PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2020
·Vol. 22
·期 15
·8006-8020
·
IF 3.43
Chris Tsz-Leung Chan,Chensheng Ma,Ruth Chau-Ting Chan,Hui-Min Ou,Han-Xin Xie,Allen Ka-Wa Wong,Ming-Liang Wang,Wai-Ming Kwok
4-Aminobenzoic acid (PABA) is one of the earliest patented and most commonly used sunscreen components. There is however a long-lasting controversy on its photo-protective efficacy owing to the lack of information on its protolytic equilibrium and photo-dynamics after absorption of ultraviolet radiation in physiologically relevant aqueous solution. The excitation dynamics in water also remains largely unknown for analogs of PABA such as 4-dimethylaminoacetophenone (DMAAP) and 4-dimethylaminobenzaldehyde (DMABA) which are recognized as prototypes for photo-induced twisted intramolecular charge transfer (TICT). Herein we report a combined application of femtosecond broadband time-resolved fluorescence and transient absorption coupled with density functional theoretical study for PABA, DMAAP, and DMABA under several solvent conditions with representative properties in terms of the pH, polarity and hydrogen bonding capacity. The results we gained demonstrate that, in a neutral aqueous solution, PABA taking the deprotonated anion form in the ground state undergoes rapid protonation after excitation, producing excited state species in the neutral form that may shift effectively by intersystem crossing (ISC) to the long-lasting triplet state capable of damaging nucleic acids. This provides evidence at the molecular level for the detrimental effect of PABA if used as a sunscreen ingredient. In contrast, our investigation on DMAAP and DMABA unveils an unusual solvent controlled deactivation dynamics rendered by the participation of the carbonyl oxygen associated nOπ* state featuring energy and structure strongly responsive to solvent properties. In particular, these molecules in water exhibit solute–solvent hydrogen bonding at the sites of the carbonyl oxygen and the amino nitrogen which is, respectively, weakened and strengthened after the excitation, leading to state reversal and formation of a nOπ* state with a peculiar non-planar structure. This quenches strongly the excitation, eliminates the TICT, suppresses the ISC and opens up the otherwise inaccessible internal conversion (IC) to account for ∼80% of the entire deactivation. The IC, observed to proceed at a rate of ∼2.5 ps, allows the effective recovery of the ground state, providing substantial protection against ultraviolet irradiation. Moreover, the revelation of highly solvent sensitive fluorescence emission from DMABA and DMAAP implies the potential application of these molecules as the functional element in the design of sensory materials for probing the polarity and hydrogen bonding character of the surrounding environment.
研究领域:
化学
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生物学
·
药理学
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
·
2020
·
IF 5.065
Jinbo Ouyang,Jian Chen,Haiqing Huang,Limin Zhou,Xin Huang
Solubility of 4-Methylumbelliferon in different pure solvents, including polar and apolar solvents, were firstly measured at varied temperatures under 0.1 MPa by a gravimetric method. Results showed that solubility in all solvents increase with rising of temperature, and 4-Methylumbelliferon is most soluble in acetone, followed by 1-butanol, isopropanol, 1-propanol, isobutanol , ethyl acetate , ethanol, methanol, methyl acetate , acetonitrile , butyl acetate and water. The experimental solubility data were correlated by several thermodynamic models, including modified Apelblat model, NRTL model and Wilson model. The accuracy of these models is determined by calculation of mean relative deviation ( MRD ). Moreover, dissolution thermodynamics i.e. dissolution enthalpy, dissolution Gibbs energy and dissolution entropy, were calculated by using Wilson equations.
研究领域:
化学工程
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物理化学
✓ 已验证
产品关联
DOI
高影响因子
COMBUSTION AND FLAME
·
2023
·
IF 4.4
Erhai An,Yihong Tan,Kehua Han,Xiaoxia Li,Xiong Cao,Yingxin Tan,Peng Deng
Molecular perovskite energetic material DAP-4 is seen as a potential high-energy oxidant due to its high energy, high density, high oxidation capacity, and facile preparation technology. However, optimizing its energy release and reducing its thermal decomposition temperature are huge challenges for its future application. In this work, the role of iron (Fe) nanospheres in the energy release of DAP-4 was studied. Our research has shown that Fe powder can not only serve as a fuel to promote combustion, but also as an important catalyst to significantly improve the thermal decomposition, energy release, and burning rate of DAP-4. By adding 25% Fe nanospheres, the decomposition temperature of DAP-4 was reduced to 299.7 °C, which is the most reduction by 84.7 °C from 384.4 °C (raw DAP-4) to 299.7 °C (DAP-4/Fe-5 with 25wt% Fe nanospheres) was obtained. The decomposition activation energy also decreases by at least 69.5 kJ mol −1 from 229.4 kJ mol −1 (DAP-4) to 159.9 kJ mol −1 (DAP-4/Fe-1 with 5wt% Fe nanospheres). The combustion performance of DAP-4/Fe composites is significantly improved by a 4∼5 times shorter burn rate. The energy-releasing mechanism of DAP-4 with the presence of Fe nanospheres was proposed. Fe x O y at the surface of Fe nanospheres played an important role in the energy releasing of DAP-4. This work showed a new idea for the potential application of molecular perovskite energetic materials.
