Room Temperature Research Articles

Organocatalytic Dearomatization of 5-Aminopyrazoles: Synthesis of 4-Hydroxypyrazolines.

Dearomatization is a fundamental chemical reaction that affords complex three-dimensional heterocyclic frameworks. We disclose the first organocatalytic dearomatization of 5-aminopyrazoles, which yields a range of structurally diversified C4-hydroxylated pyrazolines with yields of ≤95% in <1.5 h at room temperature. This catalytic process is achieved using in situ-generated hypervalent iodine. The method also yields a spirolactone via an intramolecular dearomatization process. Furthermore, we demonstrate that substrate-directed reduction of the resulting iminopyrazoline leads to 4,5-difunctionalized pyrazoline as a single diastereomer. Mechanistic studies suggest that the reaction proceeds through a dearomatized cationic intermediate.

LsFUL–LsSMU2 module positively controls bolting time in leaf lettuce (Lactuca sativa L.) under high temperature

High temperature (HT) is an environmental factor that considerably affects plant physiology, development, crop yield, and economic value. HT can cause diseases and early bolting of leaf lettuce, thereby reducing the yield and quality of leaf lettuce. Herein, we used two leaf lettuce (Lactuca sativa L.) cultivars (bolting-resistant ‘S24’ and bolting-sensitive ‘S39’) to investigate the key factors and molecular mechanism impacting bolting. We found that 14 MADS-box genes implicated in bolting and flowering, LsMADS54 (also referred to as L. sativa FRUITFULL, LsFUL), was significantly up-regulated 1,000 times after 5-d HT treatment and that HT-induced up-regulation of LsFUL was higher in bolting-sensitive than in resistant cultivars. The overexpression lines of LsFUL exhibited an earlier bolting time than that in the non-transformed ‘S39’(CK). However, the RNA interference, and CRISPR-Cas9-mediated knockout lines of LsFUL exhibited a later bolting time than that in CK. In addition, we found that L. sativa SUPPRESSORS OF MEC-8 AND UNC-52 PROTEIN 2 (LsSMU2) and L. sativa CONSTANS-LIKE PROTEIN 5 (LsCOL5) interact with LsFUL, and these interactions could stimulate or prevent bolting. We observed that elevated temperature stimulated the abundance of LsSMU2 in the stem, which collaborated with LsFUL to accelerate bolting. Conversely, room temperature (RT) condition led to relatively more stable LsCOL5, which worked with LsFUL to postpone bolting. In summary, our findings demonstrate a molecular regulatory module of LsSMU2–LsFUL associated with HT-induced premature bolting, which serves as a reference for understanding HT-induced premature bolting phenomenon in leaf lettuce.

Electrochemical and structural performances of carbon and glass fiber-reinforced structural supercapacitor composite at elevated temperatures

The structural supercapacitor can store electrical energy and withstand structural loads while saving substantial weight in many structural applications. This study investigated the development of a structural supercapacitor with a fiber-reinforced polymer composite system and explored the operating temperature’s influence on its performance. The electrochemical and mechanical properties of structural supercapacitors beyond the ambient temperature have not yet been studied; hence, evaluating parameters such as specific capacitance, energy density, cycle life, and structural performance at elevated temperatures are highly desired. We have designed and manufactured single and parallelly connected multilayer structural supercapacitor composites in this research. Carbon fibers were used as a bifunctional component, acting both as a current collector while acting as a mechanical reinforcement. In addition, glass fibers were added as the separator which is also acting as an integral reinforcement. The electrochemical and mechanical behavior of structural supercapacitors at elevated temperatures up to 85 °C were experimentally investigated. The test results revealed that at room temperature, the developed double-cell structural supercapacitor, which demonstrated an area-specific capacitance of 1.16 mF cm−2 and energy density of 0.36 mWh cm−2 at 0.24 mA cm−2, which are comparable to current achievements in structural supercapacitor research. The structural supercapacitor’s tensile, flexural, and compression strengths were measured as 109.5 MPa, 47.0 MPa, and 50.4 MPa, respectively. The specific capacitance and energy density reached 2.58 mF cm−2 and 0.81 mWh cm−2, while tensile, flexural, and compression strengths were reduced to 70.9 MPa, 14.2 MPa, and 8.8 MPa, respectively, at 85 °C. These findings provide new comprehensive knowledge on structural supercapacitor devices suitable for applications operating within a temperature range from ambient conditions to 85 °C.

