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1.
Dissociative ionization of 1,4-bis(2,5-phenyloxazolyl)benzene (POPOP) molecule by electron impact in gaseous phase is studied. Potentials of appearance of some fragments of the molecule under study are determined from the experimentally measured dependences of ionization cross-section on the ionizing electron energy. A new ion with m/z = 144 [C9H6ON]+ is detected in the mass spectrum of the POPOP molecule, being complementary to the fragment with m/z = 220 [C15H10ON]+. The threshold of appearance of this ion is determined (Eap = 9.51 eV) as well as the first ionization potential of the POPOP molecule and fragment ion appearance potentials.  相似文献   

2.
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).  相似文献   

3.
Electron paramagnetic resonance (EPR) study of Cu2+ doped bis (glycinato) Mg (II) monohydrate single crystals is carried out at room temperature. Copper enters the lattice substitutionally and is trapped at two magnetically inequivalent sites. The observed spectra are fitted to a spin-Hamiltonian of rhombic symmetry with the following values of the parameters: Cu2+ (I), gx = 2.1577 ± 0.0002, gy = 2.2018 ± 0.0002, gz = 2.3259 ± 0.0002, Ax = (87 ± 2) × 10?4 cm?1, Ay = (107 ± 2) × 10?4 cm?1, Az = (141 ± 2) × 10?4 cm?1; Cu 2+ (II), gx = 2.1108 ± 0.0002, gy = 2.1622 ± 0.0002, gz = 2.2971 ± 0.0002, Ax = (69 ± 2) × 10?4 cm?1, Ay = (117 ± 2) × 10?4 cm?1and Az = (134 ± 2) × 10?4 cm?1. The ground state wave function of the Cu2+ ion in this lattice is evaluated to be predominantly |x2 ? y2. The g-factor anisotropy is also calculated and compared with the experimental value. With the help of the optical absorption study, the nature of bonding in the complex is discussed.  相似文献   

4.
Precise structural data have been determined from a combined Rietveld refinement, based on neutron and X-ray powder diffraction data simultaneously, for the three phases LiCoPO4, LizCoPO4 with a specific intermediate Li-content z = 0.60(10) and CoPO4, which are obtained by electrochemical Li-extraction from LiCoPO4. All three phases are isopointal. Therefore, the transitions between these phases are necessarily of first order, in agreement with their observed coexistence. The same collinear antiferromagnetic structures with magnetic moments nearly parallel to the [010] direction are observed for LiCoPO4 and LizCoPO4, but with a significantly higher Néel temperature of 76 K for the latter compound in comparison with 23 K for LiCoPO4. Olivine-type CoPO4 can only be prepared from LiCoPO4 by delithiation and its physical properties were investigated for the first time. An antiferromagnetic arrangement along the [100] direction is observed for CoPO4 with an additional weak ferromagnetic component along the [001] direction (magnetic space group Pnma and TC = 45 K). The magnetic moment of 3.1(2) μB per Co-ion indicates a mainly high-spin state for Co3+ in the octahedral coordination of CoPO4, which is exceptional and probably the first example in a phosphate. The easy axes and the magnetic exchange interactions between Co-ions change dramatically with the Co2+ ? Co3+ transition. A continuous change of the formal oxidation state of a transition element by electrochemical Li-extraction and a quasi-continuous in situ observation of the resulting magnetic structure by neutron diffraction appear feasible.  相似文献   

