Publications by authors named "Ju Xie"

37 Publications

Atmospheric ozonolysis of crotonaldehyde in the absence and presence of hydroxylated silica oligomer cluster adsorption.

Chemosphere 2021 Oct 26;281:130996. Epub 2021 May 26.

Environment Research Institute, Shandong University, Qingdao, 266237, PR China. Electronic address:

As one of the main components of combustion of tobacco products occurs (CARB), crotonaldehyde has an acute toxicity and widely exists in the atmosphere, which is harmful to human health. The removal efficiency of VOCs by ozonation can reach 80-90%. Based on the theory of quantum chemistry, the degradation mechanism, kinetics and toxicity of crotonaldehyde by ozonation in gas phase and heterogeneous phase were studied. Ozone was added to the olefins unsaturated double bond to form a five-membered ring primary ozonide, which was further fractured due to its unstable structure to form a Criegee intermediate and an aldehyde compound. The reaction rate constant of crotonaldehyde with ozone was 1.24 × 10 cm molecule s at 298 K and 1 atm, which was an order of magnitude higher than the experimental value. From toxicity assessment, it was found that the ozonation of crotonaldehyde is beneficial to the removal of toxicity. Mineral dust aerosol exists in the atmosphere in large quantities, and SiO is the most abundant component. VOCs are transformed into particle state on their surface through homogeneous nucleation and heterogeneous nucleation. Referring to the crystal structure of SiO, five hydroxylated silica oligomer cluster structures were simulated and the adsorption configurations of crotonaldehyde on their surface were simulated. The adsorption of crotonaldehyde on the surface of the clusters was achieved by forming hydrogen bonds and had good adsorption effects. The adsorption of hydroxylated silica oligomer clusters didn't change the ozonation mechanism of crotonldehyde, but had a certain effect on the reaction rate.
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http://dx.doi.org/10.1016/j.chemosphere.2021.130996DOI Listing
October 2021

Self-Assembled Polyoxometalate Nanodots as Bidirectional Cluster Catalysts for Polysulfide/Sulfide Redox Conversion in Lithium-Sulfur Batteries.

ACS Nano 2021 Jun 22. Epub 2021 Jun 22.

Key Lab of Organic Optoelectronics & Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China.

Polyoxometalates (POMs) are a class of discrete molecular inorganic metal-oxide clusters with reversible multielectron redox capability. Taking advantage of their redox properties, POMs are thus expected to be directly involved in the lithium-sulfur batteries (Li-S, LSBs) system as a bidirectional molecular catalyst. Herein, we design a three-dimensional porous structure of reduced graphene-carbon nanotube skeleton supported POM catalyst as a high-conductive and high-stability host material. Based on various spectroscopic techniques and electrochemical studies together with computational methods, the catalytic mechanism of POM clusters in Li-S battery was systematically clarified at the molecular level. The constructed POM-based sulfur cathode delivers a reversible capacity 1110 mAh g at 1.0 C and cycling stability up to 1000 cycles at 3.0 C. Furthermore, Li-S pouch/beaker batteries with a POM-based cathode were successfully demonstrated. This work provides essential inputs to promote molecular catalyst design and its application in LSBs.
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http://dx.doi.org/10.1021/acsnano.1c03852DOI Listing
June 2021

Theoretical prediction on photoelectric and supramolecular properties of benzoquinone-tetrathiafulvalene macrocyclic molecules.

J Mol Model 2021 May 7;27(6):157. Epub 2021 May 7.

School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, 225002, Jiangsu, China.

Benzoquinone has the ability to serve as an electron acceptor, and tetrathiafulvalene has the ability to serve as an electron donor. Based on the facts above, this work creatively cycles the benzoquinone unit and the tetrathiafulvalene unit alternately into macrocyclic molecules, the cyclopolymers of benzoquinone-tetrafluorene (C[n]QTTF, n = 3~6). To explore their structure and properties, the M06-2X functional of density functional theory (DFT) with 6-311g(d) basis set was used to optimize the ground-state structures of C[n]QTTF. Based on the stable configurations of the ground states, the electronic structure property is analyzed systematically. The results show that these macrocyclic molecules have excellent electron transport capability and electrochemical activity. Then, the electron absorption spectra of each system are carried out by using time-dependent density functional theory (TD-DFT) at the M062X/6-311+G(d) level. It turns out that their maximum absorption wavelengths are all in the visible range. Further calculation suggests that C[n]QTTF can also be characterized with one-dimensional self-assembly, double-walled assembly, and the host-guest inclusion performance, based on which it gains a variety of supramolecular structures. In summary, the benzoquinone-tetrafluorofurene macrocyclic molecules predicted by DFT calculations may be of assistance to the potential applications in organic electronics and supramolecular chemistry.
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http://dx.doi.org/10.1007/s00894-021-04782-5DOI Listing
May 2021

The roles of HO, ClO and BrO radicals in caffeine degradation: A theoretical study.

Sci Total Environ 2021 May 23;768:144733. Epub 2021 Jan 23.

