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Mechanisms of the Diels‐Alder (D‐A) reactions between N‐alkyl and aryl‐1,2‐dihydropyridines and dienophiles have been investigated by M06‐2X‐D3/6‐31 + G(d,p) basis set, and SMD model was employed to simulate the solvent effect. The computational results show that the productive process of endo‐product is favorable with lower energy barrier. The calculations of substituent effect indicate that there are some relations between the energy barrier and the productivity. The lower energy barrier means the higher productivity, and the barrier of retro D‐A reaction could also have influence on the productivity. Finally, natural bond orbital Fukui function (NOFF) and frontier molecular orbital theory (FMOT) are employed to analyze the structures and reveal the substances of D‐A reactions. [ABSTRACT FROM AUTHOR]

Diabetic kidney disease (DKD), a major microvascular complication of diabetes, is characterized by its complex pathogenesis, high risk of chronic renal failure, and lack of effective diagnosis and treatment methods. GSK3β (glycogen synthase kinase 3β), a highly conserved threonine/serine kinase, was found to activate glycogen synthase. As a key molecule of the glucose metabolism pathway, GSK3β participates in a variety of cellular activities and plays a pivotal role in multiple diseases. However, these effects are not only mediated by affecting glucose metabolism. This review elaborates on the role of GSK3β in DKD and its damage mechanism in different intrinsic renal cells. GSK3β is also a biomarker indicating the progression of DKD. Finally, the protective effects of GSK3β inhibitors on DKD are also discussed. [ABSTRACT FROM AUTHOR]

Context: The reaction between Na and HF is a typical harpooning reaction which is of great interest due to its significance in understanding the elementary chemical reaction kinetics. This work aims to investigate the detailed reaction mechanisms of sodium with hydrogen fluoride and the adsorption of HF on the resultant NaF as well as the (NaF)4 tetramer. The results suggest that the reaction between Na and HF leads to the formation of sodium fluoride salt NaF and hydrogen gas. Na interacts with HF to form a complex HF···Na, and then the approaching of F atom of HF to Na results in a transition state H···F···Na. Accompanied by the broken of H-F bond, the bond forms between F and Na atoms as NaF, then the product NaF is yielded due to the removal of H atom. The resultant NaF can further form (NaF)4 tetramer. The interaction of NaF with HF leads to the complex NaF···HF; the form I as well as II of (NaF)4 can interact with HF to produce two complexes (i.e., (NaF)4(I-1)···HF, (NaF)4(I-2)···HF, (NaF)4(II-1)···HF and (NaF)4(II-2)···HF), but the form III of (NaF)4 can interact with HF to produce only one complex (NaF)4(III)···HF. These complexes were explored in terms of noncovalent interaction (NCI) and quantum theory of atoms in molecules (QTAIM) analyses. NCI analyses confirm the existences of attractive interactions in the complexes HF···Na, NaF···HF, (NaF)4(I-1)···HF, (NaF)4(I-2)···HF, (NaF)4(II-1)···HF and (NaF)4(II-2)···HF, and (NaF)4(III)···HF. QTAIM analyses suggest that the F···Na interaction forms in the HF···Na complex while the F···H hydrogen bonds form in NaF···HF, (NaF)4(I-1)···HF, (NaF)4(I-2)···HF, (NaF)4(II-1)···HF and (NaF)4(II-2)···HF, and (NaF)4(III)···HF complexes. Natural bond orbital (NBO) analyses were also applied to analyze the intermolecular donor-acceptor orbital interactions in these complexes. These results would provide valuable insight into the chemical reaction of Na and HF and the adsorption interaction between sodium fluoride salt and HF. Methods: The calculations were carried out at the M06-L/6-311++G(2d,2p) level of theory which were performed using the Gaussian16 program. Intrinsic reaction coordinate (IRC) calculations were carried out at the same level of theory to confirm that the obtained transition state was true. The molecular surface electrostatic potential (MSEP) was employed to understand how the complex forms. Quantum theory of atoms in molecules (QTAIM) and noncovalent interaction (NCI) analysis was used to know the topology parameters at bond critical points (BCPs) and intermolecular interactions in the complex and intermediate. The topology parameters and the BCP plots were obtained by the Multiwfn software. [ABSTRACT FROM AUTHOR]

