Experimental and theoretical study on structure-tautomerism among edaravone,isoxazolone, and their heterocycles derivatives as antioxidants

Edaravone is a heterocyclic pyrazolone compound. It has pronounced effect against free radicals, however renal and hepatic disorders have been reported. Isoxazolones are considered bioisosteric analogues of pyrazolones and may have comparable properties. Thus, we investigated the structural and electronic influences for edaravone, isoxazolone, and their tautomers on antioxidant process. Structure and tautomerism study among edaravone, isoxazolone and their heterocycles derivatives were related to antioxidant mechanisms by using the hybrid DFT method B3LYP with the basis sets 6-31++G(2d,2p). The CH tautomer was the most stable and energetically favored among them. Intramolecular NHN hydrogen bonds and polar medium were responsible for the low energy differences among all possible tautomers. NH tautomers in both systems proved to be better antioxidant by SET (single electron transfer), while OH tautomers were better antioxidant on HAT (homolytic hydrogen atom transfer) mechanism. Theoretical calculation showed that edaravone is more potent than phenylisoxazolone, however, both has similar antioxidant scavenging on experimental DPPH. The carbonyliminic system played a very important role in the antioxidant activity for both studied classes.     

Ferroelectricity and multiferroicity in anti–Ruddlesden–Popper structures

Combining ferroelectricity with other properties such as visible light absorption or long-range magnetic order requires the discovery of new families of ferroelectric materials. Here, through the analysis of a high-throughput database of phonon band structures, we identify a structural family of anti–Ruddlesden–Popper phases A4X2O (A=Ca, Sr, Ba, Eu, X=Sb, P, As, Bi) showing ferroelectric and antiferroelectric behaviors. The discovered ferroelectrics belong to the new class of hyperferroelectrics that polarize even under open-circuit boundary conditions. The polar distortion involves the movement of O anions against apical A cations and is driven by geometric effects resulting from internal chemical strains. Within this structural family, we show that Eu4Sb2O combines coupled ferromagnetic and ferroelectric order at the same atomic site, a very rare occurrence in materials physics.

Ferroelectric (FE) materials are of great fundamental and applied interest. They are currently used in many technologies such as electric capacitors, piezoelectric sensors and transducers, pyroelectric detectors, nonvolatile memory devices, or energy converters (1–8). For decades, most applications have relied on FE oxide perovskites. However, the need to combine ferroelectricity with other properties such as visible light absorption (9, 10) or long-range magnetic order (11, 12) is driving the search for materials and structural classes beyond perovskites. High-throughput (HT) computational screening is a promising approach to search for materials possessing specific properties. It has been successfully used in a wide variety of fields from thermoelectrics (13, 14) to topological insulators (15–17). Different HT computing approaches have also been used to identify new FEs (18–21). Inspired by these previous studies and using a recently developed large phonon database, we searched for materials exhibiting dynamically unstable polar phonon modes, a signature of potential ferroelectricity. Our HT search identifies a family of (anti)FE materials: the series of anti–Ruddlesden–Popper phases of formula A4X2O, where A is a +2 alkali earth or rare-earth element, and X is a −3 anion Bi, Sb, As, and P. We survey how (anti)ferroelectricity subtly depends on the chemistry of A4X2O and unveil the physical origin of the polar distortion. Interestingly, the discovered FEs belong to the new class of hyperferroelectrics (22) in which spontaneous polarization is maintained under open-circuit boundary conditions. The anti–Ruddlesden–Popper phases also lead to unique combinations of properties, for instance, a rare combination of ferroelectricity with ferromagnetism in Eu4Sb2O.     

Electrochemical and surface studies on chemically modified glucose derivatives as environmentally benign corrosion inhibitors

Three glucose derivatives, namely Ethylenediamine-modified glucose, Tetramethylenediamine-modified glucose, and Hexamethylenediamine-modified glucose with three different carbon chain lengths were synthesized using environmentally benign and low-cost reactants at ambient temperature. The synthesized derivatives were evaluated as inhibitors for mild steel corrosion in 1 M HCl using electrochemical, surface analysis (XPS, AFM and contact angle), as well as computational (DFT) techniques. The obtained results suggest that the synthesized glucose derivatives significantly mitigate the corrosion of mild steel and show a rise in the inhibition efficiency with increasing inhibitor dosage. The inhibitor adsorption obeyed the Langmuir isotherm. The XPS analyses provided an elucidation on the interaction of the inhibitors with the steel substrate. The DFT studies showed that the protonated forms of the inhibitors act more prominently compared to the neutral form. The inhibitor HMG having the alkyl chain with six carbon atoms exhibited the highest inhibition performance of >95% at 22.71 × 10^?5 mol L^?1.     