Environment Research Institute, Shandong University, Qingdao 266237, PR China. Electronic address:

ClO and BrO are newly discovered reactive radicals that contribute to the degradation of micropollutants. However, the research on pollutant degradation by ClO and BrO is still lacking. Thus, the mechanism, kinetics, and toxicity of caffeine degradation by HO, ClO, and BrO were computationally studied and compared. Results showed that radical adduct formation (RAF) reaction was dominant for HO, ClO, and BrO initiated reactions of caffeine. The main reaction sites were C5 and C8 of caffeine for HO, while only the RAF reaction on C8 was prominent for ClO and BrO. The initiated reaction rate constants of caffeine by HO, ClO, and BrO were in the order of HO (5.29 × 10 M s) > ClO (1.40 × 10 M s) > BrO (2.17 × 10 M s). The kinetic simulation verified that ClO played a crucial role in the degradation of caffeine by the UV/chlorine process. In addition to HO-adducts, the subsequent reaction mechanisms of ClO- and BrO-adducts have also been investigated. The formation mechanisms of several important products, namely dimethylparabanic acid (P2), di(N-hydroxymethyl) parabanic acid (P5), 1,3,7-trimethyluric acid (P6), and 8-oxocaffeine (P11), were elucidated. Remarkably, stable chlorinated and brominated intermediates or products were not generated in ClO- and BrO-mediated subsequent degradations of caffeine. The assessment of aquatic toxicity and health effects showed that caffeine could penetrate the blood-brain barrier (human), and caffeine and its degradation products were potentially harmful to the aquatic environment.
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http://dx.doi.org/10.1016/j.scitotenv.2020.144733DOI Listing
May 2021

Construction of Polyfunctionalized 2,4-Dioxa-8-azaspiro[5.5]undec-9-enes and 2,4,8-Triazaspiro[5.5]undec-9-enes via a Domino [2+2+2] Cycloaddition Reaction.

J Org Chem 2021 Jan 2;86(2):1827-1842. Epub 2021 Jan 2.

College of Chemistry & Chemical Engineering, Yangzhou University, Yangzhou 225002, China.

The three-component reaction of ,-unsaturated -arylaldimines, dialkyl but-2-ynedioates, and 2-arylidene Meldrum acids in DCM at room temperature gave mixtures of /-11-aryl-7-styryl-2,4-dioxa-8-azaspiro[5.5]undec-9-enes in satisfactory yields. The similar three-component reaction with 2-arylidene-,'-dimethylbarbituric acids afforded -11-phenyl-7-styryl-2,4,8-triazaspiro[5.5]undec-9-enes as major products. On the other hand, the three-component reaction of -arylaldimines, dialkyl but-2-ynedioates, and 2-arylidene Meldrum acids or 2-arylidene-,'-dimethylbarbituric acids afforded /isomeric spirocompounds in satisfactory yields with high diastereoselectivity. This domino [2+2+2] cycloaddition reaction proceeded with sequential nucleophilic addition of -arylaldimine to an electron-deficient alkyne, Michael addition, and annulation process. The stereochemistry of all / isomeric spirocompounds was clearly elucidated by the determination of 33 single-crystal structures. The diastereoselectivity of the three-component reaction was correlated by DFT calculations.
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http://dx.doi.org/10.1021/acs.joc.0c02645DOI Listing
January 2021

Theoretical Study of Ozonation of Methylparaben and Ethylparaben in Aqueous Solution.

J Phys Chem A 2020 Dec 21;124(52):10967-10976. Epub 2020 Dec 21.

Environment Research Institute, Shandong University, Qingdao 266237, P. R. China.

Parabens are widely employed in toothpaste, cosmetics, textiles, beverages, and preservatives, causing a serious environmental concern because they are endocrine-disrupting compounds (EDCs). As one of the highly reactive oxidants, ozone has a great effect on EDC removal. To understand the degradation and transformation of parabens in the aquatic environment and their toxicity to aquatic organisms, the degradation reaction of parabens initiated by O was studied meticulously using quantum chemical calculations. The degradation process includes multiple initial reaction channels and consequent degradation pathways of the Criegee intermediates. Through thermodynamic data, the rate constants were computed using the transition state theory (TST). At a temperature of 298 K and a pressure of 1 atm, the calculated rate constants were 3.92 and 3.94 M s for methylparaben (MPB) and ethylparaben (EPB), respectively. The rate constants increased as the temperature increased or as the length of the alkyl chain on the benzene ring increased. Through the ecotoxicity assessment procedure, the ecotoxicity of parabens and the products in the degradation process can be assessed. Most degradation byproducts are either less toxic or nontoxic. Some byproducts are still harmful, such as oxalaldehyde (P2) and ethyl 2,3-dioxopropanoate (P10). Furthermore, the ecological toxicity of parabens increased with augmentation of the alkyl chain on the benzene ring. The effect of the alkyl chain length on the benzene ring in the compound cannot be ignored.
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http://dx.doi.org/10.1021/acs.jpca.0c09207DOI Listing
December 2020

Full insights into the roles of pH on hydroxylation of aromatic acids/bases and toxicity evaluation.

Water Res 2021 Feb 29;190:116689. Epub 2020 Nov 29.

Environment Research Institute, Shandong University, Qingdao 266237, P. R. China. Electronic address:

Advanced oxidation processes (AOPs) based on hydroxyl radicals (•OH) are the most important technologies for the removal of bio-recalcitrant organic pollutants in industrial wastewater. The pH is one of the crucial environmental parameters that affect the removal efficiency of pollutants in AOPs. In this work, the mechanistic and kinetic insights into the roles of pH on the hydroxylation of five aromatic acids and bases in UV/HO process have been investigated using theoretical calculation methods. Results show that the reactivity of •OH towards the twelve ionic/neutral species is positively correlated with electron-donating effect of substituents, which contributes to the positively pH-dependent reactivity of aromatic acids and bases towards •OH. The hydroxylation apparent rate constants (k, M s) (at 298 K) increase as the pH values increase from about 1 to 10, but they decrease as the pH values increase from about 10 to 14. However, the best pH values for degradation are not around 10 because the [•OH] decreases continuously with the increasing pH values from 3 to 9.5. Combining the factors of k and [•OH], the best degradation pH values are around 5.5~7.5 for p-hydroxybenzoic acid, p-aminophenol, aniline and benzoic acid, 3.0~7.5 for phenol and 5.5~7.5 for mixed pollutants of these aromatic acids/bases in UV/HO process. Moreover, a significant number of hydroxylation by-products are more toxic or harmful to aquatic organisms and rat (oral) than their parental pollutants. Altogether, this work provides comprehensive understanding of the roles of pH on •OH-initiated degradation behavior of aromatic acids and bases.
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http://dx.doi.org/10.1016/j.watres.2020.116689DOI Listing
February 2021

Reactivity of aromatic contaminants towards nitrate radical in tropospheric gas and aqueous phase.

