South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie最新文献_第3页

Synthesis and characterization of amine-functionalized supported phosphine catalysts and their application in ethylene oligomerization 胺功能化负载膦催化剂的合成、表征及其在乙烯低聚反应中的应用

IF 1.5 4区化学

South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie Pub Date : 2022-01-01 DOI: 10.17159/0379-4350/2022/v76a02

Mzamo L. Shozi, Xolelwa Zulu, H. Friedrich

{"title":"Synthesis and characterization of amine-functionalized supported phosphine catalysts and their application in ethylene oligomerization","authors":"Mzamo L. Shozi, Xolelwa Zulu, H. Friedrich","doi":"10.17159/0379-4350/2022/v76a02","DOIUrl":"https://doi.org/10.17159/0379-4350/2022/v76a02","url":null,"abstract":"ABSTRACT A series of phosphorus and nitrogen-based ethylene oligomerization ligands of the type Ph2PN(X)PPh2 where X = i-propyl, n-butyl, ethylbenzene and cyclohexyl substituents are reported. These ligands were functionalized to enable tethering on amino-silica. The free ligands, amino-silica and the tethered ligands were characterized by BET, XRD, IR, TGA and NMR. The catalysts were tested for ethylene oligomerization using Cr(acac)3 (acac = acetylacetonate) as the precursor and MMAO (modified methylaluminoxane) as the activator. The activity and selectivity of these catalysts to 1-octene was monitored at 45 bar ethylene in the temperature range of45-100 °C. The activity of the supported catalysts was comparable to their homogeneous counterparts, surpassing them in some cases and selectivities to 1-octene in the C8 products were as high as 99 wt%. The steric effect of the substituent on the ligand as well as that of the support was found to influence the activity and product distribution. Keywords: 1-hexene, 1-octene, ethylene oligomerization, phosphine ligands, silica, supported catalysts","PeriodicalId":49495,"journal":{"name":"South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67464380","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

Molecular docking, dynamics, and quantum chemical study of vanillylacetone and beta-hydroxy ketone derivatives against Mpro of SARS-CoV-2 香草丙酮和β -羟基酮衍生物抗SARS-CoV-2 Mpro的分子对接、动力学和量子化学研究

IF 1.5 4区化学

South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie Pub Date : 2022-01-01 DOI: 10.17159/0379-4350/2022/v76a12

S. Amin, S. Muhammad, J. Iqbal, S. Ullah, A. G. Al-Sehemi, H. Algarni, S. S. Alarfaji, K. Ayub

{"title":"Molecular docking, dynamics, and quantum chemical study of vanillylacetone and beta-hydroxy ketone derivatives against Mpro of SARS-CoV-2","authors":"S. Amin, S. Muhammad, J. Iqbal, S. Ullah, A. G. Al-Sehemi, H. Algarni, S. S. Alarfaji, K. Ayub","doi":"10.17159/0379-4350/2022/v76a12","DOIUrl":"https://doi.org/10.17159/0379-4350/2022/v76a12","url":null,"abstract":"This study is carried out to find novel active drug candidates which can effectively bind to key residues of main protease (Mpro) of SARS-CoV-2. We performed molecular docking of fifty-seven (57) ligands from two classes: vanillylacetone and its derivatives and beta-hydroxy ketone derivatives against Mpro of SARS-CoV-2. We also docked three antiviral drugs as reference/benchmark drugs including remdesivir (RDV), chloroquine (CQ), and hydroxychloroquine (HCQ) against Mpro for comparison of inhibition tendencies of selected ligands. Binding energies of our reference drugs are as: CQ = -5.1 kcal mol-1 (with predicted inhibition constant (Ki pred) = 177 μmol), HCQ = -5.7 kcal mol-1 (Ki pred = 64.07 μmol) and RDV -6.3 kcal mol-1 (Ki pred = 13.95 μmol). We got remarkable results for our docked ligands as 79% of total ligands indicated binding energies better than CQ, 39 % better than both HCQ and CQ, and 19 % better than all reference drugs. More interestingly interaction analysis of eight best-docked ligands showed that they interacted with desired key residues of Mpro. We further selected the four best-docked ligands L1 = -6.6 kcal mol-1 (Ki pred =13.95 μmol), L6 = -7.0 kcal mol-1 (Ki pred = 7.08 μmol), L34 = -6.0 kcal mol-1 (Ki pred = 38.54 μmol), and L50 = -6.6 kcal mol-1 (Ki pred =13.95 umol) for further analysis by quantum chemical study, molecular dynamic (MD) simulations and ADMET analysis. We have also carried out MD-simulations of six more docked ligand L2, L14, L20, L36, L46 and L48 some of which were showing weak binding affinities and some average binding affinities to check their simulation behavior. Their RMSD, RMSF and binding free energy results were also quite satisfying. We believe the current investigation will evoke the scientific community and highlights the potential of selected compounds for potential use as antiviral compounds against Mpro of SARS-CoV-2.","PeriodicalId":49495,"journal":{"name":"South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie","volume":"31 15 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67464144","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

