Rydberg Matter Clusters: Theory of Interaction and Sorption Properties

Sorption capacity of Rydberg matter (RM) clusters is examined for both electronegative and neutral molecules. Sorption isotherm of RM has been determined as a function of gas pressure and time. It is shown that chemisorption is characteristic for electronegative molecules whereas molecules with no affinity to electrons are absorbed by physisorption mechanism. Sorption capacity of RM is shown to be highest for physisorption mechanism. Absorption of molecules by RM clusters can be used either to detect condensed RM formation or both to maintain high vacuum conditions and high purity of noble gas atmospheres. Sorption capacity of RM can significantly exceed conventional getter sorption capacities.     

Theoretical and Experimental Studies of Subnanoscale Molecules and Clusters

Russian Journal of Physical Chemistry A - A brief review is given of theoretical and experimental studies of a series of subnanoscale molecules and clusters performed by the authors with the staff...     

ChemInform Abstract: Experimental and Theoretical Studies of Small Homoatomic Phosphorus Clusters

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

Experimental Studies of Properties of Excited States of Cesium (Rydberg Matter) in the Interelectrode Plasma of a Low-Temperature Thermal to Electric Energy Thermionic Converter

A review is given of experimental work on the study of properties of a condensate of excited states (Rydberg matter) of cesium by electrophysical and optical methods. The work has been performed by the author with colleagues from the SSC RF-IPPE since 2002 up to the present, the results having been published in various domestic scientific editions. The findings are compared with theoretical data of various authors and experimental results of a group of L. Holmlid from the University of Gothenburg (Sweden), the only group except a group of V. Yarygin working in the field of experimental studies of Rydberg matter (RM) of cesium and other alkali metals. A concept is discussed of a practical use of RM in operation of a low-temperature thermal to electric energy thermionic converter (TIC) at the emitter temperature lower than 1,600 K, the collector temperature lower than 700 K, the generalized index of an energy loss in a TIC (so-called barrier index) V _B ~1.6 eV.     

Soft Matter Approaches for Enhancing the Catalytic Capabilities of Polyoxometalate Clusters

In this minireview, we discuss the recent efforts on expanding the catalytic capabilities of polyoxometalates (POM) through emulsion catalysis approaches with novel catalytic-active POM–organic hybrid clusters as emulsifiers. The hybrid emulsifiers include surfactant encapsulated POM complexes, molecular POMs–organic hybrids, and POM-based solid nanoparticles. With such novel approaches the catalytic efficiency of the POMs can be significantly improved by enhancing the compatibility of the POMs with organic media, providing catalytic interface for biphasic reactions, as well as easier preparation, and better recyclability. Particularly, a simple, green chemistry method to prepare metal nanoparticle materials with POMs as both reducing and capping agents in aqueous is reviewed.     

可吸入颗粒物及其危害

可吸入颗粒物形成气溶胶,是我国多数城市的首要污染物,对环境有着十分严重的危害。     

Studies of the Formation of Carbon Clusters

Experimental and theoretical studies focusing on the formation of carbon clusters are described. In the experiment on discharge in liquid chloroform, a series of perchlorinated fragments of C₆₀ was synthesized and a scarce amount of C₆₀ was detected. In the laser vaporization experiments, it was found that the production of C ₆₀ ⁺ and other fullerene ions could be promoted by doping chlorine-containing compounds into carbon targets. Chlorine atoms were found to play key roles of not only tying up the dangling bonds of the polycyclic carbon clusters, but also catalyzing the formation of fullerenes. The results showed that C₆₀ and other fullerenes are formed from growth of small carbon species and supported the Pentagon Road scheme of the fullerene formation mechanism. On the other hand, ab initio calculations were carried out on formation reactions of C₆₀ from its various perchlorinated fragments, C_60–2mCl₁₀. The monotonically decreasing calculated energies of reactions with growing size of the fragments confirm that the formation reaction is energetically favorable.     

Studies on Rydberg orbitals. IV. Basic formulas for the one-electron perturbation calculation of molecular Rydberg excited states

General expressions are obtained for the energies of complex and real forms of any hydrogenic orbital (n, l, m) in a cluster of point charges of any geometry. This is a perturbation calculation of hydrogenic Rydberg orbitals in a one-electron hard core approximation. A model calculation of 3d-electrons of carbene, ethylene and benzene with varying charge distribution is given.     