J Hazard Mater 2021 01 6;401:123396. Epub 2020 Jul 6.

Environment Research Institute, Shandong University, Qingdao, 266237, PR China. Electronic address:

Aromatic compounds (ACs) give a substantial contribution to the anthropogenic emissions of volatile organic compounds. Nitrate radicals (NO) are significant oxidants in the lower troposphere during nighttime, with concentrations of (2-20) × 10 molecules cm. In this study, the tropospheric gas and liquid phase reactions of ACs with nitrate radical are investigated using theoretical computational methods, which can give a deep insight into the reaction mechanisms and kinetics. Results show that the reactivity of ACs with nitrate radicals decreases as the electron donating characteristics of the functional group on the ACs decrease, as ΔG of the reaction with NO increasing from -1.17 to 17.84 kcal mol. The reaction of NO towards ACs in the aqueous phase is more preferable, with the atmospheric lifetime 0.07-1281 min. An assessment of the aquatic toxicity of ACs and their degradation products indicated that the risk of their degradation products remains and should be given more attention.
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http://dx.doi.org/10.1016/j.jhazmat.2020.123396DOI Listing
January 2021

Theoretical investigation on the contribution of HO, SO and CO radicals to the degradation of phenacetin in water: Mechanisms, kinetics, and toxicity evaluation.

Ecotoxicol Environ Saf 2020 Nov 30;204:110977. Epub 2020 Jul 30.

Environment Research Institute, Shandong University, Qingdao, 266237, PR China. Electronic address:

Indirect oxidation induced by reactive free radicals, such as hydroxyl radical (HO), sulfate radical (SO) and carbonate radical (CO), plays an important or even crucial role in the degradation of micropollutants. Thus, the coadjutant degradation of phenacetin (PNT) by HO, SO and CO, as well as the synergistic effect of O on HO and HO were studied through mechanism, kinetics and toxicity evaluation. The results showed that the degradation of PNT was mainly caused by radical adduct formation (RAF) reaction (69% for Г, the same as below) and H atom transfer (HAT) reaction (31%) of HO. For the two inorganic anionic radicals, SO initiated PNT degradation by sequential radical addition-elimination (SRAE; 55%), HAT (28%) and single electron transfer (SET; 17%) reactions, while only by HAT reaction for CO. The total initial reaction rate constants of PNT by three radicals were in the order: SO > HO > CO. The kinetics of PNT degradation simulated by Kintecus program showed that UV/persulfate could degrade target compound more effectively than UV/HO in ultrapure water. In the subsequent reaction of PNT with O, HO and HO, the formation of mono/di/tri-hydroxyl substitutions and unsaturated aldehydes/ketones/alcohols were confirmed. The results of toxicity assessment showed that the acute and chronic toxicity of most products to fish increased and to daphnia decreased, and acute toxicity to green algae decreased while chronic toxicity increased.
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http://dx.doi.org/10.1016/j.ecoenv.2020.110977DOI Listing
November 2020

Ozonation of diclofenac in the aqueous solution: Mechanism, kinetics and ecotoxicity assessment.

Environ Res 2020 09 1;188:109713. Epub 2020 Jun 1.

Environment Research Institute, Shandong University, Qingdao, 266237, PR China. Electronic address:

The pharmaceutical and personal care products (PPCPs) in aquatic environment have aroused more interest recently. Many of them are hard to degrade by the typical biological treatments. Diclofenac (DCF), as a significant anti-inflammatory drug, is a typical PPCP and widely existed in water environment. It is reported that DCF has adverse effects on aquatic organisms. This work aims to investigate the mechanism, kinetics and ecotoxicity assessment of DCF transformation initiated by O in aqueous solution, and provide a solution to the degradation of DCF. The O-initiated oxidative degradations of DCF were performed by quantum chemical calculations, including thirteen primary reaction pathways and subsequent reactions of the Criegee intermediates with HO, NO and O. Based on the thermodynamic data, the kinetic parameters were calculated by the transition state theory (TST). The total reaction rate constant of DCF initiated by O is 2.57 × 10 M s at 298 K and 1 atm. The results show that the reaction rate constants have a good correlation with temperature. The acute and chronic toxicities of DCF and its degradation products were evaluated at three different trophic levels by the ECOSAR program. Most products are converted into less toxic or harmless products. Oxalaldehyde (P3) and N-(2,6-dichlorophenyl)-2-oxoacetamide (P6) are still harmful to the three aquatic organisms, which should be paid more attention in the future.
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http://dx.doi.org/10.1016/j.envres.2020.109713DOI Listing
September 2020

Effect of pH on ·OH-induced degradation progress of syringol/syringaldehyde and health effect.

Chemosphere 2020 Sep 29;255:126893. Epub 2020 Apr 29.