研究领域:
材料科学
·
能源化学
✓ 已验证
产品关联
DOI
高影响因子
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2018
·Vol. 25
·期 24
·24241-24252
·
IF 2.8
Zhu Jianqiang,Tsona Narcisse T.,Du Lin
Chloroalkenes are among the important anthropogenic organic compounds emitted in the atmosphere as a result of their wide use in synthetic processes in industry. Despite their well-known adverse effects on human health and air quality, the chemistry of these chloroalkenes remains poorly explored. In this work, reactions of 4-chloro-1-butene (CBE), a representative example of chloroalkenes, with O 3 , OH, NO 3 , and Cl are investigated in a 100-L Teflon reaction chamber equipped with gas chromatography-flame ionization detector (GC-FID). The absolute rate method was used for the reaction with O 3 while the relative rate method was used for reactions with OH, NO 3 , and Cl. The following rate constants were obtained at room temperature (298 ± 2) K and atmospheric pressure: (3.96 ± 0.43) × 10 −18 , (2.63 ± 0.96) × 10 −11 , (4.48 ± 1.23) × 10 −15 , and (2.35 ± 0.90) × 10 −10 cm 3 molecule −1 s −1 , for reactions with O 3 , OH, NO 3 , and Cl, respectively. Atmospheric lifetimes of CBE calculated from rate constants of the different reactions obtained in this work showed that reaction with OH is the main loss process for CBE, while in coastal areas and in the marine boundary layer, the CBE loss by Cl reaction becomes important. Estimation of the value of the photochemical ozone creation potential (POCP) indicated that CBE has a large ozone formation potential. The present work underlines the need for further studies on the atmospheric chemistry of chlorinated VOCs.
研究领域:
大气化学
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环境科学
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有机化学
✓ 已验证
DOI
PubMed
高影响因子
CRYSTAL GROWTH & DESIGN
·
2020
·
IF 4.089
Wei Du,Huifen Wang,Runpu Wang,Xuemin Wang,Penggao Cheng,Jianping Zhang,Na Tang,Liang Zhu,Penglei Cui
To further understand the relationship among molecular conformational flexibility, thermodynamics, nucleation, and the polymorphic outcomes, the homogeneous nucleation and heterogeneous nucleation from fast cooling crystallization, evaporative crystallization, antisolvent crystallization, and solution-mediated polymorphic transformation were studied, considering the effects of temperature, supersaturation, and solvent. The conformers can rapidly fluctuate in solution with either monomers solvated by solvent molecules or carboxylic acid dimers and stacked dimers. No links between conformational flexibility and polymorphic outcome were found from both the experiment results and DFT calculation, though conformational polymorphs were obtained during the crystallization of 4-hexyloxybenzoic acid (HOBA). The stability relationship of HOBA polymorphs was confirmed, and the desolvation process was found to play a vital role in the overall self-assembly during crystallization. Finally, a process-control chart to prepare different polymorphs of HOBA was drawn to summarize the polymorphic differences caused by conformation.
研究领域:
物理化学
·
材料科学
✓ 已验证
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2024
·
IF 5.8
Bing Wang,Yao Liu,Zhuo Li,Hong Hao,YuZhen Zhao,ZeMin He,WenQi Song,EnZhou Liu,Bo Zhou,XiaoXun Ma,Zongcheng Miao
Leveraging the synergistic combination of dipole modulation and localized surface plasmon resonance effects (LSPR) effects offers a promising solution to address the low carrier separation efficiency observed at traditional Type-III heterojunction interfaces. Herein, a derivative of SubPc-4 with a high dipole moment of 7.25 Debye was successfully synthesized by introducing carbonyl functional groups axially into the parent subphthalocyanine. Silver metal was introduced during the preparation of Ag 3 PO 4 through light irradiation, and the organic supramolecule SubPc-4 self-assembled on the Ag 3 PO 4 semiconductor surface via van der Waals forces and π-π stacking interactions, forming a binary heterojunction SubPc-4/Ag 3 PO 4 with LSPR effects. Under 30 minutes of visible light irradiation, the degradation efficiencies of tetracycline and oxytetracycline by the SubPc-4/Ag 3 PO 4 supramolecular nanoarray were 88.29% and 90.20%, respectively. DFT and TDDFT calculations, combined with experimental characterization data, indicate that the LSPR supramolecular array exhibits excellent activity and stability, primarily attributed to the improved carrier separation capability at the SubPc-4/Ag 3 PO 4 interface. This work highlights the potential of combining dipole modulation and LSPR technology to enhance the performance of Type-III heterojunction photocatalysts.
