Micellar and Mixed-Micellar Effects on Alkaline Hydrolysis of tris(1,10–phenanthroline)iron(II): Kinetic Exploration

The kinetics of alkaline hydrolysis of tris(1,10–phenanthroline)iron(II) has been studied in the presence of nonionic and mixed nonionic–ionic micellar media at 308 K. The effects of mixed-micellar environments of nonionic with ionic surfactants (C₁₂E₂₃/ATABs and C₁₂E₂₃/SDS) on the hydrolytic rate have been studied. The rate decreases monotonically with an increment of [C₁₂E₂₃]_T (total Brij 35 concentration) at constant [^?OH]₀ and has been discussed with the pseudo-phase micellar model. The rate also decreases with [C₁₂E₂₃]_T at a continuous addition of ionic surfactants (ATABs and SDS). The observed rate constant k_obs follows the empirical relation: k_obs = (k₀ + θK [C₁₂E₂₃]_T)/(1 + K [C₁₂E₂₃]_T) (where θ and K are empirical constants). The values of θ remain unaffected, whereas K decreases nonlinearly with [ATABs]_T in a mixed C₁₂E₂₃?ATAB micellar system. But the k_obs in a mixed C₁₂E₂₃–SDS micellar system is much lower than that of the C₁₂E₂₃–ATAB system and do not comply with any micellar kinetic models.     

Dimetallic sulfide endohedral metallofullerene Sc2S@C76: Density functional theory characterization

In terms of density functional theory combined with statistic mechanics computations, we investigated a dimetallic sulfide endohedral fullerene Sc₂S@C₇₆ which has been synthesized without any characterization in experiments. Our theoretical study reveals that Sc₂S@T_d(19151)‐C₇₆ which satisfies the isolated‐pentagon rule (IPR) possesses the lowest energy, followed by three non‐IPR structures (Sc₂S@C_2v(19138)‐C₇₆, Sc₂S@C_s (17490)‐C₇₆, and Sc₂S@C₁(17459)‐C₇₆). To clarify the relative stabilities of those isomers at high temperatures, enthalpy–entropy interplay has been taken into consideration. Calculation results indicate that three species Sc₂S@T_d(19151)‐C₇₆, Sc₂S@C_2v(19138)‐C₇₆, and Sc₂S@C₁(17459)‐C₇₆ have noticeable molar fractions at the fullerene‐formation temperature region (500–3000K), and the Sc₂S@C₁(17459)‐C₇₆ with one pentagon pair becomes the most predominant isomer above 1800 K, suggesting that the unexpected non‐IPR structure is thermodynamically favorable at elevated temperatures. In addition, the structural characteristics, electron features, UV‐vis‐NIR adsorptions, and ¹³C NMR spectra of those three stable structures are introduced to assist experimental identification and characterization in future. © 2014 Wiley Periodicals, Inc.     

Mass spectrometric investigation of the aggregation and coalescence of fullerenes in C60-modified poly(N-vinylcarbazole) by UV-laser ablation

The phenomena of aggregation and coalescence of fullerenes in the UV-laser ablation time-of-flight mass spectrometric investigation of C₆₀-modified poly(N-vinylcarbazole) both in the positive and in the negative ion channels have been observed. The results indicate that in C₆₀ chemically modified PVK (C₆₀–PVK) copolymer the nascent fullerene fragments ruptured from main chain can easily coalesce into large fullerenes through collisions, whereas in the C₆₀-doped PVK the aggregation and coalescence of C₆₀ were relative weak due to nonbounding action and incomplete charge transfer behavior between C₆₀ and PVK. Furthermore, the photoinduced electron transfer behavior between C₆₀ and carbazole units in the C₆₀ chemically modified poly(N-vinylcarbazole) in benzonitrile by laser flash photolysis at 355 nm has also been investigated. Efficiency of the anion radical of C₆₀ in copolymer at 1080 nm is higher than that of the C₆₀-doped poly(N-vinylcarbazole) polymers. The formation of a C₆₀ radical anion may be ascribed to photoinduced electron transfer between C₆₀ pendanted on the main chain backbone and the inter-, and intrachain carbazole units in the copolymer. © 1997 John Wiley & Sons, Inc. 35 : 1185–1190, 1997     