Adsorption performance and its mechanism of uranium using rod-like hydroxyapatite by one-step hydrothermal method

Rod-like Hydroxyapatite (HAP) was synthesized using a one-step hydrothermal method. The successful synthesis of HAP has been confirmed based on the results of XRD and EDS. TEM images show that the HAP synthesized through the one-step hydrothermal method exhibits a rod-like morphology with good dispersion and minimal stacking. There was no significant aggregation observed and the diameter is about 25 nm. Both single-factor experiments and orthogonal experiments were conducted to determine the optimal conditions for adsorbing uranium from wastewater with an initial concentration of 10 mg·l−1. The optimized parameters included a pH of 5.0, a HAP dosage of m = 0.01 g, a reaction time of t = 30 min, a temperature at room temperature, and an agitation speed of R = 120 r·min−1. Under these conditions, the uranium removal efficiency exceeded 98%. The impact of anions and cations in the solution on uranium adsorption by HAP was investigated, revealing that cations with higher valence and anions with higher charge density had a more pronounced effect on the adsorption process. The fitting results obtained using adsorption isotherm and kinetic models indicated that the primary mechanism of uranium adsorption was surface monolayer chemical adsorption. Thermodynamic parameters suggested that the adsorption of uranium onto HAP was a spontaneous, endothermic process driven by entropy. Characterization results from EDS, XRD, FTIR, and XPS techniques indicated that the mechanism of uranium adsorption by HAP involved electrostatic adsorption, dissolution–precipitation, and ion exchange processes.

Palladium nanoparticles anchored on NiO particles-modified micro-size chitosan spheres: A promising, active, and retrievable catalyst system for treatment of environmental pollutants

Efficient treatment of toxic organic pollutants in water/wastewater by using innovative, cost efficient, and simple technologies has recently become an important issue worldwide. Remediation of these pollutants with chemical reduction in the presence of a nano-sized catalyst and a reducing agent is one of the most useful methodologies. In the present study, we have designed a promising heterogeneous catalyst system (Pd@CS-NiO) by easy and efficient stabilization of palladium nanoparticles on the surface of microspheres composed of chitosan-NiO particles (CS-NiO) for the reduction of organic pollutants. The nano-structure of the developed Pd@CS-NiO was successfully validated using FE-SEM, XRD, EDS, TEM, and ATR-FTIR and its particles size was determined as 10 nm. The catalytic power of Pd@CS-NiO was then assessed in the reduction of 4-nitro-o-phenylenediamine (4-NPDA), 4-nitrophenol (4-NP), 4-nitroaniline (4-NA), 2-nitroaniline (2-NA), and some organic dyes, namely methylene blue (MB), methyl orange (MO), and rhodamine B (RhB) in aqueous medium at room temperature. The reductions were thoroughly studied spectro-photometrically. The tests displayed that the synthesized Pd@CS-NiO was a highly active and useful catalyst that reduced these pollutants in 0–145 s. Moreover, the rate constants for 2-NA, 4-NP, 4-NA, 4-NPDA, MO, and RhB were found to be 0.017 s−1, 0.011 s−1, 0.006 s−1, 0.013 s−1, 0.023 s−1, and 0.03 s−1, respectively. Moreover, the recycling test indicated that Pd@CS-NiO may be recovered easily thanks to its micro size nature and could be used up to seven steps, confirming its practical application potential.

Spatially Confined Engineering Toward Deep Eutectic Electrolyte in Metal-Organic Framework Enabling Solid-State Zinc-Ion Batteries.

