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1.
Small ; : e2403334, 2024 Jul 11.
Artículo en Inglés | MEDLINE | ID: mdl-38990887

RESUMEN

Textiles with thermal/moisture managing functions are of high interest. However, making the textile sensitive to the surrounding environment is still challenging. Herein, a multimodal smart fabric is developed by stitching together the Ag coated thermal-humidity sensitive thermoplastic polyurethane (Ag-THSPU) and the hybrid of polyvinylidene fluoride and polyurethane (PU-PVDF). The porous PU-PVDF layer is used for solar reflection, infrared emissivity, and water resistance. The Ag-THSPU layer is designed for regulating thermal reflection, sweat evaporation as well as convection. In cold and dry state, the Ag domains are densely packed covering the crystalline polyurethane matrix, featuring low water transmission (102.74 g m-2·24 h-1), high thermal reflection and 2.4 °C warmer than with cotton fabric. In the hot and humid state, the THSPU layer is swollen by sweat and expands in area, resulting in the formation of micro-hook faces where the Ag domains spread apart to promote sweat evaporation (2084.88 g/m-2·24 h-1), thermal radiation and convection, offering 2.5 °C cooler than with cotton fabric. The strategy reported here opens a new door for the development of adaptive textiles in demanding situations.

2.
Angew Chem Int Ed Engl ; 61(52): e202213974, 2022 12 23.
Artículo en Inglés | MEDLINE | ID: mdl-36260531

RESUMEN

Biocatalysis is increasingly being explored for the sustainable development of green industry. Though enzymes show great industrial potential with their high efficiency, specificity, and selectivity, they suffer from poor usability and stability under abiological conditions. To solve these problems, researchers have fabricated nano- and micro-sized biocatalytic reactors based on the self-assembly of various polymers, leading to highly stable, functional, and reusable biocatalytic systems. This Review highlights recent progress in self-assembled polymeric nano- and microreactors for biocatalytic synthesis, including polymersomes, reverse micelles, polymer emulsions, Pickering emulsions, and static emulsions. We categorize these reactors into monophasic and biphasic systems and discuss their structural characteristics and latest successes with representative examples. We also consider the challenges and potential solutions associated with the future development of this field.


Asunto(s)
Micelas , Polímeros , Biocatálisis , Emulsiones
3.
J Am Chem Soc ; 143(18): 6798-6804, 2021 May 12.
Artículo en Inglés | MEDLINE | ID: mdl-33938744

RESUMEN

Spin structure of a magnetic system results from the competition of various exchange couplings. Pressure-driven spin structure evolution, through altering interatomic distance, and hence, electronic structure produces baromagnetic effect (BME), which has potential applications in sensor/actuator field. Here, we report a new spin structure(CyS-AFMb) with antiferromagnetic(AFM) nature in Fe-doped Mn0.87Fe0.13NiGe. Neutron powder diffraction (NPD) under in situ hydrostatic pressure and magnetic field was conducted to reveal the spin configuration and its instabilities. We discovered that a pressure higher than 4 kbar can induce abnormal change of Mn(Fe)-Mn(Fe) distances and transform the CyS-AFMb into a conical spiral ferromagnetic(FM) configuration(45°-CoS-FMa) with easily magnetized but shortened magnetic moment by as much as 22%. The observed BME far exceeds previous reports. Our first-principles calculations provide theoretical supports for the enhanced BME. The compressed lattice by pressure favors the 45°-CoS-FMa and significantly broadened 3d bandwidth of Mn(Fe) atoms, which leads to the shortened magnetic moment and evolution of spin structure.

4.
J Org Chem ; 86(2): 1430-1436, 2021 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-33370530

RESUMEN

Organic selenides are famous for their coordination and catalytic functions in the organic phase, albeit challenging for aqueous medium. Herein, the combination of a hydrophilic body of crown ether and substitution of one oxygen atom with a selenium one provides a new type of design route for organic selenide entities with charming functions in aqueous solution. The selenacrown ether C9Se presented here intrinsically shows an amphiphile-like property. Its nanosphere structure in water readily expands the catalysis of organic selenide to aqueous substrates in thiol/disulfide conversion.