Comparison of laser nephelometric and HPLC techniques for efficient determination of solubility of ibuprofen and its 2-hydroxypropyl-p-cyclodextrin inclusion complex 激光浊度法与高效液相色谱法测定布洛芬及其2-羟丙基-对环糊精包合物溶解度的比较

IF 1.5 4区化学

South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie Pub Date : 2022-01-01 DOI: 10.17159/0379-4350/2022/v76a08

Frank Ssengooba, Thashree Marimuthu, E. Olivier, P. Demana, Y. Choonara

{"title":"Comparison of laser nephelometric and HPLC techniques for efficient determination of solubility of ibuprofen and its 2-hydroxypropyl-p-cyclodextrin inclusion complex","authors":"Frank Ssengooba, Thashree Marimuthu, E. Olivier, P. Demana, Y. Choonara","doi":"10.17159/0379-4350/2022/v76a08","DOIUrl":"https://doi.org/10.17159/0379-4350/2022/v76a08","url":null,"abstract":"ABSTRACT Poor drug solubility is a major problem that hinders the discovery and development of new drugs. There is a need for rapid and inexpensive techniques for acquiring reliable drug solubility data. In this study, the suitability of laser nephelometry for the determination of solubility was investigated using ibuprofen, as a model drug of low solubility, and its 2-hydroxypropyl-p-cyclodextrin inclusion complex (ic). This investigation involved the preparation of ibuprofen-ic-cyclodextrin (1:1) using coprecipitation and characterisation. Thermal analysis and assessment of molecular vibrations confirmed the existence of the inclusion complex. The shake flask testing method was employed and carried out in acidic and alkaline media, and solubility data were verified against high-performance liquid chromatography (HPLC). Results obtained via nephelometry showed relative enhanced solubility of ibuprofen in both acidic (0.565 mg ml-1) and basic (7.5 mg ml-1) media, respectively, which was enabled via inclusion complex formation. Relative to nephelometry data, HPLC results showed a similar trend with increased solubility values in acidic (0.454 mg ml-1) and basic (201.73 mg ml-1) media, respectively. The application of laser nephelometry proved to be a quick and relatively cost-effective technique for solubility measurements of the parent drug and its carrier system. Keywords: cyclodextrin, ibuprofen, inclusion complex, laser nephelometry, solubility","PeriodicalId":49495,"journal":{"name":"South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67464556","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

Thermally regulated green living wall 热调节绿色生活墙

IF 1.5 4区化学

South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie Pub Date : 2022-01-01 DOI: 10.17159/0379-4350/2021/v76a13

S. Gouws, M. Gouws

{"title":"Thermally regulated green living wall","authors":"S. Gouws, M. Gouws","doi":"10.17159/0379-4350/2021/v76a13","DOIUrl":"https://doi.org/10.17159/0379-4350/2021/v76a13","url":null,"abstract":"Green living walls can improve the aesthetic quality of a building and moderate the temperature within it. The purpose of this paper is to examine whether the green wall has any effect on the interior temperature of the building in the hot and cold months of the year. Temperatures on an outside wall as well as on research and control areas were monitored to capture temperature data for a one-year period that encompassed all seasons: sunny, cold and wet. The findings of this research contribute to the knowledge of the effects provided by green living walls in terms of cooling and heating, the influence on the proximity microclimatic conditions, and overall energy transfer. Heat flux of 20-100 W/m2 was found indicating an insulating effect that brings about cooling in the interior of the building. During summer months a cooling effect of 2-4 °C was observed, while the opposite effect was observed during winter in that the temperatures did not drop by much but provide a insulating effect of 2-3 °C higher than it was for the control area. Altogether, green living walls could be implemented to reduce and insulating interior living conditions and therefore reduce building energy demands.","PeriodicalId":49495,"journal":{"name":"South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67464242","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

Catalytic hydrogen combustion using platinum supported on anodized aluminium oxide adhered to metallic aluminium 金属铝上阳极氧化铝负载铂催化氢燃烧

IF 1.5 4区化学

South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie Pub Date : 2022-01-01 DOI: 10.17159/0379-4350/2022/v76a06

