1-Hydroxy-2-aryl(alkyl)-1H-naphto[2,3-d]imidasole-4,9-diones, their alkylation and tautomerism

Nitrogen-containing polycyclic quinoid compounds are of interest because some of them have various types of biological activity including antitumor activity. Particular attention is drawn to quinoid N-oxides, which are potential oxidizers and sources of nitric oxide. It is known that 1-R-4,9-dioxo-1Н-naphtho[2,3-d]imidazole-4,9-diones and their oximation products, 1-R-4,9-dioxo-1Н-naphtho[2,3-d][1,2,3]triazol-2-oxid-4-оximes, exhibit antitumor activity comparable with that of doxorubicin. In this regard, it is of interest to study other naphthoquinone derivatives that contain the N-oxide fragment. We have improved the method for the synthesis of 1-hydroxy-2-phenyl-1H-naphtho[2,3-d]imidazole-4,9-dione and increased its yield from 67% to 84%. Two-dimensional NMR spectroscopy has been used to refine the spectral parameters of phenyl-1H-naphtho[2,3-d]imidazole-4,9-dione. It has been shown that alkylation of this compound leads to the formation of 11-methoxy(ethoxy)-2-phenyl-1H-naphtho[2,3-d]imidazole-4,9-dione. We have analyzed the 1Н and 13С NMR spectra of the synthesized alkylation products and electron absorption spectra of the studied initial compounds. Using the Gaussian-09 quantum chemical method DFT B3LYP/6-311++G(d,p), we have confirmed that 1-hydroxy-2-phenyl-1H-naphtho[2,3-d]imidazole-4,9-dione and 1-hydroxy-2-metyl-1H-naphtho[2,3-d]-imidazole-4,9-dione exists in two tautomeric forms, with the N-oxide form prevailing in dichloroethane.

INFLUENCE OF LIGANDS BASICITY ON COMPLEXATION KINETICS OF 5,10,15,20-TETRA(TRIFLUOROMETHYL)PORPHYN AND 5,10,15,20-TETRA(ISO-BUTYL)PORPHYN WITH COPPER ACETATE

Spectrophotometric studies of base and complexation properties of 5,10,15,20-tetra(trifluoromethyl)porphine and 5,10,15,20-tetra(iso-butyl)porphine were carried out in systems acetonitrile – HClO4 and CH3COOH – Cu(ОАc)2. It was found that under ligands titration with perchloric acid in acetonitrile the consecutive protonating of nitrogen atoms of pyrrolic rings occurs with formation of mono – and dicationic forms. Electron absorption spectra may be obtained for these cationic forms. Total basicity constants and concentration intervals of existence of ligands ionized forms in acetonitrile were determined. Kinetic parameters of copper(II) complex formation was measured. The influence of nature of meso-position substituents of porphyrin macrocycle on reactivity of tetrapyrrolic macrocycle was dicussed.

Synthesis of novel push-pull fluorescent dyes – 7-(diethylamino)furo[3,2-c]coumarin and 7-(diethylamino)thieno[3,2-c]coumarin derivatives

Novel push-pull fluorescent dyes, 7-(diethylamino)furo[3,2-c]coumarin and 7-(diethylamino)thieno[3,2-c]coumarin derivatives, were designed and synthesized using formyl derivatives of furo- and thieno[3,2-c]coumarins as key intermediates. Electron absorption and emission spectra of the dyes were recorded in different solvents. The longest-wave bands in the electron absorption spectra of the dyes are suggested to be of push-pull nature.

Optical properties of gumus acids of chernozem podzolized after applying litter and compostes on its basis

Investigation of electronic absorption spectra of humic acids (HA) is considered as one of their objective diagnostic features and indicators of transformation of HA components. Electron absorption spectra of the HA in the visible and ultraviolet range, in general, are gentle curves, which monotonically decrease with increasing wavelength. However, even such spectra reveal the difference in the spectral properties of the HA not only of different soils, but also of one type under excellent soil conditions, which allows the use of spectrophotometric analysis as a sensitive method for the study of humic acids. A thorough study of the properties and nature of humus substances using modern methods helps to understand the features the formation of humus substances in different natural conditions. The purpose of the study is to determine the change in the qualitative composition of humic acids extracted from chernozem podzoled after application of the litter and compost on its basis by spectrophotometry. To achieve this goal, the following methods were used: modeling, laboratory analysis, mathematical and statistical. Field studies have been carried out to determine the effect of litter and compost on its basis on the formation of the molecular structure of humic acids from chernozem podzoled. The studies carried out by us, the electronic absorption spectra of humic acids of chernozem podzoled correspond to the curves typical for a class of humus, the shape of the spectrum does not change, which indicates the similarity in the molecular structure of humic acids, but differ in the angle of incidence in the region of the ultraviolet range. The qualitative composition of structural elements of humic acids is determined on the basis of the analysis of electron absorption spectra of humic acids in the spectral range of 200–800 nm. The change of optical characteristics of humic acids extracted from chernozem of podzolized after introduction of the litter and compost on its basis was determined. The application of chicken litter and compost (scent + husk) contributes to enhancing the aroma of humic acids and increasing their resistance to mineralization. It has been established that composting has a longer-lasting effect on the formation of the structure of humic acids of black podzolized soils on the introduction of non-composting litter. In the UV range (200–400 nm), we note the characteristic intensive absorption of light for humic acids extracted from chernozem podzolized after the introduction of chicken litter and compost (scent + husk), due to the loss of weakly colored peripheral chains of molecules. The character of the inclination of the curves determined by the ratio D 465/665 allows us to conclude that the humic acids extracted from the chernozem podzolized after composting (laced + husk) have a more condensed nucleus than the introduction of chicken litter and compost (laced + husk). It is determined that the intensity of the influence on the mobility of the aromatic electronic system of humic acids depends on the period of composting of the source material and is manifested in absorption spectra in the ultraviolet light range.

Studies of the aromatic β-diketones as extractant of copper ions

Benzoylacetone 2, dibenzoylmethane 3and acetylacetone 1were studied as extractants of copper ions by liquid-liquid partition and spectrophotometric methods. Extraction ability increase in order 1< 2< 3. The values of pH1/2, corresponding to 50% of the extraction of copper, are equal to 10.75, 10.08 and 9.85 for 1, 2, 3, respectively. The extraction process is the most effective when 3was used as extractant, the maximum amount of copper ions passed to the organic phase is 50% and 99% for 1and 3, respectively. The spectra have shown that in the aqueous and in the organic phase β-diketone form two chelated complexes [CuL]+ and [CuL2]. Partition ratios (P2) of [CuL2] complexes have very high values, much higher than P1. That complexes determine the efficiency of extraction process of Cu(II) ions, what confirm the electron absorption spectra.

Electrochemical determination of antioxidant properties of a series of tetraphenylporphyrin derivatives and their zinc complexes

Zinc complexes of a series of substituted tetraphenylporphyrins containing OH-groups in the phenyl rings were synthesized. Their antioxidant capacity was estimated in reaction of the porphyrins with 2,2′-diphenyl-1-picrylhydrazyl (DPPH) by cyclic voltammetry. The electron absorption spectra of the all synthesized compounds before and after the reaction with 2,2′-diphenyl-1-picrylhydrazyl were recorded. The effect of structure of the porphyrins and zinc complexes on their antioxidant capacity was discussed.