Binary and ternary solubilities of disperse dyes and their blend in supercritical carbon dioxide

Binary and ternary solubilities of C.I. Disperse Blue 134 (1,4-bis(isopropylamino)anthraquinone) C.I. Disperse Yellow 16 (3-methyl-1-phenyl-5-pyrazolone) and their dye mixture in supercritical carbon dioxide (SC-CO₂) were measured by a flow-type apparatus. The solubility measurements were carried out at the pressure ranges from 10.0 to 25.0 MPa for the binary systems at the temperatures from 323.15 to 383.15 K and for the ternary system at 383.15 K. An empirical equation was used to correlate the experimental binary solubilities of the dyes in terms of the density of carbon dioxide. To represent accurately the binary solubility of the dyes in terms of temperature and pressure, we used a modified Peng–Robinson–Stryjek–Vera equation of state (PRSV EOS). The ternary solubilities of the dye blend could be predicted successfully from binary parameters with the modified PRSV EOS.     

Synthesis and application of some novel fluorescent heterocyclic disperse dyestuffs based on phenothiazine on polyester

A series of novel heterocyclic disperse dyestuffs derived from phenothiazine were prepared by standard reactions from phenothiazine as the starting material. Phenothiazine was nitrated and oxidized then reduced to obtain synthesized disperse dyestuffs. The reaction conditions were varied in order to obtain optimal yields for each stage of the preparation to obtain the corresponding derivative and final disperse dyestuffs. All intermediates and disperse dyestuffs were purified and characterized by DSC, FTIR, ¹H NMR, ¹³C NMR, elemental analysis and UV–Visible spectroscopic techniques. The molar extinction coefficients (ε), wavelengths of maximum absorption (λ_max) and solvatochromism effects were studied in solvents as toluene, acetone and N,N-dimethylformamide (DMF). Results represented that the dyestuffs had extinction coefficients of 2011–28189 L mol⁻¹ cm⁻¹, wavelengths of maximum absorption of 448–475 nm in acetone and positive solvatochromism by changing solvent from toluene to DMF. The disperse dyestuffs were applied to locally manufactured polyester fibers and their dyeing properties were investigated. Results showed that the buildup of dyestuffs was acceptable and dyed fibers had very good heat and wash fastness and medium light fastness on polyester fibers.     

Enantioselective 1,4-addition of arylboronic acids to α,β-unsaturated carbonyl compounds catalyzed by rhodium(I)-chiral phosphoramidite complexes

A chiral bidentate phosphoramidite (5a) was synthesized from Shibasaki’s linked-(R)-BINOL and P(NMe₂)₃ as a new ligand for rhodium(I)-catalyzed asymmetric 1,4-addition of arylboronic acids to α,β-unsaturated carbonyl compounds. The effects of 5a and Feringa’s monodentate phosphoramidite (4, R¹, R² = Et) on the yields and enantioselectivities were fully investigated. The reaction was significantly accelerated in the presence of a base such as KOH and Et₃N, allowing the reaction to be completed at the lower temperatures than 50 °C. The addition to cyclic enones such as 2-cyclopentenone, 2-cyclohexenone and 2-cycloheptenone at 50 °C in the presence of an [Rh(coe)₂Cl]₂-4 (R¹, R² = Et) complex resulted in enantioselectivities up to 98%, though it was less effective for acyclic enones (0–70% ee). On the other hand, a complex between [Rh(nbd)₂]BF₄ and 5a completed the addition to cyclic enones within 2 h at room temperature in the presence of Et₃N with 86–99% yields and 96–99.8% ee. This catalyst was also effective for acyclic enones, resulting in 62–98% yields and 66–94% ee. The 1,4-additions of arylboronic acids to unsaturated lactones and acyclic esters with rhodium(I)-phosphoramidites complexes were also investigated.     

Solubility measurement of α-asarone in supercritical carbon dioxide

The solubility of α-asarone in supercritical CO₂ (sc-CO₂) has been measured using the dynamic method. The measurement was conducted in the pressure range from 9.0 to 18.0 MPa at temperature 35–49 °C. The experimental data were correlated using the Chrastil model. The results show that the solubility increases as the pressure rises and decreases as the temperature rises, which is well correlated with the Chrastil model.     

