications. Although there is growing interest in nanoplasmonic metal luminescence, its dependence on voltage modulation has received limited attention in research investigations. Also, the hyphenated electrochemical surface-enhanced Raman spectroscopy (EC-SERS) technique typically ignores voltage-dependent spectral background information associated with nanoplasmonic metal luminescence due to limited mechanistic understanding and poor measurement reproducibility. Here, we report a combined experiment and theory study on dynamic voltage-modulated nanoplasmonic metal luminescence from hotspots at the electrode-electrolyte interface using multiresonant nanolaminate nano-optoelectrode arrays. Our EC-SERS measurements under 785 nm continuous wavelength laser excitation demonstrate that short-wavenumber nanoplasmonic metal luminescence associated with plasmon-enhanced electronic Raman scattering (PE-ERS) exhibits a negative voltage modulation slope (up to ≈30% V-1) in physiological ionic solutions. Furthermore, we have developed a phenomenological model to intuitively capture the plasmonic, electronic, and ionic characteristics at the metal-electrolyte interface to understand the observed dependence of the PE-ERS voltage modulation slope on voltage polarization and ionic strength. The current work represents a critical step toward the general application of nanoplasmonic metal luminescence signals in optical voltage biosensing, hybrid optical-electrical signal transduction, and interfacial electrochemical monitoring.

Epoxidation of Methyl Esters as Valuable Biomolecules: Monitoring of Reaction

The paper is focused on the epoxidation of methyl esters prepared from oil crops with various profiles of higher fatty acids, especially unsaturated, which are mainly contained in the non-edible linseed and Camelina sativa oil (second generation). The novelty consists in the separation and identification of all products with oxirane ring formed through a reaction and in the determination of time course. Through the epoxidation, many intermediates and final products were formed, i.e., epoxides with different number and/or different position of oxirane rings in carbon chain. For the determination, three main methods (infrared spectroscopy, high-pressure liquid chromatography and gas chromatography with mass spectrometry) were applied. Only gas chromatography enables the separation of individual epoxides, which were identified on the base of the mass spectra, molecule ion and time course of products. The determination of intermediates enables: (i) control of the epoxidation process, (ii) determination of the mixture of epoxides in detail and so the calculation of selectivity of each product. Therefore, the epoxidation will be more environmentally friendly especially for advanced applications of non-edible oil crops containing high amounts of unsaturated fatty acids.

Castor oil‐based UV‐curable polyurethane acrylate resins for digital light processing (DLP) 3D printing technology

AbstractIn this work, a novel UV‐curable polyurethane acrylate (PUA) oligomer was developed from castor oil (CO). Reaction monitoring and structures of the PUA oligomer were characterized by Fourier transform infrared (FTIR) and 1H nuclear magnetic resonance (NMR). Subsequently, a series of UV‐curable resins were prepared by combining PUA with different reactive diluents, and their effect on thermal and mechanical properties was investigated. From the overall characterization trend, it was observed that the formulation containing trimethylolpropane triacrylate (TMPTA) showed the highest mechanical strength and thermal stability. Whereas the formulation containing isobornyl acrylate (IBOA) showed the least performance, and dipropyleneglycol diacrylate (DPGDA) showed properties ranging between TMPTA and IBOA. Furthermore, incorporating 1% TiO2 into the formulation increases the resin's viscosity and mechanical properties without disturbing its thermal stability. This work offered a simple method to prepare vegetable oil‐based high‐performance PUA resins that could be used in the 3D printing industry for general‐purpose prototyping applications to make architectural models, automotive components, and medical components.

Real-Time Pyruvate Chemical Conversion Monitoring Enabled by PHIP.

In recent years, parahydrogen-induced polarization side arm hydrogenation (PHIP-SAH) has been applied to hyperpolarize [1-13C]pyruvate and map its metabolic conversion to [1-13C]lactate in cancer cells. Developing on our recent MINERVA pulse sequence protocol, in which we have achieved 27% [1-13C]pyruvate carbon polarization, we demonstrate the hyperpolarization of [1,2-13C]pyruvate (∼7% polarization on each 13C spin) via PHIP-SAH. By altering a single parameter in the pulse sequence, MINERVA enables the signal enhancement of C1 and/or C2 in [1,2-13C]pyruvate with the opposite phase, which allows for the simultaneous monitoring of different chemical reactions with enhanced spectral contrast or for the same reaction via different carbon sites. We first demonstrate the ability to monitor the same enzymatic pyruvate to lactate conversion at 7T in an aqueous solution, in vitro, and in-cell (HeLa cells) via different carbon sites. In a second set of experiments, we use the C1 and C2 carbon positions as spectral probes for simultaneous chemical reactions: the production of acetate, carbon dioxide, bicarbonate, and carbonate by reacting [1,2-13C]pyruvate with H2O2 at a high temperature (55 °C). Importantly, we detect and characterize the intermediate 2-hydroperoxy-2-hydroxypropanoate in real time and at high temperature.