5.
Macromol Rapid Commun ; 41(18): e2000320, 2020 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-33463837

RESUMEN

New functional initiators for the cationic ring-opening polymerization of 2-alkyl-2-oxazolines are described to introduce a thiol moiety at the α terminus. Both tosylate and nosylate initiators carrying a thioacetate group are obtained in multigram scale, from commercial reagents in two steps, including a phototriggered thiol-ene radical addition. The nosylate derivative gives access to a satisfying control over the cationic ring-opening polymerization of 2-ethyl-2-oxazoline, with dispersity values lower than 1.1 during the entire course of the polymerization, until full conversion. Cleavage of the thioacetate end group is rapidly achieved using triazabicyclodecene, thereby leading to a mercapto terminus. The latter gives access to a new subgeneration of α-functional poly(2-oxazoline)s (butyl ester, N-hydroxysuccinimidyl ester, furan) by Michael addition with commercial (meth)acrylates. The amenability of the mercapto-poly(2-ethyl-2-oxazoline) for covalent surface patterning onto acrylated surfaces is demonstrated in a microchannel cantilever spotting (µCS) experiment, characterized by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary-ion mass spectrometry (ToF-SIMS).


Asunto(s)
Acrilatos , Compuestos de Sulfhidrilo , Cationes , Oxazoles , Polimerizacion
6.
J Cell Mol Med ; 23(10): 6730-6743, 2019 10.
Artículo en Inglés | MEDLINE | ID: mdl-31328430

RESUMEN

Osteoclast overactivation-induced imbalance in bone remodelling leads to pathological bone destruction, which is a characteristic of many osteolytic diseases such as rheumatoid arthritis, osteoporosis, periprosthetic osteolysis and periodontitis. Natural compounds that suppress osteoclast formation and function have therapeutic potential for treating these diseases. Stachydrine (STA) is a bioactive alkaloid isolated from Leonurus heterophyllus Sweet and possesses antioxidant, anti-inflammatory, anticancer and cardioprotective properties. However, its effects on osteoclast formation and function have been rarely described. In the present study, we found that STA suppressed receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL)-induced osteoclast formation and bone resorption, and reduced osteoclast-related gene expression in vitro. Mechanistically, STA inhibited RANKL-induced activation of NF-κB and Akt signalling, thus suppressing nuclear factor of activated T cells c1 induction and nuclear translocation. In addition, STA alleviated bone loss and reduced osteoclast number in a murine model of LPS-induced inflammatory bone loss. STA also inhibited the activities of NF-κB and NFATc1 in vivo. Together, these results suggest that STA effectively inhibits osteoclastogenesis both in vitro and in vivo and therefore is a potential option for treating osteoclast-related diseases.


Asunto(s)
FN-kappa B/metabolismo , Osteoclastos/efectos de los fármacos , Osteogénesis/efectos de los fármacos , Osteólisis/tratamiento farmacológico , Prolina/análogos & derivados , Proteínas Proto-Oncogénicas c-akt/metabolismo , Actinas/metabolismo , Transporte Activo de Núcleo Celular/efectos de los fármacos , Transporte Activo de Núcleo Celular/genética , Animales , Núcleo Celular/metabolismo , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Regulación de la Expresión Génica/efectos de los fármacos , Regulación de la Expresión Génica/genética , Lipopolisacáridos/toxicidad , Macrófagos/efectos de los fármacos , Macrófagos/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Factores de Transcripción NFATC/metabolismo , Osteoclastos/metabolismo , Osteogénesis/genética , Osteólisis/inducido químicamente , Osteólisis/diagnóstico por imagen , Osteólisis/metabolismo , Prolina/farmacología , Prolina/uso terapéutico , Ligando RANK/metabolismo , Transducción de Señal/efectos de los fármacos , Transducción de Señal/genética , Linfocitos T/metabolismo , Tomografía Computarizada por Rayos X
7.
Chemistry ; 25(7): 1716-1721, 2019 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-30475411

RESUMEN

In cooperative catalysis, the combination of chemo- and biocatalysts to perform one-pot reactions is a powerful tool for the improvement of chemical synthesis. Herein, UiO-66-NH2 was employed to stepwise immobilize Pd nanoparticles (NPs) and Candida antarctica lipase B (CalB) for the fabrication of biohybrid catalysts for cascade reactions. Distinct from traditional materials, UiO-66-NH2 has a robust but tunable structure that can be utilized with a ligand exchange approach to adjust its hydrophobicity, resulting in excellent catalyst dispersity in diverse reaction media. These attractive properties contribute to the formation of MOF-based biohybrid catalysts with high activity and selectivity in the synthesis of benzyl hexanoate from benzaldehyde and ethyl hexanoate. With this proof-of-concept, we reasonably expect that future tailor-made MOFs can combine other catalysts, ranging from chemical to biological catalysts for applications in industry.

