Canadian Journal of Chemistry最新文献_第8页

Scan rate and concentration dependence of the voltammograms of substituted phenols on electrodes with different size, diffusion coefficients of phenols in different solvents 取代苯酚在不同尺寸电极上的扫描速率和浓度依赖性，苯酚在不同溶剂中的扩散系数

IF 1.1 4区化学

Canadian Journal of Chemistry Pub Date : 2023-02-24 DOI: 10.1139/cjc-2022-0096

L. Kiss, S. Kunsági-Máté

{"title":"Scan rate and concentration dependence of the voltammograms of substituted phenols on electrodes with different size, diffusion coefficients of phenols in different solvents","authors":"L. Kiss, S. Kunsági-Máté","doi":"10.1139/cjc-2022-0096","DOIUrl":"https://doi.org/10.1139/cjc-2022-0096","url":null,"abstract":"In this work, the effects of the scan rate and the concentration of the substituted phenols on the peak currents or current plateaus have been investigated. Voltammetric curves recorded by a platinum microelectrode varied significantly under different experimental conditions in cases of 4-chlorophenol, 4- tert-butylphenol, and 4-nitrophenol. In the case of 4-methoxyphenol and 4- tert-butylphenol, when the experiments were performed in the lower concentration range in acetonitrile, the plateau current and peak current showed linear dependence on phenol concentration. Therefore, these ranges offer opportunity for further characterization. The electrode reaction of 4-methoxyphenol was found to be a diffusion-controlled process in the solvents applied (water, acetonitrile, dimethyl sulfoxide, dimethyl formamide, nitrobenzene, acetone, dichloromethane, methanol, ethanol, 1-propanol, 1-butanol, and 1-pentanol). Diffusion coefficients of 4-methoxyphenol were determined with a microelectrode using the steady-state voltammograms. Diffusion coefficients of other phenols were measured only in acetonitrile with a macroelectrode. In agreement with known theories, the diffusion coefficients showed inversely proportional relationships with the solvent viscosities. Special care was needed in 1-pentanol solvent since the increasing anodic peaks appeared after the first scan and overlaid with the sigmoidal-shaped regular microelectrode voltammograms. This observation is probably due to formation of adhering residual electroactive products.","PeriodicalId":9420,"journal":{"name":"Canadian Journal of Chemistry","volume":"15 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87831001","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Synthesis of 1,2,4,5-oxadiazaboroles by three-component condensations of hydroxylamines, nitriles, and diarylborinic acids 羟胺、腈和二酰基硼酸三组分缩合合成1,2,4,5-恶二唑硼醚

IF 1.1 4区化学

Canadian Journal of Chemistry Pub Date : 2023-02-23 DOI: 10.1139/cjc-2022-0200

Zhenlu Ge, A. Lough, M. Taylor

引用次数: 0

Convenient access to β-substituted cysteines and β- and γ-mercapto prolines 方便地获得β-取代半胱氨酸和β-和γ-巯基脯氨酸

IF 1.1 4区化学

Canadian Journal of Chemistry Pub Date : 2023-02-15 DOI: 10.1139/cjc-2022-0161

Jacob C. Hansen, Marco Rabuffetti, L. Bunch

引用次数: 0

Dicarbon defect in hexagonal boron nitride monolayer - a theoretical study 六方氮化硼单层碳缺陷的理论研究

IF 1.1 4区化学

Canadian Journal of Chemistry Pub Date : 2023-02-15 DOI: 10.1139/cjc-2022-0291

T. Korona, J. Jankowska, Emran Masoumifeshani

{"title":"Dicarbon defect in hexagonal boron nitride monolayer - a theoretical study","authors":"T. Korona, J. Jankowska, Emran Masoumifeshani","doi":"10.1139/cjc-2022-0291","DOIUrl":"https://doi.org/10.1139/cjc-2022-0291","url":null,"abstract":"A comprehensive theoretical study of the lowest electronic vertical excitations of the CBCN defect in the monolayer of hexagonal boron nitride has been performed. Both the periodic boundary conditions approach and the finite-cluster simulation of the defect have been utilized at the density-functional theory (DFT) level. Clusters of increasing sizes have been used in order to estimate artefacts resulting from edge effects. The stability of the results with respect to several density functionals and various basis sets has been also examined. High-level ab initio calculations with methods like EOM-CCSD, ADC(2), and TD-CC2, were performed for the smallest clusters. It turns out that TD-DFT with the CAM-B3LYP functional gives similar lowest excitation energies as EOM-CCSD, ADC(2), and TD-CC2. The lowest excitation energies resulting from the periodic-boundary calculation utilizing the Bethe-Salpeter equation are in agreement with the results for finite clusters. The analysis of important configurations and transition densities shows that for all studied methods, the lowest excited state is localized on two carbon atoms and their closest neighbours and has a large dipole transition moment. The optimized geometries for the lowest two excited states indicate that in both cases the carbon-carbon bond becomes a single bond, while for the second excited state additionally one from boron-nitrogen bonds looses its partially double character. The calculation of the excitation energies at the respective optimal geometry reveals that these two energies become about 0.5 eV lower than vertical excitations from the ground-state geometry.","PeriodicalId":9420,"journal":{"name":"Canadian Journal of Chemistry","volume":"47 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82201004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Do we need delocalised wavefunctions for the excited state dynamics of 1,1-diﬂuoroethylene? 1,1-二氟乙烯的激发态动力学需要离域波函数吗?