Thiophene separation from aliphatic hydrocarbons using the 1-ethyl-3-methylimidazolium ethylsulfate ionic liquid

The ionic liquid 1-ethyl-3-methylimidazolium ethylsulfate has been tested as solvent for the separation of thiophene from aliphatic hydrocarbons. Liquid–liquid equilibrium data have been determined for ternary systems containing the ionic liquid, thiophene and C₆, C₇, C₁₂ or C₁₆ alkanes at T = 298.15 K. The performance of the ionic liquid as solvent in such systems has been evaluated. The experimental data were correlated using the NRTL and UNIQUAC equations, and the binary interaction parameters have been reported. The phase diagrams for the ternary mixtures including both the experimental and calculated tie-lines have been presented.     

Aromaticity of All Possible C26N2 Isomers

The aromaticity of all possible heterofullerenes C₂₆N₂ and C₂₈ based on T_d symmetry has been studied by means of the topological resonance energy and percentage topological resonance energy methods. The relationship between the aromaticity of the C₂₆N₂ isomers and the sites where nitrogen atoms dope at the C₂₈ cage has been discussed. The calculation results show that the most stable isomer of C₂₆N₂ derivatives is formed by nitrogen atoms doping at the two tetrahedral vertices. C₂₆N₂ isomers are more stable than C₂₈, but the C₂₆N₂^2? isomers are less stable than C₂₈ ^4?4. The effect of nitrogen substitution on C₂₈ stability was investigated by the topological charge stabilization rule.     

Transport through a slab membrane governed by a concentration-dependent diffusion coefficient: Part IV. D(C)/D0=1+(αC)−β(αC)

Using the specific functional form D(C)/D₀=1+(αC)−β(αC)² an investigation has been made of (isothermal) transport through a slab membrane under ‘simple’ boundary conditions and governed by a diffusion coefficient, D(C), which, with increasing concentration, at first increases, passes through a maximum value and finally decreases. The flux, integral diffusion coefficient and concentration profile characteristic of steady-state permeation have been evaluated; special attention has been paid to the positions of such profiles in relation to the corresponding linear distribution associated with a constant diffusion coefficient.The corresponding transient-state transport has been studied within a framework of the time-lag ‘early-time’ and ‘ ’ procedures. Expressions for the ‘adsorption’ and ‘desorption’ time-lags are given. The concentration-dependence of these time-lags, of the (four) integral diffusion coefficients derived from them and of the arithmetic-mean time-lag ratios have been considered in some detail. The ‘early-time’ and ‘ ’ finite-difference procedures have likewise been employed to derive four further integral diffusion coefficients, so enabling a comparison to be made of the nine integral coefficients pertaining to established experimental techniques.Particular interest attaches to the situation for which n≡β(αC₀)=1 (where C₀ is the ingoing or upstream concentration of diffusant) resulting in D(C₀) being symmetrical about C₀/2. Some consideration has been given, in general, to features of transient-state transport when governed by a symmetrical D(C).     

Weak C—H...O hydrogen bonds in anisaldehyde,salicylaldehyde and cinnamaldehyde

In situ cryocrystallization has been employed to grow single crystals of 4‐methoxybenzaldehyde (anisaldehyde), C₈H₈O₂, 2‐hydroxybenzaldehyde (salicylaldehyde), C₇H₆O₂, and (2E)‐3‐phenylprop‐2‐enal (cinnamaldehyde), C₉H₈O, all of which are liquids at room temperature. Several weak C—H...O interactions of the types C_aryl—H...O, C_formyl—H...O and Csp³—H...O are present in these related crystal structures.     

