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1.
Dalton Trans ; 53(11): 5152-5159, 2024 Mar 12.
Article in English | MEDLINE | ID: mdl-38380815

ABSTRACT

Polyiodides present high bonding flexibility already at ambient conditions, and undergo significant pressure-induced structural deformations. Resonant Raman spectroscopy has been widely used to study I-I bonds in various polyiodides, but it carries a risk of photodecomposition due to the high visible-light absorption of iodine. In this study, tetraethylammonium (bis)diiodine triiodide (TEAI) has been investigated by resonant Raman spectroscopy up to 12.02(3) GPa. The effect of pressure on the intensities and positions of Raman bands has been evaluated and correlated with the interatomic I-I distances derived from high-pressure X-ray diffraction experiments. Pressure was shown to effectively stabilize TEAI against laser-induced photodecomposition, even after a long course of irradiation with the resonant laser light. Examination of a freshly exposed crystal surface revealed that TEAI superficially passivates with the layer of lower polyiodides, which prevents further iodine loss, and shows distinct pressure-induced behaviour.

2.
Molecules ; 26(11)2021 Jun 02.
Article in English | MEDLINE | ID: mdl-34199524

ABSTRACT

Three new copper coordination compounds derived from 2,2-bis(hydroxymethyl)propionic acid (dmpa) and hexamethylenetetramine (hmta) were obtained and their crystal structures were determined. The stoichiometry of the reagents applied in the syntheses reflects the metal to ligand molar ratio in the formed solid products. Due to the multiple coordination modes of the used ligands, wide structural diversity was achieved among synthesized compounds, i.e., mononuclear [Cu(dmp)2(hmta)2(H2O)] (1), dinuclear [Cu2(dmp)4(hmta)2] (2), and 1D coordination polymer [Cu2(dmp)4(hmta)]n (3). Their supramolecular structures are governed by O-H•••O and O-H•••N hydrogen bonds. The compounds were characterized in terms of absorption (UV-Vis and IR) and thermal properties. The relationships between structural features and properties were discussed in detail. Owing to discrepancies in the coordination mode of a dmp ligand, bidentate chelating in 1, and bidentate bridging in 2 and 3, there is a noticeable change in the position of the bands corresponding to the stretching vibrations of the carboxylate group in the IR spectra. The differences in the structures of the compounds are also reflected in the nature and position of the UV-Vis absorption maxima, which are located at lower wavelengths for 1.

3.
Materials (Basel) ; 14(12)2021 Jun 10.
Article in English | MEDLINE | ID: mdl-34200900

ABSTRACT

In the present work, for the first time, the possibility of formation of CrAl2O4 was shown from the equimolar mixture of co-precipitated Al2O3 and Cr2O3 oxides under a reductive environment. The crystallographic properties of the formed compound were calculated using the DICVOL procedure. It was determined that it has a cubic crystal structure with space group Fd-3m and a unit cell parameter equal to 8.22(3) Å. The formed CrAl2O4 is not stable under ambient conditions and easily undergoes oxidation to α-Al2O3 and α-Cr2O3. The overall sequence of the phase transformations of co-precipitated oxides leading to the formation of spinel structure is proposed.

4.
Molecules ; 25(22)2020 Nov 15.
Article in English | MEDLINE | ID: mdl-33203086

ABSTRACT

Two different coordination compounds of copper were synthesized from the same building blocks (1,10-phenanthroline, bromoacetate anions, and copper cations). The synthesis parameters were carefully designed and evaluated to allow the change of the resulting compounds molecular structure, i.e., formation of mononuclear (bromoacetato-O,O')(bromoacetato-O)aqua(1,10-phenanthroline-N,N')copper(II) and dinuclear (µ-bromido-1:2κ2)bis(µ-bromoacetato-1κO,2κO')bis(1,10-phenanthroline-N,N')dicopper(II) bromoacetate bromoacetic acid solvate. The crystal, molecular and supramolecular structures of the studied compounds were determined and evaluated in Hirshfeld analysis. The UV-Vis-IR absorption and thermal properties were studied and discussed. For the explicit determination of the influence of compounds structure on radiation absorption in UV-Vis range, density functional theory and time-dependent density functional theory calculations were performed.


