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1.
The potential of the combined use of ESI–QqTOF-MS and ESI–QqTOF-MS/MS with mass-spectral library search for the identification
of therapeutic and illicit drugs has been evaluated. Reserpine was used for standardizing experimental conditions and for
characterization of the performance of the applied mass spectrometric system. Experiments revealed that because of the mass
accuracy, the stability of calibration, and the reproducibility of fragmentation, the QqTOF mass spectrometer is an appropriate
platform for establishment of a tandem-mass-spectral library. Three-hundred and nineteen substances were used as reference
samples to build the spectral library. For each reference compound, product-ion spectra were acquired at ten different collision-energy
values between 5 eV and 50 eV. For identification of unknown compounds, a library search algorithm was developed. The closeness
of matching between a measured product-ion spectrum and a spectrum stored in the library was characterized by a value called
“match probability”, which took into account the number of matched fragment ions, the number of fragment ions observed in
the two spectra, and the sum of the intensity differences calculated for matching fragments. A large value for the match probability
indicated a close match between the measured and the reference spectrum. A unique feature of the library search algorithm—an
implemented spectral purification option—enables characterization of multi-contributor fragment-ion spectra. With the aid
of this software feature, substances comprising only 1.0% of the total amount of binary mixtures were unequivocally assigned,
in addition to the isobaric main contributors. The spectral library was successfully applied to the characterization of 39
forensic casework samples.
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible to authorized users. 相似文献
2.
A series of oxovanadium(IV) complexes: TpVO(pzH)(2,4-Cl–C6H3–OCH2COO) (1), TpVO(pzH)(C6H5–OCH2COO) (2), TpVO(pzH)(p-Cl–C6H4–COO) (3), TpVO(pzH)(3,5-NO2–C6H3–COO) (4), Tp∗VO(pzH∗)(p-Cl–C6H4–COO) (5) and Tp∗VO(pzH∗)(p-Cl–C6H4–COO) · CH3OH (6) (Tp = hydrotris(pyrazolyl)borate, pzH = pyrazole, Tp∗ = hydrotris(3,5-dimethylpyrazolyl)borate, pzH∗ = 3,5-dimethylpyrazole) were synthesized and their crystal structures were determined by X-ray diffraction. In all the complexes, the vanadium ions are in a distorted-octahedral environment with a N4O2 donor set. Hydrogen bonding interaction exists in each complex. Complexes 1 and 2 are hydrogen-bonded dimers. Dimeric units of 2 are connected to one another via weak inter-molecular C–H···O interactions to form a 2D network on the bc-face. In 3–6 there exist intramolecular N–H···O hydrogen bonds between the neutral pyrazole/3,5-dimethylpyrazole and the uncoordinated carboxyl oxygen atom. In addition, the catalytic activity of complex 2 in a bromination reaction in phosphate buffer with phenol red as a trap was evaluated by UV–Vis spectroscopy. Furthermore, the elemental analyses, IR spectra and thermal stabilities were recorded. 相似文献
3.
YAN Cui-WeiDepartment of Biology Qufu Normal University Qufu Shandong ChinaLI Yan-Tuan HAN Qing-KuiDepartment of Chemistry Qufu Normal University Qufu Shandong ChinaLIAO Dai-ZhengDepartment of Chemistry Nankai University Tianjin China 《中国化学》1997,(4)
Six new μ-phthalato binuclear oxovanadium(IV) complexes,namely [(VO)2(PHTH)-(L)2]SO4 (L denotes 2,2'-bipyridine (bpy);1,10-phenanthroline (phen);4,4'-dimethyl-2,2'-bipyridine (Me2bpy);5-nitro-1,10-phenanthroline (NO2-phen);5-chloro-1,10-phenanthroline (Cl-phen) and 5-methyl-l,10-phenanthroline (CH3-phen),where PHTH is the phthalate dianion),have been synthesized and characterized by elemental analyses,IR,electronic spectra,magnetic moments at room temperature and molar conductivity measurements.The temperature dependence of the magnetic susceptibility of complexes [(VO)2(PHTH)(Phen)2]SO4 (1) and [(VO)2(PHTH)(CH3-phen)2]SO4 (2) was measured in 4-300 K range and the observed data were successfully simulated by the equation based on the spin Hamiltonian operator,H--2JS1S2,giving the exchange integrals J=-12.8 cm-1 for 1 and J=-7.9 cm-1 for 2.This indicates an antiferromagnetic spin-exchange interaction between the metal ions within each molecule. 相似文献
4.