Novel electroactive surface functionality from the coupling of an aryl diamine to carbon black

The reaction of 1,2-diaminoanthraquinone with Vulcan XC72 carbon in 4 M HCl produces two distinct surface bound anthraquinone species, with formal potentials of ca. ?0.03 and ?0.19 V vs. SCE. The more positive couple is very stable to electrochemical cycling and has been assigned to the expected benzimidazole linkage. The other wave, which decays over hours of cycling is thought to be due to an amine linkage. This type of linkage also appears to be formed spontaneously when 1,2-diaminoanthraquinone is adsorbed onto Vulcan XC72 from methanol.     

Experimental and computational thermochemistry of 1,4-benzodioxan and its 2-R derivatives

The standard molar energies of combustion, at T = 298.15 K, of crystalline 1,4-benzodioxan-2-carboxylic acid and 1,4-benzodioxan-2-hydroxymethyl were measured by static bomb calorimetry in an oxygen atmosphere. The standard molar enthalpies of sublimation, at T = 298.15 K, were obtained by Calvet microcalorimetry. These values were used to derive the standard molar enthalpies of formation of the compounds in the gas phase at T = 298.15 K: 1,4-benzodioxan-2-carboxylic acid ?(547.7 ± 3.0) kJ · mol^?1 and 1,4-benzodioxan-2-hydroxymethyl ?(374.2 ± 2.3) kJ · mol^?1.In addition, density functional theory calculations using the B3LYP hybrid exchange–correlation energy functional with extended basis sets, 6-311G⁷ and cc-pVTZ, have been performed for the compounds studied. We have also tested two more accurate computational procedures involving multiple levels of electron structure theory in order to get reliable estimates of the thermochemical parameters of the compounds studied. The agreement between experiment and theory gives confidence to estimate the enthalpies of formation of other 2-R derivatives of 1,4-benzodioxan (R = –CH₂COOH, –OH, –COCH₃, –CHO, –CH₃, –CN, and –NO₂).     

Anthracene-based macrocyclic fluorescent chemosensor for selective sensing of dicarboxylate

An anthracene-based macrocyclic receptor has been designed and synthesized for selective recognition of 1,4-phenylenediacetate (K_a = 3.34 × 10⁵ M^?1). The macrocycle binds 1,4-phenylenediacetate selectively at the charged sites of the receptor with a concomitant increase in fluorescence of anthracene. The interaction properties of the macrocycle were evaluated by ¹H NMR, UV–vis and fluorescence spectroscopic methods.     

Efficient immobilization of 9,10-anthraquinonyl moiety at solid interfaces through 2-(bromomethyl)anthraquinone one-electron cleavage

We report here a new and very efficient method for the coverage of different carbon materials with 9,10-anthraquinone attached via a methylene linker. The method is based on one-electron reduction of 2-(bromomethyl)anthraquinone (AQ-CH₂-Br) to a free radical AQ–CH₂ which was readily achieved using propylene carbonate (PC) as solvent containing tetrabutylammonium iodide. This way, the radical AQ–CH₂ adds to the abovementioned carbons forming very stable and dense covalently bound anhraquinonyl methane layers (Г ≈ 2 × 10^− 9 mol cm^− 2). The grafting could be performed by constant potential electrolyses (q < 0.5 × 10^− 3 C mm^− 2).     

Kinetic spectrophotometric method for trace determination of thiocyanate based on its inhibitory effect

A kinetic spectrophotometric method for the determination of thiocyanate, based on its inhibitory effect on silver(I) catalyzed substitution of cyanide ion, by phenylhydrazine in hexacyanoferrate(II) is described. Thiocyanate ions form strong complexes with silver(I) catalyst which is used as the basis for its determination at trace level. The progress of reaction was monitored, spectrophotometrically, at 488 nm (λ_max of [Fe(CN)₅PhNHNH₂]^3?, complex) under the optimum reaction conditions at: 2.5 × 10^?3 M [Fe(CN)₆]^4?, 1.0 × 10^?3 M [PhNHNH₂], 8.0 × 10^?7 M [Ag⁺], pH 2.8 ± 0.02, ionic strength (μ) 0.02 M (KNO₃) and temperature 30 ± 0.1 °C. A linear relationship obtained between absorbance (measured at 488 nm at different times) and inhibitor concentration, under specified conditions, has been used for the determination of [thiocyanate] in the range of 0.8–8.0 × 10^?8 M with a detection limit of 2 × 10^?9 M. The standard deviation and percentage error have been calculated and reported with each datum. A most plausible mechanistic scheme has been proposed for the reaction. The values of equilibrium constants for complex formation between catalyst–inhibitor (K_CI), catalyst–substrate (K_s) and Michaelis–Menten constant (K_m) have been computed from the kinetic data. The influence of possible interference by major cations and anions on the determination of thiocyanate and their limits has been investigated.     

