Synthesis,structure, spectral and coordination properties of a crown ether derivative of 1,3-indandione. A new structural evidence for the versatile reactivity of 2-acetyl-1,3-indandione

The current study describes the synthesis of a new 1,3-indandione derivative with conjugated N-phenylaza-15-crown-5 moiety (4). The crystal structure of compound 4 was solved and its optical properties were studied in various solvents and in presence of alkaline and alkaline-earth metal ions. Quantum chemical (DFT) methods were employed to describe the structure and the optical properties of the studied compound and its complexes. The obtained results indicated that the synthesis of compound 4 using acid-catalyzed aldol reaction between 2-acetyl-1,3-indandione and the corresponding aldehyde is accompanied with an unexpected deacetylation step. In this way, the N-phenylaza-15-crown-5 moiety is directly conjugated with the 1,3-indandione fragment, known as a very strong electron acceptor. Therefore, the absorption spectra of 4 are only slightly influenced by complexation with Ba²⁺ and Sr²⁺ ions.     

Classification of hexagonal adlayer arrangements by means of collective geometrical properties

Unequal-sphere packing model is applied for the simulation of large number of hexagonal adlayer structures with surface coverage between theta=13 and theta=1 on the hexagonal substrate, with atomic radius of the adsorbate and substrate atoms as the only input. Each structure is characterized with respect to collective adlayer properties: the average adlayer height and the adlayer roughness. The distribution of hexagonal arrangements is presented in a special plot, which can be used for identification and characterization of hexagonal adlayers of different surface coverages and atomic registries. The most likely structures are related to the extreme values of our model parameters. The usefulness of this methodology is successfully demonstrated by comparison with some real adsorbate-substrate systems, i.e., halogens and rare gases adsorbed on (111) surface. Besides the agreement with experimental results, our model offers new insight into the formation of atomic adlayers and detailed analysis of the atomic registry. We believe that our approach will be of use for identification of probable structures among the large number of combinatorial possibilities in theoretical studies and for better interpretation of experimental results (i.e., scanning-tunneling microscopy images of atomic adlayers).     

Reaction between glutaric anhydride and N-benzylidenebenzylamine, and further transformations to new substituted piperidin-2-ones

The reaction between glutaric anhydride (1) and N-benzylidenebenzylamine (3) was studied in detail by ¹H NMR spectroscopy under different reaction conditions. The major product was (±)-trans-1-benzyl-6-oxo-2-phenylpiperidine-3-carboxylic acid (2), which was converted into new substituted piperidin-2-ones via transformations of the carboxylic group. The final products are expected to possess pharmaceutical activities, and the relevant screenings are in course.     

Reactivity of OH radicals with chlorobenzoic acids—A pulse radiolysis and steady-state radiolysis study

The reactions of OH radicals with 2-, 3-, 4-chlorobenzoic acids (ClBzA) and chlorobenzene (ClBz), k(OH+substrates)=(4.5?6.2)×10⁹ dm³ mol^?1 s^?1, have been studied by pulse radiolysis in N₂O saturated solutions. The absorption maxima of the OH-adducts were in the range of 320?340 nm. Their decay was according to a second-order reaction, 2k=(1?9)×10⁸ dm³ mol^?1 s^?1. In the presence of N₂O/O₂ the formation of peroxyl radicals was detectable for 2-, 4-ClBzA and ClBz, k(OH-adduct+O₂)=(2?4)×10⁷ dm³ mol^?1 s^?1, while this reaction for 3-ClBzA was too slow to be registered. In the presence of N₂O the degradation rates induced by gamma radiation were very similar for all chlorobenzoic acids, yet the chloride formation was distinctly higher for 3-ClBzA. In the presence of oxygen the initial degradation of 2-and 4-ClBzA equaled the OH-radical concentration, whereas in case of 3-ClBzA only ～60% of OH led to degradation. The order for the efficiency of dehalogenation was 4->2->3-ClBzA. Several primary radiolytic products could be detected by HPLC. To evaluate the toxicity of final products a bacterial bioluminescence test was carried out.     

Separation and Thermal Racemization of the Enantiomers of Spiro[cyclohexadiene-dihydroacridines]

Summary.  The enantiomers of substituted spiro[cyclohexadiene-dihydroacridines] were separated by enantioselective liquid chromatography with the sorbent/solvent systems triacetylcellulose/methanol, tris-(3,5-dimethylphenylcarbamoyl)-cellulose/silica gel (Chiralcel OD^TM)/n-heptane/2-propanol, and (+)-poly-(trityl methacrylate)/silica gel/n-heptane/2-propanol. Interconversion barriers of the enantiomers were determined for a series of derivatives by thermal racemization. Electrocyclic ring opening/ring closure in terms of the Woodward-Hoffmann rules is discussed for the enantiomerization mechanism; the interconversion of the enantiomers by enolization is ruled out by deuterium exchange experiments. Received April 3, 2000. Accepted April 12, 2000     

Multifaceted Studies of the DNA Interactions and In Vitro Cytotoxicity of Anticancer Polyaromatic Platinum(II) Complexes

This study reports a detailed biophysical analysis of the DNA binding and cytotoxicity of six platinum complexes (PCs). They are of the type [Pt(P_L)(SS‐dach)]Cl₂, where P_L is a polyaromatic ligand and SS‐dach is 1S,2S‐diaminocyclohexane. The DNA binding of these complexes was investigated using six techniques including ultraviolet and fluorescence spectroscopy, linear dichroism, synchrotron radiation circular dichroism, isothermal titration calorimetry and mass spectrometry. This portfolio of techniques has not been extensively used to study the interactions of such complexes previously; each assay provided unique insight. The in vitro cytotoxicity of these compounds was studied in ten cell lines and compared to the effects of their R,R enantiomers; activity was very high in Du145 and SJ‐G2 cells, with some submicromolar IC₅₀ values. In terms of both DNA affinity and cytotoxicity, complexes of 5,6‐dimethyl‐1,10‐phenanthroline and 2,2′‐bipyridine exhibited the greatest and least activity, respectively, suggesting that there is some correlation between DNA binding and cytotoxicity.     

Phase topology of Appelrot class I of a Kowalewski top in a magnetic field

We consider an integrable case generalizing the Appelrot class I of a Kowalewski top in a magnetic field. Its phase topology is investigated by means of Fomenko-Zieschang invariants. The offered method of approach to the calculation of marks completes Bolsinov’s method in the situation where it is not usable. __________ Translated from Fundamentalnaya i Prikladnaya Matematika, Vol. 12, No. 1, pp. 95–128, 2006.     

Effect of acetate and EDTA ligands on Hydrolysis of the Iron(III) Ion in sodium chloride medium

The hydrolysis of the iron(III) ion in sodium chloride medium without organic ligands and in the presence of acetate and EDTA ligands was studied by emf method, at 25°C. The data indicate the effect of the organic ligands. In the presence of acetate ion the beginning of hydrolysis of the iron(III) ion is slightly shifted toward lower pH values, while in the presence of EDTA, as a strong complex forming ligand, the beginning of hydrolysis is shifted toward higher pH values for 2.5 pH units.     

Photolyse von Monochloressigsäure bei 253,7 nm in wäßriger Lösung

The photolysis of 0.5 mole/l monochloroacetic acid in aqueous solution at 253.7 nm was studied and as products were determined: Cl^? (?=0.34), CH₂OHCOOH (?=0.19), CO₂ (?=0.12), CH₃COOH (?=0.08), HCHO (?=0.004) and CH₄ (?=0.001). Based on these results a probable reaction mechanism is discussed to explain the rather complicated process.