Environment Research Institute, Shandong University, Qingdao, 266237, PR China. Electronic address:

Syringol and syringaldehyde are widely present pollutants in atmosphere and wastewater due to lignin pyrolysis and draining of pulp mill effluents. The hydroxylation degradation mechanisms and kinetics and health effect assessment of them under high and low-NO regimes in atmosphere and wastewater have been studied theoretically. The effect of pH on reaction mechanisms and rate constants in their ·OH-initiated degradation processes has been fully investigated. Results have suggested that aqueous solution played a positive role in the ·OH-initiated degradation reactions by decreasing the energy barriers of most reactions and changing the reactivity order of initial reactions. For Sy and Sya (anionic species of syringol and syringaldehyde), most initial reaction routes were more likely to occur than that of HSy and Hsya (neutral species of syringol and syringaldehyde). As the pH increased from 1 to 14, the overall rate constants (at 298 K) of syringol and syringaldehyde with ·OH in wastewater increased from 5.43 × 10 to 9.87 × 10 M s and from 3.70 × 10 to 1.14 × 10 M s, respectively. In the NO-rich environment, 4-nitrosyringol was the most favorable product, while ring-opening oxygenated chemicals were the most favorable products in the NO-poor environment. On the whole, the NO-poor environment could decrease the toxicities during the hydroxylation processes of syringol and syringaldehyde, which was the opposite in a NO-rich environment. ·OH played an important role in the methoxyphenols degradation and its conversion into harmless compounds in the NO-poor environment.
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http://dx.doi.org/10.1016/j.chemosphere.2020.126893DOI Listing
September 2020

Degradation of prosulfocarb by hydroxyl radicals in gas and aqueous phase: Mechanisms, kinetics and toxicity.

Ecotoxicol Environ Saf 2020 Mar 16;191:110175. Epub 2020 Jan 16.

Environment Research Institute, Shandong University, Qingdao, 266237, PR China. Electronic address:

Prosulfocarb (PSC) is a thiocarbamate herbicide mainly used in winter cereals and a relevant aerosol precursor under OH radicals (OH) photooxidation conditions. We investigated the environmental risks, mechanisms, kinetics and products for the PSC withOH by employing theoretical chemical calculations. Two reaction types of H-abstraction andOH-addition reactions were taken into account. Whether in the atmosphere or aqueous particles, the most favorable pathway was the H-abstraction in the N-alkyl groups close to nitrogen atom. Subsequent reactions of primary intermediates were considered at different conditions. The total rate constants were determined as 2.62 × 10-10 cm molecule-1 s-1 and 4.96 × 10-11 cm molecule-1 s-1 at 298 K in atmosphere and aqueous particles, respectively. In natural water with theOH concentration of 10-15-10-18 mol l-1, the half-lives (t1/2) of PSC in theOH-initiated reactions were calculated as t = 2.40 × 10-2.40 × 10 s. With regard to the influence on human health and the ecosystem, oxidized products of PSC were estimated to be mutagenicity negative and had no obvious bioaccumulation potential. The aquatic toxicity of PSC and its degradation products was evaluated and the assessment results showed that the degradation of PSC was a toxicity-reduced process but they were still at toxic and harmful levels.
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http://dx.doi.org/10.1016/j.ecoenv.2020.110175DOI Listing
March 2020

Theoretical insight into the degradation of p-nitrophenol by OH radicals synergized with other active oxidants in aqueous solution.

J Hazard Mater 2020 05 16;389:121901. Epub 2019 Dec 16.

Environment Research Institute, Shandong University, Qingdao 266237, PR China. Electronic address:

The degradation of p-nitrophenol (p-NP) based on OH radicals (HO), HO radicals (HO) and O in aqueous solution was investigated using theoretical computational methods. The complete degradation mechanisms of reaction between p-NP and HO were explored by density functional theory (DFT) methods. The 4-nitrophenoxy radicals and 1,2-dihydroxy-4-nitrocylohexadienyl radicals are confirmed to be major intermediates of the HO-initiated reactions in aqueous phase, which consistent with experimental results. The chemical structures of some products (2,4-dihydroxycyclohexa-2,4-dien-1-one and 4-nitrocyclohexa-3,5-diene-1,2-dione) which were not identified in the experiment are determined. New favorable formation channels for some intermediates were found. The primary reactions initiated by HO or HO with p-NP reveals that HO-initiated degradation is the dominant reaction. HO and O can enhance the degradation extent of p-NP in further reactions. Rate constants of the elementary reactions and overall rate constants were calculated. In addition, the HO-initiated primary reactions in a water box of 500 water molecules were studied using Monte Carlo simulation. All the OH-addition reactions are barrierless and highly feasible. The observed dynamic reaction process is similar to the DFT calculation prediction. Furthermore, the eco-toxicity evaluation shows that important products are harmless or harmful to aquatic organisms, and are much less toxic than p-NP.
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http://dx.doi.org/10.1016/j.jhazmat.2019.121901DOI Listing
May 2020

Self-Assembled Supramolecular Polyoxometalate Hybrid Architecture as a Multifunctional Oxidation Catalyst.

ACS Appl Mater Interfaces 2019 Oct 11;11(42):38708-38718. Epub 2019 Oct 11.

Polyoxometalates (POMs) are widely applied as tuneable and versatile catalysts for a variety of oxidation reactions in an aqueous/organic two-phase system. However, the practical applications of POMs-based biphasic catalysis are hampered by low space-time yields and mass-transport limitation between two layers due to extremely low solubility of the organic reactants in the aqueous phase. Here, we first introduced β-cyclodextrin (β-CD) as an inverse phase transfer agent and a supramolecular nanoreactor to construct a supramolecular POM inorganic-organic hybrid framework (KCl)Na[(β-CD)(SiWO)]·9HO {} for various oxidation catalyses. In contrast to free CD, Keggin [SiWO] catalysts, and their mixture, the {} catalyst, efficiently catalyze oxidation reactions of alcohol, alkene, and thiophene. A comprehensive strategy of experimental, crystallographic, and density functional theory (DFT) calculations elucidates that the catalytic pathway involved three combined aspects of supramolecular recognition, phase transfer property, and POM catalysis. The strategic combination of supramolecular characteristic and POM-based catalysts to fabricate supramolecular POM hybrid materials opens up new economic and green tuning options, thus paving the way to informed catalyst design.
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http://dx.doi.org/10.1021/acsami.9b12531DOI Listing
October 2019

Mechanisms and Kinetic Parameters for the Gas-Phase Reactions of 3-Methyl-3-buten-2-one and 3-Methyl-3-penten-2-one with Ozone.