Uncontrollable interfacial side reactions generated from common aqueous electrolytes, just like the hydrogen evolution reaction (HER) and dendrite growth, have severely prevented the practical application of zinc-ion batteries (ZIBs). Solid-state ZIBs are considered to be an efficient strategy by adopting high-quality solid-state electrolytes (SSEs). Here, by confining the deep eutectic electrolyte (DEE) into the nanochannels of the metal-organic framework (MOF)-PCN-222, a stable DEE@PCN-222 SSE with internal Zn2+ transport channels was obtained. A distinctive ion-transport network composed of DEE and PCN-222 in the interior of DEE@PCN-222 realizes the efficient Zn2+ conduction, contributing to a high ionic conductivity of 3.13 × 10-4 S cm-1 at room temperature, a low activation energy of 0.12 eV, and a high Zn2+ transference number of 0.76. Furthermore, experimental and theoretical investigations demonstrate that DEE@PCN-222 with its unique channel structure could homogeneously regulate the Zn2+ distribution and effectively alleviate the side reactions. Highly reversible Zn plating/stripping performance of 2476 h can be realized by the SSE. The solid-state ZIBs show a specific capacity of 306 mAh g-1 and display cycling stability of 517 cycles. This unique design concept provides a new perspective in realizing the high-safety and high-performance ZIBs.

The Gas Phase Protonation Sites of Six Naturally Occurring Nicotinoids.

The gas phase protonation sites of six naturally occurring nicotinoids, namely nicotine (NIC), nornicotine (NOR), anabasine (ANB), anatabine (ANT), cotinine (COT), and myosmine (MYO), consisting of a common Pyridine and differing non-Pyridine rings, have been determined for the first time at the physiological temperature from cryogenic ion trap infrared spectroscopy and electronic structure calculations. The protonation site on either of these two rings is related to the nicotinoid's biological activity. At room temperature, NIC is a mixture of Pyridine and Pyrrolidine (non-Pyridine) protomers, whereas NOR, ANB, ANT, and COT are pure Pyridine protomers and finally MYO is mostly a Pyroline (non-Pyridine) protomer. The nearly planar structure of MYO-H+, induced by the presence of a conjugated π system and confirmed from calculations and the UV absorption spectra, breaks from the trends observed for NIC, NOR, and ANB, since its structure is drastically different from the structures of the other nicotinoids.

Straightforward Access to Isoindoles and 1,2-Dihydrophthalazines Enabled by a Gold-Catalyzed Three-Component Reaction.

We describe herein a gold-catalyzed three-component reaction of o-alkynylbenzaldehydes, aryldiazonium salts, and trimethoxybenzene. This process enables the one-pot formation of valuable isoindoles and 1,2-dihydrophathalazines. The regioselectivity of the reaction is dictated by the nature of the aryldiazonium salt. Noticeably, the reaction is performed at room temperature under mild conditions and tolerates a variety of functional groups on both the o-alkynylbenzaldehyde and the aryldiazonium salt. Experimental mechanistic studies suggest that it is catalyzed by arylAu(III) species.

Broadband terahertz frequency-domain emission spectroscopy of DAST with a widely tunable quasi-monochromatic source and sensitive up-conversion detection

A continuous 4–32 THz emission spectrum of organic crystal DAST is obtained through a widely tunable quasi-monochromatic terahertz source and sensitive up-conversion detection. The spectrum is characterized by a frequency resolution of ∼0.05 THz and a highest signal-to-noise ratio of ∼65 dB. Terahertz signals are detectable at room temperature even in the high absorption regions of DAST, thus most of the absorption peaks of DAST are clearly located. The results verify the findings of previous works well, including density functional theory calculations and other similar experiments. This paper provides a highly sensitive instrument for broadband terahertz spectroscopic characterization.

Lewis Acid-Mediated Isothiocyanation and Chlorination of Quinoxalin-2(1H)-ones under Visible Light Conditions.