Design and engineering of highly efficient emitting materials with assembly-induced luminescence, such as room-temperature phosphorescence (RTP) and aggregation-induced emission (AIE), have stimulated extensive efforts. Here, we propose a new strategy to obtain size-controlled Eu3+-complex nanoparticles (Eu-NPs) with self-assembly-induced luminescence (SAIL) characteristics without encapsulation or hybridization. Compared with previous RTP or AIE materials, the SAIL phenomena of increased luminescence intensity and lifetime in aqueous solution for the proposed Eu-NPs are due to the combined effect of self-assembly in confining the molecular motion and shielding the water quenching. As proof of concept, we also show that this system can be further applied in bioimaging, temperature measurement and HClO sensing. The SAIL activity of the rare-earth (RE) system proposed here offers a further step forward on the roadmap for the development of RE light conversion systems and their integration in bioimaging and therapy applications. [ABSTRACT FROM AUTHOR]

Herein, we describe a new catalysis platform, supramolecular carbon‐bonding catalysis, which exploits the highly directional weak interactions between carbon centers of catalysts and electron donors to drive chemical reactions. To demonstrate this catalysis approach, we discovered a class of cyclopropane derivatives incorporated with carbonyl, ester and cyano groups as catalysts which showed general catalysis capability in different types of benchmark reactions. Among these typical examples, a challenging tail‐to‐head terpene cyclization can be achieved by supramolecular carbon‐bonding catalysis. The co‐crystal structures of catalyst and electron donors, comparison experiments, and titrations support a catalysis mode of carbon‐bonding activation of Lewis basic reactants. [ABSTRACT FROM AUTHOR]

Herein, we describe a new catalysis platform, supramolecular carbon‐bonding catalysis, which exploits the highly directional weak interactions between carbon centers of catalysts and electron donors to drive chemical reactions. To demonstrate this catalysis approach, we discovered a class of cyclopropane derivatives incorporated with carbonyl, ester and cyano groups as catalysts which showed general catalysis capability in different types of benchmark reactions. Among these typical examples, a challenging tail‐to‐head terpene cyclization can be achieved by supramolecular carbon‐bonding catalysis. The co‐crystal structures of catalyst and electron donors, comparison experiments, and titrations support a catalysis mode of carbon‐bonding activation of Lewis basic reactants. [ABSTRACT FROM AUTHOR]

The tin-oxo cage ([R12Sn12O14(OH)6]2+) is an excellent photoresist candidate in extreme ultraviolet lithography (EUVL). Photoionization that leads to plenty of photoelectrons and secondary electrons is an inevitable process upon irradiation by EUV light. The secondary electrons could cause electron blur and decrease the resolution of the photoresist. The utilization and improvement are limited owing to its poorly understood fundamental chemical process, such as exposure to EUV. In this study, the property of complexes (bare cage, binary complexes, and ternary complexes) formed by the combination of the cage and different counterions (methanesulfonate, tosylate, and triflate) was explored using density functional theory (DFT). Extended transition state-nature orbital of chemical valence (ETS-NOCV), charge decomposition analysis (CDA), and atomic dipole moment corrected Hirshfeld (ADCH) atomic charge analyses were carried out to characterize the interaction process (including ionization, electron attachment, and cleavage of the carbon–tin bond) and inherent mechanism. The number and species of counterions are closely associated with ionization and electron attachment; however, they show an inconspicuous effect on the carbon–tin bond energy. Meanwhile, tin free radical could be the reactivity site of ionization (and electron affinity). The activity of radical species is affected by counterions; this could be attributed to the changes in the charge density by diverse counterions, which could be an important factor in why the counterion affects the pattern. In addition, a superb linearity between the ADCH of tin free radical and IP/AP was found, which indicate that the atomic charge could be a simple and reliable substitution of complicated calculation for IP (or AP) to screen suitable counterions and improve the resolution of photoresist. [ABSTRACT FROM AUTHOR]