Bashir Ahmad Malik 《Journal of Coordination Chemistry》2018,71(1):104-119
Six new mixed-ligand oxovanadium(IV) and manganese(II) complexes of the general composition [VO(dhaH)(L1H)(L2)] and [Mn(dhaH)(L1H)(L2)], where dhaH=dehydroacetic acid, L1H=β-ketoenolates viz., acetoacetanilide (aaaH), o-acetoacetotoluidide (o-aatdH), o-acetoacetanisidide (o-aansH) and L2=benzimidazole (bzl), 3-methyl-1phenyl-2pyrazoline-5one (mphp), 2-aminobenzimidazole (abzl) or 2-aminobenzathiozole (abtz) have been synthesized. The resultant complexes were characterized on the basis of elemental analysis, molar conductance, magnetic measurements, mass spectrometry, thermogravimetric analysis, infrared and electron spin resonance studies. The thermal decomposition processes of one representative of the complexes are discussed and the order of reaction (n), the activation energies (Ea), the pre-exponential factor (A), have been calculated from thermogravimetric (TG) and differential thermogravimetric (DTG) curves. Gaussian 09 software package was used to carry out theoretical computation using density functional theory (DFT) methods with Becke3-Lee-Yang-Parr (B3LYP) hybrid exchange-correlation functional and the standard LANL2 MB basis set. Based on combined experimental-theoretical characterization, a suitable octahedral structure has been proposed for this class of complexes. 相似文献
5.
Teresa Kowalik-Jankowska Henryk Kozlowski Karol Kociolek Miroslaw T. Leplawy Giovanni Micera 《Transition Metal Chemistry》1995,20(1):23-25
Summary Potentiometric and spectroscopic measurements were used to characterize the binding ability of -hydroxy-methylserine (Hms) with copper(II) and oxovanadium(IV) ions. The ligand was found to be generally a more efficient chelating agent than serine. Both of the deprotonated hydroxyl groups of Hms can be involved in coordination to vanadyl ions, whereas copper(II) binds in the same way as with serine. 相似文献
6.
LC–DAD coupled with electrospray tandem mass spectrometry (LC–ESI–MS–MS) has been used to evaluate the quality of the traditional Chinese medicine Huang-Lian-Jie-Du-Tang (HLJDT). Twenty-five chromatographic peaks were obtained from a C18 analytical column by gradient elution with acetonitrile and formate buffer (containing 0.5% formic acid) at a flow rate of 1.0 mL min?1. The linearity, precision, and accuracy of the data obtained were acceptable. Thirteen components were identified by ESI–MS, and seven of these were quantitatively analyzed by LC–DAD. The method was used to analyze ten batches of HLJDT, and both chromatographic fingerprints and quantitative data were used to evaluate the quality of the HLJDT. It was concluded that this LC–DAD–ESI–MS method enables more fully validated and complete evaluation and monitoring of the quality of HLJDT. 相似文献
7.
The aroylhydrazone Schiff base ligands (E)-N’-(2-hydroxybenzylidene)benzohydrazide = H2L1, (E)-N’-(2-hydroxy-3-methoxybenzylidene)benzohydrazide = H2L2 and = (E)-N’-(5-bromo-2-hydroxybenzylidene)benzohydrazide = H2L3 gave the vanadium(V)oxo-aroylhydrazone complexes [VVOL1(OCH3)(OHCH3] (1), [VVOL2(OCH3)(OHCH3]·CH3OH (2) and [VVOL3(OCH3)(OHCH3] (3) on reaction with vanadium(IV) oxide acetylacetonate. The complexes were characterized by spectroscopic methods in the solid state (IR) and in solution (UV–Vis, 1H NMR). Single crystal X-ray analysis was performed with 3. In methanol solution six-coordinated VVOL3(OCH3)(OHCH3) was formed. VIV was oxidized to Vv by aerial oxygen in the synthesis. In the VO5N coordination sphere the alcohol oxygen lies trans to the oxo oxygen. The general V–O bond length order is oxo < methoxylato < phenoxidic < enolato < alcoholic. The complexes are mononuclear, but intermolecular O–H?N hydrogen bonding affords a zigzag chain. DFT calculations on complex 3 reproduced the geometric parameters, IR and UV–Vis spectroscopic data well in a reasonable range. 相似文献
8.