8.
Langmuir ; 35(24): 7824-7829, 2019 06 18.
Artículo en Inglés | MEDLINE | ID: mdl-31141380

RESUMEN

A biogenic macrocycle-based guest loading system has been developed by the self-assembly of membrane scaffold protein and phospholipids. The resulting 10 nm level transport system can increase the solubility of hydrophobic photodynamic agent hypocrellin B in aqueous medium and exhibited a cellular internalization capacity with substantial photodynamic activity.

9.
Macromol Rapid Commun ; 40(17): e1800731, 2019 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-30672634

RESUMEN

A new type of dynamic covalent macrocycle with self-promoted supramolecular gelation behavior is developed. Under oxidative conditions, the dithiol compound containing a diamide alkyl linker with an odd number (7) of carbon chain and an appended crown ether shows a remarkable gelation ability in acetonitrile, without any template molecules. Due to the existence of crown ethers and disulfide bonds, the obtained gel shows a multiple stimuli-responsiveness behavior. The mechanical properties and reversibility of the gel are investigated. Computational modeling suggests that the peripheral chain for diamide hydrogen bonding is responsible for the gelation process.


Asunto(s)
Materiales Biocompatibles/química , Coloides/química , Éteres Corona/química , Geles/química , Compuestos Macrocíclicos/química , Simulación por Computador , Enlace de Hidrógeno , Estructura Molecular
10.
J Shoulder Elbow Surg ; 28(5): 869-874, 2019 May.
Artículo en Inglés | MEDLINE | ID: mdl-30509611

RESUMEN

BACKGROUND: Anatomic skeletal features of the shoulder play important roles in anterior shoulder dislocation. However, studies on the effect of the humeral structure are few. This case-control study aimed to analyze the risk factors of anterior shoulder instability, including glenoid and humeral factors. METHODS: Anterior shoulder instability was found in 64 of 10,035 individuals who underwent magnetic resonance imaging. Propensity score matching was used to select controls matched for age, sex, height, and weight. We analyzed the glenoid and humeral structural data using conditional logistic regression analysis and identified cutoff points using receiver operating characteristic curve analysis. RESULTS: Significant differences were found between the control and dislocation groups in the depth-to-width ratio (0.119 ± 0.034 vs. 0.105 ± 0.037, P = .021), height-to-width ratio (1.51 ± 0.13 vs. 1.67 ± 0.16, P < .001), humeral head diameter-to-glenoid fossa diameter ratio (1.56 ± 0.11 vs. 1.64 ± 0.20, P < .001), and humeral containing angle (67.3° ± 5.9° vs. 60.4° ± 5.9°, P < .001). The humeral containing angle (odds ratio, 0.95; P = .024) and the glenoid height-to-width ratio (odds ratio, 7.88; P = .002), adjusted for the depth-to-width ratio and diameter ratio, were associated with anterior shoulder instability. The cutoff point for the humeral containing angle was 64° and for the height-to-width ratio was 1.60. CONCLUSIONS: This study revealed significant risk factors for shoulder instability in the Chinese Han population. The humeral containing angle and the glenoid height-to-width ratio were risk factors for anterior shoulder instability.


Asunto(s)
Inestabilidad de la Articulación/etiología , Luxación del Hombro/etiología , Adulto , Estudios de Casos y Controles , Femenino , Cavidad Glenoidea/patología , Humanos , Cabeza Humeral/patología , Inestabilidad de la Articulación/diagnóstico por imagen , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Oportunidad Relativa , Factores de Riesgo , Escápula/patología , Luxación del Hombro/diagnóstico por imagen , Adulto Joven
11.
Beilstein J Org Chem ; 15: 1203-1209, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31293667

RESUMEN

The synthesis of conjugates of perylene diimide (PDI) and naphthalene diimide (NDI) modified with two benzo-21-crown-7 ethers (B21C7) are herein described. Their self-assembly behavior in various solvents was investigated particularly in aqueous medium, due to the recently discovered hydrophilic properties of B21C7 crown macrocycle. An unexpected fluorescence quenching phenomenon was observed in the PDI-B21C7 macrocycle conjugate in chloroform. The detailed UV-vis absorption and fluorescence spectra of these PDI/NDI derivatives in different solvents as well as their morphologies were investigated.