J Phys Chem A 2019 Apr 14;123(13):2745-2755. Epub 2019 Mar 14.

Environment Research Institute , Shandong University , Qingdao 266237 , P. R. China.

Ozonolysis of unsaturated ketones is a common atmospheric chemical process that plays a significant role in controlling the atmospheric budget of OH and O, organic acids, and secondary organic aerosols (SOA). In this work, the detailed reaction mechanism and rate coefficients for the reactions of O with two unsaturated ketones, 3-methyl-3-buten-2-one (MBO332) and 3-methyl-3-penten-2-one (MPO332), were investigated by using density functional theory (DFT) and Rice-Ramsperger-Kassel-Marcus (RRKM) theory. The results indicate that the major products are butanedione and formaldehyde for MBO332, and butanedione and acetaldehyde for MPO332. Possible reaction mechanism and thermodynamic parameters of some complex stable Criegee intermediates (SCIs) RR'COO were also be investigated in this study. Some organic peroxides can be regarded as the main products for the further reactions of SCIs. The rate constants calculated with O are 2.59 × 10 cm molecule s and 2.28 × 10 cm molecule s for MBO332 and MPO332 at 298 K and 1 atm. The total rate constant is negatively correlated with temperature (200-400 K) and positively correlated with pressure. The atmospheric half-lives of MBO332 and MPO332 based on O are estimated.
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http://dx.doi.org/10.1021/acs.jpca.8b12025DOI Listing
April 2019

Density functional theory study of selective aerobic oxidation of cyclohexane: the roles of acetic acid and cobalt ion.

J Mol Model 2019 Feb 20;25(3):71. Epub 2019 Feb 20.

School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, 225002, Jiangsu, China.

A computational study of cyclohexane autoxidation and catalytic oxidation to a cyclohexyl hydroperoxide intermediate (CyOOH), cyclohexanol, and cyclohexanone has been conducted using a hybrid density functional theory method. The activation of cyclohexane and O is the rate-determining step in the formation of CyOOH due to its relatively high energy barrier of 41.2 kcal/mol, and the subsequent reaction behavior of CyOOH controls whether the production of cyclohexanol or cyclohexanone is favored. Using CHCOOH or (CHCOO)Co as a catalyst reduces the energy barriers required to activate cyclohexane and O by 4.1 or 7.9 kcal/mol, respectively. Employing CHCOOH improves the CyOOH intramolecular dehydration process, which favors the formation of cyclohexanone. The energy barrier to the decomposition of CyOOH to CyO·, an important precursor of cyclohexanol, decreases from 35.5 kcal/mol for autoxidation to 25.9 kcal/mol for (CHCOO)Co catalysis. (CHCOO)Co promotes the autoxidation process via a radical chain mechanism. The computational results agree with experimental observations quite well, revealing the underlying role of CHCOOH and Co ion in cyclohexane oxidation. Graphical abstract Through DFT analysis of cyclohexane autoxidation and catalytic oxidation, we reveal the mechanism of the effects of CHCOOH and Co on the reaction routes.
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http://dx.doi.org/10.1007/s00894-019-3949-zDOI Listing
February 2019

Electroic and optical properties of germanene/MoS heterobilayers: first principles study.

J Mol Model 2018 Nov 6;24(12):333. Epub 2018 Nov 6.

Collaborative Innovation Center for Marine Biomass Fibers, Laboratory of New Fiber Materials and Modern Textile, the Growing Base for State Key Laboratory, College of Chemistry and Chemical Engineering, Qingdao University, Qingdao, 266071, China.

First principles calculations have been performed to investigate the structural, electronic, and optical properties of germanene/MoS heterostructures. The results show that a weak van der Waals coupling between germanene and MoS layers can lead to a considerable band-gap opening (53 meV) as well as the preserved Dirac cone with a linear band dispersion of germanene. The applied external electric filed can not only enhance the interaction strength between two layers, but also linearly control the charge transfer between germanene and MoS layers, and consequently lead to a tunable band gap. Furthermore, the reduction in the optical absorption intensity of the heterostructures with respect to the separated monolayers has been predicted. These findings suggest that the Ge/MoS hybrid can be designed as the device where both finite band gap and high carrier mobility are required.
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http://dx.doi.org/10.1007/s00894-018-3855-9DOI Listing
November 2018

Theoretical study on host-guest interaction between pillar[4]arene and molecules or ions.

J Mol Model 2018 Jul 9;24(8):199. Epub 2018 Jul 9.

School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, 225002, Jiangsu, China.