S. D. du Preez, A. Kozhukhova, D. Bessarabov

{"title":"Catalytic hydrogen combustion using platinum supported on anodized aluminium oxide adhered to metallic aluminium","authors":"S. D. du Preez, A. Kozhukhova, D. Bessarabov","doi":"10.17159/0379-4350/2022/v76a06","DOIUrl":"https://doi.org/10.17159/0379-4350/2022/v76a06","url":null,"abstract":"The implementation of catalytic hydrogen combustion (CHC) can mitigate the dependence on solid fuel combustion typically used in SubSaharan Africa as a means of heating. However, low-cost and readily available materials for catalyst fabrication are relatively unexplored. Considering the economic constraints regarding platinum group metals generally used for CHC, the cost of support materials and its functionalization as catalyst support has to be minimized. Typically, materials such as silicon carbide foam, extruded aluminium oxidebased ceramics, and titanium oxide mesh/sintered plates are used to withstand the high temperatures associated with CHC. In this paper, nanostructured anodized aluminium oxide (AAO) was synthesized as the support material via the anodization of high purity (>99%) aluminium (Al). The AAO layer intimately adhered to a metallic Al core acted as a thermal conduit to disperse heat throughout the catalyst. Platinum (Pt), considered as the reactive metal, was deposited to the AAO as nanoparticles with a diameter of approximately 19.3 nm. The CHC reaction proceeded spontaneously on the surface of the Pt/AAO catalyst. A combustion temperature of 408 ± 18 °C was maintained for 70 h at a 100 normal (N) mL min−1 hydrogen flow rate. The Pt-particles showed a relatively appreciable increase in particle size (from 19.3 nm to 25.0 nm), but the significance thereof was not evident during the 70 h CHC procedure.","PeriodicalId":49495,"journal":{"name":"South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie","volume":"9 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67464472","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: 2

Utilisation of bis-chloroacetamide derivative in the synthesis of new biologically active sulfide compounds 利用双氯乙酰胺衍生物合成新的生物活性硫化物

IF 1.5 4区化学

South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie Pub Date : 2022-01-01 DOI: 10.17159/0379-4350/2021/v76a14

Ehab Norhan A Khalaf, Abdel-Latif, M. Ismail, H. Metwally, E. Abdel‐Latif

引用次数: 0

A non-dispersive infrared sensor for real-time detection of cyanogen chloride 用于实时检测氯化氰的非色散红外传感器

IF 1.5 4区化学

South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie Pub Date : 2022-01-01 DOI: 10.17159/0379-4350/2022/v76a03

B. Ma, L. Ren, G. Liu, J. Li, Y. Xiao, D. Li, Y. Gao, P. Kuang

引用次数: 0

The use of ex-situ nitrogen-doped olive oil-derived carbon nano-onions for application in chemi-resistive gas sensors to detect acetone at room temperature 利用非原位氮掺杂橄榄油衍生的碳纳米洋葱在室温下用于化学电阻气体传感器检测丙酮

IF 1.5 4区化学

South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie Pub Date : 2022-01-01 DOI: 10.17159/0379-4350/2022/v76a07

T. Mongwe, T. Ntuli, L. Sikeyi, N. Coville, M. Mamo, J. Serbena, M. Maubane-Nkadimeng

{"title":"The use of ex-situ nitrogen-doped olive oil-derived carbon nano-onions for application in chemi-resistive gas sensors to detect acetone at room temperature","authors":"T. Mongwe, T. Ntuli, L. Sikeyi, N. Coville, M. Mamo, J. Serbena, M. Maubane-Nkadimeng","doi":"10.17159/0379-4350/2022/v76a07","DOIUrl":"https://doi.org/10.17159/0379-4350/2022/v76a07","url":null,"abstract":"This study reports on the synthesis of carbon nano-onions (CNOs; ca. d ≤ 55 nm) and nitrogen-doped CNOs (N-CNOs) using a facile pyrolysis method and ex-situ doping of the CNOs. Elemental analysis of the N-CNOs revealed that their nitrogen content depended on the ammonia flow rate. Analysis of the N-CNOs revealed that they all exhibited structural defects. After the successful synthesis of CNOs and N-CNOs, polyvinylpyrrolidone (PVP):CNOs/N-CNOs:MnO2-nanorods (MONRs) composites were prepared and used as active sensing materials. In every case, the PVP polymer was used to stabilize the MONRs for acetone detection at 25 °C. The chemi-resistive gas sensors that showed the highest acetone sensitivity (pS = 2.0 × 10−4 ppm−1 ) was fabricated using a pristine CNOs (pCNOs) based composite. However, the N-CNOs based sensor (a1.5S) presented the lowest acetone limit of detection (LoD) at 1.2 ppm. The study implicated the effect of the nitrogen and oxygen content of the CNOs surfaces on the acetone detection. Thus, a higher sensitivity with lower LoD was observed at room temperature using the pCNOs based sensor, when compared to earlier literature reports.","PeriodicalId":49495,"journal":{"name":"South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67464544","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