12.
Med Sci Monit ; 24: 797-802, 2018 Feb 08.
Artículo en Inglés | MEDLINE | ID: mdl-29415980

RESUMEN

BACKGROUND Calcium phosphate cement (CPC) has been applied as a biodegradable antibiotic carrier in osteomyelitis. However, the drug delivery, antibacterial efficacy, and degradation rate of CPC are insufficient and require further improvement in clinical application. MATERIAL AND METHODS Vancomycin-loaded CPC columns were prepared, and eluted in simulated body fluid. The drug delivery was assessed in the ultrasound group and control group by fluorescence polarization immunoassay. The antibacterial efficacy of vancomycin in the ultrasound group and control groups was investigated by standard plate count method. Low-frequency pulsed ultrasound (46.5 kHz, 900 mW/cm²) was used to produce a sinusoidal wave in the ultrasound groups. The percentage of residual weight was evaluated to assess the degradation of CPC. RESULTS The concentration and cumulatively released percentage of vancomycin in the ultrasound group were higher than that in the control group at each time point (p<0.05). The duration of vancomycin concentration over the level of minimum inhibitory concentration was significantly prolonged in the ultrasound group (p<0.05). Antibacterial efficacy of vancomycin in the ultrasound group was significantly greater than that in the control group with same concentration of vancomycin (p<0.05). The percentage of residual weight in the ultrasound group was significantly less than that in the control group (p<0.05). CONCLUSIONS Low-frequency pulsed ultrasound can enhance vancomycin release, prolong the duration of vancomycin concentration at high levels, and accelerate the degradation rate of vancomycin-loaded CPC.


Asunto(s)
Antibacterianos/farmacología , Cementos para Huesos/farmacología , Fosfatos de Calcio/farmacología , Sistemas de Liberación de Medicamentos , Ondas Ultrasónicas , Vancomicina/farmacología , Liberación de Fármacos , Pruebas de Sensibilidad Microbiana , Staphylococcus aureus/efectos de los fármacos
13.
BMC Musculoskelet Disord ; 19(1): 177, 2018 May 30.
Artículo en Inglés | MEDLINE | ID: mdl-29848366

RESUMEN

BACKGROUND: Aseptic loosening and osteolysis are the most common indications after TKA for revision surgery. This meta-analysis which included high-quality randomized controlled trials (RCTs) aimed to analyze the effect of bisphosphonates (BPs) on maintaining periprosthetic bone mineral density (BMD) after total knee arthroplasty. METHODS: PubMed, AMED, EMBASE, the Cochrane library, ISI Web of Science, and China National Knowledge Infrastructure were systematically searched, five RCTs were included and the total number of participants was 188. The weighted mean differences with 95% confidence interval were calculated to evaluate the efficacy of BPs on total BMD of knee and the BMD of different periprosthetic regions. A descriptive review was performed for BP-related adverse effects. RESULTS: The BPs group presented significantly higher total BMD in proximal part of the tibia than the control group at 3 and 6 months (P < 0.05), but no significant difference at 12 months (P = 0.09). The BPs group presented significantly higher BMD in the distal aspect of the femur than that in the control group at 3, 6, 12 months. The BPs group presented significantly higher periprosthetic BMD than that in the control group at 3, 6 and 12 months in tibial medial and lateral metaphyseal region, and femoral anterior, central and posterior metaphyseal region (p < 0.05), but no significant difference for tibial diaphyseal region at 3, 6, and 12 months. None of the included studies described severe or fatal adverse effects related to BPs. CONCLUSION: BPs have a short-term effect on reducing periprosthetic bone loss after total knee arthroplasty. Compared with diaphyseal region, BPs are more effective on the preservation of BMD in medial lateral metaphyseal regions of proximal tibia and in anterior, central, and posterior metaphyseal region of distal femur.


