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Isolation, Characterization and Anti-Pepsin (HIV-Protease) Activity of Vernonia amygdalina Del and Cymbopogon citratus (de Condole) Stapf 苦杏仁和香茅的分离、鉴定及抗胃蛋白酶活性研究
Pub Date : 2022-12-31 DOI: 10.9734/ajocs/2022/v12i4226
S. Garba, Okubanjo, O. Olubukola
The anti-pepsin enzyme (HIV-1) activities of crude extract of Vernonia amygdalina and Cymbopogon citratus were investigated using standard methods. A portion (0.5cm3) of pepsin enzyme solution was measured and transferred into viels, 2 cm3 of hemoglobin and 1 cm3 of the extracts were mixed together. The procedure was repeated for all the different extract. A standard control was also prepared using hemoglobin, enzyme and the various concentrations of the anti-retroviral drugs. A negative control was ran using only hemoglobin and pepsin enzyme whereas positive control was ran along with the standard using hemoglobin, enzyme and various concentrations of antiretroviral drugs. The mixture was allowed to incubate at 37 ºC, after 20 mins, 700 µl of 5% TCA was added to stop the reaction. It was then centrifuged at 14000 rev/min for 5 mins and the supernatant was collected. Absorbance was recorded spectrophotometrically at 280 nm. Each sample was taken in triplicate. UV-Visible spectrophotometer was used to detect the absorbance at 280 nm. The results of the anti-pepsin enzyme (HIV-1) activities showed that petroleum ether fraction of Cymbopogon citratus exhibited wavelength of maximum absorption (גmax) ranging from 0.788 nm - 0.789 nm and its ethyl acetate fraction exhibited גmax absorption ranging from 0.785 nm- 0.788 nm. Petroleum ether fraction of Vernonia amygdalina exhibited גmax absorption ranging from 1.383 nm-1.399 nm while its ethyl acetate fraction exhibited גmax absorption ranging from 1.384 nm-1.400 nm. The result of this work shows that both Cymbopogon citratus and Vernonia amygdalina ethyl acetate fraction have higher activity with Vernonia amygdalina being the highest. Column chromatography of the ethyl acetate fraction of Vernonia amygdalina led to the isolation of the compound which shows higher activity (1.384 nm- 1.400 nm). Available spectroscopic data using 1H NMR, 13C NMR and IR showed that the compound could be β-Sitosterol. The result of this work therefore showed that the extract from the leaves of Vernonia amygdalina could be used for the treatment of HIV-1(since it has the same sequence and family with the pepsin enzyme) and other diseases caused by targeted virus.
采用标准方法研究了苦杏仁和香茅粗提物抗胃蛋白酶(HIV-1)活性。取一份0.5cm3的胃蛋白酶酶溶液,取2 cm3的血红蛋白和1 cm3的提取物混合。对所有不同的提取物重复上述步骤。还用血红蛋白、酶和不同浓度的抗逆转录病毒药物制备了标准对照。阴性对照只用血红蛋白和胃蛋白酶进行对照,阳性对照用血红蛋白、酶和不同浓度的抗逆转录病毒药物进行对照。37℃孵育,20 min后加入5% TCA 700µl停止反应。然后以14000转/分钟离心5分钟,收集上清。用分光光度法在280 nm处记录吸光度。每个样品一式三份。用紫外-可见分光光度计测定其在280 nm处的吸光度。抗胃蛋白酶(HIV-1)活性测定结果表明,香茅石油醚部位的最大吸收波长为0.788 ~ 0.789 nm,乙酸乙酯部位的最大吸收波长为0.785 ~ 0.788 nm。苦杏仁油醚组分的最大吸收光谱范围为1.383 ~ 1.399 nm,乙酸乙酯组分的最大吸收光谱范围为1.384 ~ 1.400 nm。结果表明,香茅和苦杏仁乙酸乙酯部位均具有较高的活性,其中苦杏仁活性最高。对苦杏仁的乙酸乙酯部分进行柱层析,分离得到活性较高的化合物(1.384 ~ 1.400 nm)。1H NMR、13C NMR和IR等光谱数据表明该化合物可能为β-谷甾醇。因此,这项工作的结果表明,苦杏仁叶提取物可用于治疗HIV-1(因为它与胃蛋白酶酶具有相同的序列和家族)和其他由目标病毒引起的疾病。
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引用次数: 0
Application of UV-Visible Spectroscopy in Kinetic Study of Molybdate Complexation Reactions and Phosphate Content Quantitation 紫外可见光谱法在钼酸盐络合反应动力学研究及磷酸盐含量定量中的应用
