42,666 results on '"FUNCTIONAL groups"'
Search Results
2. Water structures in tip-charged carbon nanotubes.
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Ono, Yûi, Yamamoto, Eiji, and Yasuoka, Kenji
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NANOFLUIDIC devices , *ELECTRIC fields , *MEMBRANE separation , *HELICAL structure , *FUNCTIONAL groups , *CARBON nanotubes - Abstract
Carbon nanotubes (CNTs) have potential applications in separation membranes and nanofluidic devices. It is well known that the behavior of water molecules confined in CNTs is affected by surface functional groups and external electric fields, leading to structural changes. The understanding of these structural changes of water within various CNTs is crucial, particularly in the context of material separation. While there have been many investigations into the effects of individual specific functional groups, a comprehensive understanding of the effect of these functional groups and the electric fields they generate on water molecules remains elusive. In this study, we investigate the properties of water molecules in tip-charged CNTs of (8,8), (10,10), and (12,12) chiral vectors with positive charges at one tip and negative charges at the other tip. Abstraction of ionized functional groups as tip charges enables a comprehensive understanding that is independent of individual functional groups. The symmetrically arranged tip-charges spontaneously generate a strong and symmetric electric field in the CNTs. However, the strength and directionality of the electric field are non-uniform and complex. In the interiors of (8,8) and (10,10) tip-charged CNTs, helical and square structures, which have disturbances caused by the non-uniformity of the electric field, are observed. The properties of the water molecules differed significantly in the center of the CNTs and near positive and negative charges, despite the electric field symmetry. In (12,12) tip-charged CNTs with 12 charges, a local ring structure is observed in the vicinity of negative charges but not in the vicinity of positive charges. It is concluded that the water structures in tip-charged CNTs have different characteristics from those in plain CNTs under a uniform electric field. [ABSTRACT FROM AUTHOR]
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- 2024
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3. KeldyshQFT: A C++ codebase for real-frequency multiloop functional renormalization group and parquet computations of the single-impurity Anderson model.
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Ritz, Nepomuk, Ge, Anxiang, Walter, Elias, Aguirre, Santiago, von Delft, Jan, and Kugler, Fabian B.
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RENORMALIZATION group , *ANDERSON model , *STATISTICAL correlation , *DATA structures , *FUNCTIONAL groups - Abstract
We provide a detailed exposition of our computational framework designed for the accurate calculation of real-frequency dynamical correlation functions of the single-impurity Anderson model in the regime of weak to intermediate coupling. Using quantum field theory within the Keldysh formalism to directly access the self-energy and dynamical susceptibilities in real frequencies, as detailed in our recent publication [Ge et al., Phys. Rev. B 109, 115128 (2024)], the primary computational challenge is the full three-dimensional real-frequency dependence of the four-point vertex. Our codebase provides a fully MPI+OpenMP parallelized implementation of the functional renormalization group (fRG) and the self-consistent parquet equations within the parquet approximation. It leverages vectorization to handle the additional complexity imposed by the Keldysh formalism, using optimized data structures and highly performant integration routines. Going beyond the results shown in the previous publication, the code includes functionality to perform fRG calculations in the multiloop framework, up to arbitrary loop order, including self-consistent self-energy iterations. Moreover, implementations of various regulators, such as hybridization, interaction, frequency, and temperature, are supplied. [ABSTRACT FROM AUTHOR]
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- 2024
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4. Tuning structural and electronic properties of metal-organic framework 5 by metal substitution and linker functionalization.
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Edzards, Joshua, Saßnick, Holger-Dietrich, Andreo, Julia Santana, and Cocchi, Caterina
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METAL-organic frameworks , *ALKALINE earth metals , *ENERGY conversion , *VALENCE bands , *FUNCTIONAL groups , *METALS - Abstract
The chemical flexibility of metal-organic frameworks (MOFs) offers an ideal platform to tune structure and composition for specific applications, from gas sensing to catalysis and from photoelectric conversion to energy storage. This variability gives rise to a large configurational space that can be efficiently explored using high-throughput computational methods. In this work, we investigate from first principles the structural and electronic properties of MOF-5 variants obtained by replacing Zn with Be, Mg, Cd, Ca, Sr, and Ba and by functionalizing the originally H-passivated linkers with CH3, NO2, Cl, Br, NH2, OH, and COOH groups. To build and analyze the resulting 56 structures, we employ density-functional theory calculations embedded in an in-house developed library for automatized calculations. Our findings reveal that structural properties are mainly defined by metal atoms and large functional groups, which distort the lattice and modify coordination. The formation energy is largely influenced by functionalization and enhanced by COOH and OH groups, which promote the formation of hydrogen bonds. The charge distribution within the linker is especially influenced by functional groups with electron-withdrawing properties, while the metal nodes play a minor role. Likewise, the bandgap size is crucially determined by ligand functionalization. The smallest gaps are found with NH2 and OH groups, which introduce localized orbitals at the top of the valence band. This characteristic makes these functionalizations particularly promising for the design of MOF-5 variants with enhanced gas uptake and sensing properties. [ABSTRACT FROM AUTHOR]
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- 2024
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5. ManyHF-based full-dimensional potential energy surface development and quasi-classical dynamics for the Cl + CH3NH2 reaction.
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Szűcs, Tímea and Czakó, Gábor
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POTENTIAL energy surfaces , *ENERGY development , *COLLISION broadening , *ENERGY transfer , *FUNCTIONAL groups - Abstract
A full-dimensional spin–orbit (SO)-corrected potential energy surface (PES) is developed for the Cl + CH3NH2 multi-channel system. Using the new PES, a comprehensive reaction dynamics investigation is performed for the most reactive hydrogen-abstraction reactions forming HCl + CH2NH2/CH3NH. Hartree–Fock (HF) convergence problems in the reactant region are handled by the ManyHF method, which finds the lowest-energy HF solution considering several different initial guess orbitals. The PES development is carried out with the Robosurfer program package, which iteratively improves the surface. Energy points are computed at the ManyHF-UCCSD(T)-F12a/cc-pVDZ-F12 level of theory combined with basis set (ManyHF-RMP2-F12/cc-pVTZ-F12 – ManyHF-RMP2-F12/cc-pVDZ-F12) and SO (MRCI+Q/aug-cc-pwCVDZ) corrections. Quasi-classical trajectory simulations show that the CH3-side hydrogen abstraction occurs more frequently in contrast to the NH2-side reaction. In both cases, the integral cross sections decrease with increasing collision energy (Ecoll). A reaction mechanism shifting from indirect to direct stripping can be observed from the opacity functions, scattering angle, and translation energy distributions as Ecoll increases. Initial attack angle distributions reveal that chlorine prefers to abstract hydrogen from the approached functional group. The collision-energy dependence of the product energy distributions shows that the initial translational energy mainly transfers to product recoil. The HCl vibrational and rotational energy values are comparable and nearly independent of collision energy, while the CH2NH2 and CH3NH co-products' vibrational energy values are higher than the rotational energy values with more significant Ecoll dependence. The HCl(v = 0) rotational distributions are compared with experiment, setting the direction for future investigations. [ABSTRACT FROM AUTHOR]
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- 2023
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6. Isolation of sulfate polysaccharides (Ulvan) from the green algae of Ulva lactuca and characterization of its functional groups.
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Khaerunnisa, Mira, Arfah, Rugaiyah A., and Permatasari, Nur Umriani
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GREEN algae , *HYDROCHLORIC acid , *FUNCTIONAL groups , *ULVA , *SUGAR , *POLYSACCHARIDES - Abstract
Ulvan is a water-soluble polysaccharide containing a sulfate group isolated from Ulva, a green alga with unique structural properties and the potential to be developed in biomaterials supported by biological activities such as antioxidant, antibacterial, anticoagulant and immunomodulatory. This research aims to isolate ulvan from Ulva lactuca and to study the characteristic of the ulvan functional groups. The methods used were extraction with hydrochloride acid 0.1 M and precipitation using ethanol 96% to obtain a percent yield of ulvan. The ulvan structure was characterized by UV-Vis and FTIR spectrophotometry. The amount of sugar was determined using phenol-sulfuric acid method. The results showed the yield of ulvan produced about 23.34% at maximum UV-Vis wavelength of 205 nm and the FTIR spectra significant at 854.47-1097.50 cm−1 of sulphated polysaccharides region. The sugar content of the isolated ulvan which extracted using hydrochloric acid 0.1 M was 1.4124 mg/mL. [ABSTRACT FROM AUTHOR]
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- 2024
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7. Tuning the crystallization and thermal properties of polyesters by introducing functional groups that induce intermolecular interactions.
