Zinc Porphyrin Metal‐Center Exchange at the Solid–Liquid Interface

Demetalation of zinc 5,10,15,20‐tetraphenylporphyrin (ZnTPP) under acidic conditions and ion exchange with Cu²⁺ ions at neutral pH are both rapid reactions in the liquid medium. However, for ZnTPP monolayers adsorbed on a Au(111) surface exposed to aqueous solution, we find that, although ion exchange takes place rapidly as expected, demetalation does not occur, even at pH values as low as 0. Based on this, we conclude that metal center exchange on the surface does not proceed through a free‐base porphyrin as an intermediate. Furthermore, once formed, CuTPP is stable on the surface and the reverse exchange from CuTPP to ZnTPP in the presence of Zn²⁺ ions could not be achieved. The preference for copper is so strong that even an attempt to exchange adsorbed ZnTPP with Ni²⁺ ions in the presence of traces of Cu²⁺ yielded CuTPP rather than NiTPP.     

Structural Forces near Phase Transitions of Liquid Crystals

The structure of the fragile liquid‐crystalline phases has a strong impact on the forces between bodies immersed in a liquid crystal (LC). We have equipped an atomic force microscope with a precise temperature control and measured various liquid‐crystalline structural forces at temperatures close to the phase transitions. The observed forces agree well with predictions of Landau–de Gennes phenomenological theory of LCs, even at a nanoscale length. In addition to this, we have observed a molecular layer, adsorbed on the surfactant‐covered glass surface, and determined its thickness and elastic properties.     

Capture CO2 from Ambient Air Using Nanoconfined Ion Hydration

Water confined in nanoscopic pores is essential in determining the energetics of many physical and chemical systems. Herein, we report a recently discovered unconventional, reversible chemical reaction driven by water quantities in nanopores. The reduction of the number of water molecules present in the pore space promotes the hydrolysis of CO₃^2? to HCO₃^? and OH^?. This phenomenon led to a nano‐structured CO₂ sorbent that binds CO₂ spontaneously in ambient air when the surrounding is dry, while releasing it when exposed to moisture. The underlying mechanism is elucidated theoretically by computational modeling and verified by experiments. The free energy of CO₃^2? hydrolysis in nanopores reduces with a decrease of water availability. This promotes the formation of OH^?, which has a high affinity to CO₂. The effect is not limited to carbonate/bicarbonate, but is extendable to a series of ions. Humidity‐driven sorption opens a new approach to gas separation technology.     

A Highly Stable Nonhysteretic {Cu2(tebpz) MOF+water} Molecular Spring

A molecular spring formed by a hydrophobic metal–organic framework Cu₂(tebpz) (tebpz=3,3′,5,5′‐tetraethyl‐4,4′‐bipyrazolate) and water is presented. This nanoporous heterogeneous lyophobic system (HLS) has exceptional properties compared to numerous reported systems of such type in terms of stability, efficiency, and operating pressure. Mechanical and thermal energetic characteristics as well as stability of the system are discussed and compared in detail with those of other previously reported HLS.     

Modulating Large‐Area Self‐Assembly at the Solid–Liquid Interface by pH‐Mediated Conformational Switching

Dynamic surfaces : The conformational transition of 2,6‐bis(1‐aryl‐1,2,3‐triazol‐4‐yl)pyridine (BTP) derivatives, triggered by a change in pH, has been observed with a sub‐nm resolution by STM at the solid–liquid interface. Upon addition of trifluoroacetic acid two different BTP molecules, each forming a highly ordered physisorbed monolayer, underwent significant conformational changes from their “rosette” to their “tetragon” forms, as reflected in dramatically altered 2D self‐assembly over large areas extending over hundreds of nanometers (see graphic).

     

Synthesis of Silver Selenide Bicomponent Nanoparticles by a Novel Technique: Laser–Solid–Liquid Ablation

A novel laser–solid–liquid ablation technique has been developed to synthesize Ag₂Se nanoparticles from silver nitrate and selenium powder in a mixed solvent of 2-propanol and ethylenediamine. The products were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The XRD indicated that the products were the single phase of silver selenide. The TEM images revealed that the as-prepared Ag₂Se grains were homogeneous and spherical, and their average size was about 30 nm. This novel technique can be extended to prepare other nanoparticles of various compositions.     