Monolayer Iron Oxychloride with a Resonant Band Structure for Ultrasensitive Molecular Sensing.

Two-dimensional layered materials (2DLMs) are expected to be next-generation commercial sensors for surface-enhanced Raman scattering (SERS) sensing owing to their unique structural features and physicochemical properties. The low sensitivity and poor universality of 2DLMs are the dominant barriers toward their practical applications. Herein, we report that monolayer iron oxychloride (FeOCl) with a naturally suitable band structure is a promising candidate for ultrasensitive SERS sensing. The generally boosted Raman scattering cross section of different analyte-FeOCl systems benefits from the resonant photoinduced charge transfer processes and strong ground-state interactions. In addition, the strong adsorption ability of monolayer FeOCl is crucial for rapid detection in practical applications, which is proven to be much better than those of conventional SERS sensors. Consequently, monolayer FeOCl enables diverse SERS applications, including multicomponent analysis, chemical reaction monitoring, and indirect ion sensing.

Thermochromic Photonic Crystal Microspheres with Uniform Color Display and Wide Coloration Range.

Thermochromic microspheres based on poly(N-isopropylacrylamide) attract much attention in detection and sensor due to the noticeable color response and fast response rate. However, some issues such as uneven color display and narrow coloration range still limit their practical applications. Herein, novel thermochromic microspheres with homogeneous color displays and wide thermochromic range are designed by combining the microfluidic technology with the magnetically-induced self-assembly technique and copolymerizing acrylamide (AM) with N-isopropylacrylamide. The photonic crystal structure with especially even colors is fast and conveniently constructed by magnetic assembly. The addition of AM makes the microspheres more hydrophilic and thus leading to a broader coloration range. The relationship between the structural color display and both the microstructures of photonic crystals and the thermo-responsive properties of gel matrix are elucidated. The detectable temperature of microspheres rises to as high as 60°C, and displays bright iridescent color variations from orange to blue-violet in the heating process. Importantly, their shrinking or swelling equilibrium can be reached in 80 and 105 s. Such microspheres are successfully used to visually indicate the appropriate temperature of enzymatic reaction, and have great potential in practical applications such as visual temperature detection and efficiency monitoring of chemical reactions.

In situ spatiotemporal characterization and analysis of chemical reactions using an ATR-integrated microfluidic reactor.

Determining kinetic reaction parameters with great detail has been of utmost importance in the field of chemical reaction engineering. However, commonly used experimental and computational methods however are unable to provide sufficiently resolved spatiotemporal information that can aid in the process of understanding these chemical reactions. With our work, we demonstrate the use of a custom designed single-bounce ATR-integrated microfluidic reactor to obtain spatiotemporal resolution for in situ monitoring of chemical reactions. Having a single-bounce ATR accessory allows us to individually address different sensing areas, thereby providing the ability to obtain spatially and temporally resolved information. To further enhance the spatial resolution, we utilize the benefits of synchrotron IR radiation with the smallest beam spot-size ∼150 μm. An on-flow modular microreactor additionally allows us to monitor the chemical reaction in situ, where the temporal characterization can be controlled with the operational flowrate. With a unique combination of experimental measurements and numerical simulations, we characterize and analyse a model SN2 reaction. For a chemical reaction between benzyl bromide (BB) and sodium azide (SA) to produce benzyl azide (BA), we successfully show the capability of our device to determine the diffusion coefficients of BB and SA as 0.367 ± 0.115 10-9 m2 s-1 and 1.17 ± 0.723 10-9 m2 s-1, respectively. Finally, with the above characteristics of our device, we also calculate a reaction rate of k = 0.0005 (m3s-1mol-1) for the given chemical reaction.

Surface functionalized 3D printed metal structures as next generation recyclable SERS substrates.

Combining the design flexibility and rapid prototyping capabilities of additive manufacturing with photocatalytic and plasmonic functionalities is promising for the development of next-generation SERS applications such as point of care diagnostics and in situ monitoring of chemical reactions in fuels and chemical processing. Laser powder bed fusion (LPBF) is a well-matured additive manufacturing technique which generates metallic structures through localised melting and joining of metal powders using a laser. LPBF reduces material wastage during manufacturing, is applicable to a wide range of metals and alloys, and allows printing of complex internal structures. This feature article elaborates the use of soot templating, chemical vapour deposition and electroless plating techniques for grafting plasmonic and semiconductor nanoparticles on the surface of LPBF manufactured metallic substrates. The capability to fabricate different types of intricate metallic lattices using additive manufacturing is demonstrated and technical challenges in their adequate functionalization are elaborated. The developed methodology allows tailoring of the substrate structure, composition, morphology, plasmonic and photocatalytic activities and thus unveils a new class of recyclable SERS substrates.