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Sangroniz, Leire, Jang, Yoon-Jung, Hillmyer, Marc A., and Müller, Alejandro J.
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POLYESTERS , *INTERMOLECULAR interactions , *FUNCTIONAL groups , *THERMAL properties , *CRYSTALLIZATION , *CRYSTALLIZATION kinetics , *THERMOPHYSICAL properties - Abstract
The performance of sustainable polymers can be modified and enhanced by incorporating functional groups in the backbone of the polymer chain that increases intermolecular interactions, thus impacting the thermal properties of the material. However, in-depth studies on the role of intermolecular interactions on the crystallization of these polymers are still needed. This work aims to ascertain whether incorporating functional groups able to induce intermolecular interactions can be used as a suitable systematic strategy to modify the polymer thermal properties and crystallization kinetics. Thus, amide and additional ester groups have been incorporated into aliphatic polyesters (PEs). The impact of intermolecular interactions on the melting and crystallization behavior, crystallization kinetics, and crystalline structure has been determined. Functional groups that form strong intermolecular interactions increase both melting and crystallization temperatures but retard the crystallization kinetics. Selecting appropriate functional groups allows tuning the crystallinity degree, which can potentially improve the mechanical properties and degradability in semicrystalline materials. The results demonstrate that it is possible to tune the thermal transitions and the crystallization kinetics of PEs independently by varying their chemical structure. [ABSTRACT FROM AUTHOR]
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- 2023
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8. Enhanced interlayer adhesion of wetted graphene oxide by confined water bridge.
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Zhao, Yanyan, Zhou, Ke, and Liu, Yilun
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CONSTRUCTION materials , *MOLECULAR dynamics , *FUNCTIONAL groups , *HYDROGEN bonding , *ELECTRONIC equipment , *LAMINATED materials - Abstract
Graphene oxide (GO) sheets are widely used as building blocks in flexible electronic devices, structural materials, and energy storage technology owing to physicochemical flexibility and remarkable mechanical properties. GO exists as lamellar structures in these applications and, thus, it urges to enhance interface interaction to prevent interfacial failure. This study explores the adhesion of GO with and without intercalated water utilizing steered molecular dynamics (SMD) simulations. We find the interfacial adhesion energy (γ) depends on the synergistic effect of the types of functional groups, the degree of oxidation (c), and water content (wt). The intercalated monolayer water confined within GO flakes can improve the γ by more than 50% whereas the interlayer spacing is enlarged. The enhancement of adhesion is from the cooperative hydrogen bonding bridges between confined water and functional group on GO. Furthermore, the optimal water content wt = 20% and oxidation degree c = 20% are obtained. Our findings provide an experimentally available way to improve interlayer adhesion through molecular intercalation, which opens the possibility of high-performance laminate nanomaterial-based films for versatile applications. [ABSTRACT FROM AUTHOR]
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- 2023
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9. Effect of lubricant functional groups on tribological properties of epoxy/graphene composites.
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Zheng, Wenxuan, Zhang, Guoliang, Qi, Jian, Lu, Shichao, and Li, Yang
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DRY friction ,CARBOXYL group ,FUNCTIONAL groups ,OLEIC acid ,HYDROXYL group ,INTERFACIAL friction ,LUBRICATION & lubricants - Abstract
The functional group in the molecular chain of lubricants is a key factor for a boundary lubricating film, which can further enhance the friction performance by interfacial tribochemistry. In this paper, the tribological behavior of epoxy/graphene (EP/Gra) composites was investigated through varying lubrication conditions, including dry friction, or different lubricants (such as water, hexadecane, oleylamine, and oleic acid). The porosity and Shore hardness (SHD) of the EP composites were significantly improved by the addition of graphene. Results showed that the porosity of the EP/0.75 wt.% Gra composites was reduced by 75.6% and their SHD increased by 5.4 compared with the EP/0.05 wt.% Gra composites. The average coefficient of friction (COF) of the composites was reduced by at least 27.3% under dry friction conditions. For water as lubricant, the EP/0.5 wt.% Gra composite exhibited the lowest COF (0.0455). The EP/0.75 wt.% Gra composite displayed the lowest COF (0.0466) when hexadecane acted as lubricant. By contrast, EP/0.05 wt.% Gra showed the lowest COF (0.0389) with oleylamine as lubricant, and the EP/0.25 wt.% Gra composites gave the lowest COF (0.0433) under oleic acid. The amine group of oleylamine reacted with the EP group to form a hydroxyl group, resulting in a polymer with low friction adhered to the friction interface. Simultaneously, the EP group reacted with the carboxyl group, forming a network of hydrogen bonds with graphene, which reduced the shear stress on the friction interface. Therefore, the functional groups of lubricants have a vital influence on the tribological properties of frictional composites, which may provide a new approach to solving the problem of wear. [ABSTRACT FROM AUTHOR]
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- 2024
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10. Experimental investigation of the water bypass phenomenon in light oil reservoirs using a glass micromodel and sand cores with a hydrophobic material.
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Adjou, Zakaria, Dobbi, Abdelmadjid, and Hamid, Lebtahi
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OIL field flooding , *SILICA sand , *PETROLEUM reservoirs , *CORE materials , *CONTACT angle , *WETTING , *FUNCTIONAL groups - Abstract
A large volume of water is bypassing oil and comes up without being able to push it out from the reservoir after organic material adsorption. This work investigates hydrophobicity effect on rock wettability, oil recovery, and relative permeability. The μXRF was used to characterize sand cores, and a contact angle goniometer to determine fluids contact angle. Oil recovery was evaluated by measuring the incremental oil volume recovered in a glass and PVC capillary designed micromodel. Relative permeability was studied using the steady state method, and the wettability was determined by the Amott method. The results show that cores are mainly composed of quartz 86.04%. Oil recovery was 30.50% for oil-wet state; where the wettability index was −0.283. Thereafter, it has been demonstrated that the surfactant solution increases the oil recovery with 23.54 ℅. Adsorption of surfactants on functional groups of PVC change the contact angle between water and PVC's surface from 112° to 39°, decrease the IFT and restore the water-wet state. PVC debris presents efficient new method to determine the water by pass effect on oil recovery. The findings of this study help for better understanding the surfactant-oil displacements during water flooding in light oil reservoirs with impaired wettability. [ABSTRACT FROM AUTHOR]
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- 2024
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11. Photoredox‐Catalyzed Metal‐Free Regio‐ & Stereoselective C(sp2)–H Amination of Enamides with N‐Aminopyridium Salts.
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Qin, Zheng‐Bao, Ni, Kun, Wang, Li, Wu, Xiao‐Di, Zhang, Yu, and Zhao, Kai
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RADICALS (Chemistry) , *FUNCTIONAL groups , *AMINATION , *ENVIRONMENTAL economics , *CATALYSIS - Abstract
Comprehensive Summary: A visible‐light‐induced photoredox‐catalyzed regioselective and stereoselective C(sp2)–H amination of enamides with bench‐stable and easily accessible N‐aminopyridium salts is developed, affording synthetically and biologically prominent vicinal 1,2‐diamine scaffolds with broad substrate scope and excellent functional group compatibility. The transformation proceeded through a radical pathway involving the Giese addition of the relatively electrophilic N‐centered sulfonamidyl radical species to nucleophilic β‐olefinic position of enamides followed by the ensuing single electron oxidation and β‐H elimination, delivering geometrically‐defined Z‐configured β‐sulfonamidylated enamides. The operational simplicity, environmental friendliness and cost efficiency of this methodology allowed it to pave a new avenue to enrich the arsenal of synthetically crucial functionalized enamides and their related derivatives. [ABSTRACT FROM AUTHOR]
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- 2024
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12. Asymmetric Transfer Hydrogenation of Stable NH Imines for the Synthesis of Enantiopure α‐Chiral Primary Amines.
