共查询到20条相似文献,搜索用时 15 毫秒
1.
Junfeng Geng Brian F. G. Johnson Andrew E. H. Wheatley Jack K. Luo 《Central European Journal of Chemistry》2014,12(3):307-311
Using a very popular and commonly used surfactant sodium dodecylbenzene sulfonate (SDBS, C18H29SO3Na) for a case study, we report a new method of monitoring different forms of surfactant molecules in aqueous solution and measuring their critical micelle concentration (CMC) by ultraviolet-visible (UV-Vis) spectroscopy. The forms of SDBS micelles are also investigated by synthesizing and characterizing NiB nanoparticles using the micelles as molecular templates. In addition, the observed shifts of UV-Vis bands are analysed from the viewpoint of the electrons locations and distributions within the molecules and the possible overlap of their electronic orbitals between neighbouring molecules in each micelle. 相似文献
2.
Nanosized NiO2 particles with an average diameter of 15 nm are prepared by treating of Ni(NO3)2 · 6H2O with an aqueous solution of KClO in the presence of Triton® X-100. This black fine powder of nickel peroxide was characterized by XRD diffraction, energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM). The as-prepared NiO2 can be easily transformed to nanosized NiO merely by washing it with acetone. The obtained NiO has an average diameter of 40 nm and was characterized by the same means used for NiO2. The nanoparticles of NiO2 and NiO were obtained in high yields and purities. 相似文献
3.
Nuša Hojnik Matjaž Kristl Amalija Golobič Zvonko Jagličić Miha Drofenik 《Central European Journal of Chemistry》2014,12(2):220-226
This article reports the synthesis of novel, rare-earth coordination complexes with nicotinic acid. Three compounds with the general formula Ln2[(C5H4NCOO)6(H2O)4] (Ln = Yb, 1; Ln = Gd, 2; Ln = Nd, 3) were prepared from relatively cheap and readily available reactants. Their compositions and structure were characterized by IR spectroscopy and single-crystal X-ray diffraction. The magnetic and thermogravimetric properties were also studied. The complexes consist of centrosymetric, dimeric molecules having all six nicotinato ligands coordinated with the central atom in the bidentate mode. The coordination environment of the Ln3+ for all three compounds is 8. Here we describe the crystal structure of Yb and Gd complexes with nicotinic acid. 相似文献
4.
Vitor H. Rodrigues Maria M. R. R. Costa Etelvina M. Gomes Dmitry Isakov Michael S. Belsley 《Central European Journal of Chemistry》2014,12(10):1016-1022
The crystal structure and non-linear optical properties of L-alaninium perrhenate, C3H8NO2+ ReO4 ?, are reported. The protonated amino acid and the perrhenate anion have their usual geometries. The three-dimensional hydrogen-bonded network can be seen as a stacking of layers parallel to the (100) planes. Each layer is formed by chains of alternating positive and negative ions along the b and c axes. Hydrogen bonding of adjacent layers forms alternating chains along the a axis. A high damage threshold and a second-harmonic generation efficiency three times that of KDP make this new material potentially useful in non-linear optics. 相似文献
5.
Characterization of the citrate precursor, used for synthesis of nanosized Mg-Zn ferrites 总被引:1,自引:0,他引:1
Violeta D. Kassabova-Zhetcheva 《Central European Journal of Chemistry》2009,7(3):415-422
The citrate precursor has been used to synthesize nanocrystalline Mg-Zn-ferrites. The nature of the prepared precursor is characterized and compared with those of the precursors studied earlier, prepared by the same process. The study has been performed by inorganic and organic elemental analyses, Fourier Transformed Infrared Spectroscopy (FTIR), Mössbauer spectroscopy, X-ray Photoelectron Spectroscopy (XPS), Electron Paramagnetic Resonance (EPR), Electronic absorption spectrometry in the UV-VIS region, Differential Thermal analysis/ Thermogravimetry (DTA-TG) analyses, and X-ray diffraction (XRD) analysis. The collected results determined the precursor as a coordination polymer with monomer unit (NH4)4{M [Fe(C6H5O7)2]2}, where M=Zn or Mg. 相似文献
6.