Pub Date : 2022-12-27 DOI: 10.9734/ajocs/2022/v12i4225
Josphat Kipkoech, Jonathan O. Adongo
UV-visible spectroscopic measurements were used to characterize the formation of two ammonium-molybdate complexes, to elucidate its kinetics, and to carry out spectrophotometric quantitation of percent phosphate content in selected commercially available fertilizers. The kinetic study of ammonium-molybdate [(NH3)6Mo7O24] reaction with hydrazine (N2H2) yielding ammonium-hydrazine-molybdate complex (AHM) and that of reaction of AHM with phosphate [PO4]3- to give phospho-ammonium-hydrazine-molybdate (AHPM) complex revealed that both proceed via zero-order kinetics (R2= 0.99) with rate constants in the order of 10-5 and 10-4 M/s respectively. The kinetic experiments revealed that the rate of formation of the AHM complex is sensitive to an increase in N2H2 ligand concentration. For both reactions, the highest complexation rates were observed within the first 1000 s. Complex dissociation and association equilibria events were observed at extended reaction periods in the kinetic experiments. The AHPM system (containing complexed phosphates) used in spectrophotometric quantitation of phosphate levels in fertilizer samples was found to obey the Beer-Lambert equation in the visible region at λ max. = 820 nm within the concentration range of 5 – 90% phosphate content (R2 = 0.99). Of the fertilizer randomized sampled from Nakuru Municipality in Kenya, and analyzed the percent phosphate content among the inorganic fertilizers was found to range between 61.7% - 82% with a mean of 72.86% +/- 6.98 SD. Whereas in the organic fertilizer samples investigated, it was found to range between 43.8% - 58.2% with means of 52.55% +/- 6.77 SD. The organic fertilizers were found to have significantly lower phosphate levels based on an unpaired t-test revealing that the mean percent concentrations between the two groups of fertilizer samples tested are significantly different at 95% CI (P value < 0.05).
紫外可见光谱测量用于表征两种钼酸铵配合物的形成,阐明其动力学,并在选定的市售肥料中进行磷酸盐含量百分比的分光光度定量。对钼酸铵[(NH3)6Mo7O24]与肼(N2H2)反应生成钼酸铵配合物(AHM)和AHM与磷酸[PO4]3-反应生成磷-氨-肼-钼酸铵配合物(AHPM)的动力学研究表明,两者均为零级动力学(R2= 0.99),反应速率常数分别为10-5和10-4 M/s。动力学实验表明,AHM配合物的形成速度对N2H2配体浓度的增加很敏感。对于这两种反应,在前1000秒内观察到最高的络合速率。在动力学实验中,在较长的反应周期内观察到复杂的解离和缔合平衡事件。AHPM系统(含络合磷酸盐)用于分光光度法定量肥料样品中的磷酸盐水平被发现服从Beer-Lambert方程在可见光区域在λ max。= 820 nm,磷酸盐含量为5 ~ 90% (R2 = 0.99)。在肯尼亚纳库鲁市随机抽样的肥料中,分析发现无机肥料中磷酸盐含量的百分比在61.7% - 82%之间,平均值为72.86% +/- 6.98 SD。在有机肥样品中,其变化范围为43.8% ~ 58.2%,平均值为52.55% +/- 6.77 SD。根据非配对t检验,有机肥的磷酸盐水平显著降低,两组肥料样品的平均百分比浓度在95% CI下显著不同(P值< 0.05)。
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引用次数: 0
Rapid Methods of Synthesis of Stilbene and Phenylethynylstilbene Arms 二苯乙烯和苯乙基二苯乙烯臂的快速合成方法
Pub Date : 2022-12-23 DOI: 10.9734/ajocs/2022/v12i4224
Issa Samb, V. Michelet
Stilbene and phenylethynylstilbene units are excellent candidates for fluorescent sensor synthesis. In this paper we show a fast and efficient method for the preparation of fluorophores based on biphenyl nuclei with phenylene-vinylene units functionalized by donor groups. Using pallado catalysed coupling reactions of Sonogashira types and Wittig or Wittig-Horner reaction, the stilbene and phenylethylsilbene arms functionalized with O-alkyl and N-alkyl donor groups were synthesized.