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Zhang, Mangang, Li, Hui, Wu, Keqin, Rong, Nianxin, Lin, Shaoquan, Yang, Hua, and Yin, Qin
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TRANSFER hydrogenation , *IMINES , *FUNCTIONAL groups , *AMINES , *ANILINE - Abstract
Comprehensive Summary: Although it offers a direct route to access synthetically valuable α‐chiral primary amines, asymmetric transfer hydrogenation of NH imines has been rarely studied, due in large part to the inaccessibility and instability of NH imines. Herein, we report a Rh‐catalyzed asymmetric transfer hydrogenation of a kind of novel and stable NH imines which are prepared via condensation of easily available sulfonylated 2'‐aminoacetophenones with NH3 in methanol. With this method, enantioenriched chiral 2‐(1‐aminoalkyl)anilines, which are privileged pharmacore groups, have been synthesized with good functional group compatibility, and with up to 99% ee. A gram‐scale reaction using 0.2 mol% of catalyst has been successfully performed to highlight the practicality. Furthermore, the products can be derivatized into enantiopure bioactive molecules as well as chiral tridentate ligands for metal catalysis. [ABSTRACT FROM AUTHOR]
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- 2024
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13. Enantioselective Alkylation of Aldehydes with Organoborons Enabled by Nickel/N‐Heterocyclic Carbene Catalysis†.
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Liu, Song‐Yang, Wang, Zi‐Chao, and Shi, Shi‐Liang
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LIGANDS (Chemistry) , *ALKYLATION , *FUNCTIONAL groups , *CHEMOSELECTIVITY , *ALDEHYDES - Abstract
Comprehensive Summary: Transition‐metal‐catalyzed asymmetric alkylation of aldehydes represents a straightforward strategy for the synthesis of chiral secondary alcohols. However, efficient methods using organoborons as coupling reagents are rare. Herein, we report a highly enantioselective nickel‐catalyzed alkylation reaction of aldehydes, using readily available alkylborons as nucleophiles. A wide variety of chiral secondary alcohols were prepared from commercially available aldehydes with high yields. The key to the excellent enantioselectivity and chemoselectivity was the employment of a bulky C2‐symmetric chiral NHC ligand. This protocol features excellent enantiocontrol, mild conditions, and good functional group compatibility. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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14. Nickel/Photoredox Dual Catalytic Chan‐Lam Coupling of Aryl Azides and Arylboric Acids.
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Ge, Xia, Ji, Haojie, and Lu, Hongjian
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COUPLING agents (Chemistry) , *DRUG synthesis , *CHARGE exchange , *ORGANIC synthesis , *FUNCTIONAL groups - Abstract
Comprehensive Summary: Unsymmetrical diarylamines are crucial components in many pharmaceuticals and functional materials. In this study, we introduce an efficient Chan‐Lam cross‐coupling method that utilizes phenylboronic acids and aryl azides as coupling agents in a redox‐neutral environment, enabled by a synergistic nickel/photoredox catalytic system. This approach leverages a proton‐coupled electron transfer mechanism to bypass the typical nitrene pathway associated with aryl azides, which is prone to intramolecular rearrangement, C—H amination, and reductive hydrogenation. Notably, our method exhibits broad compatibility with a variety of functional groups, including those derived from pharmaceuticals, demonstrating its versatile potential in organic synthesis and drug modification. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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15. Photoinduced Perfluoroalkyloximation of Alkenes with Simple Perfluoroalkyl Halides.
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Li, Wei, Li, Zhongji, Zhong, Deliang, Wang, Nianxing, and Li, Huaifeng
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DRUG synthesis , *FUNCTIONAL groups , *ALKENES , *INDOLE compounds , *OXIMES - Abstract
Comprehensive Summary: In this paper, the difunctionalizative perfluoroalkyloximation of alkenes has been developed for the first time. This photochemical method allows for the synthesis of various perfluoroalkyl ethanone oximes with excellent regioselectivity and good functional group tolerance. Our method employs the most common perfluoroalkyl source, perfluoroalkyl iodides, as Rf reagents. Besides long‐chain perfluoroalkyl groups, this approach could be extended to incorporating additional groups, including trifluoromethyl, difluoromethyl, sulfonyl, and malonate, selectively into olefins, resulting in a range of β‐substituted ethanone oximes. Notably, the potential of this method in the Fukuyama indole synthesis, generating novel 2‐perfluoroalkylated 3‐(α‐oximidobenzyl)indoles via a radical cascade mechanism with 2‐vinylphenylacryloyl isocyanate as the radical acceptor, presents a compelling avenue for drug synthesis. The protocol is efficient, scalable, and useful for late‐stage modification of bioactive molecules. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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16. Photocatalytic C(sp3)‐H gem‐Difluoroallylation and Alkylation with Alkenes via a Base‐Assisted Formal 1,2‐Hydrogen Atom Transfer of Amidyl Radicals.
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Tang, Meifang, Feng, Bingbing, Bao, Yanyang, Xu, Zhongtian, Huang, Chao, Zheng, Hanliang, Zhu, Gangguo, Wang, Yanan, and Yuan, Zheliang
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RADICALS (Chemistry) , *DENSITY functional theory , *FUNCTIONAL groups , *ALKENES , *PHOTOCATALYSIS - Abstract
Comprehensive Summary: Compared to well‐established 1,5‐HAT of N‐centered radicals, the synthetic applications of 1,2‐HAT process were scarce due to the high barrier and constrained three‐membered transition state. Here, we have developed a novel C(sp3)‐H gem‐difluoroallylation via a base assisted formal 1,2‐HAT of amidyl radicals with the reductive quenching cycle of photocatalyst. This transformation enables the efficient formation of α‐aminoalkyl radicals via 1,2‐HAT and showcases good functional group tolerance. Our preliminary mechanistic experiments, along with Density Functional Theory (DFT) calculations demonstrate the feasibility of 1,2‐HAT of amidyl radicals, especially when assisted by a base. Furthermore, our method also succeeds in the Giese addition of electron‐deficient alkenes as well as styrene. [ABSTRACT FROM AUTHOR]
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- 2024
- Full Text
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17. Enantioselective Alkylation of Aldehydes with Organoborons Enabled by Nickel/N‐Heterocyclic Carbene Catalysis†.
- Author
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Liu, Song‐Yang, Wang, Zi‐Chao, and Shi, Shi‐Liang
- Subjects
LIGANDS (Chemistry) ,ALKYLATION ,FUNCTIONAL groups ,CHEMOSELECTIVITY ,ALDEHYDES - Abstract
Comprehensive Summary: Transition‐metal‐catalyzed asymmetric alkylation of aldehydes represents a straightforward strategy for the synthesis of chiral secondary alcohols. However, efficient methods using organoborons as coupling reagents are rare. Herein, we report a highly enantioselective nickel‐catalyzed alkylation reaction of aldehydes, using readily available alkylborons as nucleophiles. A wide variety of chiral secondary alcohols were prepared from commercially available aldehydes with high yields. The key to the excellent enantioselectivity and chemoselectivity was the employment of a bulky C2‐symmetric chiral NHC ligand. This protocol features excellent enantiocontrol, mild conditions, and good functional group compatibility. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
18. Iodide ion-enabled highly regioselective α-C(sp3)–H triazolization of ethers with N-sulfonyl-1,2,3-triazoles.
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Deng, Yaqi, Yin, Jiabin, Hu, Zongjing, Xue, Jian, Ji, Jian, Zhu, Tong, and Liu, Shunying
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ETHERS , *RADICALS (Chemistry) , *IODIDES , *FUNCTIONAL groups , *CYCLIC ethers - Abstract
An efficient iodide ion (I−)-enabled method for direct α-C(sp3)–H triazolization of ethers via a radical cross-coupling has been developed for regioselective construction of N2-substituted hemiaminal ethers. The developed C(sp3)–H triazolization reaction features the resulting products in good yields (up to 90%) and an excellent functional group tolerance to various ethers, including cyclic and linear ethers. Preliminary mechanistic study and DFT calculation investigation indicate that the reaction proceeds via a SN2-like desulfonylation radical coupling process and an (I−)-involved ternary complex is responsible for the high conversion ratio and the high regioselectivity. I− not only promotes the process but also prevents the in situ generated carbon-centered radicals (CCRs) from being oxidized into carbon cations in an oxidative environment. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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19. Metal-free photoinduced generation and alkynylation of carbamoyl radicals: a facile synthesis of alkynyl amides.
