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1.
Nanoscale Res Lett ; 11(1): 444, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27699715

RESUMO

MnS has been attracting more and more attentions in the fields of lithium ion batteries (LIBs) because of its high energy density and low voltage potential. In this paper, we present a simple method for the preparation of urchin-like γ-MnS microstructures using L-cysteine and MnCl2 · 4H2O as the starting materials. The urchin-like γ-MnS microstructures exhibit excellent cycling stability (823.4 mA h g-1 at a current density of 500 mA g-1, after 1000 cycles). And the discharge voltage is about 0.75 V, making it a good candidate for the application as the anode material in LIBs. SEM, TEM, and XRD were employed to inspect the changes of the active materials during the electrochemical process, which clearly indicate that the structural pulverization and reformation of the γ-MnS microstructures play important roles for the maintenance of the electrochemical performance during the charge/discharge process.

2.
Inorg Chem ; 50(21): 10755-64, 2011 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-21995326

RESUMO

As part of our ongoing project involving the study of (1-C(n)H(2n+1)NH(3))(2)MCl(4)(s) (where M is a divalent metal ion and n = 8-18), we have synthesized the compounds (1-C(n)H(2n+1)NH(3))(2)ZnCl(4)(s) (n = 8, 10, 12, and 13), and the details of the structures are reported herein. All of the compounds were crystallized in the monoclinic form with the space group P2(1)/n for (1-C(8)H(17)NH(3))(2)ZnCl(4)(s), P21/c for (1-C(10)H(21)NH(3))(2)ZnCl(4)(s), P2(1)/c for (1-C(12)H(25)NH(3))(2)ZnCl(4)(s), and P2(1)/m for (1-C(13)H(27)NH(3))(2)ZnCl(4)(s). The lattice potential energies and ionic volumes of the cations and the common anion of the title compounds were obtained from crystallographic data. Molar enthalpies of dissolution of the four compounds at various molalities were measured at 298.15 K in the double-distilled water. According to Pitzer's theory, molar enthalpies of dissolution of the title compounds at infinite dilution were obtained. Finally, using the values of molar enthalpies of dissolution at infinite dilution (Δ(s)H(m)(∞)) and other auxiliary thermodynamic data, the enthalpy change of the dissociation of [ZnCl(4)](2-)(g) for the reaction [ZnCl(4)](2-)(g)→ Zn(2+)(g) + 4Cl(-)(g) was obtained, and then the hydration enthalpies of cations were calculated by designing a thermochemical cycle.

3.
Acta Crystallogr Sect E Struct Rep Online ; 67(Pt 5): o1051, 2011 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-21754378

RESUMO

In the crystal of the title compound, C(15)H(34)N(+)·CH(3)SO(4) (-), the cations and anions are joined together via strong N-H⋯O hydrogen bonds into layers parallel to (001).

4.
Acta Crystallogr Sect E Struct Rep Online ; 67(Pt 3): o717, 2011 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-21522459

RESUMO

In the title compound, C(13)H(30)N(+)·Cl(-)·H(2)O, the C(13)H(27) alkyl chain is in an all-trans conformation. In the crystal, inter-molecular N-H⋯Cl, N-H⋯O and O-H⋯Cl hydrogen bonds connect the components into layers parallel to (010), with the alkyl chains oriented approximately perpendicular to these layers.

5.
Int J Pharm ; 386(1-2): 165-71, 2010 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-19931607

RESUMO

The interaction of calf thymus deoxyribonucleic acid (ct-DNA) with betaxolol (BET) in aqueous buffer solution (pH 7.40) has been investigated using isothermal titration calorimetry (ITC), ultraviolet absorption (UV), fluorescence spectroscopy (FS) and circular dichroism (CD). Thermodynamic parameters, i.e., equilibrium constants, standard changes of enthalpy (DeltaH degrees ), Gibbs free energy (DeltaG degrees) and entropy (DeltaS degrees ), for the binding process of the drug to the bio-macromolecules have been derived from the calorimetric data. Analysis of the thermodynamic data indicates that there are two classes of binding sites on the DNA molecules being able to coordinate with BET molecules. One class of binding takes place at the sites formed by base pairs, which is synergistically driven by enthalpy and entropy, while the other one takes place on phosphate groups and shown as an entropy driven process. The thermodynamic behavior of the DNA-drug supramolecular system has been discussed in the light of the important weak interactions, hydrophobic force, hydrogen bond and electrostatic force, according to the UV, FS and CD spectra.