Structure and reactivity of Ben cycles (n = 3–12): A DFT study

In this paper, we present the electronic and structural study of Be₃–Be₁₂ cycles. In addition, a reactivity study of the Be₃–Be₈ structures toward Li⁺ was carried out, this cation receive electronic density from each cycle. We also evaluated the Be₆ cycle as acceptor of electron density by placing one and two molecules of benzene. The natural bond orbital (NBO) analysis performed shows a clear evidence of those interactions in the six-membered beryllium cycle toward benzene molecules.     

Comparative amino acid decomposition analysis of potent type I p38α inhibitors

Background and purpose of the study

p38α is a member of mitogen-activated protein kinases (MAPK) considered as a prominent target in development of anti-inflammatory agents. Any abnormality in the phosphorylation process leads to the different human diseases such as cancer, diabetes and inflammatory diseases. Several small molecule p38α inhibitors have been developed up to now. In this regard, structural elucidation of p38 inhibitors needs to be done enabling us in rational lead development strategies.

Methods

Various interactions of three potent inhibitors with p38α active site have been evaluated in terms of binding energies and bond lengths via density function theory and MD simulations.

Results

Our comparative study showed that both ab initio and MD simulation led to the relatively similar results in pharmacophore discrimination of p38α inhibitors.

Conclusion

The results of the present study may find their usefulness in pharmacophore based modification of p38α inhibitors.     

密度泛函法研究抗肿瘤钴配合物[Co（bpy）2L]（3＋）,[Co（phen）2L]（3＋）（L=ip,pip）的构效关系

目的对系列抗肿瘤钴配合物[Co（bpy）2L]3＋、[Co（phen）2L]3＋（L=ip,pip）的几何及电子结构与其抗肿瘤活性的关系进行理论计算研究。方法在B3LYP/LanL2DZ水平上,采用量子化学密度泛函（DFT）法进行计算。结果具有较大面积的插入配体,及较低的HOMO与LUMO轨道能量间隙（ΔεL-H）有利于配合物与DNA的作用,从而增加配合物的抗肿瘤活性。结论计算结果可为这类抗肿瘤配合物的分子设计与合成提供理论参考。     

11种黄酮类化合物抗氧化活性与结构关系的DFT研究

采用量子化学DFT方法对11种黄酮类化合物进行构型优化和计算,从所得量化参数与黄酮类化合物抗氧化活性进行分析。结果表明,黄酮类化合物抗氧化活性与生成的半醌式自由基的稳定性有关,而自由基的最稳定状态为同时解离3位和4'位羟基上质子生成的半醌式自由基,即最佳抗氧化状态。     

Structure/activity investigations of 5-substituted 3-methylisoxazole[5, 4-d]1, 2, 3-triazin-4-one derivatives

The series of 5-substituted 3-methylisoxazole[5, 4-d]1, 2, 3-triazin-4-one derivatives was obtained by diazotization of 5-amino-3-methylisoxazol-4-carboxylic acid hydrazide. The immunological activity of these compounds was investigated experimentally in several in vitro and in vivo assays in mice and human models. In the next step, quantum-chemical investigations were performed using density functional theory with the B3LYP hybrid exchange-correlation energy functional and 6-31G(d, p) basis set. The Polarizable Continuum (SCRF/PCM) solvent model was also taken into account in order to show solvent influence on electron density and electrostatic potential around the exemplary molecules. Correlations between molecular structure and biological properties were found using a stepwise selection of scales for the multiple linear regression (MLR).     

一个基于频谱检测是否发生心室纤颤的算法

本文提出可能利用一维滑动ＤＦＴ并行处理器实时提取ＥＣＧ信号的滑动频谱，以中间一段的频谱的模的均方值作为特征来判别病人是否发生了心室纤颤。作者对１４０个Ｖｅｎｔｒｉｃｕｌａｒ Ｆｉｂｒｉｌｌａｔｉｏｎ（ＶＦ）信号和Ｖｅｎｔｒｉｃｕｌａｒ Ｔａｃｈｙｃａｒｄｉａ（ＶＴ）信号作了统计，并用概率纸证明在特征值取值范围内是正态概率分布模型。作者使用了序贯假设检验的办法来进行判决，通过扩大判决阀值减少了误判率