Experimental Investigation of Plasma Oxidization of Diesel Particulate Matter

Particulate matter (PM) from diesel vehicles is harmful to humans and should be removed from the exhaust gases before its emission into the atmosphere. Plasma PM oxidation is an advanced method to be used for oxidative PM removal. Factors influencing plasma PM oxidation include gas temperature, gas composition, PM amount, the geometry of plasma reactors. The PM oxidation in atmospheric air discharges was carried out using a pulsed dielectric barrier discharge reactor at temperatures of 100, 150, and 200 °C. It was found that PM is oxidized to CO and CO₂. CO₂/CO concentration ratio is a function of PM amount in the discharge space. PM removal efficiency (PM amount oxidized per kWh energy injection) increased with increasing air temperature and PM amount in the discharge space. Water promotes PM oxidation, which suggested that oxygen atoms produced in the discharge space react with water to yield hydroxyl free radicals that are of more reactivity than oxygen atoms. The activation energy of plasma PM oxidation was kinetically calculated to be 15.4 kJ/mol.     

嵌入Y型分子筛中钯簇合成与结构的研究

经微波交换-焙烧-氢还原等过程制备了嵌入Y型分子筛中的钯簇化合物（Pd0Y）应用径向电子分布函数法（RedialElectronDistributionFunction），就其钯原子簇化合物进行了结构的研究．结果说明，嵌入Y型分子筛中的钯原子以A1型密堆积方式排列，聚集成约12大小的原子簇，嵌在Y型分子筛超笼之中．分子筛骨架的作用使族之间分立存在．它在超笼之中的占有率仅为0.06因此Pd0Y化合物既有纳米级金属钯的性能，又有分子筛固有的孔道结构特征．如此含有钯簇的分子筛化合物对一氧化碳完全氧化的反应具有超常的催化活性．     

微电极研究单分子层保护团簇的量子化电容充电

利用微电极在二氯甲烷溶液中研究了单分子层保护金纳米团簇 ( MPCs)的量子化电容充电效应 .用示差脉冲伏安法及循环伏安法获得了明显的 5对量子化电容充电峰 ,并测量出单个 MPCs的平均电容 .单阶跃计时库仑法的研究表明 ,每对峰对应于一个电子的充入或放出 .求得电荷传递系数α=0 .44和反应速率常数 k0 =1 .65× 1 0 -2 cm/s.与常规铂电极相比 ,微电极可获得更明显的量子化充电峰 .     

Deprotonation of C‐Alkyl Groups of Cationic Triruthenium Clusters Containing Cyclometalated C‐Alkylpyrazinium Ligands: Experimental and Computational Studies

The C‐alkyl groups of cationic triruthenium cluster complexes of the type [Ru₃(μ‐H)(μ‐κ²N¹,C² ‐L)(CO)₁₀]⁺ (HL represents a generic C‐alkyl‐N‐methylpyrazium species) have been deprotonated to give kinetic products that contain unprecedented C‐alkylidene derivatives and maintain the original edge‐bridged decacarbonyl structure. When the starting complexes contain various C‐alkyl groups, the selectivity of these deprotonation reactions is related to the atomic charges of the alkyl H atoms, as suggested by DFT/natural‐bond orbital (NBO) calculations. Three additional electronic properties of the C‐alkyl C? H bonds have also been found to correlate with the experimental regioselectivity because, in all cases, the deprotonated C? H bond has the smallest electron density at the bond critical point, the greatest Laplacian of the electron density at the bond critical point, and the greatest total energy density ratio at the bond critical point (computed by using the quantum theory of atoms in molecules, QTAIM). The kinetic decacarbonyl products evolve, under appropriate reaction conditions that depend upon the position of the C‐alkylidene group in the heterocyclic ring, toward face‐capped nonacarbonyl derivatives (thermodynamic products). The position of the C‐alkylidene group in the heterocyclic ring determines the distribution of single and double bonds within the ligand ring, which strongly affects the stability of the neutral decacarbonyl complexes and the way these ligands coordinate to the metal atoms in the nonacarbonyl products. The mechanisms of these decacarbonylation processes have been investigated by DFT methods, which have rationalized the structures observed for the final products and have shed light on the different kinetic and thermodynamic stabilities of the reaction intermediates, thus explaining the reaction conditions experimentally required by each transformation.     