Substituent size and isomerization play an important role in the polymorphism of 2-(naphthalen-n-ylamino)-benzoic acids (n = 1, 2; 2-NBAs) as each of the two previously investigated 2-NBAs was found to be polymorphic, while their parent compound fenamic acid (FA) has only one form discovered. 2-(Naphthalen-1-ylamino)-nicotinic acid (1) and 2-(naphthalen-2-ylamino)-nicotinic acid (2) (2-NNA) are isosteric compounds of 2-NBAs, and 2-(2,3-dimethyl-phenylamino)-nicotinic acid (3) and 2-(3,4-dimethyl-phenylamino)-nicotinic acid (4) are 2-NNA analogues with similar substitution patterns. All four compounds are clonixin analogues. The polymorphism of these four compounds was investigated. One solvent-free form (1-A) and one hydrate (1-H) were discovered for 1, three forms (2-I, 2-II, and 2-III) were obtained for 2, and one form was found for 3 and 4. The four systems were characterized by single-crystal XRD (SCXRD) and powder XRD (PXRD), and structural properties were compared among the crystals of the four compounds, their isosteres, and other related analogues. The phase behavior of the four systems was studied with differential scanning calorimetry (DSC). Thermogravimetric analysis (TGA) was used to investigate the dehydration of 1-H. Computational studies such as stable conformer search, π–π interaction energy calculation, and non-covalent interaction (NCI) analysis were performed to shed light on the rise of polymorphism, and the relative contribution of various intermolecular interactions to the overall stability of the crystals. The study confirmed the effect of substituent size, thus the consequent π–π interactions, on the hydrate formation of compound 1 and polymorphism of compound 2. [ABSTRACT FROM AUTHOR]

Experimental studies on the Kolbe–Schmitt reaction and its side reactions have made great progresses; however, the relative theoretical studies fall behind. In order to study the mechanism of the Kolbe–Schmitt reaction with 2,6-di-tert-butylphenol and 2,4-di-tert-butylphenol as reactants, we carried out theoretical calculation studies at the M06-2X/Def2-SVP/SMD level of theory using the Gaussian 09 D.01 software package. For the reactant 2,6-di-tert-butylphenol, there is a dynamic equilibrium between the main product and side product, which can rapidly transform into each other at 160 °C by crossing the Gibbs free energy barrier of 14.1 kcal/mol. Moreover, the relative Gibbs free energy of the main product and side product is close; both of them may be observed in the experimental system. However, for 2,4-di-tert-butylphenol, the main product is thermodynamically favorable due to its lower Gibbs free energy, while the side product is kinetically favorable due to the lower activation energy barrier; the main product and the side product compete with each other. We hope the study can shed light on the Kolbe–Schmitt reaction. [ABSTRACT FROM AUTHOR]

• The reaction mechanism of the asymmetric passerini reaction catalyzed by chiral phosphoric acid (CP6) was theoretically investigated. • The effect of weak interactions on the enantioselectivity of the reaction was revealed. • The activation mechanism of CP6 in the reaction was elucidated. The enantioselective control of the three-component Passerini reaction was successfully achieved using chiral phosphoric acid as a catalyst with a wide range of substrates and high stereoselectivity. Quantum mechanical calculations reveals the detailed reaction mechanism and enantioselective origin of the reaction. The calculations revealed that the chiral phosphoric acid first forms a stable heterodimer with the carboxylic acid substrate, followed by C- C and C- O bond formations, the generation of a five-membered cyclic intermediate, and finally acyl migration to yield the product. Four reaction paths for the overall process were identified and compared to determine the optimal major and by-product paths. The enantioselective origin of the reaction has been elucidated systematically using distortion/interaction theory and truncated model system. QTAIM and IGMH analyses demonstrated the type and strength of interaction between catalyst and the substrates. The calculated e.e. value was 93 %, which was in good agreement with the experimental value. It is expected that the results of this study will offer new insights into the field of asymmetric Passerini reactions. [Display omitted] [ABSTRACT FROM AUTHOR]