In order to systematically explore the general rule of the host-guest chemistry for pillararenes, this work investigates the weak interactions between pillar[4]arene and some typical guests (anions, cations, and dumbbell-shaped molecules) by using density functional theory (DFT) calculations at the ωB97XD/6-311G(d,p) level. The strong molecular recognition ability of pillar[4]arene has been discussed based on the geometry structure, electronic structure, and thermodynamic properties of the host-guest complexes. The results show that the equivalent lower and upper rims of the pillar[4]arene can be combined with both anion and cation, and its cavity can accommodate the alkyl part of the dumbbell-shaped molecule. The main host-guest interactions between pillar[4]arene and guests are hydrogen bond, cation-π, anion-π, and hydrophobic interaction by visualization of weak interactions using the Multiwfn program. Pillar[4]arene will form a more stable host-guest complex with the guest, which possesses conjugate structure and weak steric repulsion. This work intends to provide a theoretical basis for enriching the host-guest chemistry, understanding the supramolecular morphology, and expanding the applications of the pillararenes.
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http://dx.doi.org/10.1007/s00894-018-3736-2DOI Listing
July 2018

Controllable Supramolecular Chiral Twisted Nanoribbons from Achiral Conjugated Oligoaniline Derivatives.

J Am Chem Soc 2018 08 19;140(30):9417-9425. Epub 2018 Jul 19.

School of Chemistry and Chemical Engineering , Yangzhou University , Yangzhou , Jiangsu 225002 , P. R. China.

The fabrication of supramolecular chiral nanostructures from achiral materials without the need of pre-existing chirality is a major challenge associated with the origin of life. Herein, supramolecular chiral twisted nanoribbons of achiral oligoaniline derivatives were prepared via simply performing the chemical oxidation of aniline in an alcohol/water mixed solvent. In particular, the supramolecular chirality of the twisted nanoribbons could be controlled by facilely tuning the alcohol content in the mixed solvent. A tetra-aniline derivative CHON was attested to be the major component of the obtained nanoribbons. The main driving forces for the assembly of the oligoaniline derivative into twisted nanoribbons might be the π-π stacking and hydrogen bonding interactions among the chains which could be modulated by the alcohol content in the mixed solvent. The single-handed twisted nanoribbons could be used to separate chiral phenylalanine from a racemic mixture. Thus, it is highly anticipated that the supramolecular chirality endows π-conjugated molecules with potential application in chiral recognition.
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http://dx.doi.org/10.1021/jacs.7b12178DOI Listing
August 2018

Theoretical investigation of pillar[4]quinone as a cathode active material for lithium-ion batteries.

J Mol Model 2017 Apr 7;23(4):105. Epub 2017 Mar 7.

School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, 225002, China.

The applicability of a novel macrocyclic multi-carbonyl compound, pillar[4]quinone (P4Q), as the cathode active material for lithium-ion batteries (LIBs) was assessed theoretically. The molecular geometry, electronic structure, Li-binding thermodynamic properties, and the redox potential of P4Q were obtained using density functional theory (DFT) at the M06-2X/6-31G(d,p) level of theory. The results of the calculations indicated that P4Q interacts with Li atoms via three binding modes: Li-O ionic bonding, O-Li···O bridge bonding, and Li···phenyl noncovalent interactions. Calculations also indicated that, during the LIB discharging process, P4Q could yield a specific capacity of 446 mAh g through the utilization of its many carbonyl groups. Compared with pillar[5]quinone and pillar[6]quinone, the redox potential of P4Q is enhanced by its high structural stability as well as the effect of the solvent. These results should provide the theoretical foundations for the design, synthesis, and application of novel macrocyclic carbonyl compounds as electrode materials in LIBs in the future. Graphical Abstract Schematic representation of the proposed charge-discharge mechanism of Pillar[4]quinone as cathode for lithium-ion batteries.
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http://dx.doi.org/10.1007/s00894-017-3282-3DOI Listing
April 2017

New cytotoxic trichothecene macrolide epimers from endophytic Myrothecium roridum IFB-E012.

J Antibiot (Tokyo) 2016 08 13;69(8):652-5. Epub 2016 Jul 13.

Department of Chemistry and Biochemistry, University of North Carolina at Wilmington, Wilmington, NC, USA.

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http://dx.doi.org/10.1038/ja.2016.86DOI Listing
August 2016

Formation of a series of stable pillar[5]arene-based pseudo[1]-rotaxanes and their [1]rotaxanes in the crystal state.

Sci Rep 2016 06 28;6:28748. Epub 2016 Jun 28.

Key Laboratory of Mesoscopic Chemistry of MOE, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, P. R. China.

A series of mono-amide-functionalized pillar[5]arenes with different lengths of N-ω-aminoalkyl groups as the side chain on the rim were designed and synthesized, which all formed pseudo[1]rotaxanes in the crystal state. And these pseudo[1]rotaxanes could be transformed into [1]rotaxanes or open forms in the crystal state. In addition, they were also studied in solution by (1)H NMR spectroscopy.
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http://dx.doi.org/10.1038/srep28748DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4923850PMC
June 2016

Molecular diversity of the three-component reaction of α-amino acids, dialkyl acetylenedicarboxylates and N-substituted maleimides.

Org Biomol Chem 2016 Jul;14(27):6497-507

College of Chemistry & Chemical Engineering, Yangzhou University, Yangzhou 225002, China.

The one-pot three-component reaction of secondary α-amino acids, including proline, thiazolidine-4-carboxylic acid, and piperidine-2-carboxylic acid sarcosine with dialkyl acetylenedicarboxylate and N-substituted maleimides in refluxing ethanol afforded functionalized pyrrolo[3,4-a]pyrrolizines, pyrrolo[3',4':3,4]pyrrolo[1,2-c]thiazoles, pyrrolo[3,4-a]indolizines and octahydropyrrolo[3,4-c]pyrroles in good yields and with high diastereoselectivity. On the other hand, the similar three-component reaction containing primary α-amino acids, such as glycine, alanine, phenylalanine and leucine, with N-substituted maleimides and two molecules of dialkyl acetylenedicarboxylate obtained the corresponding hexahydropyrrolo[3,4-c]pyrrol-2(1H)-yl)maleates.
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http://dx.doi.org/10.1039/c6ob00921bDOI Listing
July 2016

Ionic S(N)i-Si Nucleophilic Substitution in N-Methylaniline-Induced Si-Si Bond Cleavages of Si2Cl6.