二苯乙烯和苯基乙基二苯乙烯是合成荧光传感器的优秀候选单位。在本文中,我们展示了一种快速和有效的方法来制备基于苯基-乙烯基基团官能团的联苯核荧光团。利用钯催化的Sonogashira型偶联反应和Wittig或Wittig- horner反应,合成了o -烷基和n -烷基给基功能化的苯乙烯臂和苯基乙基硅烷臂。
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引用次数: 0
Study of the Photodegradation Kinetics of Fluometuron by UV Absorption Spectrophotometry and Fluorescence 紫外吸收分光光度法和荧光法研究荧光素的光降解动力学
Pub Date : 2022-11-19 DOI: 10.9734/ajocs/2022/v12i3223
Diégane Sarr, D. D. Thiaré, P. A. Diaw, Khémesse Kital, A. Saba, C. Sall, A. Coly, F. Delattre, A. Tine
In order to predict the fate of fluometuron in the aquatic environment and to assess the risk that it may pose, we studied its photolysis reaction in aqueous media. This reaction was monitored by UV absorption and fluorescence spectroscopy. UV irradiation source consisting of a 254 nm mercury lamp was used.  The study showed that fluometuron is unstable under the effect of light radiation when irradiated in water. The absorption band and the emission of this product were at 244 nm and 325 nm respectively. This study also shows that the photodegradation of fluometuron in water follows first order kinetics regardless of the method followed.  However, a difference was noted in the half-life times (t1/2). Indeed, these times found in UV and fluorescence are respectively 18.2 min and 6.6 min. The relatively lower value obtained in fluorescence could be explained by the fact that the latter is more sensitive to UV and fluorescence. In all cases, the half-lives found were relatively short (t1/2<1h). For more information on the photolysis of this herbicide, these two methods were combined with NMR and GC-MS to identify the different photoproducts that may be formed.
为了预测荧光藻在水生环境中的命运和评估其可能造成的风险,我们研究了它在水介质中的光解反应。用紫外吸收光谱和荧光光谱对该反应进行了监测。采用由254 nm汞灯组成的紫外照射源。研究表明,在水中辐照时,荧光效应在光辐射作用下是不稳定的。该产物的吸收波段为244 nm,发射波段为325 nm。该研究还表明,无论采用何种方法,荧光素在水中的光降解都遵循一级动力学。然而,半衰期(t1/2)有所不同。实际上,紫外和荧光的时间分别为18.2 min和6.6 min。荧光的时间相对较低,可以解释为后者对紫外和荧光更敏感。在所有情况下,发现的半衰期都相对较短(t1/2<1h)。为了进一步了解该除草剂的光解作用,我们将这两种方法与NMR和GC-MS相结合,以鉴定可能形成的不同光产物。
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引用次数: 0
Comparative Phytochemical, Proximate and In vitro Antihyperglycemic Analyses of the Stem Bark Extracts of Kigelia africana (Lam.) Benth and Annona senegalensis Pers 非洲木(Kigelia africana)茎皮提取物的植物化学、近似和体外降糖分析南菖蒲和菖蒲
Pub Date : 2022-11-16 DOI: 10.9734/ajocs/2022/v12i3222
C. Anarado, O. F. Obumselu, N. U. Ejimofor, N. Okafor, C. Igwe, J. C. Udekute, C. Igwe, C. B. Nsofor
The present research aimed to investigate the phytochemical bioactive constituents and proximate composition of the methanol extract of Kigelia africana and Annona senegalensis stem bark, as well as its in vitro antidiabetic potential. The results suggest that the presence of bioactive compounds may be responsible for the numerous medicinal capacities of these plants, including their antidiabetic abilities. The methanol stem bark extracts of K. africana and A. senegalensis demonstrated strong α-amylase and yeast cell glucose absorption inhibition, respectively. The stem bark methanol extract of A. senegalensis exhibited the highest level of inhibition (87.61%) at 0.1 mg/ml concentration when compared to conventional acarbose medication (56.0%) on the α-amylase enzyme. The percentage of glucose uptake by both methanol stem bark extract of Kigelia africana and Annona senegalensis was recorded maximum (31.40%) at a concentration of 0.5 mg/ml. The present research establishes the antidiabetic effect of methanol stem bark extract of Kigelia africana and Annona senegalensis by in vitro assays.