Evaluating the influence of interactive simulations on learners' academic performance in stoichiometry 评价互动模拟对学习者化学计量学学习成绩的影响

IF 1.5 4区化学

South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie Pub Date : 2022-01-01 DOI: 10.17159/0379-4350/2022/v76a01

Lereko Mohafa, Makomosela Qhobela, M. George

{"title":"Evaluating the influence of interactive simulations on learners' academic performance in stoichiometry","authors":"Lereko Mohafa, Makomosela Qhobela, M. George","doi":"10.17159/0379-4350/2022/v76a01","DOIUrl":"https://doi.org/10.17159/0379-4350/2022/v76a01","url":null,"abstract":"ABSTRACT Traditional teaching strategies dominate science classrooms in Lesotho, resulting in poor academic performance at each level. Information and Communication Technology tools such as simulations offer potential benefits for improving science teaching. The purpose of this quasi-experimental study was to evaluate the effect of simulations on learners' performance and retention of stoichiometry concepts using Solomon's four-group design. Purposive sampling of two existing Form E (Grade 12) classes, with 81 learners, led to the creation of four groups. The study responds to the research question: How does using simulations as part of an intervention affect learners' academic performance in stoichiometry? Data were collected as learners' scores for pre-tests and post-tests, designed to assess their understanding of stoichiometry, and analysed through ANOVA and t-tests. After the intervention, the experimental group's mean score (M = 44.2, a = 18) was higher than that of control group (M = 32.6, a = 15.8), and the difference between the two mean scores was statistically significant, namely t(81) = 3.14, p = 0.002. The experimental group had a higher mean score for retention in post-test (M = 47.4, a =16.1) than the control group (M = 37.2, a = 13.7) which was statistically significant, namely t(81) = 3.10, p = 0.003. Therefore, it was concluded that simulations enhanced learners' performance and could improve the retention of stoichiometry concepts. This study recommends that simulations be used to supplement the teaching and learning of science, in particular chemistry. Keywords: cognitive theory of multimedia learning, high school learners' performance, interactive-simulations, stoichiometry","PeriodicalId":49495,"journal":{"name":"South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67464334","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: 3

The simultaneous synthesis of carbon dots and carbon spheres with tunable sizes using a vertical chemical vapour deposition method 采用垂直化学气相沉积法同时合成尺寸可调的碳点和碳球

IF 1.5 4区化学

South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie Pub Date : 2022-01-01 DOI: 10.17159/0379-4350/2022/v76a05

Lerato L. Mokoloko, R. Forbes, N. Coville

{"title":"The simultaneous synthesis of carbon dots and carbon spheres with tunable sizes using a vertical chemical vapour deposition method","authors":"Lerato L. Mokoloko, R. Forbes, N. Coville","doi":"10.17159/0379-4350/2022/v76a05","DOIUrl":"https://doi.org/10.17159/0379-4350/2022/v76a05","url":null,"abstract":"ABSTRACT Herein we report on the direct synthesis of solid hydrophobic carbon dots (CDs) and simultaneously carbon spheres (CSs), using a vertical chemical vapour deposition (CVD) reactor. The HRTEM data indicated that the CDs and CSs originated from different carbon building blocks indicated that the CDs and CSs originated from different carbon building blocks. The CDs were obtained by reacting acetylene (C2H2) and Ar mixtures at high flow rates (>500 sccm) and high temperatures (800-1000 °C). TEM studies indicated that the CDs produced were graphene-like quantum dots that increased in size from c. 3 nm to 8 nm as the Ar flow rate (constant C2H2 flow rate) was decreased, while small solid CSs (c. 100 nm) were also synthesised in the process. The CSs had a typical spherical layered structure with no graphitic core. A mechanism to rationalise the observation that the CDs and CSs grew simultaneously by different pathways with no formation of intermediate-sized particles is given. Keywords: carbon dots, chemical vapour deposition, nanostructure, spectroscopy","PeriodicalId":49495,"journal":{"name":"South African Journal of Chemistry-Suid-Afrikaanse Tydskrif Vir Chemie","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67464461","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