研究领域:
材料科学
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环境科学
·
化学
✓ 已验证
DOI
高影响因子
REPRODUCTIVE BIOMEDICINE ONLINE
·
2015
·
IF 3.015
Fenju Qin,Jie Zhang,Linsen Zan,Weiqiang Guo,Jin Wang,Lili Chen,Yi Cao,Ouxi Shen,Jian Tong
The aim of the present study was to elucidate whether the GATA-4/SF-1 signalling pathway is involved in the inhibitory effects of melatonin on testosterone production in both the TM3 Leydig cell line and in C57BL/6J mice. In-vitro experiments demonstrated that melatonin treatment significantly reduced testosterone levels in cell culture medium ( P < 0.05 or P < 0.01); and decreased intracellular cyclic adenosine monophospha accumulation ( P < 0.05 or P < 0.01) and mRNA/protein expression of GATA-4 , SF-1 (NR5A1) , StAR , P450SCC (CYP11A1) and 3β-HSD ( P < 0.05 or P < 0.01). These effects were blocked by N-acetyl-2-benzyltryptamin, a melatonin receptor antagonist . Similar effects of melatonin on testosterone production ( P < 0.05 or P < 0.01) and down-regulation of transcription factors GATA-4 and SF-1 ( P < 0.01) were also observed in mice treated with intratesticular injections of melatonin. Overall, the data suggest that the inhibitory effects of melatonin on testosterone production are mediated via down-regulation of GATA-4 and SF-1 expression.
研究领域:
内分泌学
·
分子生物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
APPLIED SURFACE SCIENCE
·
2016
·
IF 3.15
Wenjuan Shen,Yi Mu,Bingning Wang,Zhihui Ai,Lizhi Zhang
In this study, we demonstrate that the bimetallic iron-nickel nanoparticles (nZVIN) possessed an enhanced performance in comparison with nanoscale zero-valent iron (nZVI) on aerobic degradation of 4-chlorophenol (4-CP). The 4-CP degradation rate constant in the aerobic nZVIN process (nZVIN/Air) was 5 times that in the classic nZVI counterpart system (nZVI/Air). Both reactive oxygen species measurement and inhibition experimental results suggested that hydroxyl radicals were the major active species contributed to aerobic 4-CP degradation with nZVI, on contrast, superoxide radicals predominated the 4-CP degradation in the nZVIN/Air process. High performance liquid chromatography and gas chromatography-mass spectrometer analysis indicated the intermediates of the nZVI/Air system were p -benzoquinone and hydroquinone, which were resulted from the bond cleavage between the chlorine and carbon atom in the benzene ring by hydroxyl radicals. However, the primary intermediates of 4-CP found in the nZVIN/Air system were phenol via the direct dechlorination by superoxide radicals, accompanying with the formation of chloride ions. On the base of experimental results, a superoxide radicals mediated enhancing mechanism was proposed for the aerobic degradation of 4-CP in the nZVIN/Air system. This study provides new insight into the role of bimetallic nickel on enhancing removal of organic pollutants with nZVI.
研究领域:
环境科学
·
污染控制
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产品关联
DOI
高影响因子
JOURNAL OF SEPARATION SCIENCE
·
2019
·Vol. 42
·期 15
·2482-2490
·
IF 2.516
Lingping Cheng,Jianfeng Cai,Qing Fu,Yanxiong Ke
6-(4-Aminophenyl)-5-methyl-4,5-dihydro-3(2H)-pyridazinone is a key synthetic intermediate for cardiotonic agent levosimendan. Very few studies address the use of chiral stationary phases in chromatography for the enantioseparation of this intermediate. This study presents two efficient preparative methods for the isolation of ( R )(−)-6-(4-aminophenyl)-5-methyl-4,5-dihydro-3(2H)-pyridazinone in polar organic solvent chromatography and supercritical fluid chromatography using polysaccharide-based chiral stationary phases and volatile organic mobile phases without additives in isocratic mode. Under optimum conditions, Chiralcel OJ column showed the best performance ( α = 1.71, Rs = 5.47) in polar organic solvent chromatography, while Chiralpak AS column exhibited remarkable separations ( α = 1.81 and Rs = 6.51) in supercritical fluid chromatography with an opposite enantiomer elution order. Considering the sample solubility, runtime and solvent cost, the preparations were carried out on Chiralcel OJ column and Chiralpak AS column (250 × 20 mm i.d.; 10 µm) in polar organic mode and supercritical fluid chromatography mode with methanol and CO 2 /methanol as mobile phases, respectively. By utilizing the advantages of chromatographic techniques and polysaccharide-based chiral stationary phases, this work provides two methods for the fast and economic preparation of ( R )(−)-6-(4-aminophenyl)-5-methyl-4,5-dihydro-3(2H)-pyridazinone, which are suitable for the pharmaceutical industry.