本研究旨在研究非洲藜和塞内加尔藜茎皮甲醇提取物的植物化学活性成分和近似成分,以及其体外抗糖尿病潜能。结果表明,生物活性化合物的存在可能是这些植物具有许多药用能力的原因,包括它们的抗糖尿病能力。非洲栎和塞内加尔栎甲醇茎皮提取物分别表现出较强的α-淀粉酶和酵母细胞葡萄糖吸收抑制作用。在0.1 mg/ml浓度下,皂荚茎皮甲醇提取物对α-淀粉酶的抑制率最高(87.61%),而常规阿卡波糖药物对α-淀粉酶的抑制率为56.0%。在浓度为0.5 mg/ml时,非洲藜和塞内加尔藜甲醇茎皮提取物的葡萄糖摄取率最高,为31.40%。本研究通过体外实验建立了非洲木和塞内加尔藜甲醇茎皮提取物的抗糖尿病作用。
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引用次数: 0
Larger Intrinsic Rate Constants of Alpha-amylase is Possible if Intrinsic Forward Rate Constant is ≠ Diffusion limited Rate of Encounter 如果α -淀粉酶的正向本征速率常数≠扩散极限相遇速率,则α -淀粉酶可能具有较大的本征速率常数
Pub Date : 2022-11-07 DOI: 10.9734/ajocs/2022/v12i3219
Ikechukwu Iloh Udema
Background: Previous research has shown that the intrinsic reverse (backward) and forward rate constants are larger than the effective or apparent rate constants for the formation and dissociation of an enzyme-substrate complex (ES). It is speculated that such intrinsic rate constants could be larger if an appropriate mathematical equation was adopted for their computation.  Methods: Theoretical, experimental (Bernfeld method), and computational methods. Objectives: 1) To rederive the equations for calculating the intrinsic rate constants for forward (k1) and reverse (i.e., backward) (k2) reactions; 2) to calculate the intrinsic rate constants; and 3) to                show that the probability (1/g) (or req(r)) that an enzyme is at a distance from the substrate is a              variable.  Results and Discussion: The equations for the determination of k2 and k1 were rederived. Unlike previous findings, the intrinsic (reverse) first order rate, k2 and forward second order rate, k1 were larger than their apparent counterparts, but they were, however, very similar in magnitude. The intrinsic rate constants were much larger than previously reported values when the enzyme (E) total concentration [ET] was much less than substrate’s total concentration [ST]. The k1 and apparent forward second order rate (kf) values where [ET] is much less than [ST] were > where [ET] is less than [ST]. Therefore, the magnitude of the second order rate constant is a function of [ET]. The values of k1 and k2 where [ET] is much less than [ST] and vice-versa were respectively, 7.41 exp. (+6) L/mol. min and 81.34 exp. (+4) /min, and 15.76 exp. (+6) L/mol. min and 58.08 exp.(+4) /min. It was discovered that the probability (1/g) (or req(r))) that an enzyme is at a distance from the substrate with the possibility of mutual attraction is not constant.  Conclusion: If the intrinsic forward rate constant (k1) is not equal to diffusion limited rate (kD) of encounter, the k1 and k2 values could be larger than values where k1 is equal to kD. The probability (1/g) (or req(r)) that an enzyme is at a distance from the substrate with the possibility of mutual attraction has been discovered to be a variable constant dependent on the concentration of the reaction mixture components and the enzyme's affinity for the substrate, and vice versa. Future research may attempt to derive an equation for the determination of an intrinsic catalytic rate constant for the formation of a product.
