Bubble points of hydrogen chloride–water–isopropanol and hydrogen chloride–water–isopropanol–benzene systems and liquid–liquid equilibria of hydrogen chloride–water–benzene and hydrogen chloride–water–isopropanol–benzene systems

Bubble points of the HCl–water–isopropanol and the HCl–water–isopropanol–benzene systems and liquid–liquid equilibria (LLE) of the HCl–water–benzene and the HCl–water– isopropanol–benzene systems were measured at 25–85°C and 30–70°C, respectively. The electrolyte nonrandom two-liquid model proposed by Chen et al. [C.-C. Chen, H.I. Britt, J.F. Boston, L.B. Evans, AIChE J. 28 (1982) 588–596] can satisfactorily correlate bubble points and liquid–liquid equilibria of the present mixed-solvent electrolyte systems over the entire range of temperature and concentrations using only binary adjustable parameters.     

Electrochemical and structural characterization of sputter-deposited Mg–Nb and Mg–Nb–Al–Zn alloy films

Nanocrystalline Mg–Nb and Mg–Nb–Al–Zn alloy films were deposited by dc magnetron sputtering on glass and quartz substrates in a wide range of niobium concentrations from 6 to 80 at.%. Structural, electrochemical and corrosion properties of the films were studied by X-ray diffraction, dc voltammetry, electrochemical impedance spectroscopy and electrochemical quartz crystal microbalance. Development of body-centred cubic Nb structure in the Mg–Nb alloy matrix yielded the effects of lattice contraction, grain refining and electrochemical passivity. The measurements showed high corrosion resistance of the films in alkaline solutions when niobium content was one third or more. An increased corrosion resistance was achieved by introducing minor amounts of Al (ca. 2 at.%). In particular, such Al effect was pronounced at lower Nb concentrations (20 to 30 at.%). Semiconductor properties of spontaneously formed oxide on Mg–Nb alloy were studied by Mott–Schottky plots, which indicated highly doped n-type oxide structures on Mg–Nb surface. The paper fills some gap in understanding of niobium–magnesium systems, which show potential for applications in hydrogen storage, switchable mirrors and corrosion protection.     

Electrochemical and microgravimetric characterization of magnetron-sputtered Fe–Cr–Ni–Ta and Fe–Cr–Ni alloy films in neutral and strongly acidic media

The Fe–Cr–Ni and Fe–Cr–Ni–Ta alloy films were deposited on quartz substrates by magnetron-sputtering using targets of AISI 316 stainless steel and in combination with pure tantalum. The conventional melting of the Fe–Cr–Ni–Ta alloy formed is virtually impossible because the melting point of tantalum is higher than the boiling points of the other components. Elemental content of the films was determined by XPS analysis. Corrosion behaviour of both alloy films was studied in 5% NaCl and 10 M HCl by electrochemical quartz crystal microgravimetry (EQCM), electrochemical impedance spectroscopy (EIS) and dc-voltammetry. The corrosion resistance of Fe–Cr–Ni–Ta appeared to be significantly higher than that of Fe–Cr–Ni in both neutral (5% NaCl) and strongly acidic (10 M HCl) media. The Fe–Cr–Ni–Ta specimen exhibited an extremely high corrosion resistance in 10 M HCl, where the corrosion rates were about one order of magnitude lower than those of Fe–Cr–Ni in neutral solution. EQCM measurements in NaCl solution indicated accumulation of corrosion products on the Fe–Cr–Ni–Ta surface, which was evident from a distinctive increase in electrode mass. By contrast, the mass of the tantalum-free alloy film decreased with a constant rate, which indicated alloy dissolution to prevail. The corrosion current calculated from the mass decrease was in good agreement with that derived from voltammetric measurements. The EQCM data showed that the corrosion resistance of the Fe–Cr–Ni–Ta alloy film in 10 M HCl was about two orders of magnitude higher than that of the Fe–Cr–Ni.     

The density and surface tension of In–Sn and Cu–In–Sn alloys

Abstract  

The density and surface tension of binary In–Sn and ternary Cu–In–Sn alloys have been measured by a sessile-drop method. Decrease of the density and of the surface tension was observed with rising temperature. With increased Sn content in the alloys, the density increased while the surface tension reduced slightly. Addition of Cu could significantly increase the density and surface tension in the Cu–In–Sn system. The surface tension of the Cu–In–Sn alloys was also calculated by means of Butler’s equation, and compared with experimental values, showing good agreement.     

