M. S. Gruzdev

Preparation of 1-butyl-3-methylimidazolium salts and study of their phase behavior and intramolecular intractions

Seven organic salts of 1-butyl-3-methylimidazolium with anions Br−, BF4−, NO3−, SO42−, HSO4−, SCN−, PO43− were prepared. Structure of these compounds is elucidated and purity is confirmed. The products are characterized by melting point, thin layer chromatography, data of elemental analysis, cromatomass-, NMR and IR spectroscopy. All these compounds are ionic liquids, five are low temperature ones. Principal thermal characteristics are found that allow accounting for the phase behavior of the prepared compounds at their application. Existence of intramolecular and intermolecular interactions between the heterocyclic anion and inorganic cation in by means of the formation of hydrogen bond is established.

Binding ability of Zn-tetraarylporphyrins with two, four and eight 4-(4-(3,6-bis(t-butyl)carbazol-9-ylphenyl)-1,2,3-triazole end groups towards N-containing substrates of different nature

The binding ability of Zn-tetraarylporphyrins with two, four and eight 4-carbazolylphenyl-1,2,3-triazole end groups towards 1,4-diazabicyclo[2.2.2]octane, pyridine and 1,2,3-triazole in toluene was studied by spectrophotometric and 1H NMR titration. It was determined that due to a good geometric match of the ligand size to the size of the intramolecular cavities of the porphyrinic receptor, and by the existence of additional π–π and/or hydrogen bonding interactions between the ligand and the triazole fragments of the porphyrin, the Zn-tetraarylporphyrin with eight 4-carbazolylphenyl-1,2,3-triazole end groups could be used as an effective receptor for 1,2,3-triazole and other small heterocycles such as pyridine. Taking into account the fact that binding is accompanied by a clear and easily identifiable response in the UV–vis spectra of the reaction mixture, this metalloporphyrin could be considered as a molecular optical sensing device for small heterocyclic substrates.

Magnetic Resonance and Mössbauer Studies of Superparamagnetic γ‐Fe2O3 Nanoparticles Encapsulated into Liquid‐Crystalline Poly(propylene imine) Dendrimers

We present the first results of electron magnetic resonance (EMR) and Mössbauer spectroscopy studies of γ-Fe(2)O(3) nanoparticles (NPs) incorporated into liquid-crystalline, second-generation dendrimers. The mean size of NPs formed in the dendrimers was around 2.5 nm. A temperature-driven transition from superparamagnetic to ferrimagnetic resonance was observed for the sample. Low-temperature blocking of the NP magnetic moments has been clearly evidenced in the integrated EMR line intensity and the blocking temperature was about 60 K. The physical parameters of magnetic NPs (magnetic moment, effective magnetic anisotropy) have been determined from analyses of the EMR data. The effective magnetic anisotropy constant is enhanced relative to bulk γ-Fe(2)O(3) and this enhanced value is associated with the influence of the surface and shape effects. The angular dependence of the EMR signal position for the field-freezing sample from liquid-crystalline phase showed that NPs possessed uniaxial anisotropy, in contrast to bulk γ-Fe(2)O(3). Mössbauer spectroscopy determined that fabricated NPs consisted of an α-Fe core and a γ-Fe(2)O(3) shell.

Thermodynamics of mixed-ligand complexation of mercury(II) ethylenediaminetetraacetate with histidine and lysine in aqueous solution

The formation of mixed-ligand complexes HgEdtaIm2−, HgEdtaL3−, HgEdtaHL2−, and (HgEdta)2L5− (L is histidine, lysine; Im is imidazole) was studied by calorimetry, pH-metry, and NMR spectroscopy. The thermodynamic parameters (logK, ΔrG0, ΔrH, ΔrS) for the reactions of complex formation at 298.15 K and ion strength of 0.5 (KNO3) were determined. The most likely coordination mode for the complexone and amino acid in the mixed complexes was identified.

Bis-chelate Fe(III) complex of an azomethine at the focal point of a branched ester functionalized with cyclohexylbenzoic acid

A Fe(III) complex with Cl counter ion based on a branched Schiff base has been synthesized and studied. The compound was produced by the reaction of the Schiff base with FeCl3 at room temperature in benzene–ethanol. The complex is symmetric, i.e., bis-chelate, with an octahedral coordination of Fe. The compound revealed phase transitions of the “solid–solid” type. The complex displayed a temperature-induced spin transition (S = 1/2 ↔ 5/2) which was detected by EPR.