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Duan, Yurong, Zhang, Kai, Xing, Tongtong, Bai, Yubin, Li, Jinfeng, Yang, Xiaojun, Zhao, Yu, and Zhang, Qiuyu
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AMIDE derivatives , *RADICALS (Chemistry) , *FUNCTIONAL groups , *NATURAL products , *BIOCHEMICAL substrates , *AMIDES - Abstract
A metal-free photoinduced alkynylation of carbamoyl radicals with hypervalent iodine(III) reagents for a facile synthesis of alkynyl amides is described. This protocol features good functional group tolerance and a broad substrate scope for direct synthesis of alkynyl amide derivatives in good to excellent yields under mild and redox-neutral reaction conditions. The synthetic application is demonstrated by the late-stage installation of alkynyl amides into natural products and active pharmaceutical relevant molecules. The mechanistic studies indicated the simultaneous existence of photoredox catalytic and direct photoexcited processes, and the quantum yields confirmed the occurrence of the radical chain propagation process. [ABSTRACT FROM AUTHOR]
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- 2024
- Full Text
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20. Pd-catalyzed CO-free double carbonylation for the synthesis of 1,4-ketoesters with Mo(CO)6 as the carbonyl source.
- Author
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Guo, Wenting, Gong, Houhong, Yuan, Wei, Zhou, Hualan, Tao, Li, and Zhu, Jing
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FUNCTIONAL groups , *MOLECULES , *CARBONYLATION - Abstract
An unprecedented Pd-catalyzed CO-free double carbonylation using Mo(CO)6 as a safe carbonyl source for the efficient synthesis of 1,4-ketoesters in an atom- and step-economic manner has been developed. The current method features operational safety, a wide substrate range, good functional group compatibility and easy scale-up. The application of carbonylation using a safe carbonyl source for the synthesis of biologically and synthetically useful carbonyl-containing molecules is underway in our lab. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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21. Synthesis of polysubstituted pyridazines via Cu-mediated C(sp3)–C(sp3) coupling/annulation of saturated ketones with acylhydrazones.
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Zhou, Honggui, Li, Zhefeng, Chen, Juehong, Zhou, Si, Wang, Xinyu, Zhang, Linwei, Chen, Jiuxi, and Lv, Ningning
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KETONES , *FUNCTIONAL groups , *CHEMOSELECTIVITY , *ANNULATION , *DERIVATIZATION , *PYRIDAZINES - Abstract
Pyridazine is a significant skeleton that widely exists in drugs and bioactive molecules. We herein describe expeditious approaches to access polysubstituted pyridazines from readily accessible unactivated ketones and acylhydrazones via Cu-promoted C(sp3)–C(sp3) coupling/cyclization sequences in a single-step fashion. Notably, the disparate 3,4,6-trisubstituted pyridazines and 3,5-disubstituted pyridazines could be obtained by tailoring the ketone's structure and reaction conditions. These transformations feature good functional group compatibility, excellent step-economy, and chemoselectivity. The potential synthetic utility of these conversions is illustrated by scale-up reactions and late-stage derivatizations of the as-prepared pyridazine products. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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22. 4,7-Substituted 1,10-phenanthroline-2,9-dicarboxamides: photophysics of ligands and their complexes with the Eu-Gd-Tb triad.
- Author
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Avagyan, Nane A., Lemport, Pavel S., Polikovskiy, Trofim A., Tsorieva, Alisia V., Metlin, Mikhail T., Taydakov, Ilya V., Zonov, Roman V., Lyssenko, Konstantin A., Vokuev, Mikhail F., Rodin, Igor A., Tarasevich, Boris N., Ustynyuka, Yuri A., and Nenajdenko, Valentine G.
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RARE earth metals , *LUMINESCENCE quenching , *ENERGY transfer , *CHARGE transfer , *FUNCTIONAL groups - Abstract
The impact of substituents at the 4- and 7-positions of 1,10-phenanthroline-2,9-dicarboxamides on the photophysical properties of the ligands and their coordination compounds with the lanthanide triad--europium, gadolinium, and terbium--was analyzed. This study demonstrates how modification of the electronic nature of ligands through the incorporation of diverse functional groups affects the luminescence properties of their complexes. The introduction of various substituents leads to the appearance of intra-ligand or ligand-to-ligand charge transfer (CT) states. The highest luminescence efficiency was observed for LH·Eu(NO3)3 (Qin = 54.1% and QL = 9.6%), suggesting strong luminescence quenching of the CT state. It was found that a relatively low ΔE (-3000 cm-1) supports direct energy transfer from S1 to T1 bypassing the CT state, even though it is outside Reinhoudt's optimal range. The introduction of fluorines leads to the strongest luminescence quenching among all the substituents. [ABSTRACT FROM AUTHOR]
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- 2024
- Full Text
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23. Palladium-catalyzed 1,1-aminoxylation of 3-butenoic acid with 2-alkynylanilines.
- Author
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Zhang, Jinhui, Mao, Lihua, Liu, Chao, Tan, Xiangwen, Wu, Jiahao, Wei, Xuefeng, Wu, Wanqing, and Jiang, Huanfeng
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ALKENES , *FUNCTIONAL groups , *INDOLE , *SKELETON , *ATOMS - Abstract
Herein, a palladium-catalyzed 1,1-aminoxylation of 3-butenoic acid and 2-alkynylanilines has been developed, achieving the installation of two distinct heteroatom motifs across an olefin skeleton. The strategy features a high step and atom economy and good functional group tolerance, which outlines an efficient approach for simultaneously building up γ-butylactone and indole skeletons. Notably, an external ligand, 2,9-dimethyl-1,10-phenanthroline, has been used to succeed in this protocol to effectively suppress the production of indole byproducts. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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24. Synthesis of Secondary Boronates via Deaminative Cross‐Coupling of Alkyl Nitroso Carbamates and Boronic Acids.
- Author
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Paul, Shashwati and Brown, M. Kevin
- Subjects
- *
BORONIC acids , *CARBAMATES , *FUNCTIONAL groups , *AMINO acids , *LYSINE , *AMINES - Abstract
A strategy for transition metal‐free cross‐coupling of alkyl nitroso‐carbamates and boronic acids is reported. The N‐nitroso carbamates are easily prepared from the corresponding amine in two simple steps. This method allows for the synthesis of a wide variety of secondary boronates, benzylic boronates and formal Csp3−Csp2 cross‐coupling products under operationally simple conditions. Functional group tolerance is also demonstrated and applied in the modification of lysine to make non‐canonical amino acids. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
25. The construction of novel pyrrole-4H-chromene-embedded vinyl sulfonyl fluorides via a three-component process.
- Author
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Ajisafe, Monday Peter, Fayad, Eman, Ali, Ola A. Abu, and Qin, Hua-Li
- Subjects
- *
PHARMACEUTICAL chemistry , *FUNCTIONAL groups , *FLUOROETHYLENE , *BIOCHEMICAL substrates , *PYRROLE derivatives , *FLUORIDES , *SULFONATES , *SULFONYL compounds - Abstract
A synthetic strategy involving salicylaldehyde, 2-chloroprop-2-ene-1-sulfonyl fluoride (CESF), and pyrrole has been developed to construct novel pyrrole-4H-chromene-embedded vinyl sulfonyl fluoride derivatives with exclusive regioselectivity. This method exhibits moderate to excellent yields (45–93%) and showcases a wide substrate scope with excellent functional group compatibility. Additionally, the resulting sulfonyl fluorides were further diversified via sulfur fluoride exchange (SuFEx) reactions to produce sulfonates and sulfonamides, which are valuable structural motifs in medicinal chemistry. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
26. Synthesis of tetralone and indanone derivatives via cascade reductive Friedel–Crafts alkylation/cyclization of keto acids/esters.
- Author
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Yadav, Naveen, Mahato, Rina, Khan, Jabir, Jaiswal, Harshit, and Hazra, Chinmoy Kumar
- Subjects
- *
KETONIC acids , *ALKYLATION , *ESTERS , *RING formation (Chemistry) , *FUNCTIONAL groups - Abstract
We disclose herein a metal-free cascade reductive Friedel–Crafts alkylation/cyclization of keto acids/esters for the synthesis of tetralones and indanones. Owing to the simple reaction conditions and setup, this protocol features broad substrate generality, facile scalability, and remarkable functional group tolerance, including the synthesis of bioactive molecule sertraline. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
27. Transition-metal free, radical oxidation of 1,6-enyne cyclopropanation: synthesis of aza-bicyclo[4.1.0]heptane derivatives.
- Author
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Meena, Shivam A., Thakur, Deepika, Nandy, Abhijit, Ranjan, Rahul, Rai, Anubhav, Banerjee, Shibdas, and Verma, Akhilesh K.
