Design of nanostructured ceria-based solid electrolytes for development of IT-SOFC

A considerable interest has been shown in the application of doped ceria (CeO₂) compounds for “intermediate” (300–500 °C) temperature operation of solid oxide fuel cells. The microdomains with ordered structure of oxygen vacancy were observed in the microstructure of the M-doped CeO₂-sintered bodies (where M: Gd, Y, and Dy). We have previously shown that the conductivity of doped CeO₂-sintered bodies was lower when the sintered body contained large microdomains within grains. As a consequence of this observation, we have examined the grain size dependence and dopant content on conductivity in specimens where we adjust the microdomain size and a degree of oxygen vacancy ordering in the microdomains by controlling the microstructure. The microdomain size control in Dy-doped CeO₂ specimens was obtained by combining pulsed electric current sintering and conventional sintering. Using these techniques, we were able to improve the conductivity in Dy-doped CeO₂ specimens to a point where it became comparable to that of the more conventional Gd-doped CeO₂ specimens. It is concluded that by combining ultimate high-resolution analysis of these nanostructures with the adjusting processing route design, it is possible to further develop these materials in CeO₂-doped fuel cell application.     

光、电催化合成氘代化学品和药物分子研究综述

稳定氘同位素因其安全、易控制、廉价易得等优势而被广泛应用于探究有机反应机理和揭示药物及其代谢物的吸收、分布、代谢和排泄过程.此外,氘标记药物也被称为重氢药、重药,即把药物分子上处于代谢位点的一个或多个碳氢键(C-H)用碳氘键(C-D)替代获得的新药,以延长药物代谢周期、减少进入血液前的代谢、减少有毒代谢物产生,从而降低给药剂量、提高安全性以及获得更佳的疗效.2017年4月,第一例氘代新药,氘代四苯喹嗪(海外商品名Austedo,国内商品名:安泰坦)被美国食品药品监督管理局批准,氘代新药市场被彻底激活.临床数据显示,丁苯那嗪原药具有严重的毒副作用,19%的病人使用后表现出抑郁病症,严重者甚至有自杀倾向;氘代丁苯那嗪相对于原药,代谢动力学特征明显改善,毒副作用显著降低.目前,国内外已有多家知名药企(如BMS,Concert,Teva,苏州泽璟生物制药以及成都海创等)布局氘代新药研发.2021年6月,中国国家药品监督管理局正式批准苯磺酸多纳非尼片(商品名:泽普生),用于治疗既往未接受过全身系统性治疗的不可切除肝细胞癌患者.氘代药物的蓬勃发展使得对其精准合成提出了更高的要求和更强烈的需求.氢氘交换等传统方法由于反应条件苛刻、氘源昂贵、氘代个数和位点难以精准控制等限制,难以满足新时代氘代药物的发展需要.近年,化学家开始致力于开发温和、精准氘代新方法,其中,光或电驱动的温和、精准氘标记方法引起了广泛关注.本综述着重总结近五年光/电驱动的温和、精准的氘代方法的研究进展.基于氘原子引入的反应模式分为以下三种类型.(1)氘原子转移策略:以光/电催化单电子转移或者氢原子转移方式生成自由基中间体R^?;随后,R^?与氘原子转移试剂(由硫醇和重水原位制得)反应,得到相应的氘代产物R-D.利用该策略,目前已发展了羧酸、卤代烃、硫醚(醇)等的去官能化氘代反应以及硅烷、叔胺、醛基等的氢氘交换反应.(2)氘原子攫取策略:以光/电催化单电子转移、氢原子转移或者能量转移方式生成自由基R^?中间体,一方面,以产物碳氘键键能大于溶剂碳氘键键能为驱动力,使R^?直接从氘代溶剂中攫取氘原子制得相应的氘代产物R-D;另一方面,利用光/电催化强驱动力,使R^?再次获得一个电子形成相应负离子,从而顺利从重水中攫氘,制得相应的氘代产物R-D.利用该策略,目前已开发了羧酸、重氮、卤代物等的去官能化氘代反应,以及亚胺的加氘还原反应.(3)重水分解策略:基于光/电催化水分解制氢原理,以光或电为驱动力分解重水,使其产生高活性氘物种,原位耦合还原氘代反应.利用该策略,目前已开发了以重水为氘源的卤代物,不饱和官能团(包括烯烃、炔烃、亚胺和芳基酮等)等的氘代还原反应以及伯、仲胺的氘甲基化反应.本综述归纳了近年来光或电催化驱动的温和、精准氘代方法研究进展.在此基础上结合课题组在该领域的研究经历,分析了药物和精细化学品精准氘代面临的关键挑战和重要机遇,包括:发展温和、精准的不对称催化氘代方法用于制备手性氘代药物;针对复杂药物多个代谢位点,实现精准、可控氘代,从而更有效调节药物代谢动力学和代谢产物.此外,光合成、电合成迅猛发展也将为氘代精细化学品和药物光、电催化合成带来新的机遇.     