Assuntos
Antagonistas Adrenérgicos beta/química , Betaxolol/química , Calorimetria , Dicroísmo Circular , DNA/química , Espectrometria de Fluorescência , Espectrofotometria Ultravioleta , Animais , Berberina/química , Sítios de Ligação , Tampões (Química) , Bovinos , Ligações de Hidrogênio , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Estrutura Molecular , Conformação de Ácido Nucleico , Eletricidade Estática , Termodinâmica
6.
Acta Chim Slov ; 57(2): 370-85, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24061733

RESUMO

Low-temperature heat capacities of 2-pyrazinecarboxylic acid (C5H4N2O2)(s) were measured by a precision automated adiabatic calorimeter over the temperature range from 78 to 400 K. A polynomial equation of heat capacities as a function of temperature was fitted by least squares method. Based on the fitted polynomial, the smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated and tabulated at 10 K intervals. The constant-volume energy of combustion of the compound at T = 298.15 K was measured by a precision rotating-bomb combustion calorimeter to be ΔcU = -(17839.40 ± 7.40) J g-1. The standard molar enthalpy of combustion of the compound was determined to be ΔcH0m = -(2211.39 ± 0.92) KJ mol-1, according to the definition of combustion enthalpy. Finally, the standard molar enthalpy of formation of the compound was calculated to be ΔfH0m = -(327.82 ± 1.13) kJ mol-1 in accordance with Hess law.

7.
Acta Chim Slov ; 57(2): 458-65, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24061744

RESUMO

2-Aminopyridinium benzoate was synthesized. Chemical analysis, elemental analysis, and X-ray crystallography were applied to characterize the composition and crystal structure of the compound. The lattice potential energy of the title compound was calculated to be UPOT = 284.297 kJ mol-1. Low-temperature heat capacities of the compound were measured by a precision automatic adiabatic calorimeter over the temperature range from 78 K to 365 K. A polynomial equation of heat capacities against the temperature in the region of 78 K to 365 K was fitted by a least square method. Based on the fitted polynomial equation, the smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated at intervals of 5 K. According to the synthesis reaction, the standard molar enthalpies of dissolution for the reactants and product in the selected solvent were measured by an isoperibol solution-reaction calorimeter, respectively. Accordingly, the enthalpy change of the synthesis reaction was calculated to be ΔrHom = -(20.016 ± 0.182) kJ mol-1. Finally, the standard molar enthalpy of formation of 2-aminopyridinium benzoate was determined to be ΔfHom = - (365.416 ± 0.961) kJ mol-1 in accordance with Hess law.

8.
Acta Crystallogr Sect E Struct Rep Online ; 66(Pt 4): o910, 2010 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-21580721

RESUMO

In the title compound, C(12)H(28)N(+)·Br(-)·H(2)O, the ionic pairs formed by n-dodecyl-ammonium cations and bromide anions are arranged into thick layers; these layers are linked in a nearly perpendicular fashion [the angle between the layers is 85.84 (5)°] by hydrogen-bonding inter-actions involving the water mol-ecules. The methyl-ene part of the alkyl chain in the cation adopts an all-trans conformation. In the crystal structure, mol-ecules are linked by inter-molecular N-H⋯Br, O-H⋯Br and N-H⋯O hydrogen bonds.

9.
Acta Crystallogr Sect E Struct Rep Online ; 66(Pt 12): m1509-10, 2010 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-21589215

RESUMO

In the title layered coordination polymer, [Na(4)(C(8)H(3)NO(6))(2)(H(2)O)(3)](n), the doubly deprotonated 3-nitro-benzene-1,2-dicarboxyl-ate ligands exhibit µ(8)- and µ(6)-coordination modes to the sodium ions, generating sheets lying parallel to (001). The coordination environments of the sodium ions are distorted octa-hedral, distorted trigonal-bipyramidal and moncapped trigonal-prismatic. One of the nitro groups is disordered over two sets of sites with site-occupancy factors 0.580 (8):0.419 (2). A network of O-H⋯O and O-H⋯N hydrogen bonds helps to establish the packing.

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