Trimetallic Nickel–Lanthanum and Nickel–Gadolinium Metallomesogens

Adducts were formed between a mesomorphic Ni(salen) complex [salen=2,2′-N,N′-bis(salicylidene)ethylenediamine] with six terminal alkoxy chains and a lanthanide nitrate (Ln=La, Gd). Different alkoxy chain lengths were used: OC¹²H²⁵, OC¹⁴H²⁹, OC¹⁶H³³ and OC¹⁸H³⁷. Trinuclear nickel–lanthanum and nickel–gadolinium complexes [Ln(NO³)³{Ni(salen)}²] were obtained. The compounds exhibit a wide-temperature-range hexagonal columnar mesophase (Col^H) with rather low melting points. The mesophase stability ranges of both the parent nickel complexes and the nickel–lanthanide complexes decrease with increasing chain length. A decrease in the mesophase stability range over the lanthanide series was also observed. The results are compared with those of similar copper–lanthanide complexes. A marked difference is the higher thermal stability of the nickel–lanthanide complexes in comparison with the copper–lanthanide complexes.     

Z- and E-selective Horner–Wadsworth–Emmons reactions

In the present work, we determined and evaluated the stereochemical outcome of the Horner–Wadsworth–Emmons (HWE) reaction of 2-oxoalkylphosphonates with different ester functions (bis(2,2,2-trifluoroethyl), 2,2,2-trifluoroethyl methyl, dimethyl) and side chains (aliphatic, aromatic) with three different aldehydes (benzaldehyde, THP- and PPB-protected Corey aldehydes) under two reaction conditions. The “trans” protocol is generally used in the E-selective HWE reactions, while “cis” protocol promotes the Z-selectivity.     

Electrochemical reactivity of Li–Mn–O and Li–Fe–Mn–O spinels

Electrochemical reductive dissolution of Li–Mn–O and Li–Fe–Mn–O spinels and Li⁺ extraction/insertion in these oxides were performed using voltammetry of microparticles. Both electrochemical reactions are sensitive to the Fe/(Fe+Mn) ratio, specific surface area, Li content in tetrahedral positions, and Mn valence, and can be used for electrochemical analysis of the homogeneity of the elemental and phase composition of synthetic samples. The peak potential (E _P) of the reductive dissolution of the Li–Mn–O spinel is directly proportional to the logarithm of the specific surface area. E _P of Li–Fe–Mn–O spinels is mainly controlled by the Fe/(Fe+Mn) ratio. Li⁺ insertion/extraction can be performed with Mn-rich Li–Fe–Mn–O spinels in aqueous solution under an ambient atmosphere and it is sensitive to the regularity of the spinel structure, in particularly to the amount of Li in tetrahedral positions and the Mn valence. Electronic Publication     

Thermodynamic and surface properties of Ge–Ga and Ge–Sb liquid alloys

Thermodynamic and surface properties of Ge–Ga and Ge–Sb liquid alloys have been studied using statistical mechanical formulations based on complex formation and that based on the concept of layered structure near the interface. The study showed that low level of complex formation of the form Ge _{2 Sb} exists in Ge–Sb toward the Ge-rich end of the concentration range and the surface properties of Ge–Ga are almost equal to their corresponding bulk equivalent.     

Application of CE–ICP–MS and CE–ESI–MS in metalloproteomics: challenges,developments, and limitations

Application of capillary electrophoresis (CE) as a high-resolution separation technique in metalloproteomics research is critically reviewed. The focus is on the requirements and challenges involved in coupling CE to sensitive element and molecule-specific detection techniques such as inductively coupled plasma mass spectrometry (ICP–MS) or electrospray ionisation mass spectrometry (ESI–MS). The complementary application of both detection techniques to the structural and functional characterisation of metal-binding proteins and their structural metal-binding moieties is emphasised. Beneficial aspects and limitations of mass spectrometry hyphenated to CE are discussed, on the basis of the literature published in this field over the last decade. Recent metalloproteomics applications of CE are reviewed to demonstrate its potential and limitations in modern biochemical speciation analysis and to indicate future directions of this technique.     

HS–SPME–GC–MS for the Quantitation and Chiral Characterization of Camphor and Menthol in Creams

A GC–MS method is proposed for the analysis of camphor and menthol in “over-the-counter” (OTC) products. Sample preparation was achieved by head-space solid phase microextraction using a polydimethylsiloxane fibre. GC analysis was performed using a Phenomenex ZB-5 column and a temperature program was adopted. The method was validated by studying linearity (range 0.1–15.0% w/w), accuracy, reproducibility and sensitivity. Applications were directed to the determination of the active ingredients in four different OTC-products; the mean recoveries were in the ranges 91.30–99.74% and 94.34–102.89% for camphor and menthol, respectively and the LOD was in the order of 0.005% (w/w). Other important terpenoids (α- and β-pinene, 1,8-cineole, menthone, isomenthone, α-terpineole, t-cinnamaldehyde, eugenole) were identified by mass spectra and Kovats retention indices and quantified by peak area normalization to 100%. Further information for a comprehensive characterization of the OTC-products was achieved by the GC chiral analysis on a Cyclosil B capillary column.     