Effect of axial ligands and macrocyclic structure on redox potentials and electron-transfer mechanisms of SnIV porphyrins

The electrochemical properties of dichloro- and dihydroxo-SnIV porphyrins with three different macrocycles were examined in CH2Cl2 containing 0.1 or 0.2 M tetra-n-butylammonium perchlorate as supporting electrolyte. The investigated compounds are represented as (TPP)SnX2, (P)Sn(X)2, and (PQ)Sn(X)2, where TPP = 5,10,15,20-tetraphenylporphyrin, P = 5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)porphyrin, PQ = 5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)quinoxalino[2,3-b']porphyrin, and X = Cl or OH. Each porphyrin can be electroreduced in two one-electron-transfer steps with the half-wave potentials and stability of the eletroreduced compounds being dependent upon the type of coordinated axial ligand and specific macrocyclic structure. All reductions of (TPP)Sn(OH)2, (P)Sn(OH)2, and (PQ)Sn(OH)2 are reversible under the given experimental conditions and lead to the expected porphyrin pi-anion radicals and dianions, which were characterized by thin-layer UV-vis spectroelectrochemistry. This contrasts with what occurs upon the reduction of (PQ)SnCl2, which undergoes a chemical reaction with trace H2O in solution, leading to the formation of (PQ)Sn(OH)2 as well as to a protonated form of the quinoxalinoporphyrin, (PQH)Sn(OH)2, under the application of an applied potential. A protonation of the Q group breaks the conjugation between the fused quinoxaline unit and the porphyrin macrocycle, thus effectively giving a compound whose reduction properties resemble that of the metalloporphyrin in the absence of the fused ring. The electrooxidation of each neutral SnIV porphyrin was also investigated, and the effect of axial ligand and fused quinoxaline ring on the redox potentials and products of electron transfer are discussed.     

Functionalization of corroles: the nitration reaction

The reaction of meso-triarylcorroles with AgNO2 proceeds with concomitant metalation and peripheral substitution to give the corresponding nitro-substituted silverIII corrole complex. The substitution is highly regioselective, giving only the corresponding 3-nitro derivative, among the different possible isomers. The results obtained indicate that the reaction intermediate is the pi-cation radical of the complex, which is then attacked by nitrite ion. This was proven by the reaction of the copper corrole complexes with NaNO2: in this case, the nitration reaction proceeded without the addition of an oxidant, because of the pi-cation radical character of the copper complex. The reaction is also successful in the case of 2,3,17,18-tetraethyl-8,12-diacetoxymethyl-7,13-dimethylcorrole (AMCorH3), with the formation of the meso-substituted silver corrole derivative (NO2)3AMCorAg (fully characterized by X-ray crystallography), the first of its kind to be reported. Two of the corroles are characterized by cyclic voltammetry and spectroelectrochemistry in dichloromethane, and the site of electron transfer is elucidated.     

Quinoxalino[2,3-b']porphyrins behave as pi-expanded porphyrins upon one-electron reduction: broad control of the degree of delocalization through substitution at the macrocycle periphery