Lewis acid-mediated selective C3-isothiocyanation of quinoxalin-2(1H)-ones using N-thiocyanatosaccharin as an isothiocyanate source under visible light conditions at room temperature is described. Under similar conditions with N-chlorosaccharin, the C3-chlorination of quinoxalin-2(1H)-ones achieved a 2 h time frame. Good to an excellent yield of products was obtained in both cases with broad functional group tolerance. Control experiments suggest that the reaction proceeds through a radical mechanism. The present procedure demonstrates the applicability at gram-scale reactions and highlights the subsequent conversion of isothiocyanates into representative thiourea derivatives, and one of the chloro derivatives transformed to glycogen phosphorylase inhibitors.

Low-Temperature Decomposition and Oxidation of the Nerve Agent Simulant on Mesoporous Nickel Oxide and Cu-Doped Nickel Oxide.

In an effort to develop the next frontier filtration material for chemical warfare agent (CWA) decomposition, we synthesized mesoporous NiO and CuxNi1-xO (x = 0.10 and 0.20) and studied the decomposition of CWA simulant diisopropyl fluorophosphate (DIFP) on their surfaces. Mesoporous NiO and CuxNi1-xO were fully characterized and found to be a solid solution with no phase separation up to 20% copper dopant. The synthesized materials were successfully templated producing ordered mesoporous metal oxides with high surface areas (67.89- 94.38 m2/g). Through Raman spectroscopy, we showed that pure NiO contained a high concentration of Ni2+ vacancies, while Cu2+ reduced these defects. Through in situ infrared spectroscopy, we determined the surface species formed, potential pathways, and driving factors for decomposition. Upon exposure of DIFP, all materials produced similar decomposition products CO, CO2, carbonyls, and carbonates. However, decomposition reactions were sustained longer on mesoporous NiO, facilitated by the higher Ni2+ vacancy concentration. NiO was further studied with DIFP, first at low dosing temperatures (-50 °C), which still resulted in the production of CO and carbonates, and then, second, with a higher pretreatment temperature, which showed the importance of terminal hydroxyls/water to fully oxidize decomposition products to CO2. Mesoporous NiO demonstrated high decomposition and oxidation capabilities at temperatures below room temperature, all without any external excitation or noble metals, making it a promising frontier filtration material for CWA decomposition.

Why are clams steamed with wine in Mediterranean cuisine?

Wine is renowned for its rich content of polyphenols, including resveratrol (Res), known for their health promoting properties. Steamed clam with wine, a popular Mediterranean delicacy that highlights the role of wine as a key ingredient. However, despite these benefits, resveratrol’s low bioavailability poses challenges. Could the process of steaming together with clam alter the digestive fate of resveratrol from wine? This study explores the potential of proteoglycan-based nanoparticles from freshwater clam (CFNPs) as a delivery vehicle for enhancing the stability and bioavailability of resveratrol, compared with wine and free Res’ solution, aiming to elucidate mechanisms facilitating Res’ absorption. The results demonstrated that CFNPs can effectively encapsulate Res with an efficiency over 70%, leading to a uniform particle size of 70.5±0.1 nm (PDI < 0.2). Resveratrol loaded in CFNPs (CFNPs-Res) exhibited an improved antioxidant stability under various conditions, retaining over 90% of antioxidant capacity after three-day storage at room temperature. The controlled-release profile of Res loaded in CFNPs fits both first and Higuchi order kinetics and was more desirable than that of wine and the free Res. Examined by the simulated gastrointestinal digestion, CFNPs-Res showed a significantly higher bioaccessibility and antioxidant retention compared to free Res and the wines. The discovery and use of food derived nanoparticles to carry micronutrients and antioxidants could lead to a shift in functional food design and nutritional advice, advocating much more attention on these entities over solely conventional molecules.

A family of Cd(II) coordination polymers constructed from 6-aminopicolinate and bipyridyl co-linkers: study of their growth in paper and photoluminescence sensing of Fe3+ and Zn2+ ions.