背景:先前的研究表明,酶-底物复合物(ES)形成和解离的内在反向(向后)和正向速率常数大于有效或表观速率常数。据推测,如果采用合适的数学方程来计算,这些本征速率常数可能会更大。方法:理论方法、实验方法(Bernfeld法)和计算方法。目的:1)重新推导计算正向(k1)和反向(即反向)(k2)反应的固有速率常数的方程;2)计算本征速率常数;3)表示酶离底物一定距离的概率(1/g)(或req(r))是一个变量。结果与讨论:重新推导了测定k2和k1的方程。与先前的发现不同,本征(反向)一阶速率k2和正征二阶速率k1比它们的表观对应物要大,但它们的量级非常相似。当酶(E)总浓度[ET]远小于底物总浓度[ST]时,本征速率常数比先前报道的值大得多。当[ET]远小于[ST]时,k1和表观正向二阶速率(kf)值> [ET]小于[ST]时。因此,二阶速率常数的大小是[ET]的函数。当[ET]远小于[ST]时,k1和k2的值分别为7.41 exp. (+6) L/mol。81.34 exp. (+4) /min和15.76 exp. (+6) L/mol。Min和58.08 exp.(+4) / Min。我们发现,酶与底物之间存在相互吸引的可能性的概率(1/g)(或req(r))不是恒定的。结论:当接触的内在正向速率常数k1不等于扩散限制速率kD时,k1和k2值可能大于k1等于kD时的值。一种酶与底物之间存在相互吸引的可能性的概率(1/g)(或req(r))已被发现是一个可变常数,它取决于反应混合物组分的浓度和酶对底物的亲和力,反之亦然。未来的研究可能会试图推导出一个方程来确定产物形成的本征催化速率常数。
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引用次数: 1
Kinetic and Thermodynamic Behavior of Extraction of Oleoresin Containing Curcuminoids from Turmeric (Curcuma longa L.) in Acetone and Their Bioavailability 丙酮萃取姜黄中含姜黄素油树脂的动力学、热力学行为及其生物利用度
Pub Date : 2022-11-07 DOI: 10.9734/ajocs/2022/v12i3220
A. Kunyima, J. C. Kuburhanwa, H. M. Kaseya, M. Kunyima
Background: Why this miraculous and amphiphilic compound, the curcumin, which has a very extraordinary therapeutic potential (because can react with many targets in the organism), has a weak bioavailability in the organism and is metabolized in compounds having very weak activity or inactive compounds?. How to improve substantially its bioavailability and therefore its absorption in the organism in order to allow its incorporation in making of pharmaceuticals regardless of its nanoparticles of which obtention is furthermore hardworking? Aim: It seems indicated to search the response in the kinetic and thermodynamic behavior of this compound or in its co-administration with the other compounds in vitro in order to understand how to increase its absorption in vivo because bioavailability entails hydrosolubility (hydrophile) of curcuminoids of which the molecules are naturally hydrophobes. Objective: So our objective is to make better our understanding of the absorption of natural curcuminoids in the organism without resorting to chemical transformation in nanoparticles that is additionally hardworking. Methodology: In this paper, kinetic and thermodynamic study of extraction of oleoresin containing curcuminoids from Turmeric (Curcuma Longa L.), using KUNYIMA’s first law, has been performed in acetone that can be reduced in propan-2-ol which is water-like solvent by catalytic hydrogenating (H2,Ni ) or by chemical reduction (LiAlH4). Results: The weak global kinetic constant of extraction of oleoresin containing curcuminoids has been determined at 250 rpm (round per minute) and found the same at 500 rpm (k= 0.1520 ± 0.0005) min-1 for temperature of 27,5°C and constant pressure in acetone in closed system. Conclusion: Kunyima’s first law has made possible the kinetic and thermodynamic study of extraction of oleoresin