Subject(s)
Acetates/chemistry , Chemical Phenomena , Coordination Complexes/chemistry , Copper/chemistry , Phenanthrolines/chemistry , Acetates/chemical synthesis , Coordination Complexes/chemical synthesis , Crystallography, X-Ray , Models, Molecular , Molecular Conformation , Phenanthrolines/chemical synthesis , Quantum Theory , Spectrophotometry, Infrared , Spectrophotometry, Ultraviolet , Temperature
5.
Molecules ; 25(12)2020 Jun 18.
Article in English | MEDLINE | ID: mdl-32570910

ABSTRACT

Three series of azo dyes derived from 2-amino-5-aryl-1,3,4-thiadiazoles and aniline, N,N-dimethylaniline and phenol were synthesized in high yields by a conventional diazotization-coupling sequence. The chemical structures of the prepared compounds were confirmed by 1H-NMR, 13C-NMR, IR, UV-Vis spectroscopy, mass spectrometry and elemental analysis. In addition, the X-ray single crystal structure of a representative azo dye was presented. For explicit determination of the influence of a substituent on radiation absorption in UV-Vis range, time-dependent density functional theory calculations were performed.


Subject(s)
Azo Compounds/chemistry , Azo Compounds/chemical synthesis , Thiadiazoles/chemistry , Models, Molecular , Molecular Structure , Spectrophotometry, Ultraviolet
6.
Molecules ; 24(18)2019 Sep 16.
Article in English | MEDLINE | ID: mdl-31527386

ABSTRACT

The two coordination compounds of cobalt were designed and synthesized. The substrates were carefully selected to allow gentle tuning of the molecular structure of the designed compounds. The crystal, molecular and supramolecular structure of studied compounds has been determined and discussed. The spectroscopic and thermal properties of designed coordination compounds have been studied and their application as precursors for the synthesis of cobalt oxide nanoparticles has been demonstrated. It was proven that not only are parameters of conversion of the precursor to nanoparticles important, but also small changes in molecular structure can considerably affect the size of formed particles. For unambiguous determination of the influence of compounds structure on their UV-Vis radiation absorption, density functional theory and time-dependent density functions theory calculations have been performed. The complexity of the correct ab-initio reflection of the open shell molecular system was outlined and discussed. The results obtained from density functional theory (DFT) calculations have been also employed for discussion of the bonding properties.


Subject(s)
Cobalt/chemistry , Coordination Complexes/chemistry , Models, Molecular , Coordination Complexes/chemical synthesis , Density Functional Theory , Isomerism , Metal Nanoparticles/chemistry , Metal Nanoparticles/ultrastructure , Molecular Conformation , Molecular Structure , Oxides/chemistry , Spectrum Analysis
7.
J Mol Model ; 23(12): 338, 2017 Nov 09.
Article in English | MEDLINE | ID: mdl-29124340

ABSTRACT

Extremely extensive calculations of potential energy surfaces for the parallel-displaced configuration of pyridine dimer systems have been carried out using a dispersion-corrected density functional. Instead of focusing on stationary geometries these calculations provide much deeper insight into the "landscape" of the interaction energies of the particular systems-one can learn how the pyridine dimer stability changes along with various geometrical parameters. Other calculations such as natural bond orbital and energy decomposition have also been applied. The interplay of two significant factors, electrostatic forces and electron correlation effects, have been evaluated. The role of π···π interactions in the stacked pyridine systems has also been confirmed, and surprisingly, this happened to be true even for the geometries where the formation of C-H···π interactions might be proposed instead. The combination of many different methods has revealed the complexity of the stacking interactions. Apart from providing a "literal new look" into pyridine interaction patterns another picture has emerged. A stacking interaction in a pyridine dimer system is perceived as a combination of many different sources of the interaction energy, including orbital ones, and this is true for many different geometries.

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