Structure and electronic properties of 3,3′-diamino-4,4′-azo-1,2,4-triazole nitrate and perchlorate

Based on density functional theory with regard to the dispersion interaction the crystal structure and electronic properties of C₄H₈N₁₂O₆ and C₄H₈N₁₀Cl₂O₈ are studied. Atomic structural parameters, bond populations, atomic charges, energy and spatial electron distributions are calculated. Differences in the studied characteristics caused by the non-equivalence of atoms are shown. A partially covalent nature of anion-cation bonds is revealed. The cationic nature of the lower unoccupied states is established, which results in a small band gap of ~1.7 eV as compared to other nitrates and perchlorates.     

Synthesis,characterization and properties of 3,3′-diethyl-1,1′-oxydiethylenedicarbonyl bis(thiourea)

In this paper, 3,3′-diethyl-1,1′-oxydiethylenedicarbonyl bis(thiourea) (DEOECTU), was synthesized by phase transfer catalysis and then characterized by UV, elemental analysis, infrared spectra, mass spectrum, ¹H NMR and TGA. DEOECTU properties, such as response to metal ions, adsorption on sulfide mineral surfaces, and hydrometallurgical performance as flotation collectors, were also investigated. The results indicated that DEOECTU reacted chemically with Cu²⁺ ions through its S and N atoms in the C(=S)–NH–C(=O) group to form a new chelate compound, but no reaction of DEOECTU with Zn²⁺, Pb²⁺, Fe³⁺ or Fe²⁺ ions was observed. The results of adsorption and flotation experiments demonstrated, that compared to pyrite, sphalerite and galena, DEOECTU exhibited a superior collecting power for chalcopyrite and might attach on chalcopyrite surface by chemisorption. The further theoretical analysis from Pearson’s HSAB view point briefly explained the experimental results of the selective response of DEOECTU to Cu²⁺ ions and chalcopyrite.     

Specificity of photonics of 3,3′-diethyl-5,5′-dichloro-9-ethylthiacarbocyanine dimers in the presence of cucurbit[7]uril

Molecules of 3,3′-diethyl-5,5′-dichloro-9-ethylthiacarbocyanine form dimers in aqueous solutions, which are capable of fluorescence and intersystem crossing to the triplet state. In the presence of cucurbit[7]uril and alkali metals or ammonium cations, dye dimer complexes are formed, which exhibit phosphorescence and thermally activated delayed (E-type) fluorescence in air-saturated solutions at room temperature. With the use of quantum-chemical calculations, the structure of dimeric dye complexes with cucurbit[7]uril is suggested.     

Spectroscopic investigation of interaction of 6-methoxyflavanone and its β-cyclodextrin inclusion complex with calf thymus DNA

The interaction of 6-methoxyflavanone (6MF, 6-methoxy-2-phenyl-4H-1-benzopyran-4-one) with calf thymus DNA (ctDNA) was investigated by absorption spectroscopy, fluorescence spectroscopy, and cyclic voltammetry in the presence and absence of ??-cyclodextrin (??-CD) acting as capping agent. Molecular modelling was used to optimise the study of 6MF-??-CD and 6MF-DNA interactions. Enhancement in the fluorescence intensity of 6MF was observed due to the formation of 1 : 1 complex with ??-CD. In the presence and absence of DNA, 6MF showed different characteristics such as hyperchromic effect, red shift of absorption spectra and fluorescence quenching of 6MF due to binding between 6MF and ctDNA. The nature of the binding group was found to be different for the 6MF-ctDNA and 6MF-ctDNA-??-CD systems. An increase in fluorescence intensity was observed for the 6MF-ctDNA system while varying the concentration of ??-CD due to encapsulation of a part of 6MF in cyclodextrin. The results are compatible with the possibility of the interaction of dihydrobenzopyran-4-one moiety of 6MF with ctDNA as well as with ??-CD. Cyclic voltammetric studies confirmed the binding interaction between 6MF and ctDNA in the absence and presence of ??-CD and molecular modelling explains the site of the interaction of 6MF with cyclodextrin and ctDNA.     

Synthesis,interaction with DNA and nuclease activity of zinc complexes of 2,2′-bipyridine derivatives with tetraalkylammonium groups

Two zinc complexes of disubstituted 2,2′-bipyridine with tetraalkylammonium groups, [Zn(L¹)₃](ClO₄)₈ · 12H₂O (1) and [Zn(L²)₃](ClO₄)₈ · 2H₂O (2) (L¹ = [4,4′-(Et₃NCH₂)₂-bpy]²⁺, L² = [4,4′-((n-Bu)₃NCH₂)₂-bpy]²⁺ and bpy = 2,2′-bipyridine), have been synthesized and characterized. Species distributions in aqueous solution of both complexes were determined by potentiometeric titration. The interaction of these complexes with calf thymus DNA was explored by UV spectroscopic titration and CD spectroscopy, suggesting outside electrostatic binding mode. Both complexes were applied to the cleavage of plasmid pBR322 DNA under hydrolytic conditions; 1 can effectively cleave DNA from supercoiled to nicked form, showing quite high nuclease activity, while 2 has limited ability to cleave DNA.     

