French-Ukrainian Journal of Chemistry
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Effect of ligand substitution in [Fe(H-trz)2(trz)]BF4 spin crossover nanoparticles
Get PDFSpin crossover iron(II) 1,2,4-triazole-based coordination compounds in the form of nanoparticles were prepared using a reverse microemulsion technique. Ligand substitution approach was applied to decrease the spin crossover temperature towards room temperature in the well-known [Fe(Htrz)2(trz)]BF4 complex. The compositions of the particles were determined by elemental analysis and thermogravimetry. The morphology was monitored by transition electron microscopy (TEM). The effect associated with the ligand substitution was investigated by optical and magnetic measurements. Transition temperature has been reduced by 33 K comparing the unsubstituted sample to that with 5 % substitution
New coordination compounds of uranyl ion with 3-(2-hydroxyphenyl)-1,2,4-triazole and its derivatives: synthesis and investigation of spectral properties
Get PDFNew methods of 3-(2-hydroxyphenyl)-1,2,4-triazoles synthesis were developed. Obtained ligands was used for synthesis of three new complex compounds of uranyl-ion with general composition [UO2(HL)2(Solv)]. These compounds were characterized by NMR and IR spectroscopy
En route to a dianilinyl-substituted carbo-cyclohexadiene with promising electrical properties
Get PDFThe macro-aromatic carbo-benzene core para-disubstituted by 4-anilinyl groups is known to be an efficient single-molecule conductor, exhibiting a conductance of 106 nS measured by the scanning tunneling microscopy-break junction technique. The linear carbo-butadiene analogue bearing the same anilinyl substituents was found to be less efficient, with a conductance of 2.7 nS. The reason of this difference could be elucidated through the study of the charge transport properties of a cyclically locked carbo-butadiene core in a carbo-cyclohexadiene derivative. In this paper, advances in the synthesis of this challenging dianilinyl-substituted carbo-cyclohexadiene are presented
High-temperature microwave effects in liquid media
Get PDFThe heating behavior of high-boiling liquids under microwave (MW) irradiation was investigated. Linear and non-linear heating modes depending on the applied MW power level were observed. The non-linear interactions emerging at “high” power levels are ascribed to electromagnetic oscillations excitations resulting in non-linear heating speed growth and considerable decrease in energy input. The relationship between non-linearity degree and liquids’ viscosity was established. The observed effects have been shown to apply not only to mere heating, but also to high-temperature chemical reactions. Future perspectives and practical applications of the work are also discussed
Gas Chromatographic determination of parabens after derivatization and dispersive microextraction
Get PDFAbstract. In this study a dispersive liquid–liquid microextraction method combines with an in situ derivatization. The proposed method is used for the extraction and pre-concentration of some preservatives including methyl paraben, ethyl paraben, propyl paraben and butyl paraben from different water matrices. The extracted compounds are monitored by gas chromatography-flame ionization detector. Parabens are derivatizated by propionic anhydride. The effects of the extraction solvent type, extraction and acylation time, derivative agent volume, temperature, pH and the ionic strength of the solution on the extraction efficiency were investigated. 50 mkl chloroform and 500 mkl acetonitrile is a mixture of suitable extraction and dispersive solvents. The mixture is centrifuged for 3min at 4000 rpm. 20 mkl propionic anhydride is used for derivatization parabens in the concentration range of 0.05 - 1 mg within 2 - 3 minutes. The optimum pH range is 8 - 9. The relative standard deviations (RSDs) of parabens were in the range of 2.0–10.0% (n = 3). The method was applied to the analysis of the four parabens in water. For the analysis of the spiked samples, a recovery above 100 % were obtained
A STUDY OF NONSTOICHIOMETRIC OXIDES IN THE Ln-Ni-O (Ln=La, Pr, Nd) SYSTEM
No full textThe non-stoichiometric compositions Ln2-xNiO4-3x/2+d (Ln=La, Pr, Nd, 0£x£0,4) were obtained using coprecipitation method from nitrates solutions by K2CO3 followed by calcination of the obtained blend at 950°С. According to X-ray phase analysis compositions in the range La2NiO4.17 – La1.6NiO3.63 are monophase and crystallize in tetragonal symmetry K2NiF4, space group I4/mmm. Nd2-xNiO4-y and Pr2-xNiO4-y in the range 0£x£0,2 are monophase and have orthorombic and monoclinic(correspodingly) distorted K2NiF4 structure. Samples with 0,2<x£0,4 are polyphase and contain Ln2NiO4 (Ln=Pr, Nd), NiO and rare earth oxides. Electrical conductivity of obtained samples have semiconducting behavior and it is strong depended to nonstoichiometric oxygen content
Energy Transfer in Polystyrene Nanoparticles with Encapsulated 2,5-Diphenyloxazole
Get PDFAs the first step to design nanosystems for X-ray excited sensitising of singlet oxygen, nanoparticles of polystyrene (PS NP) and polystyrene with encapsulated diphenyloxazole molecules (PS-PPO NP) were synthesized. Inside the PS-PPO NP, the electronic excitation energy transfer from polystyrene matrix to encapsulated PPO molecules takes place; efficiency of such transfer was roughly estimated to be about 0.37. X-ray stimulated luminescence of PS-PPO NP was registered
Synthesis and evaluation of β-hydroxytriazoles and related compounds as antitubercular agents
Get PDFA new series of β-hydroxytriazoles were synthesized and evaluated as Mycobacterium tuberculosis inhibitors. Our strategy implied the synthesis of alkyne precursors through a Barbier reaction between benzaldehydes and propargyl bromide followed by click chemistry to afford substituted β-hydroxyl benzyltriazoles. These compounds are also key intermediates either for oxidation reactions leading to α,β-diketotriazoles or for elimination reactions affording styryl triazoles. Evaluation of all new compounds for in vitro antitubercular activity against Mycobacterium tuberculosis H37Rv resulted in compounds with MIC up to 7 μM
First insights into the synthesis of carbo-phospholane and carbo-phospholene oxides
Get PDFFifteen-membered ring carbo-mers of five-membered rings are considered in the heterocyclic series of the phosphole oxide and less unsaturated parents. The synthesis of the first carbo-phospholane oxides is achieved by a [14+1] two-step/one-pot macrocyclization route with 86 % yield. Reduction of the latter phosphora-[5]pericyclyne with SnCl2 allowed consistent 1H and 31P NMR characterization of the corresponding carbo-phospholene, produced with 11 % yield. The ultimate carbo-phosphole oxide could not be isolated, but preliminary results on alternative strategies towards this 14 pz-electron Hückel carbo-aromatic are reported.
α-Thioalkylation of Zinc Dienolates as an Entry to 4-Substituted 1-tert-Butoxy-7a-methylhexahydroindenes
No full textHexahydroindenes 10 are readily available in 3 steps with an overall yield of 41 – 45 % starting from the Hajos Wiechert ketone 1. Alkylation of the α,β-unsaturated ketone 1 at C-4 has been achieved by thioalkylation of the corresponding zinc dienolate 2 with α-chlorosulfides of type 3. Subsequent in situ reduction and desulfurization of the β-(phenylthio) ketones 4 leads directly to the 4-substituted hexahydroindene-5-ols 6 which can be deoxygenated via their mesylates to the hexahydroindenes 10