V. V. Pavlishchuk

“From Heteronuclear Complex to Composite Oxide” Approach in the Synthesis of Nanosized Ferrites MIIFeIII2O4 (M = Mn, Co, Ni) with Spinel Structure and Their Catalytic Properties

A study was carried out on the preparation of ferrites MIIFe2O4 (MII = Mn, Co, Ni) by the thermal decomposition of the corresponding μ3-oxoacetates [Fe2MIIO(CH3COO)6(H2O)3]·2H2O. Nanocrystallites of MIIFe2O4 were formed under mild conditions at 300-400 °C in this reaction. An increase in the temperature leads to an increase in particle size. Nickel ferrite showed high catalytic activity in the reduction of nitrogen oxides (NOx) by hydrocarbons.

Green Chemistry and Modern Technology

The basic principles, approaches, and early achievements of green chemistry are considered. The definition of green chemistry as a branch of chemistry that studies the laws of passing of chemical reactions and the properties of substances participating in such reactions, with the aim of acquiring basic knowledge that provides a basis for designing chemical technologies that eliminate (sharply curtail) the use and production of materials that pose a risk to the environment.

Solvothermal Preparation and Magnetic Properties of Monodisperse Superparamagnetic Nanosized Ferrites MFe2O4 (M = Mn, Co, Ni)

Monodisperse spherical nanoparticles of MIIFe2III O4 (M = Mn, Co, Ni) with controlled diameter (5-20 nm) were synthesized by solvothermal decomposition of [MIIFe2III O(CH3CO2)6(H2O)3] complexes in poly- and tetraethylene glycol. The samples were studied by XRD, TEM, and SQUID magnetometry. The nanoparticles have superparamagnetic behavior. The blocking temperature, magnetization, and magnetic anisotropy barrier decrease, while the magnetic anisotropy constant increases with decreasing particle size.

Stereochemistry of Copper(II) Complexes with Hexacyclen in Solution

Abstract The effect of solvent on the behaviour of the copper(II) complex of 1,4,7,10,13,16-hexaazacyclooctadecane (hexacyclen) has been investigated by cyclic voltammetry as well as visible absorption and EPR spectroscopy. Within a series of solvents with different coordination ability (pyridine, DMSO, DMF, water, acetone, acetonitrile) the Cu(II)/Cu(I) reduction potential (about –0.7 V on a mercury electrode and –1.1 V vs SCE on platinum), the d-d absorption band (15300 cm−1) and the values of gI and gII at -170°C (2.07 and 2.18, respectively) remain unchanged and indicate a stable octahedral CuN6 environment.

Metal-Centered Photoluminescence of Eu3+ and Tb3+ Coordination Polymers with Dianions of Camphoric and Tetrafluoroterephthalic Acids

It was shown that coordination polymers [Ln(Camph)(NO3)(MeOH)2]n (1Ln, Ln – Eu, Tb; Camph2––camphorate dianion) and [Ln2(tFbdc)3(DMF)2(H2O)2]n (2Ln, Ln – Eu, Tb; tFbdc2–– tetrafluoroterephtalate dianion) possess metal-centered emission with quantum yields up to 40% under UV-irradiation. It was found that tetrafluoroterephtalate dianion is better antenna ligand than camphorate dianion. It was assumed that for studied complexes the vibrational radiationless deactivation of excited states of ligands influence more significantly on the luminescence characteristics than energy of triplet states of ligands.

SPECTROSCOPIC and REDOX BEHAVIOUR OF SOME COPPER(II) ‐ THIOETHER COMPLEXES

Abstract The features of electronic spectra and redox chemistry of a number of Cu(II)-thioether complexes have been examined. The origin of the intense absorption in the region around 14,000–16,000 cm−1 is attributed to (π)S → d(Cu2+) CTB, that obscures the less intense d-d (Cu2+) band. The relationship between spectral characteristics and redox potentials of CuL2+/+ couples values is discussed.

Luminescence and Spectral Characteristics of Zinc Sulfide Nanoparticles Doped with Eu2

A method is proposed for the production of zinc sulfide nanoparticles with an average size of 6.0 ± 1.0 nm, doped with 2+ ions (molar ratio Eu : Zn ≈ 0.01%-0.19%), by simultaneous decomposition of diethyldithiocarbamate complexes of zinc(II) and europium(II) in high-boiling solvents. It was established that the position of the emission band at 645 nm for the obtained ZnS : Eu2+ nanoparticles hardly depends at all on the europium content while the luminescence intensity is highest with a dopant content of 0.05%. It was shown that the emission band for the ZnS : Eu2+ nanoparticles arises from Eu2+ emission centers localized on the surface of the nanoparticles.

trans-Stereoselective Catalysis of the Henry Reaction by a New Metal–Organic Framework of Iron(III) with 1,3,5-Benzenetricarboxylic Acid

The condensation of nitromethane and salicylaldehyde (SA) in the presence of a metal–organic framework (MOF) [Fe2(H2O)2(btc)4/3]Cl2∙3DMF (Fe-btc), where btc is the 3– anion of 1,3,5-benzenetricarboxylic acid, proceeds catalytically with the selective formation of trans-nitrovinylphenol. The condensation rate is first-order relative to the concentration of SA and MOF but is independent of the nitromethane concentration. A kinetic scheme is proposed for this reaction.

Influence of the Introduction of Organic “Guests” on the Luminescent Properties of Inclusion Compounds Based on the Coordination Polymer Eu(BTB)

It was shown that variation of luminescent organic substance in inclusion compounds «guest»/Eu(BTB) (H3BTB is benzene-1,3,5-triyl-tris(4′-benzoic acid), «guest» = naphthalene, anthracene, fluorescein, or rhodamine 6G) may change the emission color from yellow to red. It was found that comparing with the individual coordination polymer, the quantum yield of the Eu3+-centered emission of the inclusion compound (0.25 fluorescein)/Eu(BTB) is higher due to an increase of energy transfer efficiency to energy levels of Eu3+ ion, and the quantum yield of inclusion compound (0.25 rhodamine 6G)/Eu(BTB) is lower due to partial luminescence quenching due to an increase of the probability of reverse energy transfer from the Eu3+ radiative level to the singlet level of the “guest.”

Influence of the Structure of 3-Arylacetylacetonate Ligands on the Luminescence Properties of Eu 3+ and Tb 3+ Complexes

It was shown that in the series of complexes Tp2LnL (Ln = Eu, Tb; Tp– = tris(pyrazolyl)borate anion; L– = 3-arylacetylacetonate) the energy of the triplet state of L– decreases with elongation of the conjugation chain of the aromatic substituent, resulting in change of the nature of emission from metal-centered to ligand-centered. It was found, that the introduction of two antenna ligands of different nature leads to increase of the luminescence quantum yield (to 74%) in the case of the Tb3+ compounds, probably, due to optimization of energy transfer. In the Eu3+ compounds it leads to emission quenching, likely, as a result of increased efficiency of energy transfer and non-radiative deactivation of the excited states.