The selective oxidation of aniline to metastable and valuable azoxybenzene, azobenzene or nitrosobenzene has important practical significance in organic synthesis. However, uncontrollable selectivity and laborious synthesis of the expensive required catalysts severely hinders the uptake of these reactions in industrial settings. Herein, we have pioneered the discovery of Zr(OH)4 as an efficient heterogeneous catalyst capable of the selective oxidation of aniline, using either peroxide or O2 as oxidant, to selectively obtain various azoxybenzenes, symmetric/unsymmetric azobenzenes, as well as nitrosobenzenes, by simply regulating the reaction solvent, without the need for additives. Mechanistic experiments and DFT calculations demonstrate that the activation of H2O2 and O2 is primarily achieved by the bridging hydroxyl and terminal hydroxyl groups of Zr(OH)4, respectively. The present work provides an economical and environmentally friendly strategy for the selective oxidation of aniline in industrial applications. [ABSTRACT FROM AUTHOR]

The selective oxidation of aniline to metastable and valuable azoxybenzene, azobenzene or nitrosobenzene has important practical significance in organic synthesis. However, uncontrollable selectivity and laborious synthesis of the expensive required catalysts severely hinders the uptake of these reactions in industrial settings. Herein, we have pioneered the discovery of Zr(OH)4 as an efficient heterogeneous catalyst capable of the selective oxidation of aniline, using either peroxide or O2 as oxidant, to selectively obtain various azoxybenzenes, symmetric/unsymmetric azobenzenes, as well as nitrosobenzenes, by simply regulating the reaction solvent, without the need for additives. Mechanistic experiments and DFT calculations demonstrate that the activation of H2O2 and O2 is primarily achieved by the bridging hydroxyl and terminal hydroxyl groups of Zr(OH)4, respectively. The present work provides an economical and environmentally friendly strategy for the selective oxidation of aniline in industrial applications. [ABSTRACT FROM AUTHOR]

• The mechanisms for organocatalytic synthesis of chiral allene by racemic propargylic alcohol and 3-phenylindole were proposed. • Eight possible reaction pathways were found after the dehydration process. • The intermolecular interactions including HBs and π-π interactions play crucial roles in determining the enantioselectivity. Organocatalytic synthesis of chiral allene can be successfully achieved through the reaction between propargylic alcohol and 3-phenylindole catalyzed by chiral phosphoric acid with high yield and high enantioselectivity. The detailed reaction mechanism and origin of enantioselectivity were uncovered by quantum mechanical calculations. The results indicate that the reactions undergo the dehydration process, the C–C bonding reaction, the hydrogen abstraction and the regeneration of catalyst. Eight possible pathways were found and the most favorable reaction paths leading to the major and minor products were evaluated which were consistent with the experimental results. The distortion/interaction analyses of the transition states in enantioselectivity-determining steps confirm the most favorable pathway in leading the major product. QTAIM and IGM analyses are used to illustrate the role of intermolecular interactions. EDA analysis is also employed to understand the origin of selectivity. This work would provide insightful viewpoints on the asymmetric organocatalytic reaction by chiral phosphoric acid. [Display omitted] [ABSTRACT FROM AUTHOR]