Enoxacin: Polarographic Behaviour and Its Determination in Pharmaceutical Forms

Abstract

A differential pulse polarographic method for the identification and quantitative determination of enoxacin is described. The method is based on the electrochemical reduction of the drug at the dropping mercury electrode. It gives a well-developed polarographic response with a half-wave potential of -990 mV vs. SCE in 0.1 M HCl. The electroactive specie exhibits a diffusion-controlled polarographic wave and its limiting current shows a linear dependence with the enoxacin concentration in the range between 5.10^?4 mM and 1 mM. This characteristic is applied for determination of enoxacin in commercial tablets. The recovery study shows a good accuracy and precision for the developed assay (average of 101.1% and standard deviation of 1.99). Furthermore, a comparative UV spectrophotometric assay also is developed.     

In Silico and Experimental Studies of Concanavalin A: Insights into Its Antiproliferative Activity and Apoptotic Mechanism

Concanavalin A (ConA), a mannose/glucose-binding legume lectin, has been reported to induce tumor cell death via a mitochondria-mediated autophagic pathway; however, the precise mechanism by which induces cell death remains to be discovered. In this study, we simulated the three-dimensional structure of ConA monomer, its dimer, and tetramer forms and reported its molecular dynamics simulations and phylogenetic analysis. Subsequently, we showed that ConA possessed remarkable antiproliferative effects on HepG2 cells. Further data showed that there was a link among its hemagglutinating, sugar-binding, and antiproliferative activities. In addition, we found that ConA induced apoptosis in HepG2 cells. Then, we demonstrated that the treatment of ConA caused mitochondrial transmembrane potential (MMP) collapse, cytochrome c release, and activation of caspase. In conclusion, we demonstrate that there is a positive correlation between carbohydrate-binding activity and antiproliferative activity of ConA. In addition, we confirm that ConA induces HepG2 cell death through a mitochondrial apoptotic pathway.     

Experimental and Quantum Chemical Studies of 5-Fluoroisatin-3-(N-Cyclohexylthiosemicarbazone) and Its Metal Complexes

Abstract

Zn(II) and Ni(II) complexes of 5-fluoroisatin-3-[-(N-cyclohexylthiosemicarbazone)] (H₂FIC) have been prepared and characterized structurally by means of elemental analyses, FTIR, electronic, and ¹H NMR spectra. The theoretical wavenumbers, IR intensities, and molecular parameters have been calculated by the ab-initio Hartree–Fock (HF) method with the LanL2DZ basis set. The theoretical wavenumbers show a good agreement with experimental data. The bond lengths, bond angles, the highest occupied molecular orbital energy (E_HOMO), the lowest unoccupied molecular orbital energy (E_LUMO), the energy gap between E_HOMO and E_LUMO (ΔE_HOMO-LUMO), dipole moment, and charges on the atoms of H₂FIC as monomer form were studied by the density functional theory/Becke-3-Lee-Yang-Parr (DFT/B3LYP) and ab-initio HF methods using 6-31G(d,p) basis set. The trimeric possible structure of H₂FIC was also investigated using HF method. The observed IR wavenumbers of the H₂FIC were analyzed in the light of the computed vibrational spectra of its monomer and trimer forms.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

(TiNi)_x(x=2~4)团簇结构和电子结构

从团簇角度对TiNi形状记忆合金进行了量子化学从头算研究。设计并优化了等原子比(TiNi)x(x=2~4)簇的多种可能几何结构,并对较稳定构型进行电子结构的分析。结果表明,等原子比的(TiNi)n团簇以TiNi成键为主要分子骨架,小团簇有较多能量接近的异构体,TiTi成键对能量降低有较大贡献。     

铅硫二元团簇Pb5S+4的理论研究

用密度泛函方法对铅硫二元团簇Ｐb５Ｓ４＋的结构和性能进行了理论研究。结果表明,具 有Ｃ,对称性的笼状结构的异构体最稳定。根据计算所推测的该团簇的性质与实验结果下一致。     

Rydberg atoms in crossed external magnetic and electric fields: Experimental observation of an outer potential minimum

Rydberg atoms in crossed magnetic and electric fields have been investigated. The existence of field induced bound states with a large electric dipole moment was demonstrated. For this purpose the highly excited atoms were deflected by means of an inhomogeneous electric field.