IF 1.1 4区化学

Canadian Journal of Chemistry Pub Date : 2023-02-14 DOI: 10.1139/cjc-2022-0267

Sandra G'omez, N. Singer, L. Gonz'alez, G. Worth

{"title":"Do we need delocalised wavefunctions for the excited state dynamics of 1,1-diﬂuoroethylene?","authors":"Sandra G'omez, N. Singer, L. Gonz'alez, G. Worth","doi":"10.1139/cjc-2022-0267","DOIUrl":"https://doi.org/10.1139/cjc-2022-0267","url":null,"abstract":"In this work we set up a model Hamiltonian to study the excited state quantum dynamics of 1,1-difluoroethylene, a molecule that has equivalent atoms exchanged by a torsional symmetry operation leading to equivalent minima on the potential energy surface. In systems with many degrees of freedom where the minimum energy geometry is not unique, the ground state wavefunction will be delocalised among multiple minima. In this small test system, we probe the excited state dynamics considering localised (in a single minimum) and delocalised (spread over among multiple minima) wavefunctions and check whether this choice would influence the final outcome of the quantum dynamics calculations. Our molecular Hamiltonian comprises seven electronic states, including valence and Rydberg states, computed with the MS-CASPT2 method and projected onto the vibrational coordinates of the twelve normal modes of 1,1-difluoroethylene in its vibrational ground state. This Hamiltonian has been symmetrised along the torsional degree of freedom to make both minima completely equivalent and the model is supported by the excellent agreement with the experimental absorption spectrum. Quantum dynamics results show that the different initial conditions studied do not appreciably affect the excited state populations or the absorption spectrum when the dynamics is simulated assuming a delta pulse excitation. Future work will look at whether initial superpositions can be formed that guide the system, e.g. to a single minimum.","PeriodicalId":9420,"journal":{"name":"Canadian Journal of Chemistry","volume":"18 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84570707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Predicting Reaction Barriers in Solid-State Systems Under Stress via Second-Order Energy Expansion 利用二阶能量膨胀预测应力下固体体系的反应势垒

IF 1.1 4区化学

Canadian Journal of Chemistry Pub Date : 2023-02-14 DOI: 10.1139/cjc-2022-0278

L. Laverdure, N. Mosey

引用次数: 0

Award Lecture Paper: Nickel-Catalyzed N-Arylation of Optically Pure Amino Acid Esters with Activated (Hetero)aryl Electrophiles 获奖演讲论文:镍催化光学纯氨基酸酯与活化的(杂)芳基亲电试剂的n -芳基化

IF 1.1 4区化学

Canadian Journal of Chemistry Pub Date : 2023-02-02 DOI: 10.1139/cjc-2022-0290

Travis Lundrigan, Joseph P. Tassone, M. Stradiotto

引用次数: 0

Note of appreciation 感谢信

4区化学

Canadian Journal of Chemistry Pub Date : 2023-02-01 DOI: 10.1139/cjc-2023-0007

引用次数: 0

Thermal and electrical transport conductivities of novel ordered double two-dimensional MXenes via density functional theory 基于密度泛函理论的新型有序双二维MXenes的热导率和电导率

IF 1.1 4区化学

Canadian Journal of Chemistry Pub Date : 2023-01-19 DOI: 10.1139/cjc-2022-0070

Ekwevugbe Omugbe, O. Osafile, O. Nenuwe, E. Enaibe, E. E. Elemike

{"title":"Thermal and electrical transport conductivities of novel ordered double two-dimensional MXenes via density functional theory","authors":"Ekwevugbe Omugbe, O. Osafile, O. Nenuwe, E. Enaibe, E. E. Elemike","doi":"10.1139/cjc-2022-0070","DOIUrl":"https://doi.org/10.1139/cjc-2022-0070","url":null,"abstract":"In this paper, we examined the effects of transition metal replacement and ordering in 2D M3C2O2 MXene on the electronic structure, thermal and electrical conductivities using the density functional theory and also the Boltzmann transport theory within the constant relaxation time approximation. We derived the following oxygen functionalized ordered double metal MXenes Ti2YC2O2, Y2TiC2O2 Sc2YC2O2, and Y2ScC2O2 through the surface and sub-layer tuning. The results revealed that the ordered MXenes give rise to different electronic structure and transport properties. The electronic thermal conductivities obtained in terms of the relaxation time increase with increase in absolute temperature, while the electrical conductivities decrease with increase in temperature. The respective transport properties of Y2TiC2O2 and Sc2YC2O2were found to be enhanced due to the increased squared band velocity, density of state and low Seebeck coefficient compared to Ti2YC2O2 and Y2ScC2O2 MXenes. Generally, the MXene materials investigated in this work were found to possess metallic properties with the existence of energy overlap around the Fermi level. The computed formation energies support chemical stability in all the materials.","PeriodicalId":9420,"journal":{"name":"Canadian Journal of Chemistry","volume":"12 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77805423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Synthesis and thermal stability of a novel polyfunctional pyridine-based derivative featuring amino, nitro, and guanidine groups 一种新型氨基、硝基和胍基多官能团吡啶衍生物的合成和热稳定性

IF 1.1 4区化学

Canadian Journal of Chemistry Pub Date : 2023-01-17 DOI: 10.1139/cjc-2022-0057

Xu-Qing Liu, Lina Hao, Renfa Zhang, Congming Ma, P. Ma

引用次数: 1