Multiplication of Selenium with 3,3′-Diaminobenzidine1

Abstract

In order to increase sensitivity, an element may be multiplied with a polynuclear complexing agent before its measurement and determination is made. An example for the multiplication of selenium with 3,3′-diaminobenzidine is proposed. The procedure is based on the formation and separation of H₄N₂BPN₂Se and SeN₂BPN₂Se (BP = biphenyl) at different acidities.     

Synthesis and structural investigation of 4,4′-dimethyl-[3,3′-bi(1,2,5-oxadiazole)] 5,5′-dioxide

The oxidation of hexane-2,3,4,5-tetraone tetraoxime with dinitrogen tetroxide was studied in different solvents. The primary furoxan ring closure was found to occur involving either two central or two terminal oxime groups to form 4,7-dimethyl[1,2,5]oxadiazolo[3,4-d]pyridazine 1,5,6-trioxide and the previously unknown 4,4′-dimethyl-[3,3′-bi(1,2,5-oxadiazole)] 5,5′-dioxide. The structure of the latter compound was established by X-ray diffraction.     

Introduction of novel brønsted acidic ionic liquids with perchlorate counter-anion for one-pot synthesis of symmetric 3,3′-diaryloxindoles

Research on Chemical Intermediates - In this work, three novel 1,4-butane sultone-based Brønsted acidic ionic liquids with Perchlorate conter-anion are prepared. These newly introduced ionic...     

Electrochemical studies of (−)-epigallocatechin gallate and its interaction with DNA

In this paper, an electrochemical investigation of (−)-epigallocatechin gallate (EGCG) and its interaction with DNA is presented. Via an electrochemical approach assisted by ultraviolet–visible (UV–Vis) spectroscopy, we propose that EGCG can intercalate into DNA strands forming a nonelectroactive complex, which results in the decrease of the anodic peak current of EGCG. Meanwhile, an electrochemical study with the DNA–Cu(II)–EGCG system shows that damage to DNA can be recognized electrochemically via the increase in the anodic peak current resulting from the oxidation of guanine and adenine bases. The damage can also be recognized spectrophotometrically via an increase in the 260 nm absorption band. In addition, it was found that EGCG is able to discriminate dsDNA from ssDNA, making a potential electrochemical indicator for the detection of DNA hybridization events. A rapid and convenient method of detecting EGCG was also developed in this work. Figure Interaction of EGCG with DNA and damage to DNA in the presence of Cu(II) Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

Synthesis of Schiff bases by aromatic amine condensation with 3,3′-bithiophenes-2,2′ and 4,4′-dicarbaldehydes

Reactions of aromatic amines with 3,3′-bithiophene-2,2′-dicarbaldehyde 1 and 3,3′-bithiophene-4,4′-dicarbaldehyde 2 gave the 2,2′-(N-(aryl)diimino)-3,3′-bithiophene 3 and 4,4′-(N-(aryl)diimino)-3,3′-bithiophene 4 in good yields. Orthophenylenediamine reacted with 1 and 2 to give dithieno[3,4-c;4′,3′-e]azepino[1,2-a]benzimidazole 5 and dithieno[2,3-c;3′,2′-e]azepino[1,2-a]benzimidazole 6. All these original products have been characterized by spectroscopic techniques and elemental analysis.     

Stepwise synthesis and characterization of oligomers based on 1,1′-binaphthol with 3,3′-acetylene spacer

A selective mono de-iodination led to an alternative preparation of a mono-iodo binaphthol-derivative in high yield. With the mono-iodo compound, several structurally well-defined, 1,1′-binaphthol-based optically active oligomers with a 3,3′-acetylene spacer were synthesized through palladium catalyzed, stepwise-coupling methods. The electrical and photo-physical properties of the oligomers have been examined. The electrical, photo-absorption, excitation and fluorescent data for various oligomers indicated that there is a very limited conjugation present between the naphthylene rings. The atropic of 1,1′-binaphthyl moiety led to twist and rigid main chain in the oligomers and polymers. With the changes of the external environment such as solvents, solvent viscosity and ambient temperature, the wavelengths of absorption and fluorescence and the intensities of absorption are changed slightly, but the fluorescent intensity and quantum yield can be influenced. The luminescent behaviors of the longer chain oligomer exhibit the twisted intramolecular charge transfer characteristic, which has a potential application in wavelength-stable light emitting material adaptable to ambient temperature and the solvent used in wide range.     

