Model reaction related to cytochrome P-450: effect of substitution on the rate of naphthalene oxidation

A kinetic method for measuring the relative rates of hydroxylation of naphthalene derivatives/cyclohexene has been developed. With this technique a linear relationship between the logarithm of the rates of oxidation products and the oxidation potentials of the naphthalene derivatives has been observed. Plots of σ Hammett and σ⁺ Hammett–Brown with logarithm of relative rates have been linear and shown ρ = −0.98 and ρ⁺ = −0.58, respectively. This contrast aromatic oxidation in protic solvents in which the oxidation products are naphthoquinones and provides further evidence for the intermediacy of carbocation in the hemin catalyzed hydroxylation of aromatic rings.     

4-Methyl morpholinium bis-(thio)barbiturates: Synthesis,structure, anticancer evaluation,and CoMFA study

The reaction of symmetrical (thio)barbituric acids with aldehydes in the presence of 4-methyl morpholine yielded a new form of 4-methyl morpholinium bis-(thio)barbiturate containing charge-separated intermolecular and eight-membered intramolecular H-bonds. X-ray Crystallography, FT-IR, and ¹H and ¹³C-NMR spectroscopy techniques were used for structure characterizations. Some of these compounds showed potent anticancer activities. Cytotoxicity of the synthetic compounds against HeLa and MCF-7 cell lines were performed by MTT assay. In addition, a comparative molecular field analysis was carried out, and the effects of substituents on the biological activities of these compounds were explained.     

Synthesis,characterization and crystal structure determination of mononuclear and dinuclear copper(II) carboxylates: [Cu(Hdpa)2(en)] and [{Cu2(μ-na)4(CH3OH)2}·2CH3OH]

Two new copper complexes [Cu(Hdpa)₂(en)] (1) and [{Cu₂(μ-na)₄(CH₃OH)₂}·2CH₃OH] (2) (where en is ethylene diamine, Hdpa is 2′-carboxy-[1,10-biphenyl]-2-carboxylate anion and na is 1-naphtalenecarboxylate) have been synthesized and their crystal structures were determined by X-ray crystallography. Complex 1 was prepared from the reaction of Cu(NO₃)₂·3H₂O with ethylene diamine and 2,2′-biphenyldicarboxylic acid in a mixture of water and methanol and complex 2 was prepared from the reaction of CuSO₄·5H₂O with 1-naphtalenecarboxylic acid in methanol. The two complexes were characterized by IR, UV–vis, luminescence and elemental analysis. Moreover, complex 2 was characterized by EPR spectroscopy and thermogravimetric analysis. Complex 1 is a monomer and complex 2 is a dimer with a paddle-wheel structure; both structures are without precedent in the literature.     

Detailed mapping of intramolecular energy transfer in field-effect single-molecule nanoelectronic devices

The electronic and vibrational atomic responses to external electric field (EF) are computed to detail intramolecular energy transfer in a proposed molecular nanoelectronic field-effect system. The parallel and perpendicular electronic and vibrational contributions to intramolecular energy transfer are computed using, respectively, quantum theory of atoms-in-molecule and an energy partitioning scheme based on normal modes vibrational analysis. The symmetrical and asymmetrical intramolecular energy transfers are interpreted, respectively, as Peltier-like and Joule-like effects and quantified in terms of appropriate coefficients. Dependencies of these coefficients on EF are investigated. In addition, a semiclassical temperature model is introduced to describe symmetrical and asymmetrical temperature distributions which are attributed, respectively, to the Joule-like and Peltier-like heatings. This procedure can be used to map out intramolecular energy distribution in molecular nanoelectronic systems.     

Co-solvent Effect on Spontaneous Formation of Large Nanoscale Structures in Catanionic Mixtures in the Anionic-Rich Region

Journal of Solution Chemistry - The aggregation behavior was investigated in mixtures of sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB) (anionic-rich catanionic) solutions....     

A rapid and efficient method for synthesis of new 3-arylideneisobenzofuran-1(3H)-one derivatives catalyzed by acetic anhydride under solvent-free and microwave conditions

In this study we have described the synthesis of new 3-arylidene isobenzofuran-1(3H)-one derivatives. Condensation reaction of phthalic anhydride and quinoline derivatives under solvent-free condition and microwave irradiation in the presence of acetic anhydride as catalyst in good excellent yield is reported.     

Endo-inulinase Stabilization by Pyridoxal Phosphate Modification: A Kinetics, Thermodynamics, and Simulation Approach

The structural and storage and functional thermostabilization of endo-inulinase (EC 3.2.1.7) through semi-rational modification of surface accessible lysine residues by pyridoxal-5'-phosphate (PLP) and ascorbate reduction have been explored. Improved stability was observed on modifications in the absence or presence of inulin, which indicates storage or functional thermostabilization, respectively. Comparisons have been made between non-modified and modified enzyme by the determination of Tm as an indicator of structural stability, temperature-dependent half-lives (t1/2), energy barrier of the inactivation process, and thermodynamic parameters (ΔH, ΔG, and ΔS) in a storage thermostability approach. These parameters coincided well with the observed stabilization of the engineered enzyme. Moreover, relative activities with sucrose and inulin were determined for non-modified and modified endo-inulinases at different temperatures. A comparison of the sucrose-to-inulin ratios of the initial rate of hydrolysis as an indicator of substrate specificity revealed about twofold improvement in inulinase versus sucrose activity by enzyme modification. Molecular dynamics simulations and molecular docking approaches were employed to explain the observed structural and functional thermostabilization of endo-inulinase upon modification. We hypothesize the establishment of intramolecular interactions between the covalently attached PLP-Lys381 and Arg526 and Ser376 residues as a representative of modification-originated intramolecular contacts in the modified enzyme.     

A rapid and efficient ultrasound-assisted synthesis of 5,5-diphenylhydantoins and 5,5-diphenyl-2-thiohydantoins

To obtain a rapid, efficient and mild synthesis of 5,5-diphenylhydantoin and 5,5-diphenyl-2-thiohydantoin derivatives, ultrasonic irradiation has been applied to the reaction mixtures containing substituted benzils and urea or thiourea derivatives catalyzed by KOH in DMSO/H(2)O, which allowed us to achieve products at room temperature in a good yield and short time without any side product. This convenient procedure will allow a further increase of the diversity within the hydantoin family.     

A facile green synthesis of MgCoFe2O4 nanomaterials with robust catalytic performance in the synthesis of pyrano[2,3-d]pyrimidinedione and their bis-derivatives

Molecular Diversity - In this study, an efficient, rapid and simple plant-mediated green sol–gel auto-combustion procedure was presented to synthesis magnesium–cobalt ferrite...