Voltammetric and Fluorimetric Studies of Dibenzoylmethane on Glassy Carbon Electrodes and Its Interaction with Tetrakis (3,5-Dicarboxyphenoxy) Cavitand Derivative

Due to the medical importance of dibenzoylmethane, one of the aims of the study was to find an appropriate packing material and a biologically friendly co-solvent to help its introduction into living systems. Accordingly, redox properties of dibenzoylmethane were investigated on glassy carbon electrodes in acetonitrile and in 1-propanol with cyclic voltammetry, and showed a diffusion-controlled process. In the anodic window, an oxidation peak appeared at around 1.9 V in both solvents. Cycling repeatedly between 0 and 2 V, the reproducibility of this peak was acceptable, but when extending the window to higher potentials, the electrode deactivated, obviously due to electrode material. The addition of the investigated tetrakis(3,5-dicarboxyphenoxy) cavitand did not significantly change the voltammograms. Further electrochemical experiments showed that the coexistence of water in acetonitrile and 1-propanol drastically reduces the solubility of dibenzoylmethane. Moreover, very rapid electrode deactivation occurred and this fact made the use of electrochemical methods complicated. Considering that both the cavitand and dibenzoylmethane are soluble in dimethyl sulfoxide, the interaction of these species was investigated and formation of stable complexes was detected. This observation was verified with fluorescence quenching studies. The mixture of water and dimethyl sulphoxide also dramatically improved the solubility of the cavitand–dibenzoylmethane complex at high excess of water. The addition of cavitand improved the solubility of dibenzoylmethane, a property which supports the application of dibenzoylmethane in therapy.     

Electronic structure and absorption spectra of acetylacetone and its analogs

The molecules of acetylacetone, benzoylacetone, dibenzoylmethane, and thiodibenzoylmethane have been calculated by the simple MO LCAO method and their absorption spectra recorded. The chelation of acetylacetone with a hydrogen atom does not affect the energy of the first allowed transition ¹A₁-¹B₁. Calculations correctly predict the change in the energy for this transition in the -diketone series: acetylacetone > benzoylacetone > dibenzoylmethane > thiodibenzoylmethane; the intensity reaches a maximum value for dibenzoylmethane and dropping sharply for thiodibenzoylmethane. The secondary absorption bands for benzoylacetone and dibenzoylmethane are examined experimentally and interpreted theoretically.     

Synthesis of dibenzoylmethane derivatives and inhibition of mutagenicity in Salmonella typhimurium.

Twenty dibenzoylmethanes with methyl, methoxy, bromo, chloro, or fluoro substitution on either one or both benzene rings were synthesized and assayed for inhibition of the mutagenicity of 2-nitrofluorene in S. typhimurium TA98. 2,2-Dimethoxy, 3,3-dimethoxy and 3,3,4,4-tetramethoxydibenzoylmethane was as active as dibenzoylmethane. None of the halogen-substituted dibenzoylmethanes were active. These results demonstrate that dibenzoylmethanes can inhibit the mutagenicity of 2-nitrofluorene, and that modifications made on the benzene rings of dibenzoylmethane cannot enhance the antimutagenicity of this parent compound.     

Convenient synthesis of 3-arylazopyrazoles and 2-arylazo-1,3,4-Δ2- thiadiazoline derivatives from 3-nitroformazans

Reactions of 3-nitro-1,5-diarylformazans 1a-c with carbanions of acetylacetone, dibenzoylmethane, aceto-acetanilide, benzoylacetonitrile, ω-benzenesulfonylacetophenone and malononitrile yielded the corresponding 3-arylazopyrazole derivatives 4-9 respectively. Reactions of 1 with nucleophiles result in displacement of the nitro group and the formation of the corresponding 3-substituted formazans 10-13 . Treatment of 1 with potassium thiocyanate gave, however, 5-imino-2-arylazo-1,3,4-Δ²-thiadiazolines 14. Structural assignments have been made on the basis of spectral and elemental analyses, chemical behaviour and alternate synthesis wherever possible.     

Synthesis of Functionally Substituted Pyrrolo[3,2-<Emphasis Type="Italic">g</Emphasis>]quinolines from 6-Amino-7-methoxy-1,2,3-trimethylindole

The comparative reactivities of 6-amino-1,2,3-trimethyl- and 6-amino-7-methoxy-2,3-dimethylindoles with acetylacetone, dibenzoylmethane, and with aceto- and trifluoroacetoacetic esters have been studied. Methods have been developed for the preparation of some functionally substituted pyrrolo-[3,2-g]quinolines. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1529–1539, October, 2005.     

