Thermal,spectroscopic, X-ray and theoretical studies of metal complexes (sodium,manganese, copper,nickel, cobalt and zinc) with pyrimidine-5-carboxylic and pyrimidine-2-carboxylic acids

Journal of Thermal Analysis and Calorimetry - The new 3d metal complexes of pyrimidine-2-carboxylic (2PCA) and pyrimidine-5-carboxylic (5PCA) acids were synthesized and characterized using thermal...     

Molecular structure and microbiological activity of alkali metal 3,4-dihydroxyphenylacetates

The changes in physical, chemical and biological properties of chemical compounds decide about their biological activity. In this paper the molecular structure of alkali metal 3,4-dihydroxyphenylacetates is studied in comparison to 3,4-dihydroxyphenylacetic acid (3,4-DHPAA) using FT-IR, FT-Raman and UV–Vis spectroscopy as well as density functional theory (DFT) calculations. The B3LYP/6-311++G⁷ method is used to calculate optimized geometrical structures of studied compounds, atomic charges (Mulliken, APT, NBO), dipole moments, energies as well as the wavenumbers and intensities of the bands in vibrational spectra. Theoretical parameters are compared to the experimental data. The relationship between spectroscopic parameters of studied compounds and their biological activity is analyzed. Antioxidant activity is studied using FRAP and DPPH methods. IC₅₀ parameter is also calculated. Bacillus subtilis, Pseudomonas aeruginosa, Escherichia coli and Klebsiella oxytoca are used in microbiological analysis of 3,4-DHPAA as well as its sodium and potassium salts.     

Evaluation of influence of selected metal cations on antioxidant activity of extracts from savory (<Emphasis Type="Italic">Satureja hortensis</Emphasis>)

The analysis of the antioxidant activity of ethanol, methanol, acetone and aqueous extracts from the dried leaves and stems of savory is presented. The culinary herb used to study was procured from ecological agriculture in the Podlasie region of Poland. The antioxidant properties of extracts were calculated using the 1,1-diphenyl-2-picryl-hydrazyl radical (DPPH) and ferric-reducing antioxidant power (FRAP) (expressed as mg Trolox per g of dry mass) methods. In addition, the total phenolics contents of the herbal extracts were determined using the Folin-Ciocalteu reagent. The antioxidative activity of extracts as dependent on the type of solvent used for the extraction and concentration of savory in extracts is discussed. The influence of the concentration of different metal ion solutions on the anti-radicals’ properties of savory extracts was evaluated.     

Influence of alkaline earth metals on molecular structure of 3-nitrobenzoic acid in comparison with alkali metals effect

The influence of beryllium, magnesium, calcium, strontium and barium cations on the electronic system of 3-nitrobenzoic acid was studied in comparison with studied earlier alkali metal ions [1]. The vibrational FT-IR (in KBr and ATR techniques) and ¹H and ¹³C NMR spectra were recorded for 3-nitrobenzoic acid and its salts. Characteristic shifts in IR and NMR spectra along 3-nitrobenzoates of divalent metal series Mg → Ba were compared with series of univalent metal Li → Cs salts. Good correlations between the wavenumbers of the vibrational bands in the IR spectra for 3-nitrobenzoates and ionic potential, electronegativity, inverse of atomic mass, atomic radius and ionization energy of metals were found for alkaline earth metals as well as for alkali metals. The density functional (DFT) hybrid method B3LYP with two basis sets: 6-311++G** and LANL2DZ were used to calculate optimized geometrical structures of studied compounds. The theoretical wavenumbers and intensities of IR spectra as well as chemical shifts in NMR spectra were obtained. Geometric aromaticity indices, atomic charges, dipole moments and energies were also calculated. The calculated parameters were compared to experimental characteristic of studied compounds.     