V. A. Livshits B. B. Meshkov V. G. Avakyan B. G. Dzikovskii M. V. Alfimov 《High Energy Chemistry》2017,51(5):381-389
Host–guest complexes are of interest as promising nanodevices for molecular recognition and chemosensors. In this work, the structure and molecular dynamics of complexes of the nitroxyl radical TEMPO (I), as models of indicator and analyte, with cucurbituril CB[7] in solution and in the solid phase have been studied by ESR and DFT methods. The kinetic accessibility of the NO group of I for water-soluble reagents has been determined. By simulation of the ESR spectra of the complex, the rotational diffusion coefficients and the anisotropy of its rotation have been determined. To study the rotational mobility of the guest in the CB[7] cavity, solid solutions of I@CB[7] in the CB[7] matrix have been obtained. The ESR spectra indicate rapid jump-like rotation of I about an axis oriented along the normal to the CB[7] portals. The formation energy and the spatial structure of the complex have been calculated by the DFT method; a change in the spin density on the NO group with changing the orientation of I in the CB[7] cavity has been found. 相似文献
9.
I. V. Fedorova E. A. Khatuntseva M. A. Krest’yaninov L. P. Safonova 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2016,90(2):293-299
Proton transfer along the hydrogen bond in complexes of DMF with Н3РО4, Н3РО3, СН3Н2РО3, and their dimers has been investigated by the B3LYP/6-31++G** method in combination with the C-PCM model. When the Оacid···ОDMF distance (R) in the scanning procedure is not fixed, the energy profile in all cases has a single well. When this distance is fixed, there can be a proton transfer in all of the complexes in the gas phase at R > 2.6 Å; if solvation is taken into account, proton transfer can take place at R > 2.4 Å (R > 2.5 Å for DMF complexes with СН3Н2РО3 and its dimer). The height of the energy barrier to proton transfer increases with increasing R. Proton transfer is energetically most favorable in the DMF–phosphoric acid complexes. The structural and energetic characteristics of the hydrogen-bonded complexes calculated on the basis of the solvation model are compared with the same parameters for the complexes in the gas phase. 相似文献
10.
Edward S. Chen Edward C. M. Chen Frank C. Anderson Sunil Pai 《Structural chemistry》2012,23(2):407-410
Only one electron affinity of oxygen, 43(1) kJ mol−1 is generally cited since the molecular orbital theory anion bond order [3/4] gives an electron affinity, 14 kJ mol−1. However, electron correlation rules predict 27 bonding and 27 antibonding spin orbital coupling states. The relative bond
orders (RBOs), 12/13 to [1/4] and the 13 valence electrons of superoxide are used to calculate electron affinities 103 to
−243 kJ mol−1 consistent with experimental and theoretical values. These are used to construct 54 ionic Morse potentials. 相似文献
11.
Ferouani Ghaniya Ameur Nawal Bachir Redouane 《Research on Chemical Intermediates》2020,46(2):1373-1387
Research on Chemical Intermediates - Bimetallic gold–iron catalysts supported on ZrO2 and TiO2 were prepared by under potential deposition. The characterization of the catalysts was performed... 相似文献
12.