β-二酮化合物光稳定行为的研究

研究了β-二酮类化合物二苯甲酰甲烷、苯甲酰丙酮、对苯二甲酰乙酸乙酯的光稳定行为,在β-二酮类化合物的溶液中存在着烯醇式和酮式平衡。当以紫外光进行辐照时,烯醇式异构体不断减少,酮式的含量则不断增多。由于这些化合物有不同的互变异构化过程以及不同的氢键形成能力,因此,它们对高聚物有着不同的稳定化能力。我们提出的二苯甲酰甲烷的光稳定机理,不同于Otterstedt提出的机理。新的统一的光稳定机理尚待进一步深入研究.     

The mass spectra of metal complexes of dibenzoylmethane

The mass spectra of a series of metal complexes of dibenzoylmethane have been rationalized. The paths of novel rearrangement reactions involving both hydrogen and oxygen migration may differ according to the type of metal atom in the complex. Further examples are proposed of the effect of metal valency changes in ion reactions.     

On the photosensitivity of dibenzoylmethane,benzoylacetone and ethyl benzoylacetate in solution

The influence of sunlight on the keto-enol ratio of dibenzoylmethane, benzoylacetone and ethyl benzoylacetate in heptane solution was examined. It was shown that the tautomeric equilibrium is strongly displaced to the keto form. Important differences in the photosensitivity of β-diketones and β-ketoesters depending on the structural features and the nature of irradiation have been established.     

Reaction of iodonium ylides of 1,3-dicarbonyl compounds with HF reagents

Reaction of dibenzoylmethane with (diacetoxyiodo)benzene in the presence of KOH in MeCN quantitatively gave the corresponding iodonium ylide, which was treated with a HF reagent to afford the corresponding 2-fluorinated dibenzoylmethane in 14-50% yields. The similar reaction of the iodonium ylides obtained from 1-phenylbutan-1,3-dione, ethyl benzoylacetate, and ethyl p-nitrobenzoylacetate with TEA·3HF gave the corresponding fluorinated products in 17-34% yields. It is suggested that the fluorinated products were formed through the C-protonation of the ylide, followed by displacement with fluoride ion. The same reaction of the iodonium ylide of dibenzoylmethane with concentrated HCl gave the corresponding chlorinated product in 45% yield.     

Electronic dissymmetry in chiral recognition

The pi-bonding of the beta-diketonate ligands in C2-symmetric (dike)2TiX2 complexes engenders a significant electronic dissymmetry, with the LUMO of the complex resembling a "tipped" dz2 orbital whose tilt with respect to the plane containing the metal and the two X groups is determined by the configuration at titanium. The ability of this electronic dissymmetry to promote chiral recognition has been probed in 1,1'-bi-2-naphtholate complexes (RCOCHCOR)2Ti(BINOL) (R = CH3, Ph, or tBu). The complexes show exclusively one diastereomer by NMR, which has been established as the one predicted on electronic grounds by crystallography of the dibenzoylmethane and 2,2,6,6-tetramethylheptanedione complexes. Confirmation that the selectivity is due to electronic rather than steric factors is given by the behavior of the tin analogues, which are structurally similar but show much smaller diastereoselectivities.     

Determination of small amounts of uranium in hafnium,zirconium and zircaloy-2

To meet specification requirements, selected methods for determining uranium have been examined and two satisfactory procedures have been developed for application to the analysis of reactor-grades of hafnium, zirconium and Zircaloy-2.These procedures are based on extraction of uranyl ions from a solution of the sample with a tri-n-butyl phosphate-iso-octane mixture. Following this extraction, uranium over the range 10–150 p.p.m. is determined by a spectrophotometric method, using dibenzoylmethane. For smaller amounts of uranium, down to about 0.5 p.p.m., the determination is completed by squarewave polarography.     

1-(1-Carboxy-2-R-4-methylcyclohex-4-enyl)carbonyl- and 1-(2-R-4-Methylcyclohex-4-enyl)carbonyl-3,5-dimethyl(diphenyl)pyrazoles

1-(1-Carboxy-2-R-4-methylcyclohex-4-enyl)carbonyl- and 1-(2-R-4-methylcyclohex-4-enyl)carbonyl-3,5-dimethyl(diphenyl)pyrazoles have been obtained from the reaction of monohydrazides of 2-R-methyl-4-cyclohexen-1,1-dicarboxylic acids and hydrazides of 2-R-4-methyl-4-cyclohexen-1-monocarboxylic acids with acetylacetone and dibenzoylmethane. The conditions for the formation of the pyrazoles depend on the nature of the substituents in the hydrazide starting materials and the structure of the 1,3-diketone used.     

