红外光谱法研究胺与几种溶质的缔合性质

室温下在3800—3000 cm~(-1)内测定了苯脓、N-甲基苯胺与正庚烷、四氯化碳、苯和甲苯二元混合稀溶液的红外光谱, 考察了溶剂对溶质特征红外光谱的影响。测定了苯胺、N-甲基苯胺与吡啶在四氯化碳中作用的红外光谱, 以及苯胺、N-甲基苯胺、三乙胺、三丁胺和吡啶与乙醇在四氯化碳中作用的红外光谱, 计算了相应的交叉缔合常数, 对不同种分子间的相互作用进行了探讨。几种含氮分子与乙醇缔合时, 给予电子的能力按以下次序递增: 苯胺～N-甲基苯胺<三丁胺<吡啶<三乙胺。此外, 还对乙醇+吡啶+氯仿三元体系的特征红外光谱随溶剂比例的变化进行了分析讨论。     

New-phase retention in colloidal core/shell nanocrystals via pressure-modulated phase engineering

Core/shell nanocrystals (NCs) integrate collaborative functionalization that would trigger advanced properties, such as high energy conversion efficiency, nonblinking emission, and spin–orbit coupling. Such prospects are highly correlated with the crystal structure of individual constituents. However, it is challenging to achieve novel phases in core/shell NCs, generally non-existing in bulk counterparts. Here, we present a fast and clean high-pressure approach to fabricate heterostructured core/shell MnSe/MnS NCs with a new phase that does not occur in their bulk counterparts. We determine the new phase as an orthorhombic MnP structure (B31 phase), with close-packed zigzagged arrangements within unit cells. Encapsulation of the solid MnSe nanorod with an MnS shell allows us to identify two separate phase transitions with recognizable diffraction patterns under high pressure, where the heterointerface effect regulates the wurtzite → rocksalt → B31 phase transitions of the core. First-principles calculations indicate that the B31 phase is thermodynamically stable under high pressure and can survive under ambient conditions owing to the synergistic effect of subtle enthalpy differences and large surface energy in nanomaterials. The ability to retain the new phase may open up the opportunity for future manipulation of electronic and magnetic properties in heterostructured nanostructures.

Core/shell MnSe/MnS nanocrystals with the B31 phase are thermodynamically stable under high pressure and can survive under ambient conditions owing to the synergistic effect of subtle enthalpy differences and high surface energy in nanomaterials.     

Precise potential harmonic approach to directly solving Schrödinger equations of helium-like three-body systems

A complete potential harmonic scheme is presented, including the linked coupled hyperradial ordinary differential equations and the secular equation of eigenenergy. It has been used to directly solve the Schrödinger equations of helium-like three-body systems (nuclear chargeZ = 1–9). and very accurate ground state eigenenergies as well as low-lying singlet excited state ones have been obtained.     

掺杂钙钛矿型氧化物的固体结构及其可交换氧

钙钛矿型氧化物具有稳定的立方结构，以不同价态元素（Ｖ＾５＋，Ａｌ＾３＋，Ｍｇ＾２＋，Ｌｉ＾＋）对ＳｒＴｉＯ３中的Ｔｉ＾４＋进行取代，ＸＲＤ表明基基本结构保持不变，同时其谱线有不同程度的宽化。这种宽化归因于取代所引起的晶体不完整性。取代元素的价态及量将在不同程度上破坏晶体的完成性。这种不完整性导至氧空位Ｖｏ的形成，从而可使晶格氧与气相氧在较低温度进行交换，ＴＰＤ显示３００～６００℃的可交换氧量决定于     

金属-半导体催化剂的相互作用的研究—Pt/TiO2和Pt/ZnO界面结构变化对其化学行为的影响

为研究Pt-TiO_2和Pt-ZnO体系经过加温氢处理后其金属-半导体(金-半)界面性质的变化, 本工作以测量电流-电压曲线的方法检验金-半界面势垒。用动电位扫描的方法考察金-半电极在Fe(CN)_6~(4-)/Fe(CN)_6~(3-)溶液中的电化学行为。并通过Auger剖面分析证明加温氢处理可导致在金-半界面上形成一个扩散区, 说明界面扩散可能是金-半相互作用及其电学、电化学乃至催化性能发生重大变化的主要原因。     