Rafał Frański Tomasz Kozik Bartosz Staniszewski Włodzimierz Urbaniak 《Central European Journal of Chemistry》2010,8(3):508-512
It has been demonstrated that phenylcopper(I)-containing clusters are generated in the gas phase from bis(dibenzoylmethane) copper(II) (Cu(dbm)2) by laser desorption/ ionization (LDI) method. For example, the [Cu5dbm2(C6H5)2]+ ion can be considered as consisting of two Cudbm molecules, two CuC6H5 molecules and a Cu+ cation. The [Cu5(C6H5)4]+ ion can be considered as phenylcopper(I) cluster (consisting of four phenylcopper molecules) ionized by additional Cu+ cation. Results from MS/MS (tandem mass spectrometry) experiments have confirmed the presence of phenylcopper molecules in the analyzed clusters. Ease of preparation of dibenzoylmethane-metal complexes and straightforward method to obtain LDI mass spectra offer a wide range of possibilities to study similar organometallic clusters in the gas phase. 相似文献
7.
Mehmet Senel Hüseyin Kavas Mehmet Tutgun Abdulhadi Baykal 《Central European Journal of Chemistry》2013,11(11):1768-1779
Nanocomposites of Polyacrylic acid/polyvinylimidazole (PAA/PVI) with grafted and ungrafted iron oxide nanoparticles were prepared by a Reflux method. The Fe3O4 nanoparticles with 10 nm average diameter were synthesized by controlled co-precipitation and silanization of Si-PVI on Fe3O4 was used to obtain the grafted ones. Grafting becomes important at composites of less PVI that cause drastic decreases in AC conductivity. The content of PVI has important effects on the conductivity mechanism of these composites. The effect of grafting and Polyacrylic acid/polyvinylimidazole molar ratio on the conduction mechanism were studied. The conduction mechanism of iron oxide nanocomposites can be adjusted by changing molar ratio of Polyacrylic acid/polyvinylimidazole and grafting of Fe3O4 NPs. 相似文献
8.
Mukesh Kumar Atal Veena Dhayal Meena Nagar Rakesh Bohra Kuldeep S. Rathore Narendra S. Saxena 《Journal of Sol-Gel Science and Technology》2010,53(1):67-78
Reaction of [VO(OPr i )3] (1) with [O(CH2CH2OH)2] in 1:1 molar ratio in anhydrous benzene yield glycol-modified precursor, [VO{OCH2CH2OCH2CH2O}{OPr i }] (2). Further reactions of (2) with internally functionalized oximes in anhydrous benzene yield heteroleptic complexes of the type [VO{OCH2CH2OCH2CH2O}{ON=C(R)(Ar)}] (3–8) {where R=CH3, Ar=C4H3O-2 (3), C4H3S-2 (4), C5H4N-2 (5); and when R=H, Ar=C4H3O-2 (6), C4H3S-2 (7), C5H4N-2 (8)}. All these derivatives have been characterized by elemental analyses, molecular weight measurements and spectroscopic techniques. The crysoscopic molecular weight measurement as well as FAB mass study suggests dimeric nature of (2). However, FAB mass spectrum of (4), and the crysoscopic molecular weight measurements of (3), (4), (5) and (6) indicate the monomeric behavior of the oximato derivatives (3–8). Hexa-coordination around vanadium(V) has been proposed for both monomeric and dimeric derivatives. Sol–gel transformations of (1), (2) or (4) to vanadia [(a), (b) or (c), respectively] have been carried out at low sintering temperature (600 °C). The XRD patterns of (a), (b) or (c) indicate formation of a single orthorhombic phase in all the three cases. The SEM images suggest grain like [for (a) and (b)] and rod like [for (c)] morphology of the crystallites. IR, Raman spectra as well as EDX analyses indicate formation of pure vanadia. Absorption spectra of the vanadia (b) and (c) suggest energy band gaps of 2.53 and 2.65 eV, respectively. 相似文献
9.
Alicja Gackowska Maciej Przybyłek Waldemar Studziński Jerzy Gaca 《Central European Journal of Chemistry》2014,12(5):612-623
2-Ethylhexyl 4-methoxycinnamate (EHMC) is one of the most commonly used sunscreen ingredient. In this study we investigated photodegradation of EHMC in the presence of such common oxidizing and chlorinating systems as H2O2, H2O2/HCl, H2O2/UV, and H2O2/HCl/UV. Reaction products were detected by gas chromatography with a mass spectrometric detector (GC-MS). As a result of experimental studies chloro-substituted 4-methoxycinnamic acid (4-MCA), 4-methoxybenzaldehyde (4-MBA) and 4-methoxyphenol (4-MP) were identified. Experimental studies were enriched with DFT and MP2 calculations. We found that reactions of 4-MCA, 4-MBA and 4-MP with Cl2 and HOCl were in all cases thermodynamically favorable. However, reactivity indices provide a better explanation of the formation of particular chloroorganic compounds. Generally, those isomeric forms of mono- and dichlorinated compounds which exhibits the highest hardness were identified. Nucleophilicity of the chloroorganic compounds precursors were examined by means of the Fukui function. 相似文献
10.