Experimental (FT-IR, FT-Raman, H, C NMR) and theoretical study of alkali metal 2-aminonicotinates

The influence of lithium, sodium, potassium, rubidium and cesium on the electronic system of 2-aminonicotinic acid (2-ANA) was studied by the methods of molecular spectroscopy. The vibrational (FT-IR, FT-Raman) and NMR (¹H and ¹³C) spectra of 2-aminonicotinic acid and its alkali metal salts were recorded. Characteristic shifts and changes in intensities of bands along the metal series were observed. The changes of chemical shifts of protons (¹H NMR) and carbons (¹³C NMR) in the series of studied alkali metal 2-aminonicotinates (2-AN) were observed too.Optimized geometrical structures of the studied compounds were calculated by the B3LYP method using the 6-311++G** basis set. Aromaticity indices, atomic charges, dipole moments and energies were also calculated. The theoretical chemical shifts in ¹H and ¹³C NMR spectra and theoretical wavenumbers and intensities of IR and Raman spectra were determined. The calculated parameters were compared to the experimental characteristics of the studied compounds.     

Experimental and theoretical IR,Raman, NMR spectra of 2‐, 3‐, and 4‐nitrobenzoic acids

The influence of the position of nitro group toward the carboxylic group on the vibration structure of the molecule was estimated. Optimized geometrical structures were calculated (HF, B3PW91, B3LYP). Experimental and theoretical FT‐IR, FT‐Raman, and nuclear magnetic resonance (NMR) spectra of the title compounds were recorded and analyzed. The most important vibrational bands of nitro and carboxyl groups and the benzene ring were assigned. Wavenumbers and intensities for the three acids studied were compared and discussed. Data of chemical shifts in ¹H and ¹³C NMR spectra of 2‐, 3‐, and 4‐nitrobenzoic acids were analyzed in comparison with benzoic acid molecule. The calculated parameters are compared with experimental characteristics of these molecules. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

Molecular structure of 3-aminobenzoic acid complexes with alkali metals

The vibration (FT-IR, FT-Raman), electronic (UV-Vis) and NMR (1H and 13C) spectra for 3-aminobenzoic acid and its alkali metal salts were recorded. The influence of lithium, sodium, potassium, rubidium and cesium on the electronic system of the 3-aminobenzoic acid was studied. The assignment of the vibration spectra was done. Characteristic shifts of band wavenumbers and changes in band intensities along the metal series were observed. Good correlation between the wavenumbers of the vibrational bands in the IR and Raman spectra for 3-aminobenzoates and ionic potential, electronegativity, atomic mass and affinity of metal cations were found. The chemical shifts of protons (1H NMR) and carbons (13C NMR) in the series of studied alkali metals were also observed. Optimized geometrical structures of studied compounds were calculated by ab initio and density functional methods.     

Molecular structure of alkali metal 4‐nitrobenzoates

The influence of lithium, sodium, potassium, rubidium, and cesium on the electronic system of the 4‐nitrobenzoic acid molecule was studied. The vibrational (FT‐IR, FT‐Raman) and NMR (¹H and ¹³C) spectra for 4‐nitrobenzoic acid salts of alkali metals were recorded. The assignment of vibrational spectra was done. Characteristic shifts of band wavenumbers and change in band intensities along the metal series were observed. Good correlation between the wavenumbers of the vibrational bands in the IR and Raman spectra for 4‐nitrobenzoates and ionic potential, electronegativity, atomic mass, and affinity of metals were found. The chemical shifts of protons and carbons (¹H, ¹³C NMR) in the series of studied alkali metal 4‐nitrobenzoates were observed too. Optimized geometrical structures of studied compounds were calculated by HF, B3PW91, B3LYP methods using 6‐311++G** basis set. The theoretical IR, Raman, and NMR spectra were obtained. The theoretical vibrational spectra were interpreted by means of potential energy distributions (PEDs) using VEDA 3 program. The calculated parameters were compared to experimental characteristic of studied compounds. Copyright © 2007 John Wiley & Sons, Ltd.