The literature data on melting points (
T
m
) of silicon, germanium, tin, and lead compounds of 26 narrow series has been analyzed. The considered compounds form weak intermolecular complexes, which ...leads to the appearance of the polarizability effect. Using the correlation analysis, it was established for the first time that the
T
m
values depend on the combined influence of the inductive, resonance, polarizability, and steric effects of substituents. The contribution of the polarizability effect reaches 65%.
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•The dipole moments μ of organometallic complexes have been analyzed.•The μ values depend on the polarizability effect of substituents X.•The contribution of the polarizability effect ...ranges up to 50%.
The mechanism of the substituent influence on polarity of organometallics is poorly understood. In this work, literature data on the substituent influence on dipole moments μ as a measure of the bond polarity for 43 narrow series of organometallic complexes have been considered using correlation analysis. Generally, the μ values for series studied, including complexes of organometallics with benzene, were first established to depend on the joint influence of the inductive, resonance, polarizability, and steric effects of substituents. The presence or absence of certain effects are dictated by the type of series. The polarizability effect (an electrostatic ion-dipole interaction) is caused by an excess charge appearing on indicator centre as a result of the complexation. The contribution of the polarizability effect ranges up to about 50%.
The published data on the substituent influence on the boiling points
T
b
for 19 series of boron, aluminium, silicon, germanium, tin, and phosphorus compounds were considered using correlation ...analysis. It was established for the first time that the
T
b
values depend not only on the classical (inductive, resonance, and steric) effects, but also on the polarizability effect of substituents. In some series, the polarizability effect has a major influence on
T
b
.
Literature data on the solubility (
Sol
) and Gibbs energy of dissolution (Δ
G
°) reported for 26 series of derivatives of benzene, pyridine, and fluorocarbons in various solvents were considered ...using correlation analysis. An excess charge appears on the reaction center due to the formation of weak solute—solvent complexes, which results in the manifestation of polarizability effect. It was established for the first time that the values of
Sol
and Δ
G
° depend on the joint influence of inductive, resonant, polarization, and steric effects of substituents, whereas contribution of the polarizability effect reaches 50%.
The published data on the enthalpy of sublimation Δ
H
sub
for 13 series of organic and metal-organic compounds are considered using the correlation analysis. Each series has a fixed reaction center ...and variable substituents. It is shown for the first time that Δ
H
sub
values depend not only on the classical inductive, resonance, and steric effects, but also on the polarization effect of substituents. In some series, the polarization effect has a major influence on Δ
H
sub
.
Di-
tert
-alkyl-substituted catechols with a heterocyclic imidazole-type substituent were synthesized in three steps from catecholaldehydes. The 1,1,4,4-tetramethylbutanediyl substituent was shown to ...be resistant to the action of acids in the demethylation reaction. The isomerization of 3,4,5-substituted catechols to the 3,4,6-substituted isomers was observed. The molecular structures of the synthesized compounds in the crystalline state were established by X-ray diffraction analysis. For the catechol derivatives, the tertiary substituent in the
ortho
position to the imidazole moiety was shown to have an effect on the mutual arrangement of the catechol and heterocyclic moieties. The electrochemical properties of the synthesized imidazole-containing catechols were studied and their anti-radical activity was evaluated by the 2,2-diphenyl-1-picrylhydrazyl assay.
An approach of self-propagating high-temperature synthesis of ytterbium doped mixed yttria, scandia and lutetia powders Yb0.1(RE1xRE21-x)1.9O3 (RE1 and RE2 = Sc, Y, Lu, x = 0, 0.25, 0.5, 0.75, 1) was ...developed. A comparative study of the structural properties of the powders obtained by XRD analysis and Raman spectroscopy was carried out. The formation of rare earth oxides solid solutions throughout the studied compositional range was confirmed. The presence of residual hydroxyl groups in the resulting powders, most notable for scandia, was demonstrated. The broadening of Yb3+ ions luminescence bands in the matrices of structurally disordered mixed oxides was ascertained in comparison with individual rare earth oxides from 16 nm for Yb:Sc2O3 up to 25 nm for Yb0.1(Y0.75Sc0.25)1.9O3.
•An approach of self-propagating high-temperature synthesis of Yb0.1(RE1xRE21-x)1.9O3 (RE1 and RE2 = Sc, Y, Lu,) was developed.•The luminescence spectra and the luminescence decay of Yb3+ ions were measured.•The broadening of Yb3+ ions luminescence bands from 16 nm up to 25 nm for mixed oxides is ascertained.
A series of 4-hydroxy-4,9-dihydro-4
H
-xanthen-4-one derivatives were synthesized using the oxidative cyclization reaction of space-shielded catecholphenols. The structure of 1,3,5,7-tetra-
tert
...-butyl-4a,8-dihydroxy-9
H
-xanthen-4(4a
H
)-one was determined by X-ray diffraction analysis (CCDC 2345899). The antiradical properties of new compounds were studied by their reaction with 2,2-diphenyl-1-picrylhydrazyl (DPPH radical).
Water insoluble calcium hydroxide Ca(OH)
2
or calcium carbonate CaCO
3
react with aqueous solution of (1-hydroxyethylidene)diphosphonic acid and nitrilotrimethylenephosphonic acid to form poorly ...soluble calcium (1-hydroxyethylidene)diphosphonate trihydrate and calcium nitrilotrimethylenephosphonate trihydrate, respectively. The reaction of calcium chloride CaCl
2
with the disodium salt of ethylenediaminetetraacetic acid afforded poorly soluble calcium ethylenediaminetetraacetate hexahydrate. The reaction of suspensions of complexes of (1-hydroxyethylidene)calcium diphosphonate trihydrate, calcium ethylenediaminetetetraacetate hexahydrate and calcium nitrilotrimethylenephosphonate trihydrate with 2-aminoethanol led to the formation of water-soluble (1-hydroxyethylidene)bis(2-aminoethanol)calcium diphosphonate, tris(2-aminoethanol)calcium nitrilotrimethylenephosphonate, and bis(2-aminoethanol)calcium ethylenediaminetetraacetate, respectively. The molecular structure of calcium ethylenediaminetetraacetate hexahydrate was characterized by single-crystal X-ray diffraction method.
The sol-gel synthesis of ZnAl2O4 ceramic powders from alkoxide and acetate sources of metals, as well as the microstucture and the hardness of the hot-pressed ZnAl2O4 specimens were considered. ...ZnAl2O4 powders were prepared by the hydrolysis of an alcohol solution of aluminium isopropoxide using an aqueous solution of zinc acetate followed by heat treatment. The thermal evolution of the ZnAl2O4 precursor was investigated. The effect of calcination temperature on the morphology and the specific surface area of ZnAl2O4 powders were also studied. The sintering of the resultant powders to the high transparent ceramic using a hot pressing with 1 wt% ZnF2, as a sintering additive was successfully demonstrated. The in-line transmittance of ZnAl2O4 ceramics (1 mm thickness) achieved 80% in the visible region and 85% at 5 µm; Vickers hardness was 11.6 GPa.