5.
《Polyhedron》2005,24(16-17):2215-2221
The reaction of MnX2 · 4H2O (X = Cl or Br) with 2,6-bis(hydroxymethyl)-4-methylphenol (H3L) and NaOH in methanol solution yielded two tetranuclear manganese complexes, [Mn4(HL)4(MeOH)4Cl2] (1) and [Mn4(HL)4(MeOH)4Br2] (2). Both compounds crystallize in the monoclinic space group C2/c with cell parameters: a = 26.0945(19) Å, b = 11.4999(8) Å, c = 21.2188(16) Å, β = 121.050(1)° and z = 4 for 1 · 2Et2O; a = 25.8145(3) Å, b = 11.6734(2) Å, c = 21.3956(3) Å, β = 120.1277(6)° and z = 4 for 2 · 2Et2O. Both complexes consist of a mixed-valence dicubane structure, which comprises two MnII and two MnIII ions. Magnetic susceptibilities and magnetization of complexes 1 and 2 in the solid state indicate that two clusters have an S = 9 ground state. Frequency-dependent out-of-phase signals of alternating current magnetic susceptibilities were observed in the low temperature range (<3 K) for both complexes indicating a slow magnetic relaxation.  相似文献   

6.
Hydrous vanadium oxide (denoted as VOx·yH2O) deposited at 0.4 V shows promising capacitive behavior in aqueous media containing concentrated Li ions. VOx·yH2O annealed in air at 300 °C for 1 h shows highly reversible Li-ion intercalation/de-intercalation behavior with specific capacitance reaching ca. 737 and 606 F g? 1 at 25 and 500 mV s? 1 in 12 M LiCl between ?0.2 and 0.8 V. In 14 M LiCl, retention of specific capacitance is about 95% when the scan rate is increased from 25 to 500 mV s? 1. This work is the first report showing the ultrahigh rate of Li-ion intercalation/de-intercalation in VOx·yH2O. A so-called Li-ion supercapacitor of the asymmetric type consisting of a VOx.yH2O cathode and a WO3.zH2O anode is proposed here.  相似文献   

7.
(Solid + liquid) equilibria (SLE) and (liquid + liquid) equilibria (LLE) for the binary systems: {ionic liquid (IL) N-butyl-4-methylpyridinium tosylate (p-toluenesulfonate) [BM4Py][TOS], or N-butyl-3-methylpyridinium tosylate [BM3Py][TOS], or N-hexyl-3-methylpyridinium tosylate [HM3Py][TOS], or N-butyl-4-methylpyridinium bis{(trifluoromethyl)sulfonyl}imide [BM4Py][NTf2], or 1,4-dimethylpyridinium tosylate [M1,4Py][TOS], or 2,4,6-collidine tosylate [M2,4,6Py][TOS], or 1-ethyl-3-methylimidazolium thiocyanate [EMIM][SCN], or 1-butyl-3-methylimidazolium thiocyanate [BMIM][SCN], or 1-hexyl-3-methylimidazolium thiocyanate [HMIM][SCN], or triethylsulphonium bis(trifluoromethylsulfonyl)imide [Et3S][NTf2] + thiophene} have been determined at ambient pressure. A dynamic method was used over a broad range of mole fractions and temperatures from (270 to 390) K. In the case of systems (pyridinium IL, or sulphonium IL + thiophene) the mutual immiscibility with an upper critical solution temperature (UCST) was detected at the very narrow and low mole fraction of the IL. For the binary systems containing (imidazolium thiocyanate IL + thiophene), the mutual immiscibility with the lower critical solution temperature (LCST) was detected at the higher mole fraction range of the IL. The basic thermal properties of the pure ILs, i.e. melting and glass-transition temperatures as well as the enthalpy of fusion have been measured using a differential scanning microcalorimetry technique (DSC). The well-known NRTL equation has been used to correlate experimental SLE/LLE data sets.  相似文献   

8.
Two new hybrid materials, (C4H14N2)[MII(H2O)6](SO4)2·4H2O (MII: Co (I), Ni (II)), have been synthesised by slow evaporation method at room temperature and crystallographically characterized. They crystallise isotypically in the monoclinic system, space group P21/n, with the following unit-cell parameters a = 9.2285(3), b = 11.3333(4), c = 10.6693(4) Å, β = 109.004(2)°, Z = 2 and V = 1055.07(6) Å3 for I and a = 9.2127(2), b = 11.3182(2), c = 10.6434(2) Å, β = 109.094(1)°, Z = 2 and V = 1048.74(4) Å3 for II. The structure of the two supramolecular compounds consists of metallic cation octahedrally coordinated to six water molecules, sulfate anions, 1,4-butanediammonium cation and water molecules linked together via two types of hydrogen bonds, O–H?O and N–H?O. The two compounds are not stable at room temperature and their partial dehydration depends on the humidity of the environment. The thermal decomposition of precursors, studied by thermogravimetric analysis (TG) and temperature-dependent X-ray diffraction (TDXD), shows successive intermediate hydrates and crystalline anhydrous compounds upon dehydration.  相似文献   