• Phenolic acids inhibit the volatilization of ethyl acetate. • The hydroxyl and methoxy groups of phenolic acids affected the inhibition effect. • Hydrophobic effect might drive the spontaneous binding of the two compounds. • There was an electron transfer between phenolic acids and ethyl acetate. Hydroxycinnamic acids and ethyl acetate were assessed in simulated alcohol-free wine solutions to explore the effect of phenolic acids on the aroma volatility of esters. The results showed that the phenolic acids could inhibit the volatilization of ethyl acetate, and the extent of inhibition was influenced by the concentration and structure of the phenolic compounds. The ultraviolet absorption spectra of the phenolic acids and ethyl acetate confirmed the interaction between the two compounds. The thermodynamic parameters of the interaction implied a spontaneous exothermic interaction, driven primarily by hydrophobic effects. Meanwhile, the results of the fluorescence-quenching analysis indicated electron transfer between the reactants. The quantum chemical investigations revealed negative and positive charge density distributions in the structures of ethyl acetate and the phenolic acids, respectively. These results will provide some data reference and theoretical support for further research on the effects of phenolic acid matrix on other structural esters. [ABSTRACT FROM AUTHOR]

The high-energetic and low-sensitive explosive material of 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) was theoretically investigated by first principles calculations and Hirshfeld surface analysis. The experimental and partly optimized LLM-105 crystals were compared which indicated that it is important to correct the hydrogen positions. Hirshfeld surface analyses of the experimental and partly optimized LLM-105 crystals were also compared, which showed that the intermolecular H⋯O interactions significantly contribute to the stability of the LLM-105 crystal, while the contributions of other intermolecular interactions in the experimental and partly optimized LLM-105 crystals are quite different. The geometrical and electronic structures of LLM-105 molecules in the experimental and partly optimized crystals as well as that in the gas phase were compared. QTAIM analysis was employed to illustrate the existences of intermolecular interactions in the molecular pairs taken from partly optimized LLM-105 crystal, and the types of intermolecular interactions from QTAIM analysis are in agreement with the results of Hirshfeld surface analysis. The reason why the LLM-105 molecule in the partly optimized crystal adopts a non-coplanar structure in which the NO 2 and NH 2 groups is not coplanar with the six-membered ring is elaborated. The existence of cooperativity among different intermolecular interactions were verified by analysing the trimeric complexes formed among three LLM-105 molecules in the partly optimized crystal. The non-coplanar of the NO 2 and NH 2 groups with the six-membered ring in LLM-105 molecule is favorable in forming more intermolecular interactions which cooperate and stabilize the crystal. [Display omitted] • The explosive material of 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) crystal was investigated theoretically. • The single LLM-105 molecule, the dimeric and trimeric complexes were analyzed. • The non-coplanar LLM-105 molecule favors the formation of more intermolecular interactions which stabilize the crystal. • The cooperativity among the intermolecular interactions was verified. [ABSTRACT FROM AUTHOR]

Ternary NiO/Ag/RGO nanocomposites were synthesized as an electrochemical sensor for nanomolarity detection of Sunset Yellow in soft drink. [Display omitted] • Ternary NiO/Ag/RGO exhibited high electrocatalytic activity for SY oxidation. • NiO/Ag/RGO held a low LOD of 13 nM and good selectivity for SY detection. • The electrochemical sensor was successfully employed for SY detection in soft drinks. NiO nanoparticles (NPs) with small Ag NPs loading supported on reduced graphene oxide nanosheets (ternary NiO/Ag/RGO nanocomposites) were synthesized via a hydrothermal process followed by high-temperature calcination, extending the synergistic effects among noble metal, metal oxide and carbon materials. Based on ternary NiO/Ag/RGO nanocomposites, a new electrochemical sensor was fabricated for the detection of sunset yellow (SY) in soft drinks through cyclic voltammetry, Tafel plot and differential pulse voltammetry. The experimental conditions were optimized and kinetic parameters studied. Due to the synergistic effect of the ternary components, the prepared sensor exhibited superior electroanalytical performance toward SY detection, including wide linear range from 0.1 to 50 μM and from 50 to 450 μM, low detection limit of 13 nM, excellent specificity against various interfering colorants, good reproducibility and stability. Importantly, the electrochemical sensors was successfully employed for quantitative SY analysis in soft drinks with satisfactory recoveries, where the analyzed results were also in agreement with LC/MS analysis. [ABSTRACT FROM AUTHOR]