Construction of Cd(II)–ferrocenesuccinate coordination complexes via changing adjuvant ligands and anions

Seven Cd(II)–ferrocenesuccinate coordination complexes with the formulas [Cd(η²-FcCOC₂H₄COO)₂(pbbbm)]₂ (1), [Cd(η²-FcCOC₂H₄COO)(pbbbm)Cl]₂ (2), [Cd(η²-FcCOC₂H₄COO)(pbbbm)I]₂ (3), {[Cd(η²-FcCOC₂H₄COO)₂(btx)₂]₂(CH₃OH)_0.5} (4), [Cd(η²-FcCOC₂H₄COO)₂(bix)]₂(H₂O) (5), {[Cd(η²-FcCOC₂H₄COO)(bbbm)_1.5Cl] · (CH₃OH)_0.5}_n (6), and {[Cd(η²-FcCOC₂H₄COO)(mbbbm)Cl] · (H₂O)_2.75}_n (7) [pbbbm = 1,4-Bis(benzimidazole-1-ylmethyl)benzene), btx = 1,4-bis(triazol-1-ylmethyl)benzene), mbbbm = 1,3-bis(benzimidazole-1-ylmethyl)benzene), bix = 1,4-bis(imidazol-1-ylmethyl)benzene, bbbm = 1,1-(1,4-Butanediyl)bis-1H-benzimidazole)] have been synthesized and characterized. Single-crystal X-ray analysis reveals that complexes 1–5 are all dimers and bridged by pbbbm, btx and bix, respectively. But the five complexes present some differences in their dimeric conformations, which can be ascribed to the impacts of adjuvant ligands and counter anions. In contrast to complexes 1–5, both 6 and 7 are of 1-D structures (with the same counter anions), and the former is double ladder-like structure only bridged by bbbm, while the latter is chain-like structure bridged by chlorine anions and adjuvant ligand mbbbm. Notably, various π–π interactions are found in complexes 1–7, and they have significant contributions to molecular self-assembly processes. The electrochemical studies of complexes 1–7 in DMF solution display irreversible redox waves and indicate that the half-wave potentials of the ferrocenyl moieties in these complexes are all shifted to positive potential compared with that of ferrocenesuccinate.     

Temperature dependent Raman study of SB → SC transition in liquid crystalline compound N-(4-n-pentyloxybenzylidene)-4′-heptylaniline (5O.7)

Temperature dependent Raman study of C–H in-plane bending mode (～1163 cm^?1 and ～1190 cm^?1) and C–C stretching mode of phenyl ring (～1571 cm^?1 and ～1594 cm^?1) of N-(4-n-pentyloxybenzylidene)-4′-heptylaniline (5O.7) has been done. Vibrational assignment and potential energy distribution (PED) of individual modes have been calculated employing density functional theory (DFT) for the first time. The S_B → S_C transition is nicely depicted in the variation of the linewidth of the ～1163 cm^?1 band and the peak position of ～1594 cm^?1 band with temperature. Because of a small amount of charge density transfer from the core part to the alkyl chain region, the ～1163 cm^?1 band shifts towards lower wavenumber side whereas the ～1190 cm^?1 band towards higher wavenumber side at S_B → S_C transition. The ～1571 cm^?1 and ～1594 cm^?1 bands are assigned as 8a and 8b modes, whose relative intensity variation with temperature gives the evidence of increased possibility of C–H bending motion of the linking group and the C–C stretching of the alkyl chain in S_C phase.     