Excess Gibbs Energy of Mixing for Organic Carbonates from Fitting of Their Binary Phase Diagrams with Nonideal Solution Models

The excess Gibbs energies of mixing in the liquid state were evaluated for all the ten binary combinations of these five organic carbonates: ethylene carbonate (EC), propylene carbonate, dimethyl carbonate (DMC), ethyl methyl carbonate, and diethyl carbonate by fitting their measured binary phase diagrams with thermodynamic nonideal solution models based on the regular solution model. Using the results of these model fits, activity coefficients of the components in the solvent mixtures were calculated for the binary series containing EC and DMC as the common component, and the composition-averaged excess Gibbs energies of mixing were calculated by integrating the energy in the whole composition range for all the binaries. The results showed the excess Gibbs energy of mixing, and therefore the intermolecular forces, to be responsible for the changes in the phase diagrams, in the activity coefficients, and in the composition-averaged excess energy for the different binary solution combinations.     

Ion binding to bilayers of the iridescent phase in aqueous tetradecyldimethylaminoxid studied by mass spectrometry.

The behaviour of a tetradecyldimethylaminoxid (C14DMAO) iridescent solution with a strict composition has been investigated in the presence of NaCl, KCl, NaF, KF, NaClO4, or NH4ClO4 at a constant ionic strength. Specific ion effects (the Hofmeister effects), arising when changing ions of the same valency, have been studied. The interactions of C14DMAO molecules with the added ions have been investigated by electrospray ionisation mass spectrometry (ESI-MS). The ESI-MS results indicate that C14DMAO bilayer interactions are stronger with cations than with anions. Among the cations studied here, potassium ions are more favourably bound at the C14DMAO bilayers than sodium ions. The aminoxide groups of the C14DMAO molecules do not bind NH4+ ions. The positive charge of the electric double layers on the C14DMAO bilayers is neutralised by anions of the added electrolytes. Consequently, the separation distance between the lamellar layers decreases and the ordering in the studied systems is broken. Among the studied counterions, chloride ions are most strongly bound to the interface causing the greatest breakdown of the ordering in the iridescent solution.     

Analysis of Mixtures by Ion Kinetic Energy Spectrometry

Abstract

A mass spectrometric method in which separation and compound identification are accomplished in a mass-analyzed ion kinetic energy spectrometer (MIKES) is described. This procedure is possible in a reversed sector (source-magnet-energy analyzer-detector) mass spectrometer when ions characteristic of each mixture component are caused to fragment after mass analysis. For each mass-selected ion, a scan of the ion kinetic energy spectrum identifies the daughter ions arising from unimolecular and/or collision-induced dissociations. Straightforward application of this method to isomeric C₅H₁₀0 ketone mixtures allows separation, identification, and quantitative analysis which is easy, rapid, and unambiguous.     

Nanofluidic Ion Transport and Energy Conversion through Ultrathin Free‐Standing Polymeric Carbon Nitride Membranes

Ions transport through confined space with characteristic dimensions comparable to the Debye length has many applications, for example, in water desalination, dialysis, and energy conversion. However, existing 2D/3D smart porous membranes for ions transport and further applications are fragile, thermolabile, and/or difficult to scale up, limiting their practical applicability. Now, polymeric carbon nitride alternatively allows the creation of an ultrathin free‐standing carbon nitride membrane (UFSCNM), which can be fabricated by simple CVD polymerization and exhibits excellent nanofluidic ion‐transport properties. The surface‐charge‐governed ion transport also endows such UFSCNMs with the function of converting salinity gradients into electric energy. With advantages of low cost, facile fabrication, and the ease of scale up while supporting high ionic currents, UFSCNM can be considered as an alternative for energy conversion systems and new ionic devices.     