Iron(III) complexes on the basis of azomethine derived from 4,4′-dodecyloxybenzoyloxybenzoyl-4-oxy-2-hydroxybenzaldehyde

This work deals with the synthesis and investigation of phase behavior of iron(III)-containing complexes of linear azomethine derived from 4,4′-dodecyloxybenzoyloxybenzoyl-4-oxy-2-hydroxybenzaldehyde with NO3−, PF6−, Cl−, and BF4− counterions. All semiproducts and target substances are characterized by TLC, elemental analysis, IR and NMR spectroscopy, and melting points. It is established that the reaction of Schiff base with metal salts at room temperature leads to the formation of complexes having presumably the linear structure. Phase behavior of the compounds obtained depending on the nature of counterion was studied.

Structure of Iron(III)-containing complexes based on the azomethine — 4,4′-dodecyloxy-benzoyloxybenzoyl-4-salicylidene-N′-Ethyl-N-ethylenediamine molecule

Iron(III)-containing complexes with an asymmetric tridentate azomethine 4,4′-dodecyloxybenzoyloxybenzoyl-4-salicylidene-N′-ethyl-N-ethylenediamine ligand with NO3−, PF6−, Cl−, and BF4− counterions are synthesized. The presence of the complexation ion is confirmed by the far FTIR spectra. The structure of the compounds is determined by the matrix-assisted laser desorption/ionizationtime of flight (MALDI-ToF) method. The results of mass-spectrometric studies are consistent with the elemental analysis data. The complexation of iron salts with the asymmetric tridentate ligand is found to yield compounds of the 1:1 composition with octahedral packing of iron in the complex.

Solvent effect in the preparation of iron(III) azomethine complexes based on 4,4′-dodecyloxybenzoyloxybenzoyl-4-salicylidene-N′-ethyl-N-ethylenediamine

Mono- and bis-chelate iron(III)-containing complexes with a tridentate azomethine ligand based on n-dodecyloxybenzoic acid ester derivatives with oxybenzoyl-4-salidene-N′-ethyl-N-ethylenediamine with NO3− counterions are obtained. The structure of the compounds is determined by IR spectroscopy, elemental analysis, and mass spectrometry (MALDI-ToF MS). It is found that the complexation of iron salts with tridentate ligands in a mixture of solvents (alcohol:benzene) results in the formation of bischelate compounds of the composition 1:2 with octahedral packing of iron in the complex, while in pure alcohol solutions, asymmetric mono-chelate complexes are obtained.

Conversion of low spin states in a monochelate complex of Fe(III) with an asymmetric tridentate azomethine ligand

An iron(III)-containing complex with the asymmetric tridentate azomethine ligand 4,4′-dodecyloxybenzoyloxybenzoyl-4-salicylidene-N′-ethyl-N-ethylenediamine with a PF6− counterion is obtained. The presence of the complexing ion is confirmed by far IR Fourier spectra. The structure of the compounds is determined by matrix-assisted laser desorption/ionization with a time-of-flight mass analyzer (MALDI-ToF). The results of mass spectrometric studies are consistent with the elemental analysis data. It is found that the complexation of iron salt with an asymmetric tridentate ligand results in the formation of compounds of the composition 1:1 with octahedral packing of a metal ion in the complex. The electrochemical behavior of the compound in organic solvents is examined. The EPR study shows that iron(III) ions are in both low spin (LS) and high spin (HS) states in the complex. The LS and HS iron(III) centers are coupled into dimers in which a water molecule and the PF6− counterion act as bridges. It is also found that for LS complexes in the lowtemperature phase (4.2–300 K), the (dxz,dyz)4(dxy)1 electronic state is the ground state. It is revealed that the conversion of the sample into a high-temperature liquid crystalline (387–405 K) phase is accompanied by the conversion of the LS states of the Fe(III) ion: (dxz,dyz)4(dxy)1 ↔ (dxy)2(dxz,dyz)3. The conversion of LS states is temperature reversible and is driven by the temperature. X-ray crystallographic data confirm that the compound obtained consists of dimer formed by a hydrogen (O-H...F) bond.

Synthesis of liquid-crystalline 4,4′-dodecyloxybenzoyloxybenzoyl-4-oxy-2-hydroxybenzaldehyde and related azomethine

Abstract4,4′-Dodecyloxybenzoyloxybenzoyl-4-hydroxy-2-hydroxybenzaldehyde and the related linear azomethine, the intermediates at the formation of iron(III)-containing complexes, were synthesized. These compounds were characterized by thin layer chromatography, elemental analysis, IR, NMR spectroscopy, mass spectrometry, and by the data of differential scanning calorimetry. The aldehyde and the azomethine show mesomorphic properties.