Iron–cobalt and iron–cobalt–nickel nanowires deposited by means of cyclic voltammetry and pulse-reverse electroplating

Metal nanowires composed of Fe–Co and Fe–Co–Ni alloys were successfully prepared by means of cyclic voltammetry (CV) and pulse-reverse (PR) electroplating techniques from acidic metal chloride solutions. The anodic dissolution process in the CVs or in the reverse electroplating period was found to be the key factor influencing the formation of metal nanowires. The addition of nickel into the Fe–Co alloy was found to extend the diameter of these nanowires. The morphology and crystalline information of these alloy deposits prepared by CV and PR deposition techniques were obtained from the field-emission scanning electron microscopic (FE-SEM) photographs and X-ray diffraction (XRD) patterns, respectively.     

On hydrolysis of Ba–Bi–O and K–Ba–Bi–O oxide systems

Fundamentally different behavior of Ba–Bi–O (Ba : Bi = 11 : 4, 1 : 1, 2: 3, and 1 : 5 mol/mol) and K_nBa_mBi_m+nO_y (m = n = 1, 2,...; exhibiting superconducting properties with T_c = 28–32 K) oxides and BaO₂ in hydrolysis reactions has been revealed by means of potentiometry and chemical analysis. Products of the oxides treatment with water do not contain H₂O₂, evidencing the absence of peroxide ions in their structure. The perovskite-type barium-bismuth(III) oxides are completely hydrolyzed into Ba(OH)₂ and Bi₂O₃ at room temperature.     

Synthesis and characterization of N-heterocyclic carbene–PdCl2–1H-benzotriazole complexes and their catalytic activities toward Mizoroki–Heck and Sonogashira reactions

Four heteroleptic palladium complexes containing both N-heterocyclic carbenes and 1H-benzotriazole were synthesized and characterized. The solid-state structures show mononuclear carbene palladium complexes with each palladium coordinated by an NHC, the 3-position nitrogen of 1H-benzotriazole and two trans chlorides. The catalytic performance of the complexes for Mizoroki–Heck and Sonogashira reactions were further investigated. The results reveal that the complexes show high catalytic activities for coupling of aryl bromides with alkenes and alkynes.     

Hermann Jahn and Rudolf Renner of the Jahn–Teller and Renner–Teller effects

Vibronic interactions have received increasing attention in modern structural chemistry. Edward Teller played a pioneering role in understanding and describing them during the “molecular physics” period of his scientific career. Very little is known about the two scientists who contributed significantly to our knowledge about these effects and whose names have become associated with Teller’s. This Editorial is devoted to Hermann Jahn and Rudolf Renner and attempts to lift them out of oblivion by paying them tribute for their contributions.

Synthesis and properties of covalently linked BF2–oxasmaragdyrin–porphyrin dyads and triad

Two covalently linked diphenyl ethyne bridged unsymmetrical dyads containing porphyrin and BF₂–oxasmaragdyrin and Zn(II)porphyrin and BF₂–oxasmaragdyrin units and one covalently linked triad containing Zn(II)porphyrin, porphyrin and BF₂–oxasmaragdyrin units were synthesized by coupling appropriate functionalized macrocycles under Pd(0) coupling reaction conditions. The dyads and triad were freely soluble in common organic solvents and confirmed by ES-MS spectra. 1D and 2D NMR techniques were used to characterize the dyads and triad. Absorption and electrochemical studies of dyads and triad showed the overlapping features of the constituted macrocycles indicating that the macrocycles retain their basic features in the dyads and triad. The BF₂–oxasmaragdyrin absorbs at lower energy and emits strongly in the visible region compared to porphyrin/Zn(II)porphyrin. Thus, BF₂–oxasmaragdyrin acts as energy acceptor and porphyrin/Zn(II) porphyrin act as energy donor in dyads and triad. The steady state and time-resolved fluorescence studies supported an efficient energy transfer from porphyrin/Zn(II)porphyrin to BF₂–oxasmaragdyrin unit in dyads and triad.     

Retro–Leapfrog and structure elucidation

Operations on maps are topological-geometrical tools used for transforming a given polyhedral tessellation. Investigation of fullerene structure often needs information on the original map which transformed into a larger molecular structure. Operations leading to the previous, smaller structures are called Retro-operations. They appear particularly useful in studies of structure elucidation or stability of series of fullerenes. The paper presents the first structure affiliation of the well-known C₆₀ fullerene to a family of Leapfrog fullerenes with relatedness being established by map operation. Thus, the tessellation of C₆₀ is described as an Archimedean, joint Sumanene-hexagon covering, in tetrahedral disposition. The other members of family show essentially the same covering and predicted good stability. Related Leapfrog fullerenes showing a disjoint Sumanene covering are also given.     

Relation between geometric–arithmetic and arithmetic–geometric indices

The paper is concerned with the two topological indices, GA and AG, constructed from the geometric and arithmetic means of the end-vertices of edges. Inequalities involving GA and AG are established. The two indices are linearly correlated, whereas for molecular graphs of benzenoid and similar polycyclic conjugated systems, the linear relation between GA and AG is exact. This indicates that introducing (in 2015) the index AG, after GA has already been conceived (in 2009), was fully unjustified.