9.
The enthalpies of solution of 1,4-dioxane in {(1  x)F + xH2O}, {(1  x)NMF + xH2O}, and {(1  x)DMF + xH2O} have been measured within the whole mole fraction range at T = 298.15 K. Based on the obtained data, the effect of substituting methyl groups at the nitrogen atom in formamide on the preferential solvation of 1,4-dioxane has been analyzed. A simple model has been proposed to describe the influence of structural and energetic properties of the mixed solvent on the energetic effect of hydrophobic hydration and preferential solvation of 1,4-dioxane by the components of the examined mixture.  相似文献   

10.
Benzhydryl protection by diphenyldiazomethane of an alcohol in enantiomeric base-sensitive ribonolactones allows short efficient syntheses of 1,4-dideoxy-1,4-imino-d-lyxitol (DIL) and of 1,4-dideoxy-1,4-imino-l-lyxitol (LIL). DIL showed potent [Ki = 0.13 μM]—and LIL showed weak [Ki = 113 μM]—competitive inhibition of α-d-galactosidase. Both enantiomers N-benzyl-DIL [Ki = 64 μM] and N-benzyl-LIL [Ki = 13 μM] were moderate competitive inhibitors of naringinase, an α-l-rhamnosidase.  相似文献   

11.
The title compound MIL-131 (MIL stands for Material from Institut Lavoisier) was prepared hydrothermally (4 days, 473 K, autogenous pressure) in the presence of an organic base (N((CH2)2NH2)3). The structure of MIL-131 or TiIIITiIV(OH)F4(HPO4)·(PO4)·(N((CH2)2NH3)3) has been determined ab initio from X-Ray synchrotron powder diffraction data using simulated annealing methods and was refined in the triclinic space group P-1 (no. 2). MIL-131 exhibits a one-dimensional structure built up from inorganic chains of corner sharing TiO5(OH) titanium(III) octahedra and PO4 and HPO4 phosphate tetrahedra, related to TiO2F4 titanium octahedra. Protonated triamine cations are located between the inorganic motifs, and interact strongly with the mineral network through hydrogen bondings both with terminal fluorine atoms and hydroxo or oxo groups. Multinuclear solid state NMR has allowed a clear attribution of the protons, fluoride, and phosphate groups environment within the framework of MIL-131. The large values of chemical shift anisotropy together with the absence of any 13C NMR response confirmed the presence of paramagnetic titanium(III) species deduced from the crystal structure. Finally, 2D MAS 1H-31P CP-HETCOR NMR correlation experiment gives some insight on the nature of the intra-framework hydrogen bonding.Crystal data for MIL-131: a = 14.109(1) Å, b = 8.462(3) Å, c = 7.179(1) Å, α = 93.772(1)°, β = 96.566(2)°, γ = 98.004(1)°, V = 840.36(2) Å3, z = 2.  相似文献   

12.
The carbene complex [Pd0(NHC)(quinone)]2with NHC = 1,3-bis(2,4,6-trimethylphenyl)-imidazol-2-ylidene and quinone = 1,4-naphthoquinone shows two long-wavelength absorptions at 312 and 399 nm which are assigned to (NHC→quinone) LLCT and (Pd0  quinone) MLCT transitions. The MLCT state is not reactive, but emissive (λmax = 564 nm at 77 K). At r.t., the complex undergoes a photoredox decomposition which is initiated by the LLCT state.  相似文献   