Synthesis and Transformations of Substituted 3,3′-Diquinolinyl Sulfides

Abstract

Reactions of the 1,4-dithiin ring opening in 1,4-dithiinodiquinoline 1 with selected oxygen nucleophiles followed by S- and N-alkylation led to sulfides possessing one or two quinolinyl or quinolonyl units. Diquinolinyl sulfides 2 were transformed into quinolinyl-quinolonyl sulfides 3 or diquinolonyl sulfides 9 via thermal rearrangement (the O-N alkyl migration) or hydrolysis of the alkoxy and alkylthio groups with the hydrochloric acid-ethanol mixture.     

Synthesis and properties of 8-phenylindolo-3,3′-trimethinecyanines

The condensation of 1-methyl-2-aryl-3-(2-benzoylvinyl)indoles with substituted indoles in acetic anhydride in the presence of a mineral acid afforded 8-phenylindolo-3,3-trimethinecyanines. Their spectral, polarographic, and photographic properties were studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 499–501, April, 1992.     

Synthesis,characterization, and interaction with DNA of Cu(II) and Zn(II) complexes with 2,2′-bipyridyl-6,6′-dicarboxylic acid

Two transition metal complexes, [Cu₂(bpdc)₂H₂O]·2H₂O (1) and Zn(bpdc)(H₂O)₂ (2) (H₂bpdc?=?2,2′-bipyridine-6,6′-dicarboxylic acid), were synthesized and characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Complex 1 is dinuclear with two five-coordinate cupric ions and 2 is mononuclear with one six-coordinate zinc. Interactions of 1 and 2 with DNA have been investigated using UV–Vis absorption spectra. The cleavage reaction on DNA has been monitored by agarose gel electrophoresis.     

DNA Effect on Cis–Trans Equilibrium and Fluorescent Properties of 3,3′-Diethyl-9-thiomethylthiacarbocyanine Iodide in Aqueous Solution

The influence of DNA on the cis–trans equilibrium and fluorescent properties of 3,3-diethyl-9-thiomethylthiacarbocyanine iodide (DTTC) in a phosphate buffer (pH 7) was studied by various photochemical techniques. The interaction of dye molecules with DNA leads to the formation of stable noncovalently bonded complexes. Data obtained from DTTC absorption and fluorescence spectra suggest that complexation proceeds primarily through the cis-form of the dye. Complexation with DNA leads to a substantial increase in the quantum yield of the triplet state of DTTC molecules. The rate constant for quenching the dye triplet state by oxygen turned out to be significantly lower than the diffusion-controlled value.     

Oxidative macrocyclocondensation of 3,4-diaminofurazan and 4,4′-diamino-3,3′-azofurazan with dibromoisocyanurate. Crystal structures of hexa- and octadiazenofurazan macrocycles

The oxidative cyclocondensation of 3,4-diaminofurazan and 4,4-diamino-3,3-azofurazan with dibromoisocyanurate afforded macrocyclec polydiazenofurazans. The reaction can be directed towards the formation of both the four-membered cycle alone or the three-, six-, and eight-membered macrocycles.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1250–1254, May, 1996.Deceased in 1995.     

Characterization and thermal kinetic studies on charge-transfer complexes of 4,4′-bipyridine with benzoquinone derivatives

4,4′-Bipyridine belong to an important class of compounds with wide applications in different fields and since the formation charge transfer compounds give opportunity to improve the physical and chemical properties of different donors so charge transfer compounds of 4,4′-bipyridine (Bpy) with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone [chloranilic acid] (CHA) and 2,3,5,6-tetrachloro-1,4-benzoquinone [choloranil] (CHL) were studied. The stoichiometries of the reactions were determined from photometric titration methods. Although the thermodynamic parameters [Gibbs free energy (ΔG°), enthalpy (ΔH°), and entropy change (ΔS°)] were calculated. The thermal decomposition of the complexes follows first order kinetics and thermodynamic parameters of the decomposition were calculated. The structural morphology was investigated by scanning electron microscopy (SEM) and Transmission Electron Microscopy (TEM) and show that these molecules are of nanosize.     

Spectral and Electrochemical Investigation of Intercalations of Adrenaline and CT－DNA

A strong interaction between double stranded calf-thymus DNA (ds-DNA) and adrenaline in solution, but no interaction between single stranded calf-thymus DNA (ss-DNA) and adrenaline was observed by the use of UV-visible spectroscopy and voltammetric techniques. It is suggested that the interaction leads to an intercalation of adrenaline molecules into the groove of ds-DNA and the formation of ds-DNA (adrenallne)n complex. The binding site size of the interaction of adrenaline with CT-DNA in nucleotide phosphate [ NP] has been determined as 25. The interaction of different concentration adrenaline with DNA modified GCE shows that the DNA modified GCE can be a good tool to detect lower concentration adrenaline.