Heat capacity of a polydiacetylene single crystal from 3 to 300 K

Heat capacities C_p of a polydiacetylene-bis(toluene sulfonate) single crystal and its monomer have been measured in the temperature range from 3 to 300 K. The temperature dependence of C_p for both monomer and polymer crystals differs from that for monoatomic solids. By applying a chain lattice model for a polymer crystal, the temperature dependence of the heat capacity can be described assuming a phonon density of states given by bending and stretching modes of the polymer backbone. With a combination of one-dimensional and three-dimensional elastic continuum approximations, the heat capacity has been calculated and a good fit to the data has been obtained. A small peak in C_p was detected at 161 K for the monomer and at 198 K for the polymer. This may be ascribed to a lower-temperature phase transition in the polydiacetylene crystals evidenced by previous x-ray and spectroscopic measurements.     

Specific heat studies in a-Se and a-Se<Subscript>90</Subscript>M<Subscript>10</Subscript> (M = In,Sb, Te) alloys

Specific heat measurements have been made in a-Se and a-Se₉₀M₁₀ (M = In, Sb, Te) alloys using differential scanning calorimetry (DSC) technique to see the effect of additives In, Sb and Te on the specific heat in a-Se. An extremely large increase in the specific heat values has been observed at the glass transition temperature. It has also been found that the values of C _p below glass transition temperature (C _pg ) and after glass transition (C _pe ) are highly composition dependent. This indicates that the additives used in the present study influences the structure of the a-Se. Specific heat and atomic mass values of the additive elements are found to be significant for the explanation of present results.     

Rotation dynamics of C60 molecules in organic superconductor K3C60

The rotation dynamics of C₆₀ molecules in organic superconductor K₃C₆₀ has been investigated from the viewpoint of intramolecular interaction. It is determined that the rotation of C₆₀ at mom temperature has been frozen up within a small region of rotation angle (0°–50°), and pointed out that the reason for the freeze is the physical interaction rather than the geometrical hindrance. The computations of the interactions for alkali-doped compounds A_3-x A′ _x C₆₀ (x = 1, 2, 3; A, A′ = K, Rb, Cs) other than K₃C₆₀ have also been camed out. Fmm the obtained results, it is seen that the superconducting transition temperatures T, are strongly connected with the interactions in them, and this observation is consistent with the discovery of the correlation between T_c, and lattice constants a. Project supported by the National Natural Science Foundation of China.     

The behaviour of 2-nitrothiophene and of 3-nitrothiophene with some nucleophiles

The reactivity of 2-nitrothiophene (1) and of 3-nitrothiophene (II) with some nucleophiles has been studied. According to calculated electronic densities I can receive nucleophilic attack at C₃ and C₅ depending on the nucleophile used, but II only at C₂. With N-lithium piperidine both I and II also give coupling products (VII and XI respectively) of the hithienyl type.     

Stability studies of an electrochemically formed [C60]fullerene-palladium two-component film

The stability of C₆₀ and palladium two-component films, C₆₀/Pd, has been investigated. The effect of different polymerization conditions on the electrochemical stability of the film upon prolonged potential cycling has been studied. Stable voltammetric behavior was observed for polymers formed at potentials less negative than the potential of third C₆₀ reduction step. The incorporation of palladium particles into the structure of C₆₀/Pd polymers increases the polymer stability. The C₆₀/Pd films are doped with supporting electrolyte cations during reduction. The size of these cations is a crucial factor in determining the stability of the film. A strong solvent effect on the potential stability of the film was also observed. The wildest range of stable voltammetric properties was found for acetonitrile and N,N-dimethylformamide. No effect of the temperature on the film stability was observed. The results reported in this work allow for the determination of the optimal conditions for the formation of stable C₆₀/Pd films.     