- Subjects
- *
CYCLOPROPANATION , *HEPTANE , *FUNCTIONAL groups , *BIOCHEMICAL substrates , *REAL-time control , *OXIDATION - Abstract
A straightforward transition-metal-free sustainable methodology for oxidative cyclopropanation of aza-1,6-enynes has been devised, enabling the synthesis of valuable, functionalized azabicyclo[4.1.0]heptane-2,4,5-triones, via four bond formation in a single step under mild conditions. Control experiments and real-time mass data monitoring using online ESI-MS spectroscopy support the pathway proposed for this reaction. The synthesized products have been utilized in diverse product transformations. Key advantages of this reaction include its operational ease, transition metal-free nature, rapid completion, and compatibility with a wide range of functional groups and substrates. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
28. Effects of clean fracturing fluids on coal microstructure and coalbed gas adsorption.
- Author
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Zhang, Qian, Cai, Feng, Xie, Haotian, and Fang, Yu
- Abstract
Nowadays, some fracking fluids can enable resourceful extraction of coalbed methane and reduce greenhouse gas emissions. However, their toxicity or corrosiveness will cause harm to downhole workers and pollute groundwater resources. Thus, five kinds of clean composite fracturing fluids were developed in this paper by using starch solution as the matrix and adding various preparations. The change rule of methane adsorption capacity by microstructure changes of coal samples was investigated systematically, and the optimal composite fracturing fluid was determined. The results showed that the new fracturing fluid increased the degree of aromatic ring condensation by 43.3% and the average pore size by 52.1%. Also, the adsorption constants of a value decreased by 11.6% and b value decreased by 23.9%, which can remarkably reduce the methane adsorption. The experimental results provide theoretical support for the clean production of coalbed methane. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
29. Theoretical and experimental investigation of the impact of oil functional groups on the performance of smart water in clay-rich sandstones.
- Author
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Kazemi, Alireza, Khezerloo-ye Aghdam, Saeed, and Ahmadi, Mohammad
- Subjects
- *
ELECTRIC double layer , *FUNCTIONAL groups , *PETROLEUM , *INTERFACIAL tension , *SANDSTONE - Abstract
This research investigated the effect of ion concentration on the performance of low salinity water under different conditions. First, the effect of injection water composition on interparticle forces in quartz-kaolinite, kaolinite-kaolinite, and quartz-oil complexes was tested and modeled. The study used two oil samples, one with a high total acid number (TAN) and the other with a low TAN. The results illustrated that reducing the concentration of divalent ions to 10 mM resulted in the electric double layer (EDL) around the clay and quartz particles and the high TAN oil droplets, expanding and intensifying the repulsive forces. Next, the study investigated the effect of injection water composition and formation oil type on wettability and oil/water interfacial tension (IFT). The results were consistent with the modeling of interparticle forces. Reducing the divalent cation concentration to 10 mM led to IFT reduction and wettability alteration in high TAN oil, but low TAN oil reacted less to this change, with the contact angle and IFT remaining almost constant. Sandpack flooding experiments demonstrated that reducing the concentration of divalent cations incremented the recovery factor (RF) in the presence of high TAN oil. However, the RF increment was minimal for the low TAN oil sample. Finally, different low salinity water scenarios were injected into sandpacks containing migrating fines. By comparing the results of high TAN oil and low TAN oil samples, the study observed that fine migration was more effective than wettability alteration and IFT reduction mechanisms for increasing the RF of sandstone reservoirs. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
30. Enhanced UV Nonlinear Optical Properties in Layered Germanous Phosphites through Functional Group Sequential Construction.
- Author
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Tian, Yao, Zeng, Wei, Dong, Xuehua, Huang, Ling, Zhou, Yuqiao, Zeng, Hongmei, Lin, Zhien, and Zou, Guohong
- Subjects
- *
FUNCTIONAL groups , *OPTICAL properties , *FREQUENCY changers , *PHOSPHITES , *COHERENCE (Optics) , *NONLINEAR optical spectroscopy - Abstract
This study pioneers a novel strategy for synthesizing solar‐blind ultraviolet (UV) nonlinear optical (NLO) crystals through functional groups sequential construction, effectively addressing the inherent trade‐offs among broad transmittance, enhanced second‐harmonic generation (SHG), and optimal birefringence. We have developed two innovative van der Waals layered germanous phosphites: GeHPO3, the first Ge(II)‐based oxide NLO crystal which exhibits a black phosphorus‐like structure, and K(GeHPO3)2Br, distinguished by its exceptional birefringence and graphene‐like structure. Significantly, GeHPO3 exhibits a remarkable array of NLO properties, including the highest SHG coefficient recorded among all NLO crystals for phase‐matching and generating 266 nm coherent light via quadruple frequency conversion. It delivers a potent SHG intensity, surpassing KH2PO4 (KDP) by 10.3 times at 1064 nm and β‐BaB2O4 by 1.3 times at 532 nm, complemented by a distinct UV absorption edge at 211 nm and moderate birefringence of 0.062 at 546 nm. Comprehensive theoretical analysis links these exceptional characteristics to the unique NLO‐active GeO34− units and the distinctive, highly ordered layered structures. Our findings deliver essential experimental insights into the development of Ge(II)‐based optoelectronic materials and present a strategic blueprint for engineering structure‐driven functional materials with customized properties. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
31. Novel Synthetic Industrial Approach for Efficient Synthesis of Baclofen through C–C Bond Formation.
- Author
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Raut, Changdev, Qureshi, Shafiya Kausar, Kadam, Nitin, Mungase, Kailas, Marepu, Nagaraju, Jagtap, Ashutosh, and Ambhaikar, Narendra
- Subjects
- *
BACLOFEN , *SPASTICITY , *CHLOROACETIC acids , *FUNCTIONAL groups , *SUSTAINABLE chemistry - Abstract
Baclofen is an active pharmaceutical ingredient used for the treatment of muscle spasticity. We describe our efforts to develop a novel synthetic approach through C–C bond formation and a cost-effective route to baclofen. The synthesis involved a two-step approach through C–C bond formation using the extensively and commercially available starting material 4-chlorobenzyl cyanide with chloroacetic acid as a reagent in an aprotic solvent, followed by reduction of the nitrile functional group. The synthetic route to baclofen has been demonstrated to be commercially viable, cost-effective, and environmentally friendly. Execution of the developed process led to the isolation of (+)-baclofen in an overall yield of 60% at a multikilogram scale with >99.5% HPLC purity. This article also discusses the cost-effectiveness of the process, the impurity profiling, and the product quality. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
32. Ag(I)-catalyzed asymmetric (2+4) annulation reaction of 5-alkenyl thiazolones: synthesis of enantioenriched spiro[cyclohexenamines-thiazolones].
- Author
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Choudhary, Kavita, Deshpande, Akanksha Santosh, and Singh, Vinod K.
- Subjects
- *
ANNULATION , *RING formation (Chemistry) , *FUNCTIONAL groups , *ISOMERIZATION , *STEREOSELECTIVE reactions - Abstract
The first metal-catalyzed (2+4) annulation of 5-alkenyl thiazolones and α,α-dicyanoalkylidenes has been developed via vinylogous Michael/cyclization/isomerization reaction. This (2+4) annulation reaction is catalyzed by a chiral Ag-(R)-DTBM-SEGPHOS catalyst, delivering enantioenriched spiro[cyclohexenamines-thiazolone] having contiguous quaternary and tertiary stereocenters in good to excellent yield (up to 80%) and excellent stereoselectivities (up to 97% ee and >20 : 1 dr). This methodology has high functional group tolerance and produces a broad range of enantioenriched products under mild reaction conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
33. CuBr2-mediated dehydrogenative [4+2] annulation of 1-naphthyl-1,3-indandiones and alkenes.
- Author
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Zhang, Xu, Chang, Mengfan, Ni, Tongtong, Liu, Shuhan, Li, Wenguang, and Xu, Xuefeng
- Subjects
- *
ALKENES , *COPPER catalysts , *ANNULATION , *FUNCTIONAL groups , *NITROALKENES , *MOLECULES - Abstract
Intermolecular annulation reactions of 1-naphthyl-1,3-indandiones with alkenes proceed efficiently in the presence of a copper catalyst to generate spirocarbocycle compounds. Various spirocyclic molecules bearing an all-carbon quaternary center could be obtained by this novel method with good yields, excellent regioselectivity, and good functional group tolerance. A radical mechanism is proposed based on the HRMS analysis results of control experiments. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