Asunto(s)
Artroplastia de Reemplazo de Rodilla/tendencias , Conservadores de la Densidad Ósea/uso terapéutico , Densidad Ósea/efectos de los fármacos , Resorción Ósea/tratamiento farmacológico , Difosfonatos/uso terapéutico , Ensayos Clínicos Controlados Aleatorios como Asunto/métodos , Densidad Ósea/fisiología , Conservadores de la Densidad Ósea/farmacología , Resorción Ósea/diagnóstico por imagen , Difosfonatos/farmacología , Humanos , Resultado del Tratamiento
14.
Chemistry ; 22(35): 12533-41, 2016 Aug 22.
Artículo en Inglés | MEDLINE | ID: mdl-27465930

RESUMEN

Three porous organic polymers (POPs) containing H, COOMe, and COO(-) groups at 2,6-bis(1,2,3-triazol-4-yl)pyridyl (BTP) units (i.e., POP-1, POP-2, and POP-3, respectively) were prepared for the immobilization of metal nanoparticles (NPs). The ultrafine palladium NPs are uniformly encapsulated in the interior pores of POP-1, whereas uniform- and dual-distributed palladium NPs are located on the external surface of POP-2 and POP-3, respectively. The presence of carboxylate groups not only endows POP-3 an outstanding dispersibility in H2 O/EtOH, but also enables the palladium NPs at the surface to show the highest catalytic activity, stability, and recyclability in dehalogenation reactions of chlorobenzene at 25 °C. The palladium NPs on the external surface are effectively stabilized by the functionalized POPs containing BTP units and carboxylate groups, which provides a new insight for highly efficient catalytic systems based on surface metal NPs of porous materials.

15.
Angew Chem Int Ed Engl ; 55(22): 6462-6, 2016 05 23.
Artículo en Inglés | MEDLINE | ID: mdl-27061042

RESUMEN

A new approach to prepare heterometallic cluster organic frameworks has been developed. The method was employed to link Anderson-type polyoxometalate (POM) clusters and transition-metal clusters by using a designed rigid tris(alkoxo) ligand containing a pyridyl group to form a three-fold interpenetrated anionic diamondoid structure and a 2D anionic layer, respectively. This technique facilitates the integration of the unique inherent properties of Anderson-type POM clusters and cuprous iodide clusters into one cluster organic framework.

16.
Spectrochim Acta A Mol Biomol Spectrosc ; 319: 124555, 2024 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-38823242

RESUMEN

Indoles are notable for their distinct photophysical and photochemical properties, making them useful indicators in biological systems and promising candidates for a variety of pharmaceutical applications. While some indoles exhibit room temperature phosphorescence, such a phenomenon has not been observed in nitroindoles. Typically, adding of a nitro group into aromatic compounds promotes ultrafast intersystem crossing and increases the formation quantum yield of the lowest excited triplet (T1). Therefore, understanding the reactivity of nitroindoles' T1 states is imperative. This study investigated the physical properties and chemical reactivities of the T1 state of 6-nitroindole (3HN-6NO2) in both polar aprotic and protic solvents, using transient absorption spectroscopy. Our results demonstrate the basicity and acidity of 3HN-6NO2, emphasizing its potential for protonation and dissociation in mildly acidic and basic conditions, respectively. Furthermore, 3HN-6NO2 has a high oxidizing capacity, participating in electron transfer reactions and proton-coupled electron transfer to produce radicals. Interestingly, in protic solvents like alcohols, 3HN-6NO2 dissociates at the -NH group and forms N-H…O hydrogen-bonded complexes with the nitro group. By identifying transient absorption spectra of intermediates and quantifying kinetic reaction rate constants, we illuminate the unique properties of the T1 state nitroindoles, enriching our understanding of their photophysical and photochemical behaviors. The results of this study have significant implications for their potential application in both biological systems and materials science.

17.
Materials (Basel) ; 17(4)2024 Feb 08.
Artículo en Inglés | MEDLINE | ID: mdl-38399076

RESUMEN

The effect of aging treatments at various temperatures on the mechanical properties and microstructure of 10B21 cold heading steel with a 20% reduction in area (ε = 0.1) was investigated. The mechanical properties were evaluated based on tensile tests and hardness tests, while the evolution of microstructure was observed by using an optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). The results reveal that aging treatment enhance the strength and hardness of 10B21 cold heading steel after drawing, and the highest values of strength and hardness are attained at an aging temperature of 300 °C. Specifically, the yield and ultrahigh tensile strength after aging at 300 °C are measured at 620 MPa and 685 MPa, respectively, which are 30 MPa and 50 MPa higher than the cold-drawn sample. Moreover, the hardness after aging at 300 °C reaches 293 HV, which has an increase of 30 HV compared to the cold-drawn state. The improvement in mechanical properties may be related to the strain-aging mechanism and the increased density of dislocations. In addition, the analysis of the TEM results reveal that the presence of the second-phase Ti(C,N) contributes to pinning the dislocations, whereas the dislocations are pinned between the cementite (Fe3C) lamellar and stacked at the grain boundaries, leading to strain hardening of the material.