Surface structures and electrochemical characteristics of surface-modified carbon anodes for lithium ion battery

Petroleum coke and those heat-treated at 1860 °C, 2100 °C, 2300 °C 2600 °C and 2800 °C (abbreviated as PC, PC1860, PC2100, PC2300, PC2600 and PC2800) were fluorinated by elemental fluorine of 3 × 10⁴ Pa at 200 °C and 300 °C for 2 min. Natural graphite powder samples with average particle sizes of 5 μm, 10 μm and 15 μm (abbreviated as NG5μm, NG10μm and NG15μm) were also fluorinated by ClF₃ of 3 × 10⁴ Pa at 200 °C and 300 °C for 2 min. Transmission electron microscopic (TEM) observation revealed that closed edge of PC2800 was destroyed and opened by surface fluorination, which increased the first coulombic efficiencies of PC2300, PC2600 and PC2800 by 12.1–18.2% at 60 mA/g and by 13.3–25.8% at 150 mA/g in 1 mol/dm³ LiClO₄–ethylene carbonate (EC)/diethyl carbonate (DEC) (1:1 in volume). Light fluorination of NG10μm and NG15μm increased the first coulombic efficiencies by 22.1–28.4% at 150 mA/g in 1 mol/dm³ LiClO₄–EC/DEC/PC (PC: propylene carbonate, 1:1:1 in volume).     

Cyanamide-derived non-precious metal catalyst for oxygen reduction

Cyanamide was used in the preparation series of metal–nitrogen–carbon (M–N–C) oxygen reduction catalysts. The best catalyst, treated at 1050 °C, shows good performance versus previously reported non-precious metal catalysts with an OCV ~ 1.0 V and a current density of 105 mA/cm² (iR-corrected) at 0.80 V in H₂/O₂ fuel cell testing (catalyst loading: 4 mg cm^? 2). Although nitrogen content has been previously correlated positively with ORR activity, no such trend is observed here for any nitrogen type. The combined effects of nitrogen and sulfur incorporation into the carbon may account for the high activity of the 1050 °C catalyst.     

The quest for magnets composed of vanadium and 1,4-benzoquinones

The reaction of V^o(CO)₆ and representative quinones, A (A = benzoquinone, chloranil, 2,3-dicyano-1,4-naphthoquinone, and dihydroxy-1,4-benzoquinone), form materials of V(A)₂ · zCH₂Cl₂ (z < 0.1) composition, which exhibits antiferromagnetic coupling and do not magnetically order above 5 K.     

Vibrational interactions in dimethylgold(III) halides and carboxylates

The far-infrared and Raman spectra of binuclear molecules [Me₂AuX]₂ (X = Cl, Br, I) and [Me₂Au(OOCR)]₂ (R = Me, CF₃, Bu^t, Ph) in the 600–70 cm⁻¹ region are reported. The experimentally measured vibrational frequencies of [Me₂AuX]₂ are in a good agreement with density functional theory predictions. The Au…Au vibrational interactions predicted to be in the 270–60 cm⁻¹ region of [Me₂AuX]₂ far-IR and Raman spectra have been observed. The Raman-active Au…Au vibrations of the [Me₂Au(OOCR)]₂ molecules were found to be in the same region as those of [Me₂AuX]₂. The Au–X stretching modes were observed between 100 and 250 cm⁻¹ in accordance with the DFT predictions. Their frequencies in the IR spectra of [Me₂AuX]₂ increase in the sequence I < Br < Cl while the AuC₂ stretching frequencies decrease in the same order. This fact might be an evidence of the decreasing covalent character of the gold-halogen bridges. The Au–O stretching bands of dimethylgold(III) carboxylates have been observed in the 500–250 cm⁻¹ region, and Au–C stretching frequencies of both [Me₂AuX]₂ and [Me₂Au(OOCR)]₂ compounds have been found between 600 and 500 cm⁻¹.     