The synthesis and redox properties of a series of free-base and metal(II) quinoxalino[2,3-b']porphyrins and their use in an investigation of the substituent effects on the degree of communication between the porphyrin and its beta,beta'-fused quinoxalino component are reported. ESR, thin-layer spectroelectrochemistry, and quantum chemical calculations of the resultant radical anions from one-electron reduction indicate that localization of the unpaired electron across both the porphyrin and the fused quinoxalino group can be controlled, the system as a whole behaving as a highly polarizable pi-expanded porphyrin radical anion. ESR studies on the radical anions of zinc(II) quinoxalino[2,3-b']porphyrin derivatives indicate that nitrogen-atom spin distribution changes as a function of chemical substitution: 27% quinoxaline character when the porphyrin ring bears a 7-nitro substituent, 34% quinoxaline character in the unsubstituted parent, and 51-61% nitroquinoxaline character when the quinoxalino unit has one or more nitro groups. Close analogies are found between the calculated and observed nitrogen-atom spin distributions, indicating that the calculations embody the key chemical effects. The calculations also indicate that the nitrogen-atom spin distributions closely parallel the important total porphyrin, quinoxaline, and nitro spin distributions, indicating that the observed quantities realistically depict the change in the nature of the delocalization of the radical anion as a function of chemical substitution. The profound effects observed indicate long-range communication of the type that is essential in molecular electronics applications.     

Cytotoxic kurubasch aldehyde from Trichilia emetica

Kurubasch aldehyde, a sesquiterpenoid with an hydroxylated humulene skeleton, was isolated as free alcohol from Trichilia emetica Vahl. (Meliaceae), belonging to the order Sapindales. Related substances have been previously found in plants as esters of aromatic acids, and these plants were species belonging to the distant order Apiales. This is the first report of humulenes found in the genus Trichilia and only the second of humulenes in the order Sapindales. The aldehyde is a modest inhibitor of the growth of Plasmodium falciparum (IC50 76 microM) and slow-proliferating breast cancer cells MCF7 (78 microM), but a potent inhibitor of proliferation of S180 cancer cells (IC50 7.4 microM).     

Alkyne Insertion Enabled Vinyl to Acyl 1,5-Palladium Migration: Rapid Access to Substituted 5-Membered-Dihydrobenzofurans and Indolines

“Through space” palladium/hydrogen shift is an efficient strategy to achieve selective functionalization of a specific remote C−H bond. Compared with relatively extensive exploited 1,4-palladium migration process, the relevant 1,5-Pd/H shift was far less investigated. We herein report a novel 1,5-Pd/H shift pattern between a vinyl and an acyl group. Through the pattern, rapid access to 5-membered-dihydrobenzofuran and indoline derivatives has been achieved. Further studies have unveiled an unprecedented trifunctionalization (vinylation, alkynylation and amination) of a phenyl ring through 1,5-palladium migration relayed decarbonylative Catellani type reaction. A series of mechanistic investigations and DFT calculations have provided insights into the reaction pathway. Notably, it was unveiled that the 1,5-palladium migration in our case prefers a stepwise mechanism involving a Pd^IV intermediate.     

On the Second Boundary Value Problem for a Class of Fully Nonlinear Equations

We proved the existence of convex solution to a class of fully nonlinear elliptic equations with second boundary condition on uniformly convex domains in \(\mathbb {R}^{n}\), and then applied it to solve a boundary value problem for minimal Lagrangian graphs in the pseudo-Euclidean space \(\mathbb {R}^{2n}_n\).     

Functionalization of a Rigid Divalent Ligand for LecA,a Bacterial Adhesion Lectin

The bacterial adhesion lectin LecA is an attractive target for interference with the infectivity of its producer P. aeruginosa. Divalent ligands with two terminal galactoside moieties connected by an alternating glucose-triazole spacer were previously shown to be very potent inhibitors. In this study, we chose to prepare a series of derivatives with various new substituents in the spacer in hopes of further enhancing the LecA inhibitory potency of the molecules. Based on the binding mode, modifications were made to the spacer to enable additional spacer–protein interactions. The introduction of positively charged, negatively charged, and also lipophilic functional groups was successful. The compounds were good LecA ligands, but no improved binding was seen, even though altered thermodynamic parameters were observed by isothermal titration calorimetry (ITC).     

Synthesis and crystal structures of four three-dimensional hybrid materials based on polyoxovanadate bridging macrocyclic copper/nickel complexes

Transition Metal Chemistry - In this research, four hybrid materials, namely [Ni(MC)]3[VO3]6·12.25H2O (1), [Cu(MC)]3[VO3]6 (2), [Ni(PC)]3[VO3]6·2H2O (3), and [Cu(PC)]3[VO3]6·2H2O (4)...