The Orthogonal (e,e,e)‐Tris‐Adduct of 9,10‐Dimethylanthracene with C60‐Fullerene: A Hidden Cornerstone of Fullerene Chemistry. Preliminary Communication

Tris(9′,10′‐dimethyl[9,10]ethanoanthracene[11′,12′: 1,9;11″,12″: 16,17;11′′′,12′′′: 30,31])[5,6]fullerene C₆₀, the orthogonal (e,e,e)‐tris‐adduct of C₆₀ and 9,10‐dimethylanthracene, was obtained from [4+2]‐cycloaddition (Diels–Alder reaction) at room temperature. The thermally unstable orange red (e,e,e)‐tris‐adduct was purified by chromatography and was isolated in the form of red monoclinic crystals. Its C₃‐symmetric addition pattern was established spectroscopically. Its structure could be further investigated by single crystal X‐ray diffraction. The (e,e,e)‐tris‐adduct of C₆₀ and 9,10‐dimethylanthracene has earlier been suggested as intermediate and reversibly formed critical component in ‘template directed’ addition reactions of C₆₀. This previously elusive compound has now been isolated and structurally characterized.     

Luminescent Amphiphilic 2,6‐Bis(1‐alkylpyrazol‐3‐yl)pyridyl Platinum(II) Complexes: Synthesis,Characterization, Electrochemical,Photophysical, and Langmuir–Blodgett Film Formation Studies

Two series of novel platinum(II) 2,6‐bis(1‐alkylpyrazol‐3‐yl)pyridyl (N5Cn) complexes, [Pt(N5Cn)Cl][X] ( 1 – 9 ) and [Pt(N5Cn)(C?CR)][X] ( 10 – 13 ) (X=trifluoromethanesulfonate (OTf) or PF₆; R=C₆H₅, C₆H₄‐p‐CF₃ and C₆H₄‐p‐N(C₆H₅)₂), with various chain lengths of the alkyl groups on the nitrogen atom of the pyrazolyl units have been successfully synthesized and characterized. Their electrochemical and photophysical properties have been studied. Some of their molecular structures have also been determined by X‐ray crystallography. Two amphiphilic platinum(II) 2,6‐bis(1‐tetradecylpyrazol‐3‐yl)pyridyl (N5C14) complexes, [Pt(N5C14)Cl]PF₆ ( 7 ) and [Pt(N5C14)(C?CC₆H₅)]PF₆ ( 13 ), were found to form stable and reproducible Langmuir–Blodgett (LB) films at the air–water interface. The characterization of such LB films has been investigated by the study of their surface pressure–area (π–A) isotherms, UV/Vis spectroscopy, XRD, X‐ray photoelectron spectroscopy (XPS), FTIR, and polarized IR spectroscopy. The luminescence property of 13 in LB films has also been studied.     

A New Approach to Enantiopure C3‐Symmetric Molecules

Chiral base chemistry has been used to create three chiral centres in one pot on a C₃‐symmetric substrate. The potential of this new approach to C₃‐symmetric molecules is exemplified by the creation of an enantiopure C_3v‐symmetric triol, triphosphane and tripyridine. A ruthenium complex of the last compound has been studied by X‐ray crystallography.     

Studies with inorganic precipitate membranes. IV. Evaluation of apparent fixed charge on membranes

Membrane potentials arising across four parchment-supported ferrocyanide membranes of manganese, cobalt, silver, and cadmium when they separate 1:1 electrolyte solutions of concentration C₁ and C₂ such that C₁ = 10C₂, have been measured. The data have been used according to the procedure prescribed by one of the theories of membrane potential due to Teorell and Meyers and Sievers to derive values for the quantity of charge present on the membranes. An alternative procedure employed by Altug and Hair has been considered and found to overestimate the value for the charge on the membranes.     