In this work, we report on five novel coordination polymers (CPs) based on the linkage of the [Cd(6apic)2] building block [where 6apic = 6-aminopicolinate] by different bipyridine-type organic spacers, forming different coordination compounds with the following formulae: [Cd(μ-6apic)2]n (1), {[Cd(6apic)2(μ-bipy)]·H2O}n (2), {[Cd(6apic)2(μ-bpe)]·2H2O}n (3), [Cd(6apic)(μ-6apic)(μ-bpa)0.5]n (4) and {[Cd2(6apic)4(μ-tmbp)]·7H2O}n (5) [where bipy = 4,4'-bipyridine, bpe = 1,2-di(4-pyridyl)ethylene, bpa = 1,2-di(4-pyridyl)ethane (bpa) and tmbp = 1,3-di(4-pyridyl)propane]. Most of the synthesized compounds form infinite metal-organic rods through the linkage of the building block by the bipyridine-type linker, except in the case of compound 4 whose assembly forms a densely packed 3D architecture. All compounds were fully characterized and their photoluminescence properties were studied experimentally and computationally through density functional theory (DFT) calculations. All compounds display, upon UV excitation, a similar blue emission of variable intensity depending on the linker employed for the connection of the building units, among which compound 2 deserves to be highlighted for its room temperature phosphorescence (RTP) with an emission lifetime of 32 ms that extends to 79 ms at low temperature. These good photoluminescence properties, in addition to its stability in water over a wide pH range (between 2 and 10), motivated us to study compound 2 as a sensor for the detection of metal ions in water, and it showed high sensitivity to Fe3+ through a fluorescence turn-off mechanism and an unspecific turn-on response to Zn2+. Furthermore, the compound is processed as a paper-based analytical device (PAD) in which the phosphorescence emission is preserved, improving the sensing capacity toward Fe3+ ions.

Room Temperature Emission Line Narrowing and Long‐Range Photon Transport in Colloidal Quantum Wells Coupled to Metasurface Resonance

Room Temperature Emission Line Narrowing and Long‐Range Photon Transport in Colloidal Quantum Wells Coupled to Metasurface Resonance

Research Progress of ARTP Mutagenesis Technology Based on Citespace Visualization Analysis.

Atmospheric and room temperature plasma (ARTP) mutagenesis technology has been developed rapidly in recent years because of its simple operation, safety, environmental friendliness, high mutation rate, and large mutation library capacity. It has been widely used in traditional fields such as food, agriculture, and medicine, and has been gradually applied in emerging fields such as environmental remediation, bioenergy, and microalgae utilization. In this paper, the Web of Science Core Collection (WOSCC) was used as the data source, and the keywords and core literature of ARTP mutagenesis technology were plotted by citespace software, and the research progress and research hotspots of ARTP mutagenesis technology were analyzed. Through citespace visualization analysis, it is concluded that the country with the largest number of studies is China, the institution with the largest number of studies is Jiangnan University, and the author of the most published papers is Jiangnan University. Through keyword analysis, it is concluded that the most widely used ARTP mutagenesis technology is fermentation-related majors, mainly for biosynthesis and microbial research at the molecular level. Among them, the most widely used microorganisms are Escherichia coli and Saccharomyces cerevisiae.

Highly efficient storage of cavity SPDC single photons in room temperature gradient echo memory

Highly efficient storage of cavity SPDC single photons in room temperature gradient echo memory

Resonance-Induced Dynamic Triplet Exciton Population for Photoactivated Organic Ultralong Room Temperature Phosphorescence.