34. Biochemical and functional groups characteristics of tea blends from Ficus capensis and Justicia secunda.
- Author
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Uchegbu, Nneka Nkechi, Fasuan, Temitope Omolayo, Onuoha, Nchekwube Love, and Adepeju, Adefisola Bola
- Abstract
Tea is one of the most consumed drinks in the world, second only to water, and is renowned for its wide range of health benefits.This study examined the development of tea blends from blends of Ficus capensis, and Justicias ecunda leaves. Dried leaves of F. capensis and J. Secunda were milled, sieved, and processed into tea using a three-level factorial design. The process was modelled and optimized. The tea was evaluated for physicochemical, phenolic compounds profile, antioxidants, and functional groups using standard procedures. The blood-boosting potentials of the herbal tea blends were investigated through animal experiment and haematological evaluations were carried out on the fed animals. The results gave the optimal extracts blends of 48 g/100 g of F. capensis and 52 g/100 g of J. secunda. Antioxidants showed 2,2-diphenyl-1-picryl-hydrazl value of 6464.95 ± 1.97 µmol Trolox equivalents/100 g, ferric reducing power (40.13 ± 0.07 mmol Fe
2+ /100 g), and metal chelating (57.40 ± 0.62%). Physicochemical property showed total dissolved solids value of 6.51 ± 0.11 mg/g, *L (78.35 ± 0.42), *a (3.14 ± 0.09), and*b (13.57 ± 0.12). Phenolic compounds profile showed the presence of epicatechin (115.63 ± 0.052 mg/100 g), which have been associated with ability to improve healthy-living and lower the risk of some degenerative health issues. The in vivo results showed that developed tea was able to recover up to 95.28% of the packed cell volume, red blood cell (94.78%), and haemoglobin (97.52%), which compared well with the commercial product. The study showed the potential application of F. Capensis and J. Secunda leaves extracts in the formulation of functional beverage. The formulation procedures is scalable and has domestic and industrial applications. The tea blend could serve as a functional food ingredient and beverage to improve human health. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
35. Ultrathin (15 nm) Carbon Sheets with Surface Oxygen Functionalization for Efficient Pseudocapacitive Na‐ion Storage.
- Author
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Etacheri, Vinodkumar, Maça, Rudi Ruben, Avvaru, Venkata Sai, Hong, Chulgi Nathan, Alazemi, Abdullah, and Pol, Vilas G.
- Abstract
Disordered carbon is the state of the art anode material for Na‐ion batteries due to their increased interlayer spacing and good electronic conductivity. However, its practical application is hindered by average specific capacity, poor rate performance, low coulombic efficiency and limited cycling stability. Herein, we report the superior pseudocapacitance enhanced Na‐ion storage of in situ surface functionalized carbon nanosheets. Anodes composed of ultrathin (~15 nm) carbon nanosheets demonstrated excellent reversible specific capacity (375 mAh/g at 25 mA/g), rate performance (150 mAh/g at 2 A/g), long‐term cycling performance (1000 cycles at 1 A/g) and coulombic efficiency (~100 %). Considerably higher pseudocapacitance (up to ~78 %) is also identified in this case compared to amorphous carbon particles. Spectroscopic and electrochemical studies proved Na‐ion intercalation in to the disordered carbon and pseudocapacitive storage driven by oxygen‐containing surface functional groups. Outstanding electrochemical performance is credited to the synergy between diffusion limited intercalation and pseudocapacitive surface Na‐ion storage. The demonstrated synthetic method of in situ functionalized carbon nanosheets is inexpensive and scalable. The strategy of functional group and morphology induced pseudocapacitive Na‐ion storage offer new prospects to design high‐performance Na‐ion battery electrodes. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
36. Effect of functional groups of plasticizers on starch plasticization.
- Author
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Chen, Yanxue, Wang, Ziyi, Jia, Lexin, Niu, Chaodan, Hu, Ziyue, Wu, Chengyuan, Zhang, Siqun, Ren, Jie, Qin, Guoqiang, Zhang, Guanglei, and Yang, Jinhui
- Abstract
To investigate the impact of plasticizer functional groups on starch plasticization, three distinct plasticizers were selected in this study: ethylene glycol (EG), ethylenediamine (EDA), and ethylenebisformamide (EBF). Three models of the plasticizer/starch system were constructed using molecular dynamics (MD) simulations, and the analysis encompassed the computation of mean square displacement (MSD), radial distribution function (RDF), and hydrogen bonding energy for each system. Additionally, the proportions of simulation were used to prepare thermoplastic starch films, which were subsequently subjected to examinations such as DSC, XRD, FT-IR, SEM, and mechanical property testing. Comparative analysis of the simulation data from the three systems and the properties of the manufactured thermoplastic starch (TPS) established that the diverse functional groups of plasticizers significantly influenced starch plasticization. In different plasticizer functional group types, it was observed that hydroxyl groups in EG and amino groups in EDA predominantly form hydrogen bonds with hydroxyl groups in starch molecular chain. In contrast, amide groups in EBF can establish hydrogen bonds not only with hydroxyl groups of starch but also with ether bonds on the starch main chain, thereby resulting in more effective starch plasticization. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
37. Effect of biochar structure on the selective adsorption of heavy components in bio‐oil.
- Author
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Zhu, Haonan, Yan, Shanshan, Wu, Yansheng, Xu, Hao, Chen, Haoran, Zhang, Hong, Guo, Xin, Hu, Xun, Zhang, Shu, and Gao, Wenran
- Subjects
- *
BIOCHAR , *POROSITY , *AROMATIC compounds , *ADSORPTION capacity , *FUNCTIONAL groups - Abstract
In this study, biochars with different structures were prepared through HNO3 oxidation and secondary pyrolysis to study the relationship between the structure of biochar and its selectivity for the adsorption of light and heavy aromatics in bio‐oil. The results showed that the adsorption rates of biochar with different structures ranged from 2.90 to 4.00 g bio‐oil per g biochar. The influence of pore structure was dominant, followed by the influence of O‐containing functional groups and the degree of graphitization. The higher the adsorption capacity of biochar for bio‐oil, the smaller the concentrations of the light aromatic model compounds in the absorbed bio‐oil (ABO). Among the five light aromatics, biochar has the best adsorption selectivity for dihydroxybiphenyl and the worst for eugenol and propyl phenol. This is attributed to the diphenyl ring structure of dihydroxybiphenyl, which makes it more susceptible to adsorption, and other light model compounds only have one benzene ring. In summary, biochar demonstrates better adsorption selectivity for heavy aromatics than light aromatics. The more developed the pore structure is, the more enriched O‐containing functional groups are, and the higher the graphitization degree of biochar is, the better the selective adsorption of aromatic compounds in bio‐oil. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
38. Hydrogen bond formation may enhance RDC‐based discrimination of enantiomers.
- Author
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Sager, Emine, Tzvetkova, Pavleta, Lingel, Andreas, Gossert, Alvar D., and Luy, Burkhard
- Subjects
- *
HYDROGEN bonding , *NUCLEAR magnetic resonance spectroscopy , *FUNCTIONAL groups , *HYPOTHESIS - Abstract
The distinction of enantiomers based on residual anisotropic parameters obtained by alignment in chiral poly‐γ‐benzyl‐L‐glutamate (PBLG) is among the strongest in high‐resolution NMR spectroscopy. However, large variations in enantiodifferentiation among different solutes are frequently observed. One hypothesis is that the formation of hydrogen bonds between solute and PBLG is important for the distinction of enantiomers. With a small set of three almost spherical enantiomeric pairs, for which 1DCH residual dipolar couplings are measured, we address this issue in a systematic way: borneol contains a single functional group that can act as a hydrogen bond donor, camphor has a single group that may act as a hydrogen bond acceptor, and quinuclidinol can act as both hydrogen bond donor and acceptor. The results are unambiguous: although camphor shows low enantiodifferentiation with PBLG and alignment that can be predicted well by the purely steric TRAMITE approach, the distinction of enantiomers for the other enantiomeric pairs is significantly higher with alignment properties that must involve a specific interaction in addition to steric alignment. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
39. Liquid‐phase NMR of asphaltenes.
- Author
-
Krivdin, Leonid B.
