Role of axial ligand on the electronic structures of active intermediates in cytochrome P-450, peroxidase and catalase

DFT method (B3LYP) with 6-31G^* basis set was utilized in the computation of a fully optimized structure, net atomic charges and spin densities of the intermediate of cytochrome P-450-oxoiron(IV) porphyrin cation radical, compound I – in the presence of axial ligand such as thiolate (SMe⁻) imidazole (IM), phenoxide (OPh⁻), methoxide (OMe⁻) and chloride (Cl⁻). The results show doublet states in compound I are about 2–4 kcal/mol more stable than quartet states for all aforementioned ligands, and the doublet state is the ground state in all cases. However, electron donor ability of the ligands are in the order of SMe⁻ > IM > OMe⁻ > OPh⁻ > Cl⁻. Also the active oxidant intermediate of cytochrome P-450 between different mesomeric structures select sulfur oxygen radical type structure and can be viewed as (RS^↓)Fe^↑(IV)(O^↑)(Por). In horseraddish peroxidase (HRP) and peroxidase with histidine axial ligand π cation radical character of porphyrin ring is preferred (Im)Fe^↑(IV)(O^↑)(Por^↓). For the ligands such as OMe⁻, OPh⁻ and Cl⁻ oxidation mainly took place on the iron and the active intermediate can be viewed as (L)Fe^↑(V)(O)(Por) with one unpaired electron localized on the iron.     

Three component reactions：An efficient and green synthesis of 3, 4-dihydropyrimidin-2-(1H)-ones and thiones using silica gel-supported L-pyrrolidine-2-carboxylic acid-4-hydrogen sulfate

An environmentally benign aqueous protocol for the synthesis of 3,4-dihydropyrimidin-2-(1H)-ones and thiones promoted by a green catalyst,silica gel-supported L-pyrrolidine-2-carboxylic acid-4-hydrogen sulfate,has been developed.The use of nontoxic,thermally stable and inexpensive amino acid catalyst makes the process simple with minimal amount of chemical waste.Compared with classical Biginelli reaction conditions,this new method has the advantages of high yields and simple workup procedures.     

Theoretical study of structure, bonding, and aromaticity of borazyne and B-substituted borazynes

The density functional theory (DFT) is used to study the geometries, and electronic structures of triplet and singlet of borazyne and B-substituted of borazyne. The aromaticity of these systems is analyzed in the light of nucleus-independent chemical shift (NICS), average of two-center indices (ATI). These methods show increasing of aromaticity in deactivating groups. The relation between electron density in ring critical point (RCP) and NICS(1.0) is observed. The most important interaction in these molecules has been investigated by natural bonding orbital method (NBO).     

Effect of the Solvent Polarity on the Optical Properties in the (OC)5Cr=(OEt)(Ph) Complex: A Quantum Chemical Study

Russian Journal of Physical Chemistry A - In this study, using the B3LYP* method, quantum chemical computations were applied for analyzing the effects of solvent on the electronic spectrum features...     

Preparation of a dual-functionalized fumed silica nanoparticle catalysis for synthesis of azaluorenone derivatives

Research on Chemical Intermediates - A dual-functional silica-based catalyst was prepared by treating fumed silica with amino-containing silane then 1,4-butane sultone. The presence of functional...     

Decorations of graphene oxide with cisplatin toward investigation of fluorescence quencher on regulatory sequence of BRCA1 and BRCA2

Journal of the Iranian Chemical Society - Herein, we investigated the interaction of cisplatin loaded on GO (GO@CDDP) with two regulatory sequences, BRCA1 and BRCA2, synthesized from ssDNA based on...     

One‐pot,four‐component synthesis of 1,3,4‐oxadiazole derivatives containing a ferrocene unit and their antimicrobial activity

A four‐component reaction between aromatic carboxylic acids, (N‐isocyanimino)triphenylphosphorane, ferrocenecarbaldehyde and dibenzylamine is reported. This approach is an efficient, simple and high‐yield procedure for the synthesis of 1,3,4‐oxadiazole derivatives containing a ferrocene unit. The antimicrobial activities of the products were investigated against Staphylococcus aureus and Pseudomonas aeruginosa in in vitro and in vivo assays. Copyright © 2015 John Wiley & Sons, Ltd.     

Three-component solvent-free synthesis of 5-substituted-1H-tetrazoles catalyzed by unmodified nanomagnetite with microwave irradiation or conventional heating

Research on Chemical Intermediates - A convenient, rapid, and highly efficient procedure for synthesis of 5-substituted-1H-tetrazoles was developed via multicomponent domino Knoevenagel...