containing curcuminoids from Turmeric. Kinetic constant is a measure of solubility of oleoresin containing curcuminoids and therefore a measure of solubility of curcuminoids in a given solvent, ethanol and acetone being concerned in this paper as solvents. Results show that kinetic constant is inversely proportional to solubility of solvent and it can be a parameter abling the determination of the endothermic or exothermic behavior of extraction of curcuminoids. The endothermic behavior of curcuminoids hereby determined in ethanol and acetone in vitro, increased by magnetic stirring, suggests their weak bioavailability and therefore the weak bioavailability of curcumin. The challenge of this actual research is to improve our understanding of kinetics and thermodynamics of extraction of oleoresin containing curcuminoids from Turmeric in vitro in order to presage their bioavailability still weak for an efficient validated action. The increase of bioavailability will be done whether through improved formulations of curcumin or through new pathways of administration. The conception of curcumin analogous is also a way to promote its effec
背景:为什么姜黄素这种神奇的两亲性化合物,具有非常非凡的治疗潜力(因为可以与生物体中的许多靶点发生反应),在生物体中的生物利用度很弱,并且代谢成活性非常弱或无活性的化合物?如何实质性地提高其生物利用度,从而提高其在生物体中的吸收,以便将其纳入药物制造中,而不管其纳米颗粒是如何引起进一步的注意的?目的:研究姜黄素在体外的动力学和热力学行为或与其他化合物共同给药的反应,以了解如何增加其在体内的吸收,因为生物利用度需要姜黄素的水溶性(亲水性),而姜黄素分子是天然疏水的。目的:因此,我们的目标是更好地了解天然姜黄素在生物体中的吸收,而不诉诸于纳米颗粒中的化学转化,这是额外的努力。方法:以丙酮为溶剂,利用KUNYIMA第一定律对姜黄(Curcuma Longa L.)中含有姜黄素的油树脂进行了动力学和热力学研究,丙酮可通过催化加氢(H2,Ni)或化学还原(LiAlH4)在类水溶剂丙烯-2-醇中还原。结果:测定了含姜黄素的油树脂在250 rpm(圆/ min)和500 rpm (k= 0.1520±0.0005)min-1条件下在封闭体系中27,5℃、恒压丙酮中提取的弱总动力学常数。结论:昆依马第一定律为从姜黄中提取含姜黄素的油树脂的动力学和热力学研究提供了可能。动力学常数是测定含有姜黄素的油树脂溶解度的一种方法,因此也是测定姜黄素在给定溶剂中的溶解度的一种方法,本文所讨论的溶剂是乙醇和丙酮。结果表明,动力学常数与溶剂溶解度成反比,可以作为测定姜黄素提取吸热或放热行为的参数。姜黄素在乙醇和丙酮中的体外吸热行为,通过磁搅拌增加,表明其生物利用度较弱,因此姜黄素的生物利用度较弱。本实际研究的挑战是提高我们对姜黄中含姜黄素的油树脂的体外提取动力学和热力学的理解,以预测其生物利用度仍然较弱,从而有效地验证其作用。提高生物利用度将通过改进姜黄素的配方或通过新的给药途径来实现。姜黄素类似物的概念也是促进其作用的一种方式。这种现象在类水溶剂中越放热,所涉及的化合物就越具有生物可利用性。本研究通过含姜黄素的油树脂提取的吸热行为和较弱的整体动力学常数揭示了姜黄素在丙酮中的酮型优势和姜黄素(姜黄素)缺乏生物利用度。丙酮中熵的变化毫不奇怪地显示了萃取后系统的扰动。比较了姜黄素在丙酮和乙醇中作为类水溶剂的动力学常数值,发现姜黄素在丙酮中的溶解度较好,动力学常数较弱。姜黄素预示着充满希望的未来。
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引用次数: 0
Physico-chemical Characterization of Some Metal Complexes Formed by Substituted Thiourea 取代硫脲形成的一些金属配合物的物理化学性质
Pub Date : 2022-10-21 DOI: 10.9734/ajocs/2022/v12i2218
G. Swarnabala, S. Khatavkar, G. Sadana, A. Bharadwaj
In view of unique physico-chemical observations affecting the geometry and various properties of the substituted thiourea complexes in literature along with several biological activities, N-(hydroxy)-N,N-diphenyl thiourea was taken up for study.  