Synergistic co-removal of zinc(II) and cefazolin by a Fe/amine-modified chitosan composite

A novel Fe/amine modified chitosan composite (Fe/N-CS) was facilely synthesized and showed higher affinity to both Zn(II) and cefazolin (CEF) than its precursors. Synergistic co-adsorption of them by Fe/N-CS was observed in varied conditions. The adsorption amount maximally increased by 100.1% for Zn and 68.2% for CEF in bi-solute systems. The initial adsorption rate of Zn(II) also improved with CEF. The increasing temperature facilitated coadsorption. The results of the preloading tests, FTIR/XPS characterizations and DFT calculations suggested that (1) both polyamines and Fe sites participated in the adsorption of Zn(II) and CEF, (2) Zn(II) could serve as a new efficient site for CEF, forming [amine-Zn-CEF]/[FeOH-Zn-CEF] ternary complexes, and (3) the co-presence of CEF shielded the electrostatic repulsion between protonated amines and Zn(II), contributing to the enhancement of Zn(II) adsorption. Further, the ion strength exerted positive and negative influences on the adsorption of Zn(II) and CEF, respectively. Additionally, CEF and Zn(II) were successively recovered by 0.1 mol/L NaOH followed by 2 mmol/L HCl. Fe/N-CS could be stably reused five times. The findings imply that Fe/N-CS is promising for the highly efficient co-removal of concurrent heavy metals and antibiotics.     

Mesoporous Cu-Ce-Ox Solid Solutions from Spray Pyrolysis for Superior Low-Temperature CO Oxidation

Development of Pt group metal-free catalysts for low-temperature CO oxidation remains critical. In this work, active and stable mesoporous Cu-Ce-O_x solid solutions are prepared by using spray pyrolysis. The specific surface areas and pore volumes reach as high as 170 m² g⁻¹ and 0.24 cm³ g⁻¹, respectively. The results of CO oxidation study suggest that (1) the catalyst obtained by spray pyrolysis possesses much higher activity than those made by co-precipitation, sol-gel, and hydrothermal methods; (2) the optimal Cu_0.2-Ce_0.8-O_x solid solution presents a reactivity over 28 times that of both single-component CuO and CeO₂ at 70 °C. Based on the study of pure-phase Cu-Ce-O_x solid solutions by selective leaching of segregated CuO_x species, the active center for CO oxidation is confirmed as the bimetallic Cu-Ce-O site, whereas the individual CuO_x particles not only act as spectators but also block the active Cu-Ce-O sites. A low apparent activation energy of approximately 48 kJ mol⁻¹ is detected for CO oxidation at the Cu-Ce-O site, making Cu-Ce-O_x solid solutions able to present high activity at low temperature. Furthermore, the Cu-Ce-O_x catalysts exhibit excellent stability and thermal tolerance toward CO oxidation.     

On the bonding of small group 12 clusters

Characteristic properties as well as possible differences in bonding of small group 12 clusters M_n{\rm M}_n (M = Zn{\rm M} = {\rm Zn}, Cd, Hg; n = 2, ?, 6n = 2, \ldots, 6) have been investigated by quantum chemical ab initio methods, i.e., relativistic large-core pseudopotentials, core-polarization potentials and coupled-cluster correlation treatments. A comparison of cohesive energies and spectroscopic properties like ionization potentials, electron affinities, and vibrational frequencies reveals a close similarity between the clusters of Cd and Hg. For Zn clusters we observed an exceptional increase in stability between Zn₃\rm Zn_3 and Zn₄\rm Zn_4. In order to get a more qualitative picture of the covalent contributions to bonding we have calculated the electron localization function (ELF). The ELF analysis is in accordance with the calculated spectroscopic properties and shows predominant van der Waals interactions with weak covalent contributions for all the cluster sizes considered.     

A new xanthone from <Emphasis Type="Italic">Penicillium oxalicum</Emphasis>

A new tetrasubstituted xanthone (6,8-dihydroxy-3-methyl-9-oxo-9H-xanthene-1-carboxylic acid), together with four known compounds, was isolated from the EtOAc extract of Penicillium oxalicum. Their structures were elucidated by spectrometric and chemical methods, including ESI-MS and one- and two-dimensional NMR experiments.