18.
Artículo en Inglés | MEDLINE | ID: mdl-39315994

RESUMEN

Chemo-biocatalytic cascades have emerged as a promising approach in the realm of advanced synthesis. However, reconciling the incompatible reaction conditions among distinct catalytic species presents a significant challenge. Herein, we introduce an innovative solution using an emulsion system stabilized by Janus silica nanoparticles, which serve as a bridge for both chemo-catalysts and biocatalysts at the interface. The chemo-catalyst is securely anchored within a hydrophobic polymer matrix, ensuring its residence in an organic environment. Meanwhile, the negatively charged E. coli cells containing enzymes are attracted to the aqueous phase at the interface, facilitating their optimal positioning. We demonstrate the efficacy of this system through a two-step cascade reaction. Initially, the oxidation of styrene to acetophenone using palladium as a chemocatalyst achieves a 6-fold increase in yield compared to the control system. Subsequently, the reduction of achiral acetophenone to its chiral alcohol derivative presents a 17-fold yield enhancement relative to that of the control reaction. Importantly, our system exhibits versatility, accommodating a wide range of substrates for both individual and sequential reactions. This work not only validates the concept but also paves the way for the integration of chemo- and biocatalysts in the synthesis of a broader array of high-value chemical compounds.

19.
Sci Rep ; 14(1): 1249, 2024 Jan 13.
Artículo en Inglés | MEDLINE | ID: mdl-38218940

RESUMEN

Polyoxometalates (POM) are anionic oxoclusters of early transition metals that are of great interest for a variety of applications, including the development of sensors and catalysts. A crucial step in the use of POM in functional materials is the production of composites that can be further processed into complex materials, e.g. by printing on different substrates. In this work, we present an immobilization approach for POMs that involves two key processes: first, the stable encapsulation of POMs in the pores of mesoporous silica nanoparticles (MSPs) and, second, the formation of microstructured arrays with these POM-loaded nanoparticles. Specifically, we have developed a strategy that leads to water-stable, POM-loaded mesoporous silica that can be covalently linked to alkene-bearing surfaces by amine-Michael addition and patterned into microarrays by scanning probe lithography (SPL). The immobilization strategy presented facilitates the printing of hybrid POM-loaded nanomaterials onto different surfaces and provides a versatile method for the fabrication of POM-based composites. Importantly, POM-loaded MSPs are useful in applications such as microfluidic systems and sensors that require frequent washing. Overall, this method is a promising way to produce surface-printed POM arrays that can be used for a wide range of applications.

20.
Spectrochim Acta A Mol Biomol Spectrosc ; 286: 121997, 2023 Feb 05.
Artículo en Inglés | MEDLINE | ID: mdl-36308824

RESUMEN

Nitro-polycyclic aromatic hydrocarbons (nitro-PAHs), often found in polluted air, are carcinogenic and mutagenic. The nitro group increases the spin-orbit coupling and results in the lowest excited triplet (T1) on the picosecond time scale with a high yield. The electron-donating substituents have a significant influence on the photophysics and photochemistry of nitro-PAHs. We used transient absorption spectroscopy and kinetic analysis to investigate the reactivities of the T1 state 1-methoxy-4-nitronaphthalene (3MeO-NN) and 1-methyl-4-nitronaphthalene (3Me-NN). The results show that the methoxy and methyl substitutions have a minor effect on their hydrogen abstraction and electron accepting abilities. The main distinction is their reaction rates towards protons. The second order rate constant of 3MeO-NN towards protons is three orders of magnitude greater than that of 3Me-NN, indicating that 3MeO-NN has a stronger hydrogen bond accepting ability. The kinetic analysis reveals that the dimer of 2,2,2-trifluoroethanol participates in the reaction with 3MeO-NN. These results suggest that the formation of the hydrogen-bonded complex is responsible for the unusually short lifetime of 3MeO-NN in methanol solution and the lack of hydrogen abstraction radicals during the decay of 3MeO-NN in methanol.


Asunto(s)
Electrones , Hidrocarburos Policíclicos Aromáticos , Cinética , Protones , Metanol , Hidrocarburos Policíclicos Aromáticos/química
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