Complexes with geometries of high spin octahedral for iron(II), cobalt(II); tetrahedral & square planar for nickel(II); and dimeric square planar for copper chloride, copper perchlorate, copper acetate and distorted octahedral for copper nitrate were synthesized and characterized based on magnetic moments, visible spectra, diffuse reflectance spectra, electron spin resonance, infrared spectral studies, and thermal analysis. Interestingly, the nature of anion influenced the geometry, the complex from copper nitrate salt resulted in a distorted octahedral structure and complexes formed from copper chloride, copper perchlorate, copper acetate exhibited sub-normal magnetic moments, highly insoluble in the most common organic solvents and water. Based on these and spectral data, polymeric or square-planar dimeric geometry with sulfur bridging between copper atoms is proposed.  It was confirmed by the application of Bleaney-Bower’s equation for magnetic susceptibility, applicable to dimeric copper complexes. The overall thermal behavior of the ligand and complexes were observed and the detailed calculations interestingly lead to confirmation of the above proposed geometrical structures.
鉴于文献中对取代硫脲配合物的几何形状和各种性质有独特的物理化学观察,并具有多种生物活性,本文选择了N-(羟基)-N,N-二苯基硫脲进行研究。铁(II)、钴(II)的高自旋八面体配合物镍(II)为四面体和方形平面;通过磁矩、可见光谱、漫反射光谱、电子自旋共振、红外光谱研究和热分析,合成了氯化铜、高氯酸铜、乙酸铜的二聚体方形平面和硝酸铜的畸变八面体。有趣的是,阴离子的性质影响了其几何形状,硝酸铜形成的配合物导致了扭曲的八面体结构,而氯化铜、高氯酸铜、醋酸铜形成的配合物表现出亚正常磁矩,在最常见的有机溶剂和水中高度不溶。基于这些数据和光谱数据,提出了铜原子之间有硫桥接的聚合物或方形平面二聚体几何结构。用适用于二聚铜配合物的Bleaney-Bower磁化率方程证实了这一结论。观察了配体和配合物的整体热行为,有趣的是,详细的计算证实了上述提出的几何结构。
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引用次数: 0
Synthesis and Characterization of Mango Wood Nanocellulose Fibers 芒果木纳米纤维素纤维的合成与表征
Pub Date : 2022-08-11 DOI: 10.9734/ajocs/2022/v12i219145
J. K. Prasannakumar, G. Prakash, B. Basavarajappa, B. Suresh
Agricultural biomasses are the prominent natural sources of cellulose currently available on the planet. When this was treated chemically, this acquire the properties such as toughness, good biocompatibility, and higher thermal stability. In this study, Nanocellulose was extracted from Mango wood (Mangifera indica) a largely available agricultural biomass. The cellulose was alkali-treated followed by bleaching to remove lignin and hemicellulose, pectins, and waxes. The green solvent i.e Ionic liquid (1-butyl-3-methylimidazolium chloride ([Bmim] Cl) was used to dissolve cellulose to yield Nanocellulose through sonication and centrifugation. The functional groups and significant conversion of cellulose to nanocellulose are confirmed by FT-IR spectra. The crystallinity of synthesized nanocellulose is illustrated by XRD. The surface architecture and size obtained are represented by SEM and TEM monographs. The TEM images show the synthesized nanocellulose has a dimension between 27.33 to 34.85 nm. The thermal stability of the obtained nanocellulose was evidenced using TGA/DTA. The thermal studies records that synthesized nanocellulose shows superior thermal stability up to 473.8°C. The efficient conversion of agricultural waste into value added material is achieved through a greener pathway.