Insertion of the p-complex structure of silylenoid H2SiLiF into X–H bonds (X = C,Si, N,P, O,S, and F)

The insertion reactions of the p-complex structure (A) of silylenoid H₂SiLiF into XH_n molecules (X = C, Si, N, P, O, S, and F; n = 1–4) have been studied by ab initio calculations at the G3(MP2) level. The results indicate that the insertion reactions of A into X–H bonds proceed via three reaction paths, I, II, and III, forming the same products, substituted silanes H₃SiXH_n − 1 with dissociation of LiF, respectively, and all insertion reactions are exothermic. All the seven X–H bonds can undergo insertion reactions with A via path I and II, but only four of them, C–H, Si–H, P–H, and S–H, undergo insertion reactions via path III. The following conclusions emerge from this work: (i) the X–H insertion reactions of A occur in a concerted manner via a three-membered ring transition state; (ii) for path I and II, the stabilization energies of the A–XH_n complexes decrease in the order HF > H₂O > H₂S > NH₃ > SiH₄ > CH₄; (iii) for path I and II, the greater the atomic number of heteroatom (X) in a given row, the easier the insertion reaction of XH_n hydrides and the larger the exothermicity, and for the second-row hydrides, the reaction barriers are lower than for the first-row hydrides; (iv) The barriers of path I are lowest in those of three pathways with the exception of A + SiH₄ system, which barrier of path III is lowest. Moreover, the present study demonstrates that both electronic and steric effects play major roles in the course of insertion reactions of A into X–H bonds.     

Isoprene polymerization using a neodymium phenolate pre-catalyst combined to aluminum based co-catalysts

The discrete phenolate Nd(2,6-di-tert-butyl-OC₆H₃)₃ has been assessed as pre-catalyst for the polymerization of isoprene using various aluminum based co-catalysts. In combination with MAO and MMAO in toluene, the reaction is quantitative in 1 h at 60 °C, yielding activities comparable to neodymium versatate and isopropylate in similar conditions. In contrast with the abovementioned systems, the phenolate leads to a single site catalyst species in combination with MAO and MMAO. Increasing amounts of MAO in the reactive medium lead to a decrease of the number–average molecular weight of polyisoprene, highlighting the occurrence of chain transfer between neodymium and aluminum. The polymerization is modestly 1,4-trans selective, in the range 60–75%. Using pentane as a solvent and MMAO, ultra high activities up to 3000 kg PI/mol Nd/h can be reached at room temperature, as well as 85% 1,4-cis selectivity. Ternary systems with co-catalysts based on the chlorinated AlEt₂Cl in combination with AlⁱBu₃ afford finally a 90–98% 1,4-cis stereoselective polymerization depending on the solvent used for the reaction. The SEC traces are in agreement with the presence of several active species for the latter systems.     

Catalytic cyclopropanation of olefins using copper(I) diphosphinoamines

Catalytic cyclopropanation reactions of olefins with ethyl diazoacetate were carried out using copper(I) diphosphinoamine (PPh₂)₂N(R) (R = ⁱPr, H, Ph and –CH₂–C₆H₄–CHCH₂) complexes at 40 °C in chloroform. High yields of the cyclopropanes were obtained in all cases. The rate of the reaction was influenced by the nuclearity of the complex and the binding mode of the ligand which was either bridging or chelating. Comparison of isostructural complexes shows that the rate follows the order R = ⁱPr > H > Ph, where R is the substituent on the N. However, cyclopropane formation versus dimerization of the carbene, and trans to cis ratios of cyclopropane was similar in all cases. The nearly identical selectivity for different products formed was indicative of a common catalytic intermediate. A labile “copper–olefin” complex which does not involve the phosphine or the counterion is the most likely candidate. The differences in the reaction rates for different complexes are attributed to differences in the concentration of the catalytically active species which are in equilibrium with the catalytically inactive copper–phosphinoamine complex. To test the hypothesis a diphosphinoamine polymer complexed to copper(I) was used as a heterogeneous catalyst. Leaching of copper(I) and deactivation of the catalyst confirmed the proposed mechanism.     

Molecular Stark-effect spectroscopy of Prodan and Laurdan in different solvents and electric dipole moments in their equilibrated ground and Franck–Condon excited state

The results from electrooptical absorption measurements (EOAM) on the ground and excited Franck–Condon state dipole moments of Prodan and Laurdan in 1,4-dioxane and cyclohexane are presented. The ground and excited Franck–Condon state electric dipole moments as well as the respective transition moment of both probes are parallel. The electric dipole moments of Prodan and Laurdan in the ground state in cyclohexane and 1,4-dioxane have values within the range (15.7–16.5) × 10⁻³⁰ C m. On optical excitation the dipole moments increase by (42.1–49.5) × 10⁻³⁰ C m. The obtained results are compared with the values of the dipole moments of Prodan and Laurdan determined by other methods.