Utilizing the Space‐Charge Region of the FeNi‐LDH/CoP p‐n Junction to Promote Performance in Oxygen Evolution Electrocatalysis

The modulation of electron density is an effective option for efficient alternative electrocatalysts. Here, p‐n junctions are constructed in 3D free‐standing FeNi‐LDH/CoP/carbon cloth (CC) electrode (LDH=layered double hydroxide). The positively charged FeNi‐LDH in the space‐charge region can significantly boost oxygen evolution reaction. Therefore, the j at 1.485 V (vs. RHE) of FeNi‐LDH/CoP/CC achieves ca. 10‐fold and ca. 100‐fold increases compared to those of FeNi‐LDH/CC and CoP/CC, respectively. Density functional theory calculation reveals OH^? has a stronger trend to adsorb on the surface of FeNi‐LDH side in the p‐n junction compared to individual FeNi‐LDH further verifying the synergistic effect in the p‐n junction. Additionally, it represents excellent activity toward water splitting. The utilization of heterojunctions would open up an entirely new possibility to purposefully regulate the electronic structure of active sites and promote their catalytic activities.     

Hexahomotrioxacalix[3]arene derivatives as ionophores for molecular recognition of dopamine, serotonin and phenylethylamine

The lower rim functionalized hexahomotrioxacalix[3]arene derivatives cone-3 and cone-5 bearing three benzyl and three N,N-diethyl-2-aminoethoxy groups, respectively, were synthesized from triol 1. Their complexation with 2-(3,4-dihydroxyphenyl)ethylamine (dopamine), 5-hydroxytryptamine (serotonin), and 2-phenylethylamine (phenethylamine), which have biologically important activities, has been studied by (1)H-NMR spectroscopy. The chemical shifts of the aromatic protons of the host and guest molecules and the up-field shifts of the ethyl protons of the guest molecules strongly suggest the formation of inclusion complexes in solution. The formation of the host-guest complexes is assisted by a hydrogen bond and/or an electrostatic interaction between the host and ammonium ion (RNH(3)(+)) of the guest. The structures of receptors cone-3 and cone-5 have been determined by X-ray crystallography.     

Synthesis of selective inhibitors against V. cholerae sialidase and human cytosolic sialidase NEU2

Sialidases or neuraminidases catalyze the hydrolysis of terminal sialic acid residues from sialyl oligosaccharides and glycoconjugates. Despite successes in developing potent inhibitors specifically against influenza virus neuraminidases, the progress in designing and synthesizing selective inhibitors against bacterial and human sialidases has been slow. Guided by sialidase substrate specificity studies and sialidase crystal structural analysis, a number of 2-deoxy-2,3-dehydro-N-acetylneuraminic acid (DANA or Neu5Ac2en) analogues with modifications at C9 or at both C5 and C9 were synthesized. Inhibition studies of various bacterial sialidases and human cytosolic sialidase NEU2 revealed that Neu5Gc9N(3)2en and Neu5AcN(3)9N(3)2en are selective inhibitors against V. cholerae sialidase and human NEU2, respectively.     

Gold nanoparticle-embedded porous graphene thin films fabricated via layer-by-layer self-assembly and subsequent thermal annealing for electrochemical sensing

A uniform three-dimensional (3D) gold nanoparticle (AuNP)-embedded porous graphene (AuEPG) thin film has been fabricated by electrostatic layer-by-layer assembly of AuNPs and graphene nanosheets functionalized with bovine serum albumin and subsequent thermal annealing in air at 340 °C for 2 h. Scanning electron microscopy (SEM) investigations for the AuEPG film indicate that an AuNP was embedded in every pore of the porous graphene film, something that was difficult to achieve with previously reported methods. The mechanism of formation of the AuEPG film was initially explored. Application of the AuEPG film in electrochemical sensing was further demonstrated by use of H(2)O(2) as a model analyte. The AuEPG film-modified electrode showed improved electrochemical performance in H(2)O(2) detection compared with nonporous graphene-AuNP composite film-modified electrodes, which is mainly attributed to the porous structure of the AuEPG film. This work opens up a new and facile way for direct preparation of metal or metal oxide nanoparticle-embedded porous graphene composite films, which will enable exciting opportunities in highly sensitive electrochemical sensors and other advanced applications based on graphene-metal composites.     