农业生物质是目前地球上纤维素的主要天然来源。经化学处理后,获得韧性、良好的生物相容性和较高的热稳定性等特性。在这项研究中,纳米纤维素是从芒果木(Mangifera indica)一种大量可用的农业生物质中提取的。对纤维素进行碱处理,然后漂白去除木质素、半纤维素、果胶和蜡。采用绿色溶剂离子液体(1-丁基-3-甲基咪唑氯([Bmim] Cl))对纤维素进行超声和离心溶解,得到纳米纤维素。FT-IR光谱证实了纤维素的官能团和向纳米纤维素的显著转化。用XRD表征了合成的纳米纤维素的结晶度。得到的表面结构和尺寸由SEM和TEM表征。TEM图像显示,合成的纳米纤维素的尺寸在27.33 ~ 34.85 nm之间。用热重热分析/差热分析证实了纳米纤维素的热稳定性。热稳定性研究表明,合成的纳米纤维素在473.8℃下表现出优异的热稳定性。将农业废弃物有效转化为增值材料是通过更环保的途径实现的。
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引用次数: 0
Bermuda Triangle in Chemistry 化学百慕大三角
Pub Date : 2022-07-25 DOI: 10.9734/ajocs/2022/v12i219143
Dumitru Petru I. Iga, D. Popescu, V. Niculescu
It is believed that the place called Bermuda triangle is able to hide of human seeing objects entered its area. A Bermuda triangle in chemistry is able to hide (mask) atoms or planar molecular fragments cut by their mirror plane of symmetry, not of human eyes but, of polarized light. A triangular skeleton (frame) has been imagined, possessing the ability to cover many hundreds of molecular formulae, providing the latter refer to aliphatic, or partially aliphatic, compounds, and with a low degree of oxidation. This skeleton (frame) is based on a very general and strong principle, valid in meso entities. The idea is advanced that isomers coming up from a molecular formula could be of four types (groups): meso, C2 symmetrical (CTS), irrechi (from irregular chiral) and constitutional (constit.). The following universal rule is revealed: all CTS and irrechi can be converted to meso ones, but the reverse is not true, at least for the same skeleton. At the same time, an impressive number of constitutional natural or synthetic combinations are characterized by at least one real or envisaged meso isomer. Thus, from a structural point of view, meso isomers are justified as reference compounds. The above mentioned principles have been applied to numerous natural compounds: amino acids, lipids, carbohydrates, nucleosides, vitamins, steroids, alkaloids,  hydrocarbons. A mathematical equation sustaining the triangular representation has been proposed. One raises the question which of the four types is the upper. A tentative answer is given to this question.
人们相信,百慕大三角能够隐藏人类看到的进入该区域的物体。化学中的百慕大三角能够隐藏(掩盖)原子或被对称镜面切割的平面分子碎片,不是人眼的,而是偏振光的。一个三角形的骨架(框架)已被设想,具有覆盖数百个分子式的能力,提供后者指脂肪族或部分脂肪族化合物,并且具有低程度的氧化。这个骨架(框架)基于一个非常普遍和强大的原则,适用于中观实体。提出了从分子式中产生的同分异构体可以有四种类型(基团):中介体,C2对称(CTS),不规则手性(irchi)和构象(构成)。揭示了以下普遍规律:所有的CTS和irchi都可以转化为中位体,但反之则不成立,至少对同一骨架而言是如此。同时,令人印象深刻的结构天然或合成组合具有至少一种实际或设想的中位异构体的特征。因此,从结构的角度来看,中位异构体可以作为参考化合物。上述原理已应用于许多天然化合物:氨基酸、脂类、碳水化合物、核苷、维生素、类固醇、生物碱、碳氢化合物。提出了一个支持三角表示的数学方程。有人提出了四种类型中哪一种是上层的问题。对这个问题作了初步的回答。
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引用次数: 1
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Asian Journal of Chemical Sciences
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