Mihaela Vlassa Gheorghe Borodi Cristian Silvestru Mircea Vlassa 《Central European Journal of Chemistry》2014,12(1):14-24
Reaction of Na4TCM (1) (H4TCM = tetra[4-(carboxyphenyl)oxamethyl]methane) with [Cu(CHA)](ClO4)2 (2)(CHA = 1,3,6,8,11,14-hexaaz atricyclo[12.2.1.1.8,11] octadecane) in a DMF-water mixture yields [Cu(CHA)]2[TCM] (3). Structural analysis of [Cu(CHA)]2[TCM]·11H2O (3·11H2O) by single crystal X-ray diffraction reveals strong copper-oxygen bonds between two complex cations and the tetraanion leading to a 3D coordination network (zwitterionic structure), consolidated through additional NH...O=C hydrogen bonding within the cation/anion association. The resulting coordination geometry around a copper atom is a distorted square pyramidal with an oxygen atom of the anionic ligand in the apical position. A 3D supramolecular network is developed in the crystal based only on NH...OC hydrogen bonds between the macrocyclic metallic tecton and the carboxylate groups of neighboring 3D coordinated (zwitterionic) moieties. The pseudotetrahedral TCM4? tetraanionic ligand induces a diamondoid architecture formed of large distorted adamantanoid cages. 相似文献
11.
A novel triply bridged dinuclear copper(I) complex: Cu2(μ-paa)(μ-dcpm)2(BF4)2·2CH2Cl2 [ paa = pyridine-2-carbaldehyde azine (C12H10N4) and dcpm = bis(dicyclohexylphosphino)methane(C25H46P2) ] has been synthesized and structurally characterized. Crystallographic studies of the complex showed that two copper(I) ions were bridged by one paa ligand and two dcpm ligands. The paa ligand adopted the Z configuration at the partially double N-N bond and the two copper ions have distorted tetrahedral coordination geometry. Because of the steric effect of dcpm, the pyridine rings of the paa ligand are obviously not on the same plane (the dihedral angle is 43.610). The interaction between neighboring ligands results in a N-N bond length (1.374(7) Å) contraction. The UV-vis spectra of the complex exhibited intense high-energy absorptions at λmax < 340 nm and broad visible bands in a range of 380?550 nm, ascribed to intraligand (IL π-π*) transitions and metal-to-ligand charge-transfer (MLCT) transitions, respectively. Interestingly, the absorbtion peaks varied regularly with the solvent polarity. Although the complex has a rigid structure with the copper ions held firmly by triply bridged ligands, the emission and excitation spectra revealed that the complex exhibits weak fluorescence. 相似文献
12.
Beata Zielinska Magdalena Janus Ryszard J. Kalenczuk 《Central European Journal of Chemistry》2013,11(6):920-926
The Co3O4/LiNbO3 composites were synthesized by impregnation of LiNbO3 in an aqueous solution of cobalt nitrate and next by calcination at 400°C. The activity of produced samples has been investigated in the reaction of photocatalytic hydrogen generation. The crystallographic phases, optical and vibronic properties were studied using X-ray diffraction (XRD), diffuse reflectance (DR) UV-vis and resonance Raman spectroscopic techniques, respectively. The influence of cobalt content (range from 0.5 wt.% to 4 wt.%) on the photocatalytic activity of Co3O4/LiNbO3 composites for photocatalytic hydrogen generation has been investigated. Co3O4/LiNbO3 composites exhibited higher than LiNbO3 photocatalytic activity for hydrogen generation. The highest H2 evolution efficiency was observed for Co3O4/LiNbO3 composite with 3 wt.% cobalt content. The amount of H2 obtained in the presence of LiNbO3 and Co3O4/LiNbO3 (3 wt.% of cobalt content) was 1.38 µmol/min and 2.59 µmol min?1, respectively. 相似文献
13.