Characterization of supramolecular polymers

Supramolecular polymers are made of monomers that are held together by noncovalent interactions. This is the reason for the wide range of novel properties, such as reversibility and responses to stimuli, exhibited by supramolecular polymers. A range of supramolecular polymerization methods have been developed leading to a number of novel supramolecular materials. However, standard techniques for the characterization of supramolecular polymers have yet to be established. The dynamic nature of supramolecular polymers makes them difficult to be fully characterized using conventional polymer techniques. This tutorial review summarizes various methods for characterizing supramolecular polymers, including theoretical estimation, size exclusion chromatography, viscometry, light scattering, vapor pressure osmometry, mass spectrometry, NMR spectroscopy, scanning probe microscopy, electron microscopy, and atomic force microscopy-based single molecule force spectroscopy. Each of these methods has its own particular advantages and disadvantages. Most of the methods are used to characterize the supramolecular polymer chain itself. However, some of the methods can be used to study the self-assembled state formed by supramolecular polymers. The characterization of a supramolecular polymer cannot be realized with a single method; a convincing conclusion relies on the combination of several different techniques.     

Co3O4/CeO2的氧化还原性能及反应条件对其CO氧化活性的影响

采用沉淀氧化法制备了Co₃O₄/CeO₂催化剂。运用XRD、BET和TPR表征手段,考察了不同钴铈比及焙烧温度对钴铈复合氧化物物理及化学性能的影响,并分别在干、湿条件下进行了一氧化碳氧化反应研究。结果表明,与纯的Co₃O₄相比,在不同比例的Co₃O₄/CeO₂均经723 K焙烧的各种催化剂中,钴铈原子比为9∶1的复合氧化物粒径较小,比表面积较大,说明适当比例铈的添加能使Co₃O₄具有较小的粒径。此氧化物经538 K温度焙烧制得的钴铈比为9∶1的复合氧化物中Co₃O₄平均粒径为7.2 nm, BET比表面积为167.6 m²/g。经TPR考察发现其具有最优的氧化还原性能。     

Synthesis and characterization of poly(amide sulfonamide)s (PASAs)

New diamino monomers IIa – IIg were synthesized in a two-step reaction sequence starting from p-acetamidobenzenesulfonyl chloride. Solution polymerization of these monomers in DMAC with terephthaloyl or isophthaloyl chloride resulted in the formation of a series of 14 poly(amide sulfonamide)s (PASAs) in excellent yield (> 95%). The polymers have in-trinsic viscosities of 0.32–1.11 dL g^?1. Except for polymers IIIa ? p and IIId - p , all other PASAs were readily soluble in aprotic polar solvents including DMAC, DMF, and DMSO. Thermogravimetric analyses of the polymers showed moderate thermal stability with 10% weight loss being recorded in the range of 325–408°C. In addition, these polymers exhibit moderate chemical stabilities toward alkali, acidic, and chromic acid solution. © 1995 John Wiley & Sons, Inc.     

Metallocene ion pairs: A direct insight into the reaction equilibria and polymerization by 13C NMR spectroscopy

The reaction equilibria of Cp₂Ti¹³CH₃Cl and Cp₂Ti(CH₃)₂ with AlMe₃ (TMA) and/or methylaluminoxane (MAO) have been investigated by ¹³C NMR. Several adducts have been identified. A study of the ¹³C 90% enriched ethylene polymerization in an NMR tube in the presence of the above catalytic systems, in the most experimentally significant conditions, and a comparison of the NMR data with the catalytic activity have been made as well. It has been shown that: i) some species are side products, inactive for addition ethylene polymerization; ii) active cation-like species such as Cp₂TiMe⁺Cl·[AlMeO]_n- and Cp₂TiMe⁺Me·[AlMeO]_n- are formed in titanocene-MAO systems. Concerning the role of AlMe₃, contained in MAO solutions, it has been shown that: a) AlMe₃ is mainly bound to MAO; b) if some “free” AlMe₃ exists in solution it is not the actual cocatalyst in the metallocene-MAO based catalytic systems; c) the amount of AlMe₃ influences either active or inactive species.     

螺旋链聚甲基丙烯酸三苯甲酯包敷硅胶分离旋光异构体

用螺旋链聚甲基丙烯酸三苯甲酯（ＰＴｒＭＡ）包敷硅胶高效液相色谱法分离了十五对ＰＴＨ衍生氨基酸和药物旋光异构体,十四对系首次在ＰＴｒＭＡ柱上进行分离,其中十三对旋光异构体获得了分离。     

三氯化一缬氨酸六水合稀土固体配合物的合成及红外光谱

在水溶液中合成了Ｌｎ（Ｖａｌ）·Ｃｌ＿３·６Ｈ＿２Ｏ（Ｌｎ＝Ｌａ，Ｎｄ，Ｓｍ，Ｇｄ，Ｅｒ）．利用元素分析和容量滴定法确定了其组成。测定了配合物的红外光谱，对其主要红外吸收带进行了归属。红外光谱结果表明，缬氨酸以内盐的形式存在于配合物中，并通过羟基与稀土离子配位，６个水分子亦参与了配泣，推测Ｌａ和Ｎｄ配合物具有一维无限长锭结构，而Ｓｍ、Ｇｄ和Ｅｒ配合物为双核配合物．