The visible electronic absorption band of two 4�-phenyl-1,2,4-triazol-1-ium phenacylids was studied in two binary solvents: water (1) + ethanol (2) and water (1) + methanol (2) with variable content in water. The nature and the contribution of the intermolecular interactions to the spectral shifts in ternary solutions of the studied ylids were estimated based on the Kamlet Taft parameters (�*, a and a) previously measured by Buhvestov and all. The influence of the universal and specific interactions on the visible electronic band of the studied ylids depends on the water concentration in binary solvent. At small water concentrations in binary solvent, the hydrogen complexes of the type ylid-alcohol are predominant, while at high water concentrations, the complexes made by hydrogen bonds between water and ylid molecules prevail. The difference between the energies corresponding to molecular pairs of the types: ylid-water and ylid-alcohol was estimated based on the statistic cell model of the ternary solutions.
Some electro-optical characteristics of four carbanion monosubstituted triazolium ylids - precursors in obtaining new heterocycle derivatives with pharmaceutical and industrial applications - were evaluated by spectral and quantum-mechanics studies. The physical properties were established for the optimized structures of triazolium ylids using HyperChem 8. The nature of the interactions solute-solvent in the triazolium ylid solutions was established by correlations between the polarity/polarizability characteristics of the solution components and the wavenumbers of the visible band.
Four carbanion monosubstituted 4’-aryl-1,2,4-triazol-1-ium-4-R2-phenacylids, used as precursors in obtaining new heterocyclic compounds, and their corresponding derivatives belonging to the C2v point group of symmetry were studied by computational means in dimethylformamide (DMF) solutions compared with their isolated state. The changes in the computed parameters induced by the solvent compared with those of the isolated molecules were analyzed in this paper. The charge distribution and the molecular energies in the HOMO and LUMO, the electronic states responsible for the visible absorption band of 4’-aryl-1,2,4-triazol-1-ium-4-R2-phenacylids, in their isolated state and in solutions achieved in DMF were computed and compared with the visible electronic absorption spectra. The molecular descriptors of the studied compounds were computed, and the higher reactivity of the carbanion monosubstituted 4’-aryl-1,2,4-triazol-1-ium-4-R2-phenacylids compared with symmetric derivatives was established. The obtained results can help researchers to obtain new heterocycles with applications in the drug industry.
<p>This study addresses a topical issue, which is a particularly important indicator in assessing the evolutionary trends of the global climate system, namely the storage of carbon in the soil in the form of organic matter. The aim of the research is to estimate and characterize the organic matter from soils with different types of uses and depths located in the North-East Region of Romania, which occupies an area of 36,850 km&#178;, characterized by a special natural complexity that has undergone recent structural changes. Soil samples from organic and mineral horizons located at different depths were analyzed. The influence of different land use on the content and chemical composition of organic matter in soils in a topsoil located on the North South was analyzed. The analysis includes a number of 200 soil samples collected from seven different sites (Humor, Pipirig, Vanatori, Tg Neamt, Timisesti, Raducaneni and Munteni) including forest, pastures, arable land, orchards, whether or not subject to specific traditional amendments. Quantitative determination was performed by dry combustion using the combination of equipment: Analytik Jena multi N / C 2100 analyzer and HT 1300 solids module, while for the chemical composition of organic matter the Fourier transform infrared spectroscopy is used (Vertex 70 Bruker), using DRIFT as a sample preparation technique. The amount and chemical composition of organic matter, as well as the location and properties of the soil, have had a strong influence on DRIFT spectra, which are sensitive to the degree of decomposition of organic matter. Differences in absorbance intensity for several spectral bands indicated a higher abundance of recent residues, phenolic-OH, aliphatic and carbohydrate compounds in soils under agricultural use compared to the dominant presence of amide and aromatic groups, carboxylic acids and their salts, C = C bonds in forest soils occupied by deciduous, mixed or coniferous vegetation. Drift spectra have been associated with a number of physicochemical attributes of the soil, such as land cover type, parent material, depth and bulk density, pH, texture, etc. The main conclusion from the regional study indicates that the information recorded in the DRIFT spectra of soils combines the amount and chemical composition of soil organic matter with soil properties highlighting the potential use of this information to assess the state of organic matter degradation stored in the soils of the North East region of Romania.</p><p>Keywords: soil organic matter, FTIR, functional groups, Romania, soil composition</p><p><em>"This work was supported by a grant of the "Alexandru Ioan Cuza" University of Iasi, within the Research Grants program, Grant UAIC, code </em><em>GI-UAIC-2021-12</em><em>"</em><strong>.</strong></p>
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