13.
An anthracene-based macrocyclic receptor has been designed and synthesized for selective recognition of 1,4-phenylenediacetate (Ka = 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.  相似文献   

14.
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 15 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 17, and they have significant contributions to molecular self-assembly processes. The electrochemical studies of complexes 17 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.  相似文献   

15.
The measurement of excess enthalpies, HE, at T=298.15 K and densities at temperatures between 283.15 K and 313.15 K are reported for the (2-methoxyethanol + 1,4-dioxane) and (1,2-dimethoxyethane + benzene) systems. The values of HE and the excess volumes, VE, are positive, and the temperature dependence of VE is quite small for (2-methoxyethanol + 1,4-dioxane). The (1,2-dimethoxyethane + benzene) system shows a negative HE and sigmoid curves in VE, which change sign from positive to negative with an increase in 1,2-dimethoxyethane. The temperature dependence of VE for this system is negative.  相似文献   

16.
Excess molar enthalpies HmEand excess molar volumesVmE of (1,3-dimethyl-2-imidazolidinone  +  benzene, or methylbenzene, or 1,2-dimethylbenzene, or 1,3-dimethylbenzene, or 1,4-dimethylbenzene, or 1,3,5-trimethylbenzene, or ethylbenzene) over the whole range of compositions have been measured at T =  298.15 K. The excess molar enthalpy values were positive for five of the seven systems studied and the excess molar volume values were negative for six of the seven systems studied. The excess enthalpy ranged from a maximum of 435 J · mol  1for (1,3-dimethyl-2-imidazoline  +  1,3,5-trimethylbenzene) to a minimum of   308 J · mol  1for (1,3-dimethyl-2-imidazoline  +  benzene). The excess molar volume values ranged from a maximum of 0.95cm3mol  1 for (1,3-dimethyl-2-imidazoline  +  ethylbenzene) and a minimum of   1.41 cm3mol  1for (1,3-dimethyl-2-imidazoline  +  methylbenzene). The Redlich–Kister polynomial was used to correlate both the excess molar enthalpy and the excess molar volume data and the NRTL and UNIQUAC models were used to correlate the enthalpy of mixing data. The NRTL equation was found to be more suitable than the UNIQUAC equation for these systems. The results are discussed in terms of the polarizability of the aromatic compound and the effect of methyl substituents on the benzene ring.  相似文献   

17.
Reactions of Be2+ and Mg2+ with O2– in molten eutectic mixture (CsCs + KCl + NaCl) (0.455:0.245:0.30) at T = 783 K were studied by a potentiometric method using Pt(O2)|ZrO2(Y2O3) indicator electrode. Addition of O2– ions to the melt containing Mg2+ results in precipitation of MgO (pKs,MgO = 11.89 ± 0.3, molality) whereas interaction of Be2+ with O2– is accompanied with sequential formation of Be2O2+ (pK = 15.68 ± 0.5, molality) and precipitation of BeO (pKs,BeO = 9.62 ± 0.3, molality). On the basis of the obtained and known data pKs,MgOT−1 dependence in molten (CsCs + KCl + NaCl) eutectic is constructed. The slope of the said dependence in T/K = (from 583 to 1073) range is in good agreement with the value predicted by the Shreder equation, that extends the range of use of the Shreder equation for predictions of metal oxide solubilities in molten halides.  相似文献   

18.
The vapour pressures of {ethanediamine (EDA) + water}, {1,2-diaminopropane (1,2-DAP) + water}, {1,3-diaminopropane (1,3-DAP) + water} or {1,4-diaminobutane (1,4-DAB) + water} binary mixtures, and of pure EDA, 1,2-DAP, 1,3-DAP, 1,4-DAB, and water components were measured by means of two static devices at temperatures between (293 and 363) K. The data were correlated with the Antoine equation. From these data, the excess Gibbs function (GE) was calculated for several constant temperatures and fitted to a fourth-order Redlich–Kister equation using the Barker’s method. The {ethanediamine (EDA) + water}, and {1,2-diaminopropane (1,2-DAP) + water} binary systems show negative azeotropic behaviour. The aqueous solutions of EDA, 1,2-DAP, or 1,3-DAP exhibit negative deviations in GE for all investigated temperatures over the whole composition range whereas the (1,4-DAB + water) binary mixture shows negative GE for temperatures (293.15 < T/K < 353.15) and a sinusoidal shape for GE at T = 363.15 K.  相似文献   