Chemistry 2016 Mar 24;22(14):5010-6. Epub 2016 Feb 24.

Key Laboratory of Special Functional Aggregated Materials and, Key Laboratory of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan, 250100, P.R. China.

N-Methylaniline-induced Si-Si bond cleavage of Si2Cl6 has been theoretically studied. All calculations were performed by using DFT at the MPWB1K/6-311++G(3df,2p)//MPWB1K/6-31+G(d,p) levels. An ionic SN i-Si nucleophilic substitution mechanism, which is a newly found nucleophilic substitution in silicon-containing compounds, is proposed in the N-methylaniline-induced Si-Si bond cleavage in Si2Cl6. Unlike general S(N)i-Si nucleophilic substitutions that go through a pentacoordinated silicon transition state, ionic nucleophilic substitution goes through a tetracoordinated silicon transition state, in which the Si-Si bond is broken and siliconium ions are formed. Special cleavage of the Si-Si bond is presumably due to the good bonding strength between Si and N atoms, which leads to polarization of the Si-Si bond and eventually to heterolytic cleavage. Calculation results show that, in excess N-methylaniline, the final products of the reaction, including (NMePh)(3-n) SiHCl(n) (n=0-2) and (NMePh)(4-n) SiCl(n) (n=2-3), are the Si-Si cleavage products of Si2Cl6 and the corresponding amination products of the former. The ionic S(N)i-Si nucleophilic substitution mechanism can also be employed to describe the amination of chlorosilane by N-methylaniline. The suggested mechanisms are consistent with experimental data.
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http://dx.doi.org/10.1002/chem.201504927DOI Listing
March 2016

Synthesis of 1'-C-cyano pyrimidine nucleosides and characterization as HCV polymerase inhibitors.

Nucleosides Nucleotides Nucleic Acids 2015 23;34(11):763-85. Epub 2015 Sep 23.

b Kainos Medicine, Inc. , Seoul , Republic of Korea.

Ribose modified 1'-C-cyano pyrimidine nucleosides were synthesized. A silver triflate mediated Vorbrüggen reaction was used to generate the nucleoside scaffold and follow-up chemistry provided specific ribose modified analogs. Nucleosides and phosphoramidate prodrugs were tested for their anti-HCV activity.
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http://dx.doi.org/10.1080/15257770.2015.1075550DOI Listing
August 2016

Computational simulation study on the anion recognition properties of functionalized tetraphenyl porphyrins.

J Mol Model 2015 Jun 10;21(6):140. Epub 2015 May 10.

College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, 225002, China,

The anion recognitions of tetra-(2-formamido) phenyl porphyrin (APP), tetra-(2-ureido) phenyl porphyrin (UPP), and their zinc derivatives (ZnAPP and ZnUPP) to three anions (Cl(-), H2PO4 (-), CH3COO(-)) were studied using quantum mechanical calculations (QM) and molecular dynamics (MD) simulations. The density functional theory (DFT) calculations at M06-2X/6-31G (d, p) level indicated that the anion recognition ability of ZnAPP was better than that of APP, and the anion selectivity was in the order Cl(-) < H2PO4 (-) < CH3COO(-). The selectivity trends for ZnUPP and UPP were found to be H2PO4 (-) < Cl(-) < CH3COO(-). The structures, thermodynamic properties, and recognition mechanisms were discussed in detail. The 2 ns MD simulations were then carried out for [email protected] and [email protected] complexes in mixed solvent DMSO/water. The MD simulation results showed that [email protected] complexes exhibited higher stability than [email protected], which was in good agreement with QM results. H-bonds formed between the anions and the side-chains of receptors, and zinc coordination bonds with anions contributed significantly to the stability of complexes. The anion selectivity of ZnAPP and ZnUPP in the solvent phase were also discussed and compared with those in the gas phase.
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http://dx.doi.org/10.1007/s00894-015-2688-zDOI Listing
June 2015

Specific binding and inhibition of 6-benzylaminopurine to catalase: multiple spectroscopic methods combined with molecular docking study.

Spectrochim Acta A Mol Biomol Spectrosc 2014 Apr 25;123:327-35. Epub 2013 Dec 25.

College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002, China. Electronic address:

6-Benzylaminopurine (6-BA) is a kind of cytokinin which could regulate the activities of the antioxidant defense system of plants. In this work, its interaction with and inhibition of beef liver catalase have been systematically investigated using spectroscopic, isothermal titration calorimetric and molecular docking methods under physiological conditions. The fluorescence quenching of beef liver catalase (BLC) by 6-BA is due to the formation of 6-BA-BLC complex. Hydrogen bonds and van der Waals interactions play major roles in stabilizing the complex. The Stern-Volmer quenching constant, binding constant, the corresponding thermodynamic parameters and binding numbers were measured. The results of UV-vis absorption, three-dimensional fluorescence, synchronous fluorescence and circular dichroism spectroscopic results demonstrate that the binding of 6-BA results in the micro-environment change around tyrosine (Tyr) and tryptophan (Trp) residues of BLC. The BLC-mediated conversion of H2O2 to H2O and O2, in the presence and absence of 6-BA, was also studied. Lineweaver-Burk plot indicates a noncompetitive type of inhibition. Molecular docking study was used to find the binding sites.
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http://dx.doi.org/10.1016/j.saa.2013.12.021DOI Listing
April 2014

Synergistically enhanced electrochemical response of host-guest recognition based on ternary nanocomposites: reduced graphene oxide-amphiphilic pillar[5]arene-gold nanoparticles.