研究领域:
药物化学
·
分析化学
✓ 已验证
DOI
PubMed
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2021
·
IF 8.128
Xiangquan Liu,Jiaqi Tang,Jinglun Yang,Helan Zhang,Yu Fang
Preparation of nanofilms which are able to reject water-soluble low molecular weight organic compounds in nanofiltration remains to be a challenge. Herein, we report a new kind of self-standing, defect-free, robust, centimeter-sized and thickness controllable calix[4]pyrrole (C[4]P)-based nanofilms with excellent molecular sieving performance in nanofiltration. The nanofilms were prepared via confined dynamic condensation of the tetra-benzoyl-hydrazine derivative of calix[4]pyrrole (CPTBH) with 1,3,5-benzenetricarboxaldehyde (BTC) at the air/dimethyl sulfoxide (DMSO) interface. Nanofiltration tests under 2 bar pressure with porous polyethylene terephthalate (PET) as the support and a CsF treated CPTBH-BTC nanofilm (∼100 nm) as the selective layer depicted a water permeance of 15 L m -2 h −1 bar −1 and a methanol permeance of 45 L m -2 h −1 bar −1 . High rejection rates (>95%) were found in aqueous solution for most of the tested dyes and pharmaceuticals. Remarkably, the composite membrane also demonstrated good separation performance in aqueous phase to some amino acids and organic dyes with molecular weights around 200 g/mol. High-performance nanofiltration in methanol was also realized. In this case, the molecular weight cutoff value is ∼ 800 g/mol. These findings showed that introduction of macrocyclic hosts is an effective way to develop nanofilms with high solvent permeance but low molecular weight cutoff value.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2019
·Vol. 26
·期 9
·9161-9173
·
IF 2.914
Zhang Tingting,Yang Yanling,Li Xing,Wang Nan,Zhou Zhiwei
Ultrasound-assisted regeneration of powdered activated carbon (PAC) saturated with 4-chlorophenol (4-CP) was investigated in this work. The variables, i.e., acoustic frequency, density levels, regenerating solution species, spent PAC mass, and the number of repeated cycle, were optimized. The UV–Vis spectra, thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), and pore structure analysis were used to characterize the regenerated PAC as compared to the virgin and spent PAC. The adsorption experiments indicated that the adsorption kinetics of 4-CP fitted well with the pseudo-second-order model, and the main chemisorption process was nonlinear and heterogeneous. The desorption results showed that the optimized regenerated conditions were identified as 40 kHz of frequency, 0.18 W/mL of sonication intensity, 0.1 M NaOH and 50% ( v / v ) ethyl alcohol mixture of regeneration solution, and 1 g/L of saturated PAC mass. Under this condition, the regeneration efficiency reached up to 86.81%. Hydroxylated oxidation products especially benzoquinone and hydroquinone were formed during ultrasound regeneration. Ultrasound mainly acted on surface functionalities, mesopores, and macropores of PAC through the hydroxyl radical oxidization resulted from the cavitation effect.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF THE ELECTROCHEMICAL SOCIETY
·
2020
·Vol. 167
·期 6
·066509
·
IF 3.721
Xia Qiu,Xiang Qing,Wang Sufan,Yinggui Zhu
4-Chromanone and chromone, these two structurally similar pharmaceutical intermediates play a vital role in drug synthesis, but their related electrochemical properties have not been reported. In this work, we have found that 4-chromanone and chromone can generate strong electrochemiluminescence (ECL) during their reduction by using K2S2O8 as co-reactant in H3BO3-Na2B4O7 buffer solution. The ECL reaction mechanism has been investigated carefully by studying their fluorescence (FL) spectrum, ECL spectrum, and the important role of co-reactants in the system. Moreover, it has been found that iodide ion (I−) can inhibit the ECL signal of 4-chromanone and the ECL decrease degree is related to the amount of added I−. Therefore, a new ECL method for the detection of iodide ion has been established with high sensitivity, good selectivity and wide linear range, which can be used for detecting I− in real samples.
研究领域:
分析化学
·
药物化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）