Dispersive solid–liquid phase microextraction based on nanomagnetic Preyssler heteropolyacid: A novel method for the preconcentration of nortriptyline

In this study, a new, simple, rapid, and efficient method combined with ultraviolet visible spectrophotometry and high‐performance liquid chromatography analysis was developed for the extraction and determination of nortriptyline. The tendency of the Preyssler tungsten heteropolyacid, H₁₄[NaP₅W₃₀O₁₁₀], immobilized on the surface of mesoporous nanomagnetite to adsorb the drug from the solution has been investigated. This method involves the use of an appropriate mixture of nanosorbent that was homogenized in disperser solvent (1.0 mL, ethanol). At first, the mixture containing the nanomagnetic sorbent and disperser solvent was injected into the aqueous sample, and a cloudy solution was formed. Subsequently, separation of the two phases was carried out using a magnet. In the second stage, analyte was desorbed from the sorbent by methanol as the optimal desorption solvent using sonication method. The elution solvent containing enriched analyte was introduced to the instruments for further analysis. Optimization of experimental conditions with respect to the extraction efficiency was investigated. The method was linear in the range of 25–5000, while the detection limit (LOD = 3S_B/m) was 7.9 ng/mL and the limit of quantification (LOQ = 10S_B/m) was 26.4 ng/mL. The relative standard deviation was 4.66%. The method was successfully applied to human hair samples.     

The Role of Functional Moieties on Carbon Nanotube Surfaces in Solar Energy Conversion

An easily dispersible multiwalled carbon nanotube (MWCNT) derivative is prepared, and provides a platform for the synthesis of the phenyl butyric acid methyl ester (PCBM) analog. The carbene addition reaction of MWCNTs makes derivatives that are less soluble in organic solvents; by exploiting this differential solubility, PCBM analogs can be separated from the unreacted functionalized MWCNTs. Our experimental evidences indicate that it is the unique properties of the butyric acid methyl ester moiety that makes the acceptor material perform better in organic photovoltaics (OPVs). Studying the combination of the butyric acid methyl ester moiety and the deagglomerated functionalized MWCNT structures provides us an insight into nanoscale charge transfer and transportation inside the donor–acceptor domain. It is demonstrated that a strong structure–property relationship exists for the functionalized MWCNTs, which enables us to correlate the functionality on the carbon nanostructures with performance in OPVs.     

太阳能光解水制氢的研究进展

本文概述了利用光催化技术催化分解水制氢的反应机理和研究进展。结合作者的最近研究,重点描述了TiO2及过渡金属氧化物,层状金属氧化物以及某些能利用可见光的光催化材料的结构和光催化特性,阐述了核课题的意义和今后的研究方向。     

Core–Shell α‐Fe2O3@α‐MoO3 Nanorods as Lithium‐Ion Battery Anodes with Extremely High Capacity and Cyclability

α‐Fe₂O₃ nanoparticles are uniformly coated on the surface of α‐MoO₃ nanorods through a two‐step hydrothermal synthesis method. As the anode of a lithium‐ion battery, α‐Fe₂O₃@α‐MoO₃ core–shell nanorods exhibit extremely high lithium‐storage performance. At a rate of 0.1 C (10 h per half cycle), the reversible capacity of α‐Fe₂O₃@α‐MoO₃ core–shell nanorods is 1481 mA h g^?1 and a value of 1281 mA h g^?1 is retained after 50 cycles, which is much higher than that retained by bare α‐MoO₃ and α‐Fe₂O₃ and higher than traditional theoretical results. Such a good performance can be attributed to the synergistic effect between α‐Fe₂O₃ and α‐MoO₃, the small size effect, one‐dimensional nanostructures, short paths for lithium diffusion, and interface spaces. Our results reveal that core–shell nanocomposites have potential applications as high‐performance lithium‐ion batteries.     

端烯基液晶冠醚推动钠离子在微液/液界面的转移

用循环伏安法研究新型载体端烯基液晶冠醚推动钠离子的转移,结果表明,钠离子的转移由扩散控制.探讨了影响钠离子转移的因素,如端烯基液晶冠醚和钠离子的浓度等.求算出端烯基液晶冠醚在1,2-二氯乙烷中的扩散系数为(2.61±0.12)×10^-6cm²/s,端烯基液晶冠醚和钠离子在1,2-二氯乙烷中所形成的配合物稳定常数lgβ_o=5.7.