ACS Appl Mater Interfaces 2013 Nov 21;5(21):11218-24. Epub 2013 Oct 21.

College of Chemistry and Chemical Engineering, Yangzhou University , Yangzhou 225002, Jiangsu, People's Republic of China.

An amphiphilic pillar[5]arene (AP5) was modified onto the surface of reduced graphene oxide (RGO) to form the water-dispersive RGO-AP5 nanocomposite. And then, as-prepared gold nanoparticles (AuNPs) self-assembled onto the surface of RGO-AP5 through amido groups of AP5 to achieve RGO-AP5-AuNPs nanocomposites. It was verified that a large amount of AP5 molecules had been effectively loaded onto the surface of RGO and lots of AuNPs could be uniformly dispersed on RGO-AP5. Electrochemical results showed that the RGO-AP5 could exhibit selective supramolecular recognition and enrichment capability toward guest molecules. More significantly, in electrochemical sensing the guest molecules, ternary nanocomposites RGO-AP5-AuNPs performed the synergetic action of multifunctional properties, which were excellent performances of RGO, selective supramolecular recognition, and enrichment capability of AP5 and catalytic property of AuNPs for guest molecules. Therefore, RGO-AP5-AuNPs showed an outstanding analyzing performance for DA with broad linear range (1.5 × 10(-8) to 1.9×10(-5) M) and low detection limit (1.2 × 10(-8) M) at a signal-to-noise ratio of 3.
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http://dx.doi.org/10.1021/am403463pDOI Listing
November 2013

Theoretical study on ion-pair recognition of M(+)X(-) (M = Li, Na, K and X = F, Cl, Br) by formylaminocalix[4]arene derivatives.

J Mol Model 2012 Dec 26;18(12):4985-93. Epub 2012 Jun 26.

College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, China.

DFT calculations were reported for calix[4]arene derivatives [i.e., formylaminocalix[4]arene (1) and formylaminocalix[4]bis-crown-3 (2)] binding cations M(+) (Li(+), Na(+), and K(+)) and anions X(-) (F(-), Cl(-), and Br(-)) simultaneously. The B3LYP function together with the LANL2DZp basis set was used in order to obtain insights into the factors determining the nature of the interactions of these compounds with X(-) and M(+). Based on the molecular electrostatic potential (MEP) analysis, the result complexes M(+)X(-)/H (H = 1, 2) were investigated. For all the complex structures, the most pronounced changes in geometric parameters upon interaction were observed in the host segment compared with the free receptors. Two main types of driving force, N-H∙∙∙X(-) hydrogen bonds and electrostatic interactions between M(+) and oxygen atoms, were confirmed. The recognition trends for 1 and 2 toward M(+)X(-) followed the same order: M(+)F(-) > M(+)Cl(-) > M(+)Br(-) (M(+) is same to each other) and Li(+)X(-) > Na(+)X(-) > K(+)X(-) (X(-) is same to each other). The binding energy, enthalpy change, Gibbs free energy change, and entropy change of complexation formation have been studied by the calculated thermodynamic data. In all cases, the inclusion energy changes with 2 were more negative than those with 1, correlating with the flexible space available by the two crown ether moieties in 2. The calculated results of the model system have been reported and should be useful to the experimental research in this field.
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http://dx.doi.org/10.1007/s00894-012-1498-9DOI Listing
December 2012

Binding characteristics and molecular mechanism of interaction between ionic liquid and DNA.

J Phys Chem B 2010 Feb;114(5):2033-43

School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, P. R. China.

The binding characteristics and molecular mechanism of the interaction between a typical ionic liquid (IL), 1-butyl-3-methylimidazolium chloride ([bmim]Cl), as a green solvent and DNA were investigated for the first time by conductivity measurements, fluorescence spectroscopy, dynamic light scattering (DLS), cryogenic transmission electron microscopy (cryo-TEM), circular dichroism spectroscopy, (31)P nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared spectroscopy, isothermal titration calorimetry (ITC), and quantum chemical calculations. It was found that the critical aggregation concentration of [bmim]Cl is decreased in the presence of DNA, and the addition of [bmim]Cl induced a continuous fluorescence quenching of the intercalated probe ethidium bromide (EtBr), indicating that the interaction between the ionic liquid and DNA is sufficiently strong to exclude EtBr from DNA. DLS results show that [bmim]Cl can induce a coil-to-globule transition of DNA at a low IL concentration, which was confirmed by the cryo-TEM images of DNA-IL complexes. With [bmim]Cl added, the resulting globular DNA structures and the extended DNA coils are first compacted, and then grow in size. During the binding process, DNA maintains the B-form, but the base packing and helical structure of DNA are altered to a certain extent. The (31)P NMR and IR spectra indicate that the cationic headgroups of bmim(+) groups interact with the phosphate groups of DNA through electrostatic attraction, and the hydrocarbon chains of bmim(+) groups interact with the bases through strong hydrophobic association. ITC results reveal the interaction enthalpy between [bmim]Cl and DNA and show that the hydrophobic interaction between the hydrocarbon chains of [bmim]Cl and the bases of DNA provides the dominant driving force in the binding. On the basis of quantum chemical calculations, it can be inferred that at a low IL concentration, the cationic headgroups of [bmim]Cl would be localized within several angstroms of the DNA phosphates, whereas the hydrophobic chains would be arranged parallel to the DNA surface. When the IL concentration is above 0.06 mol/L, the cationic headgroups are near DNA phosphates, and the hydrocarbon chains are perpendicularly attached to the DNA surface.
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http://dx.doi.org/10.1021/jp9104757DOI Listing
February 2010
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