19.
《Vibrational Spectroscopy》2007,43(2):297-305
The new zinc(II) coordination polymer catena-poly[{aqua(η2-indole-3-carboxylato-O,O′)zinc}-μ-indole-3-carboxylato-O:O′], [Zn(I3CA)2(H2O)]n [Zn(I3CA)2(H2O)]n has been synthesized and characterized using infrared and Raman spectroscopy and X-ray single-crystal diffraction analysis. The crystals are monoclinic, space group Cc, with a = 33.319(7), b = 5.985(1), c = 8.291(2) Å, V = 1653.1(6) Å3 and z = 4. Each zinc centre is five-coordinated by the bidentate chelating indole-3-carboxylato, one oxygen atom bridging indole-3-carboxylato, water molecule and one oxygen atom bridging indole-3-carboxylato from an adjacent [Zn(I3CA)2(H2O)] unit. The Zn–O distances of 1.978(4), 1.987(3), 1.977(4), 1.983(3) and 2.519(4) Å, are typical for distances of such complexes. The infrared and Raman spectroscopic data of [Zn(I3CA)2(H2O)]n in the solid state are supported by X-ray analysis. The theoretical wavenumbers, infrared intensities and Raman scattering activities have been calculated by the density functional methods (B3LYP and mPW1PW) with the D95V**/LanL2DZ and 6-311++G(d,p)/LanL2DZ basis sets. The theoretical wavenumbers, infrared intensities and Raman scattering activities show a good agreement with experimental. Detailed band assignment has been made on the basis of the calculated potential energy distribution (PED). The results provide information on the strength of zinc-ligand bonding in complex.  相似文献   

20.
We have extended our research interest on titanium oxyphosphates (MII(TiO)2(PO4)2, with MII = Mg, Fe, Co, Ni, Cu, Zn) to vanadium oxyphosphates MII(VIVO)2(PO4)2 (MII = Co, Ni). For each compound two phases, named α and β according to synthesis conditions, have been stabilized at room temperature, then characterized. The four crystal structures M(VO)2(PO4)2 (α and β for M = Co, Ni) have been determined in monoclinic P21/c space group using X-ray single crystals diffraction data. Structure of the α phase is derived from the Li(TiO)(PO4) (orthorhombic Pnma) and LiNi0.50(TiO)2(PO4)2 (monoclinic P21/c) types, with cell parameters: a = 6.310(1) Å, b = 7.273(1) Å, c = 7.432(1) Å, β = 90.43(1)° for M = Co, and a = 6.297(2) Å, b = 7.230(2) Å, c = 7.421(2) Å, β = 90.36(2)° for M = Ni. Structure of the β phase is derived from the Ni(TiO)2(PO4)2-type (monoclinic P21/c) with cell parameters: a = 7.2742(2) Å, b = 7.2802(2) Å, c = 7.4550(2) Å, β = 120.171(2)° for M = Co, and a = 7.2691(2) Å, b = 7.2366(2) Å, c = 7.4453(2) Å, β = 120.231(2)° for M = Ni. All these structures consist of a three dimensional (3D) framework built up of infinite chains of tilted corner-sharing [VO6] octahedra, cross-linked by corner-sharing [PO4] tetrahedra. The M2+ ion (M = Co, Ni) is located in a triangular based antiprism which shares faces with two [VO6] octahedra. Structural filiation is discussed based on a common structural unit, a sheet where divalent cations M2+ (M = Co, Ni) are inserted. A thermal study of the α ? β transition is also presented.  相似文献   

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