A. V. Naumov T. V. Samofalova V. N. Semenov I. V. Nechaev 《Russian Journal of Inorganic Chemistry》2011,56(4):621-627
Solid solutions of the CdS-ZnS system deposited as polycrystalline films by aerosol pyrolysis from aqueous solutions of cadmium
and zinc thiourea complexes have been studied. The phase composition and solid-phase solubility are dictated by the nature
of initial complexes. From solutions of [M(thio)2(CH3COO)2] complexes, sphalerite sulfides are precipitated, which form a continuous solid solution s-Cd1−x
Zn
x
S, whereas the use of the [M(thio)2Cl2] precursor leads to crystallization of the wurtzite w-Cd1−x
Zn
x
S solid solution based on CdS (the homogeneity range 0–20 mol % ZnS) and the s-Cd1−x
Zn
x
S solid solution based on zinc sulfide (50–100 mol % ZnS). The structure of the solid phase in the sulfide system is attributed
to the specific features of the stereochemistry of complex precursors. 相似文献
13.
V. Yu. Buz’ko Kh. B. Kushkhov M. B. Buz’ko 《Russian Journal of Inorganic Chemistry》2010,55(3):395-400
The structural and energetic characteristics of ThF
n
(4−n)+ (n = 1–8) complexes have been calculated by the ab initio RHF and MP2 methods. 相似文献
14.
15.
R. Lalrempuia Patrick J. Carroll K.A. Kreisel 《Journal of organometallic chemistry》2005,690(17):3990-3996
The reactions of [(ind)Ru(PPh3)2CN] (ind = η5-C9H7) (1) and [CpRu(PPh3)2CN] (Cp = η5-C5H5) (2) with [(η6-p-cymene)Ru(bipy)Cl]Cl (bipy = 2,2′-bipyridine) (3) in the presence of AgNO3/NH4BF4 in methanol, respectively, yielded dicationic cyano-bridged complexes of the type [(ind)(PPh3)2Ru(μ-CN)Ru(bipy)(η6-p-cymene)](BF4)2 (4) and [Cp(PPh3)2Ru(μ-CN)Ru(bipy)(η6-p-cymene)](BF4)2 (5). The reaction of [CpRu(PPh3)2CN] (2), [CpOs(PPh3)2CN] (6) and [CpRu(dppe)CN] (7) with the corresponding halide complexes and [(η6-p-cymene)RuCl2]2 formed the monocationic cyano-bridge complexes [Cp(PPh3)2Ru(μ-CN)Os(PPh3)2Cp](BF4) (8), [Cp(PPh3)2Os(μ- CN)Ru(PPh3)2Cp](BF4) (9) and [Cp(dppe)Ru(μ-CN)Os(PPh3)2Cp](BF4) (10) along with the neutral complexes [Cp(PPh3)2Ru(μ-CN)Ru (η6-p-cymene)Cl2] (11), [Cp(PPh3)2Os(μ-CN)Ru(η6-p-cymene)Cl2] (12), and [Cp(dppe) Ru(μ-CN)Ru(η6-p-cymene)Cl2] (13). These complexes were characterized by FT IR, 1H NMR, 31P{1H} NMR spectroscopy and the molecular structures of complexes 4, 8 and 11 were solved by X-ray diffraction studies. 相似文献
16.
《Physics and Chemistry of Liquids》2012,50(1):128-130
The present authors have given an exact theory of the exchange-correlation potential V xc (r) in terms of (i) the exact ground-state electron density n(r) and (ii) the idempotent Dirac density matrix γ(r,?r′) generated by the DFT one-body potential V(r), having n(r) as its diagonal element. Here, we display two approximate consequences: (a) a form of V xc (r) generated by the semiempirically fine-tuned HF density of Cordero et al. (N.A. Cordero, N.H. March, and J.A. Alonso, Phys. Rev. A 75, 052502 (2007)) and (b) the exchange-only potential V x (r) determined solely by the HF ground state density for the Be atom. 相似文献
17.