Juliana Ivanova Ivayla N. Pantcheva Mariana Mitewa Svetlana Simova Heike Mayer-Figge William S. Sheldrick 《Central European Journal of Chemistry》2010,8(4):852-860
The single crystal X-ray structures and the spectroscopic properties of complexes of monensic acid (C36H62O11·H2O) with toxic metal ions of Cd(II) and Hg(II) are discussed. The cadmium(II) complex (1) is of composition [Cd(C36H61O11)2(H2O)2] and crystallizes in the monoclinic system (space group P2(1), Z = 2) with a = 12.4090(8), b = 24.7688(16), c = 14.4358(11) Å, β = 91.979(7)°. Two ligand monoanions are bound in a bidentate coordination mode to Cd(II) via the carboxylate and the primary hydroxyl oxygens occupying the equatorial plane of the complex. The axial positions of the inner coordination sphere of Cd(II) are filled by two water molecules additionally engaged in intramolecular hydrogen bonds. The Hg(II) complex (2), [Hg(C36H60O11)(H2O)], crystallizes in the orthorhombic system (space group P2(1)2(1)2(1), Z = 4) with a = 12.7316(2), b = 16.4379(3), c = 18.7184(4) Å. The monensic acid reacts with Hg(II) in a tetradentate coordination manner via both oxygen atoms of the carboxylate function and oxygens of two hydroxyl groups. The twofold negative charge of the ligand is achieved by deprotonation of carboxylic and secondary hydroxyl groups located at the opposite ends of the molecule. Hg(II) is surrounded by five oxygen atoms in a distorted square pyramidal molecular geometry.
相似文献
14.
Ana-Maria Ungureanu Ovidiu Oprea Bogdan Stefan Vasile Corina Andronescu Georgeta Voicu Ioana Jitaru 《Central European Journal of Chemistry》2014,12(9):909-917
We successfully synthesized tin dioxide nanoparticles with polyhedral morphology via an ethylene glycol assisted sol-gel approach. The structural characteristics of three tin dioxide samples were investigated after being thermally treated at 400°C, 600°C and 800°C. X-ray diffraction (XRD) patterns clearly show the formation of single phase tin dioxide nanoparticles, with crystallite size of 6–20 nm, in good correlation with Fourier transform infrared (FTIR) spectra. Transmission electron microscopy (TEM) analysis confirms the formation of 6nm polyhedral nanoparticles for the 400°C sample. Ultraviolet-visible (UV-Vis) and photoluminescence (PL) spectra suggest a high concentration of oxygen vacancies. The oxygen vacancy concentration increases with temperature, due to the combined action of the formation of VO and the energetic O compensation. X-ray photoelectron spectroscopy (XPS) analysis also confirms the formation of single phase tin dioxide and the presence of oxygen vacancies in good agreement with UV-VIS and PL data. 相似文献
15.
Mirela Călinescu Ticuţa Negreanu-Pîrjol Rodica Georgescu Octavian Călinescu 《Central European Journal of Chemistry》2010,8(3):543-549
Three new copper(II) complex compounds with chlorhexidine diacetate as a ligand have been prepared and characterized by elemental
and thermogravimetrical analyses, molar conductances, magnetic susceptibility measurements, infrared, electronic and EPR spectra.
The complexes correspond to the formulas: [Cu2(CHX)Cl4]·2C2H5OH, [Cu2(CHX)Br4]·2C2H5OH and [Cu2(CHX)(CH3COO)2] (CH3COO)2·2C2H5OH, where CHX = chlorhexidine, their composition and stereochemistry depending on the reaction conditions and the metal salt
used. Chlorhexidine acts as neutral tetradentate NNNN donor, coordinating through the four imine nitrogen atoms. Investigations
on antimicrobial activity in vitro show that all the complexes are active against the tested microorganisms, the complex with chloride being more active against
Gram negative bacteria than chlorhexidine diacetate..
相似文献
16.
İlkay Şişman Çağla Tütünoğlu Ali Osman Aydın 《Central European Journal of Chemistry》2008,6(2):253-257
Sub-micrometer nickel powders of controlled size and morphology were produced by a surfactant-assisted polyol method, using
ethylene glycol (EG) as solvent and reductant in the presence of sodium dodecyl sulfate (SDS) surfactant and NaOH. The resultant
Ni powders were characterized by XRD, SEM, EDS, and FTIR. Spherical, hexagonal, and triangular fcc Ni powders from 0.30 to
0.60 μm were obtained in the presence of SDS; irregular spherical fcc Ni powders were obtained in its absence. The concentrations
of SDS, NaOH and Ni(CH3COO)2·4H2O greatly influence the product morphology and size.
相似文献
17.
Waleed Azzam 《Central European Journal of Chemistry》2009,7(4):884-899
Self-assembled monolayers (SAMs) of ω-(4′-methylbiphenyl-4-yl)ethanethiol (CH3(C6H4)2(CH2)2SH, BP2) prepared at different temperatures on Au(111) substrates were investigated using scanning tunneling microscopy (STM).