Coordination compounds of europium(III) and samarium(III) dibenzoylmethanates with 5-phenyl-2-(2′-pyridyl)-7,8-benzo-6,5-dihydro-1,3,6-triazaindolizine

Novel heteroligand europium(III) and samarium(III) complexes with dibenzoylmethane (HDBM) and 5-phenyl-2-(2??-pyridyl)-7,8-benzo-6,5-dihydro-1,3,6-triazaindolizine (L), Ln(DBM)₃L (Ln = Eu, Sm), were synthesized. The structure of the europium complex was determined by X-ray diffraction. It was shown that the use of L as an auxiliary ligand increases the luminescence intensity of lanthanides severalfold as compared with analogous complexes containing phenanthroline as the second ligand.     

环戊-2-烯酮的研究Ⅰ.环戊-2-烯酮与醛反应的区域选择及非对映立体选择性

本文系统研究了环戊-2-烯酮在碱性条件下与醛类的羟醛缩合反应,并通过结构及过渡状态的分析,解释了所得的这类反应的区域及非对映立体选择性.     

Preparation and Characterization of Ternary Europium ComplexDoped Thin SolGel Hybrid Film by Fluorescence Spectroscopy*

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｌｏｗ－ｔｅｍｐｅｒａｔｕｒｅｐｒｏｃｅｓｓｉｎｇｏｆｔｈｅｓｏｌ－ｇｅｌｍａｔｅｒｉａｌｍａｋｅｓｉｔｐｏｓｓｉｂｌｅｔｏｅｎｔｒａｐｏｒｇａｎｉｃｓｐｅｃｉｅｓｅａｓｉｌｙｗｉｔｈｉｎａｒｉｇｉｄｇｌａｓｓｍａｔｒｉ...     

Cationic Ruthenium(II) Carbonyl Complexes with Nitrile Ligands

Stable cationic complexes of the type [RuCO(PPh₃)₂(L)(RCN)]⁺[ClO₄]^? derived from acetonitrile and acrylonitrile have been synthesized. The bidentate ligands (LH) used are acetylacetone, benzoylacetone, dibenzoylmethane, trifluorothenoyl acetone and 8-hydroxyquinoline. The complexes have been characterized by elemental analysis, IR, conductivity, ¹H and ³¹P NMR and ESCA studies, and possible stereochemistry has been established.     

Reaction of vanadium(v) complexes with some adduct-forming substances in benzene

Vanadium(V) reacts with monobasic and bidentate extracting agents, i.e. 8-quinolinol, 2-methyl-8-quinolinol, salicylaldoxime, hinokitiol, benzoylphenylhydroxylamine, maltol, cupferron, dibenzoylmethane, salicylaldehyde, and phenylmethylbenzoylpyrazolone-5, to form 1:2 complexes containing a basic V=O group and an acidic V—OH group in the same molecule. The basic group reacts with acidic substances to give a hyper- and bathochromic effect; the acidic group reacts with basic substances to give a hyper- and hypsochromic effect. These reactions are observed in benzene solutions.     

Contribution à l'étude du dosage de traces d'acide borique par luminescence

A highly sensitive luminescent reaction is proposed for the determination of submicrotraces of boric acid by complexation with dibenzoylmethane in ether-concentrated sulfuric acid. The optimal conditions of complex formation between boric acid and dibenzoylmethane are investigated, luminescence spectral caracteristics of the solutions of the complex are described, and the phosphorescence mean lifetime of the dibenzoylmethane-boric acid system is evaluated. Analytical curves, established by fluorimetry and phosphorimetry, are satisfactory. 0.0005 μg B/ml is the minimum detectable concentration.     

Using of 4-amino-2-phenylindoles in the synthesis of pyrroloquinolines by the combes reaction

The reaction of 4-amino-2-phenyl- and 4-amino-l-methyl-2-phenylindoles with a free β-position of the pyrrole ring with acetylacetone and dibenzoylmethane was studied. It was found that primary condensation occurs only on aminogroups and produces the corresponding enaminoketones, which under conditions of enamine acidic cyclization on the basis of dibenzoylmethane, turn into pyrrolo[2,3-h]-quinolines. The products of cyclization with participation of indole 3 atom were not detected.     

Über Metall-Stickoxid-Komplexe. XXVI. Nitrosyl-Komplexe von Kobalt und Eisen mit Chelatbildnern

Under replacement of NaBr five- and sixmembered nitrosyl chelat complexes are formed by the reaction of nitrosyl halides of iron and cobalt with sodium salts of acyloines like benzoin and 1,3-diketones such as actylacetone, benzoylacetone and dibenzoylmethane. In the same way react sodium salicylate and pyrocatechol yielding monomeric chelat complexes; by the reaction of disodium pyrocatechol with dinitrosylcobaltbromide a dimeric compound (ON)₂CoOC₆H₄OCo(NO)₂ was found containing oxobridges only. The IR-spectra are discussed.