Five oxovanadium(Ⅳ) dinuclear complexes described by the overall formula [(VO)2(IA)L2]-SO4, where IA represents the dianion of iodanilic acid and L denotes 2,2'-bipyridine (bpy) ; 4,4'-dimethyl-2,2'-bipyridine (Me2-bpy); 1,10-phenanthroline (phen); 4,7-diphenyl-1, 10-phenanthroline (Ph2-phen) and 5-nitro-l, 10-phenanthroline (NO2-phen) , have been synthesized and characterized by elemental analyses, molar conductivity and room-temperature magnetic moment measurements, IR and electronic spectral studies. It is proposed that these complexes have IA-bridged structures and consist of two oxovanadium(Ⅳ) ions each in a square- pyramidal environment. The complexes [ ( VO)2 (IA) (bpy )2 ] SO4 (1) and [ ( VO )2 ( IA) ( phen)2 ] -SO4 (2) were further characterized by variable temperature (4.2-300 K) magnetic susceptibility measurements and the observed data were fitted to the modified Bleaney-Bowers equation by the least-squares method, giving the exchange integral J = -2.15 cm-1 for 1 and J = - 9.88 cm-1 for 2 相似文献
18.
Synergistic enhancement of carrier separation-transport and acceleration of water oxidation kinetics is an effective way to boost the current density of photoanode. Therefore, in this work, we constructed Ti3C2Tx MXene conductive framework by cyclic voltammetric (CV) deposition within BiVO4 to force carrier separation-transfer while also depositing O-vacancied FeOOH by in situ self-hydrolysis to accelerate water oxidation kinetics. Predictably, the constructed MXene–BiVO4–FeOOH composite photoanode exhibits an impressive current density of 4.95 mA/cm2 (1.23 V vs. RHE) and 4.1 times higher than that of pristine BiVO4, as well as an ultra-low onset potential and high stability. This fantastic enhancement is attributed to the MXene conductive framework avoiding carrier recombination, tightening the interface of BiVO4–FeOOH, moreover O-vacancied FeOOH improves the adsorption of H2O to accelerate the water oxidation kinetics. This work demonstrates a successful method for constructing efficient and stable photoanodes as well as diversifying the application of MXene in photoelectrocatalysis. 相似文献
19.
《Electrochemistry communications》2008,10(6):876-879
A novel synthesis route, concerning in situ interfacial polymerization of pyrrole on carbon black and following co-deposition of Pt and Fe on polypyrrole–carbon support, is developed to prepare the bimetallic Pt–Fe/polypyrrole–carbon catalyst. In this synthesis process, ferrous precursor simultaneously functions as an oxidant for the polymerization of pyrrole. The Pt–Fe/polypyrrole–carbon catalyst shows improved catalytic activity towards methanol oxidation compared to commercial Pt/C catalyst, which may be of great potential in direct methanol fuel cells. 相似文献
20.
Density functional theory (DFT) calculations are reported for 16 binuclear transition-metal complexes. Structural motifs studied include face-shared and edge-shared bioctahedra, carboxylate-bridged "paddlewheel" complexes, and nonbridged dimers possessing direct metal-metal bonds. Most of these structure types are represented both by multiply charged (tri- and tetra-anionic, and tetracationic) and by neutral or singly charged examples. Geometry optimizations for these species, in the vacuum phase, use the "broken-symmetry" approach coupled with nine different DFT methods. We find a clear dichotomy in the performance of different DFT approaches. For the eight neutral or singly charged complexes, orthodox gradient-corrected DFT methods such as BP and PBE perform generally very well in reproducing in vacuo the complex geometries obtained from X-ray crystallographic studies. In contrast, these orthodox approaches fail to reliably mimic the crystalline geometries for more highly charged complexes such as Mo(2)Cl(9)(3-), Cr(2)(CH(3))(8)(4-), and Rh(2)(NCCH(3))(10)(4+). Much closer agreement with experimental condensed-phase structures for the multiply charged dinuclear complexes is seen for two "local-density-approximation" approaches, X alpha and VWN, and for VWN+B-LYP, an unorthodox combination of the VWN local and B-LYP nonlocal density functionals. The very good performance of the latter approaches arises from an essentially fortuitous cancellation of errors: while the generally overbinding nature of these approaches suggests that they will not reliably describe true gas-phase structures, this overbinding compensates very well for the coulombic distortion expected when complexes are removed from the charge-stabilizing environment of the crystalline or solvated state. We recommend that, as an alternative to the (computationally expensive) incorporation of solvent-field corrections, VWN+B-LYP is the preferred method for structural characterization of triply or more highly charged dinuclear complexes, while orthodox approaches such as PBE perform best for neutral or mildly charged complexes. 相似文献