Dynamically populating triplet excitons under external stimuli is desired to develop smart optoelectronic materials, but it remains a formidable challenge. Herein, we report a resonance-induced excited state regulation strategy to dynamically modulate the triplet exciton population by introducing a self-adaptive N-C═O structure to phosphors. The developed phosphors activated under high-power ultraviolet irradiation exhibited enhanced photoactivated organic ultralong room temperature phosphorescence (PA-OURTP) with lifetimes of up to ∼500 ms. The enhanced PA-OURTP was ascribed to activated N-C═O resonance variation-induced intersystem crossing to generate excess triplet excitons. The excellent PA-OURTP performance and ultralong deactivation time under ambient conditions of the developed materials could function as a reusable recorded medium for time-sensitive information encryption through optical printing. This study provides an effective approach to dynamically regulating triplet excitons and offers valuable guidance to develop high-performance PA-OURTP materials for security printing applications.

Research Progress on Ammonia Sensors Based on Ti3C2Tx MXene at Room Temperature: A Review

Ammonia (NH3) potentially harms human health, the ecosystem, industrial and agricultural production, and other fields. Therefore, the detection of NH3 has broad prospects and important significance. Ti3C2Tx is a common MXene material that is great for detecting NH3 at room temperature because it has a two-dimensional layered structure, a large specific surface area, is easy to functionalize on the surface, is sensitive to gases at room temperature, and is very selective for NH3. This review provides a detailed description of the preparation process as well as recent advances in the development of gas-sensing materials based on Ti3C2Tx MXene for room-temperature NH3 detection. It also analyzes the advantages and disadvantages of various preparation and synthesis methods for Ti3C2Tx MXene’s performance. Since the gas-sensitive performance of pure Ti3C2Tx MXene regarding NH3 can be further improved, this review discusses additional composite materials, including metal oxides, conductive polymers, and two-dimensional materials that can be used to improve the sensitivity of pure Ti3C2Tx MXene to NH3. Furthermore, the present state of research on the NH3 sensitivity mechanism of Ti3C2Tx MXene-based sensors is summarized in this study. Finally, this paper analyzes the challenges and future prospects of Ti3C2Tx MXene-based gas-sensitive materials for room-temperature NH3 detection.

Solidify Eutectic Electrolytes via the Added MXene as Nucleation Sites for a Solid-State Zinc-Ion Battery with Reconstructed Ion Transport.

Stationary energy storage infrastructure based on zinc-ion transport and storage chemistry is attracting more attention due to favorable metrics, including cost, safety, and recycling feasibility. However, splitting water and liquid electrolyte fluidity lead to cathode dissolution and Zn corrosion, resulting in rapid attenuation of the capacity and service life. Herein, a new architecture of solid-state electrolytes with high zinc ionic conductivity at room temperature was prepared via solidification of deep eutectic solvents utilizing MXene as nucleation additives. The ionic conductivity of MXene/ZCEs reached 6.69 × 10-4 S cm-1 at room temperature. Dendrite-free Zn plating/stripping with high reversibility can remain for over 2500 h. Subsequently, the fabricated solid-state zinc-ion battery with eliminated HER and suppressed Zn dendrites exhibited excellent cycling performance and could work normally in a range from -10 to 60 °C. This design inspired by eutectic solidification affords new insights into the multivalent solid electrochemistry suffering from slow ion migration.

Detection of ethanol gas at room temperature by In2O3-based screen-printed films fabricated through particle-free aqueous solution combustible inks

Abstract The current work investigates the room temperature ethanol gas detection capabilities of pristine, Sn doped, Zn doped, Sn &amp; Zn co-doped In2O3-based screen-printed films that are developed using particle-free aqueous solution combustible inks. The fabricated films were pure, polycrystalline with cubic bixbyite crystal structure, porous, and transparent (~75 to 95 % in the visible range). High surface roughness was detected in pristine film than in doped films. Ethanol gas of 50 to 100 ppm concentration was traced by all the films at room temperature. Among all, the pristine film showed a greater gas response at all concentrations of ethanol gas, and it was because of high oxygen vacancy concentration (OV/OL) and more relative area fraction of adsorbed oxygen (% of OA). Diminished amounts of OV/OL and % of OA caused a relatively low gas response in the doped films. The maximum ethanol gas response was discerned to be 17.3 at 100 ppm by the pristine film. The demonstrated film was also highly selective towards ethanol gas.