Hydration behavior of C2S and C2AS nanomaterials, synthetized by sol–gel method

Hydration behavior of dicalcium silicate (C₂S) (Cement chemistry nomenclature is used where C=CaO, S=SiO₂, A=Al₂O₃, S=SO₃) and gehlenite (C₂AS), synthesized by sol–gel method was investigated by means of isothermal heat flow calorimeter at different temperatures. These phases were obtained by crystallization processing at different temperatures from their xerogels (nano-crystalline) prepared by the sol–gel method at ambient temperature. The crystallization of C₂S begins below 600°C and it is well crystallized at 900°C. X-ray diffraction patterns reveal that β-C₂S is formed and it remains stable since after slow cooling. The crystallization of C₂AS xerogels starts with the formation of C₂S, then it reacts with alumina to form mineral C₂AS at 1100°C. The effect of hydration temperature upon the hydration reaction of C₂S obtained at 600 and 900°C and C₂AS annealed at 600 and 1100°C was investigated by means of isothermal calorimeter. An increase in the temperature of hydration brought about initial acceleration of all samples, as indicated by the increased magnitude of peak of calorimetric curves. The microstructure of the samples cured at hydrothermal condition after 1 and 7 days has been examined by means of scanning electron microscopy (SEM). Fine crystals of calcium silicate hydrate (C–S–H) were developed in C₂S samples, while C₂AS has been hydrated to form gehlenite hydrate supplemented by C–S–H.     

Convolutive Cyclic Voltammetry,Chronoamperometry and Chronopotentiometry Studies of C6Me6-isocloso-ruthenaborane Complex in Non-aqueous Medium at a Glassy Carbon Electrode

Electroreduction of the C₆Me₆‐isocloso‐ruthenaborane complex {(C₆Me₆)‐isocloso‐1‐RuB₁₀H₁₀} has been investigated using cyclic voltammetry, convolutive voltammetry, chronoamperometry and chronopotentiometry techniques at a glassy carbon electrode in 0.1 mol·L⁻¹ tetrabutyl ammonium perchlorate dissolved in methylene chloride. The investigated complex has been reduced via the consumption of two sequential electrons leading to the formation of monoanion and dianion, respectively. The electrode reaction pathway and the electrochemical parameters of the investigated system were determined. The extracted electrochemical parameters were verified via digital simulation treatments. Diffusion coefficient and heterogeneous electron transfer kinetics of the {(C₆Me₆)‐isocloso‐1‐RuB₁₀H₁₀} complex at low temperature were studied and discussed.     

Quantum chemistry study on B32 and B32H2–32

The structures of B32 and B₃₂H^2–₃₂ with I_h symmetry have been investigated by means of ab initio calculations at STO-3G level. The relationship between molecular orbitals of them has been analyzed and their bonding properties have been discussed. Then the possibility of their existence, as well as the similarity and difference between B₃₂ (B₃₂H^2–₃₂) and C₆₀ (C₆₀H₆₀) have been inferred.     

Effect of water on the mechanical properties of collagen films

The effect on water on mechanical properties of collagen films has been studied. The S-shaped sorption isotherm is separated into an adsorption curve C₁ and a solution curve C₂. From the C₂ curve, a value of 0.8 is calculated for the Flory-Huggins interaction parameter χ₁. The dynamic shear modulus G′, loss modulus G″, and loss tangent tan δ determined as functions of water content indicate two dispersions at low and at high water content. The region of water content from about 0.05 to 0.1 g/g, G′ decreases suddenly, G″ has a peak, and tan δ increases, corresponds to the region where the C₂ component of sorption becomes detectable. Another dispersion occurs at water contents above 0.2 g/g. A composite curve can be obtained by shifting stress-relaxation curves obtained at different humidities along the log time axis. When only the C₂ component of sorbed water is taken into account, the shift factor a_c is explained by a relation of Fujita and Kishimotos' based on free-volume theory. Shift factor for the relaxation curves of wool fibers, except for an initial part at times of less than 1 sec, are described by the same equation. The parameter β in the equation has the same value of 0.16 for both collagen and wool.