- Subjects
- *
HEAVY oil , *PETROLEUM , *ASPHALTENE , *FUNCTIONAL groups , *HYDROCARBONS - Abstract
The present review focuses on the most recent advances in liquid‐phase NMR of asphaltenes, leaving apart an overwhelming amount of publications dealing with solid‐state NMR investigations in this field. Owing to the complexity of the coal‐derived products, and in particular, asphaltenes, their 1H and 13C NMR spectra consist of a number of overlapping signals belonging to different hydrocarbon types. Comprehensive studies of asphaltenes by means of NMR reveal the characteristic functional groups of their fractions together with the spectral regions in which they resonate. NMR studies of asphaltenes provide a straightforward guideline for their chemical composition and that of the related coal‐derived products. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
40. Local Solutions of RG Flow Equations from the Nash–Moser Theorem.
- Author
-
D'Angelo, Edoardo and Pinamonti, Nicola
- Subjects
- *
QUANTUM field theory , *QUANTUM states , *QUANTUM theory , *FUNCTIONAL groups , *FAME - Abstract
We prove local existence of solutions of a functional renormalisation group equation for the effective action of an interacting quantum field theory, when a suitable local potential approximation is considered. To obtain this equation in a Lorentzian setting a quantum state for the theory is selected and a regulator consisting in a mass is added to the action. The flow equation for mass rescalings is then studied using the renown Nash–Moser theorem. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
41. Evolutionary history and root trait coordination predict nutrient strategy in tropical legume trees.
- Author
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Marcellus, Mia, Goud, Ellie M., Swartz, Natalie, Brown, Emily, and Soper, Fiona M.
- Subjects
- *
NITROGEN fixation , *FUNGAL colonies , *CARBON metabolism , *LEAF morphology , *FUNCTIONAL groups - Abstract
Summary: Plants express diverse nutrient use and acquisition traits, but it is unclear how trait combinations at the species level are constrained by phylogeny, trait coordination, or trade‐offs in resource investment. One trait – nitrogen (N) fixation – is assumed to correlate with other traits and used to define plant functional groups, despite potential confounding effects of phylogeny.We quantified growth, carbon metabolism, fixation rate, root phosphatase activity (RPA), mycorrhizal colonization, and leaf and root morphology/chemistry across 22 species of fixing and nonfixing tropical Fabaceae trees under common conditions.Belowground trait variation was high even among closely related species, and most traits displayed a phylogenetic signal, including N‐fixation rate and nodule biomass. Across species, we observed strong positive correlations between physiological traits such as RPA and root respiration. RPA increased ~ fourfold per unit increase in fixation, supporting the debated hypothesis that N‐fixers 'trade' N for phosphatases to enhance phosphorus acquisition. Specific root length and root N differed between functional groups, though for other traits, apparent differences became nonsignificant after accounting for phylogenetic nonindependence.We conclude that evolutionary history, trait coordination, and fixation ability contribute to nutrient trait expression at the species level, and recommend explicitly considering phylogeny in analyses of functional groupings. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
42. Elucidating the Correlation of Lignocellulosic Compositions and Physicochemical Alterations in Oil Palm (Elaeis guineensis) Biomass on Enzymatic Saccharification Yield.
- Author
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Hemashini, Tannimalay, Lee, Chee Keong, Goh, Choon Fu, Tye, Ying Ying, Ismayati, Maya, H'ng, Yin Ying, and Leh, Cheu Peng
- Subjects
- *
LIGNOCELLULOSE , *BIOMASS chemicals , *X-ray diffraction , *CELLULOSE , *FUNCTIONAL groups - Abstract
This study investigates the correlation between both the chemical compositions and physicochemical properties of pretreated oil palm empty fruit bunch (OPEFB) fibre and their enzymatic saccharification/total glucose yield (TGY). Twenty OPEFB samples, pretreated with various aqueous pretreatments, with diverse cellulose (25.63–44.23%), hemicellulose (0.01–42.49%), and lignin (3.7–47.1%) levels, were examined for their correlation with TGY (8.5–40%). The quadratic regression model was verified significant (p-value = 0.0006, R2 = 0.8006). It was found that the pre-refined OPEFB experienced greater cellulose loss (35%) compared to unrefined ones (9%), adversely affecting TGY. Among physicochemical properties analysed using SEM, FTIR, XRD, Py-GCMS, and XPS, only crystallinity index (CrI) was significantly correlated with TGY based on theoretical glucose concentration (TGC) (R2 = 0.77, 0.91). Other characteristics (morphology, functional groups, crystallite size, S/G ratio, and O/C ratio) exhibited no significant correlation to saccharification efficiency, exhibiting random trends (R2 < 0.5). OPEFB fibres with CrI of 30–40 could achieve 100% TGY based on TGC. In conclusion, regardless of pretreatments, chemical compositions predominantly affected TGY in the enzymatic saccharification of biomass. Among commonly used physicochemical analytical methods, CrI is most significant in this evaluation and OPEFB should be unrefined before treatment to avoid cellulose loss. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
43. The bifunctional and reusable catalyst of cerium/L‐arginine on mesoporous KIT‐6 in the chemoselective oxidation of sulfides and homoselective synthesis of tetrahydrobenzo[b]pyrans.
- Author
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Darabi, Mitra, Nikoorazm, Mohsen, Tahmasbi, Bahman, and Ghorbani‐Choghamarani, Arash
- Subjects
- *
MESOPOROUS silica , *NANOPARTICLES , *X-ray diffraction , *FUNCTIONAL groups , *SURFACE area - Abstract
In this work, KIT‐6@Schiff‐base@Ce nanocatalyst was synthesized by immobilizing the Ce complex on KIT‐6 mesoporous silica framework modified with 3‐iodopropyltrimethoxysilane group. The surface area, total volume, and average diameter of pores, physical properties, functional groups, organic content, and element combination of the obtained nanocatalyst were identified using different techniques including BET, FT‐IR, XRD, WDX, SEM, and EDX. The KIT‐6@Schiff‐base@Ce was investigated as a novel stable and reusable catalyst with excellent performance for the selective synthesizing of sulfoxide and tetrahydrobenzo[b]pyrans. The designed catalyst successfully oxidized a large number of sulfides using hydrogen peroxide under solvent‐free conditions or in ethanol as a safe, green, and available solvent with good efficiency within short reaction times. Also, KIT‐6@Schiff‐base@Ce catalyzed a number of tetrahydrobenzo[b]pyrans using multicomponent condensation of dimedone, aldehydes, and malononitrile in water/ethanol (1:1) as ideal, safe, green and available solvent. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
44. Investigation of the effect of EDTA modification on golden yellow removal: optimisation with response surface methodology.
- Author
-
Samdan, Canan, Demiral, Ilknur, and Bozkurt, Tugce
- Subjects
- *
CHEMICAL processes , *RESPONSE surfaces (Statistics) , *ACTIVATED carbon , *FUNCTIONAL groups , *SURFACE area - Abstract
Physical or chemical processes can enrich surface functional groups of activated carbon. EDTA grafting was applied to the carbon surface using a chemical treatment in this study. In this way, while there was no significant change in the surface area of the carbon, the Golden Yellow (GY) removal performance increased. The changes caused by EDTA grafting on the carbon surface have been revealed using various methods. Environmental conditions affecting the adsorption process were statistically investigated using Central Composite Design (CCD). Different equations were used to determine the stability, capacity, and mechanism of the GY removal with activated carbon and EDTA grafted carbon. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
45. Influence of climate, physical and chemical variables on the taxonomic and functional responses of macroinvertebrate communities in tropical island rivers.
- Author
-
Cinéas, Chevelie and Dolédec, Sylvain
- Subjects
- *
FOREST declines , *VOLCANIC eruptions , *FUNCTIONAL groups , *STREAM function , *ISLANDS , *RAINFALL - Abstract
Rivers of tropical islands formed by volcanic eruptions experience unpredictable and heavy rainfall and are characterised by irregular topography. During the 2019 and 2020 low-water season, we investigated the responses of benthic macroinvertebrate assemblages to variations in local environmental conditions in four rivers located in areas of different rainfall intensity. We found that changes in local environmental conditions associated with lower rainfall intensity reduced abundance and taxonomic richness and modified taxonomic composition but did not impact the balance of functional feeding groups of macroinvertebrate communities amongst streams, except for piercer herbivores. Heterotrophy associated with substrate instability and autotrophy with a more stable substrate co-occurred in semi-arid climate rivers. In contrast, a change from heterotrophy upstream to autotrophy and substrate stability downstream was apparent in the two humid rivers studied. Surrogates of stream ecosystem function revealed a very low ratio of coarse to fine particulate organic matter related to the quasi-absence of shredders in these streams and suggested a low allochthonous input contribution, which could be the result of the 5% decline in forest cover over the two past decades. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
46. Drivers of macroinvertebrate assemblages in littoral and pelagic habitats of a large shallow lake: implications for bioassessment.