Also, the effect of the incubation time of the gold substrate in the thiol solution was examined. The STM results showed that
samples prepared at room temperature were significantly different from those prepared at elevated temperatures in their surface
morphology, space group and size of unit cell. The micrographs of samples prepared at higher temperatures revealed a pronounced
and progressive increase in the size of the well-known etch-pits at the expense of their density with increasing preparation
temperature (but the increase did not continue for SAMs prepared at 348 K). The average domain size was found to increase
significantly with increasing preparation temperature. In addition, polymorphism was observed in BP2 SAMs at all investigated
temperatures. This study has demonstrated that solution temperature and incubation time are key factors controlling the two-dimensional
SAM structure of BP2 molecules.
相似文献
18.
Synthesis and spectral characterization of stannocanes of the type [O(CH2CH2S)2SnR2](R=Me1,Bun2,Ph3)
The stannocanes of the type [O(CH2CH2S)2SnR2](R=Me1,Bun 2,Ph3) have been synthesized in an improved method by the reaction of R2SnCl2 with 2, 2′-oxydiethanethiol O(CH2CH2SH)2 in molar ratio of 1:1 at the presence of sodium ethoxide in anhydrous ethanol. The reactions are carried out under inert atmosphere. These compounds have been extensively characterized by FT-IR, UV-Vis spectrophotometry, multi-nuclear (1H, 13C, 119Sn) NMR, elemental analysis and mass spectrometry. The obtained data clearly indicates that, there is a strong interaction between oxygen atom of the ligand as a donor and Sn atom of the organotin species as a Lewis acid acceptor. Therefore, the resulted dithiostannocanes possess a transannular secondary bonding and hypervalency at the central Sn atom which leads to an increase in the coordination number of tin from four to five-coordinated tin. 相似文献
19.
Venera Giurcan Domnina Razus Maria Mitu Dumitru Oancea 《Central European Journal of Chemistry》2014,12(3):391-402
The structure of premixed free one-dimensional laminar ethane-air flames was investigated by means of numerical simulations performed with a detailed mechanism (GRI-Mech version 3.0) by means of COSILAB package. The work provides data on ethane-air mixtures with a wide range of concentrations ([C2H6] = 3.0–9.5 vol.%) at initial temperatures between 300 and 550 K and initial pressures between 1 and 10 bar. The simulations deliver the laminar burning velocities and the profiles of temperature, chemical species concentrations and heat release rate across the flame front. The predicted burning velocities match well the burning velocities measured in various conditions, reported in literature. The influence of initial concentration, pressure and temperature of ethane-air mixtures on maximum flame temperature, heat release rate, flame thickness and peak concentrations of main reaction intermediates is examined and discussed. 相似文献
20.
Amitabha Chakraborty Swapan K. Saha Subrata Chakraborty 《Colloid and polymer science》2008,286(8-9):927-934
Different tetraalkylammonium, viz. N+(CH3)4, N+(C2H5)4, N+(C3H7)4, N+(C4H9)4 along with simple ammonium salts of bis (2-ethylhexyl) sulfosuccinic acid have been prepared by ion-exchange technique. The critical micelle concentration of surfactants with varied counterions have been determined by measuring surface tension and conductivity within the temperature range 283–313 K. Counterion ionization constant, α, and thermodynamic parameters for micellization process viz., $\Delta G_m^{\text{0}} $ , $\Delta H_m^{\text{0}} $ , and $\Delta S_m^{\text{0}} $ and also the surface parameters, Γmax and Amin, in aqueous solution have been determined. Large negative $\Delta G_m^{\text{0}} $ of micellization for all the above counterions supports the spontaneity of micellization. The value of standard free energy, $\Delta G_m^{\text{0}} $ , for different counterions followed the order $${\text{N}}^{\text{ + }} \left( {{\text{CH}}_{\text{3}} } \right)_4 >{\text{NH}}_{\text{4}}^{\text{ + }} >{\text{Na}}^{\text{ + }} >{\text{N}}^{\text{ + }} \left( {{\text{C}}_{\text{2}} {\text{H}}_5 } \right)_{\text{4}} {\text{ $>$ N}}^{\text{ + }} \left( {{\text{C}}_{\text{3}} {\text{H}}_{\text{7}} } \right)_4 >{\text{N}}^{\text{ + }} \left( {{\text{C}}_{\text{4}} {\text{H}}_{\text{9}} } \right)_4 $$ , at a given temperature. This result can be well explained in terms of bulkiness and nature of hydration of the counterion together with hydrophobic and electrostatic interactions. 相似文献