- Author
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Zhang, You, Li, Mingjie, Zhang, Ying, Gong, Zhijun, Johnson, Richard K., Cai, Yongjiu, and Li, Kuanyi
- Subjects
- *
SPECIES diversity , *HABITATS , *LITTORAL zone , *LAKES , *FUNCTIONAL groups - Abstract
Different measures of macroinvertebrate diversity (species diversity, functional diversity, phylogenetic diversity) and functional feeding groups (FFGs) are commonly used to assess the ecological status of large shallow lakes. In this study, biodiversity and FFGs in a large shallow lake, Lake Hongze, differed between littoral and pelagic habitats, with the spatial variability of littoral assemblages more correlated with nutrient concentrations, whilst pelagic assemblages were more associated with wave-induced disturbance (e.g., mean effective fetch). Species diversity was poorly correlated with measures of nutrient concentrations, whereas functional diversity, phylogenetic diversity, and functional feeding groups are promising indicators of nutrient concentrations. Lastly, our findings support the use of biodiversity and FFGs to disentangle the effects of nutrients and wave-induced disturbance on macroinvertebrate assemblages. Furthermore, monitoring both littoral and pelagic habitats in large shallow lakes is recommended to better understand and quantify ecosystem changes. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
47. Dietary fiber modification: structure, physicochemical properties, bioactivities, and application—a review.
- Author
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Tang, Wei, Lin, Xinyi, Walayat, Noman, Liu, Jianhua, and Zhao, Peicheng
- Subjects
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MOLECULAR structure , *DIETARY fiber , *MOLECULAR weights , *FUNCTIONAL groups , *POLYSACCHARIDES - Abstract
There is increasing attention on the modification of dietary fiber (DF), since its effective improvement on properties and functions of DF. Modification of DF can change their structure and functions to enhance their bioactivities, and endow them with huge application potential in the field of food and nutrition. Here, we classified and explained the different modification methods of DF, especially dietary polysaccharides. Different modification methods exert variable effects on the chemical structure of DF such as molecular weight, monosaccharide composition, functional groups, chain structure, and conformation. Moreover, we have discussed the change in physicochemical properties and biological activities of DF, resulting from alterations in the chemical structure of DF, along with a few applications of modified DF. Finally, we have summarized the modified effects of DF. This review will provide a foundation for further studies on DF modification and promote the future application of DF in food products. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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48. Mechanical properties and micromechanics of graphene oxide modified calcareous sand-cement mortar.
- Author
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Hu, Jun, Xu, Chenming, Cheng, Po, Xiong, Hui, Zhou, Yuxuan, and Ren, Junhao
- Subjects
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GRAPHENE oxide , *CHEMICAL formulas , *COMPRESSIVE strength , *FUNCTIONAL groups , *MICROSTRUCTURE , *MORTAR - Abstract
In the engineering context of island blowing and reclamation, the modification effect of graphene oxide on the mechanical properties of calcareous sand cement mortar is analyzed, and the modification mechanism is elaborated from the microscopic perspective. The experimental results show that graphene oxide promotes the hydration reaction of calcareous sand-cement mortar, and the amount of graphene oxide doping significantly affects the modification effect. The modification effect gradually enhances when the graphene oxide doping amount increases from 0 to 0.06%, and the unconfined compressive strength of the specimens increases up to 36.96%. However, the modification effect decreases when the doping amount is 0.1% compared with that of 0.06%. The results of scanning electron micrographs and energy dispersive spectrometer tests indicate that the addition of graphene oxide accelerates the agglomeration of C-S-H gel produced by the reaction of calcareous sand cement mortar, forming a dense mesh-like structure, which enhances the unconfined compressive strength of the specimens. The oxygen-containing functional groups in graphene oxide are interlinked with the free Ca2+ in the hydration products, eventually producing crystals with the chemical formula (3CaO·Al2O3·CaSO4·12H2O). The generation of crystals leads to the reduction of pores inside the cement mortar and improves the specimen's compression strength. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
49. Supramolecular channels via crown ether functionalized polyaniline for proton-self-doped cathode in aqueous zinc-ion battery.
- Author
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Jiang, Chaoyan, Hu, Fang, Zhang, Hao, Tang, Yixin, Shu, Jie, and Yue, Chuang
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CROWN ethers , *CATHODES , *DIFFUSION kinetics , *POLYANILINES , *ENERGY storage , *FUNCTIONAL groups , *PROTON transfer reactions - Abstract
[Display omitted] Polyaniline (PANI) has been widely used as a cathode in aqueous zinc-ion batteries (AZIBs) because of its attractive conductivity and energy storage capability. However, the extensive application of PANI is limited by spontaneous deprotonation and slow diffusion kinetics. Herein, an 18-crown-6-functionalised PANI pseudorotaxane (18C6@PANI) cathode is successfully developed through a facile template-directed polymerisation reaction. The 18C6@PANI cathode exhibits a high specific capacity of 256 mAh g−1 at 0.2 A/g, excellent rate performance of 134 mAh g−1 at 6 A/g and outstanding cycle stability at a high current density of 3 A/g over 10,000 cycles. Experimental and theoretical analyses demonstrate the formation of the –N–Zn–O– structure. The abundant supramolecular channels in pseudorotaxane, induced by crown ether functional groups, are beneficial for achieving superior cyclability and rate capability. These encouraging results highlight the potential for designing more efficient PANI-based cathodes for high-performance AZIBs. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
50. Modulating solvated structure of Zn2+ and inducing surface crystallography by a simple organic molecule with abundant polar functional groups to synergistically stabilize zinc metal anodes for long-life aqueous zinc-ion batteries.
- Author
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Zhang, Xiaoqin, Zhai, Yijun, Xie, Bin, Li, Min, Lang, Haoran, Yang, Yi, Chen, Ji, Chen, Yuxiang, Zheng, Qiaoji, Huo, Yu, Zhao, Ruyi, Lam, Kwok-Ho, and Lin, Dunmin
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POLAR molecules , *FUNCTIONAL groups , *ANODES , *CRYSTALLOGRAPHY , *POWER resources , *ELECTRIC batteries , *ZINC , *LITHIUM cells - Abstract
2,2,2-trifluronate (TF) infiltrates into the solvated sheath of hydrated Zn2+ and adheres to the surface of Zn anode, guiding the homogeneous deposition of Zn2+ along the Zn(0 0 2) crystal surface, significantly inhibiting the formation of Zn dendrites and mitigrating side reactions. [Display omitted] Aqueous zinc-ion batteries (AZIBs) have attracted significant attention owing to their inherent security, low cost, abundant zinc (Zn) resources and high energy density. Nevertheless, the growth of zinc dendrites and side reactions on the surface of Zn anodes during repeatedly plating/stripping shorten the cycle life of AZIBs. Herein, a simple organic molecule with abundant polar functional groups, 2,2,2-trifluoroether formate (TF), has been proposed as a high-efficient additive in the ZnSO 4 electrolyte to suppress the growth of Zn dendrites and side reaction during cycling. It is found that TF molecules can infiltrate the solvated sheath layer of the hydrated Zn2+ to reduce the number of highly chemically active H 2 O molecules owing to their strong binding energy with Zn2+. Simultaneously, TF molecules can preferentially adsorb onto the Zn surface, guiding the uniform deposition of Zn2+ along the crystalline surface of Zn(0 0 2). This dual action significantly inhibits the formation of Zn dendrites and side reactions, thus greatly extending the cycling life of the batteries. Accordingly, the Zn//Cu asymmetric cell with 2 % TF exhibits stable cycling for more than 3,800 cycles, achieving an excellent average Columbic efficiency (CE) of 99.81 % at 2 mA cm−2/1 mAh cm−2. Meanwhile, the Zn||Zn symmetric cell with 2 % TF demonstrates a superlong cycle life exceeding 3,800 h and 2,400 h at 2 mA cm−2/1 mAh cm−2 and 5 mA cm−2/2.5 mAh cm−2, respectively. Simultaneously, the Zn//VO 2 full cell with 2 % TF possesses high initial capacity (276.8 mAh/g) and capacity retention (72.5 %) at 5 A/g after 500 cycles. This investigation provides new insights into stabilizing Zn metal anodes for AZIBs through the co-regulation of Zn2+ solvated structure and surface crystallography. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
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