|1- Hassani, L., Hakimian, F., Safaei, E., "Spectroscopic investigation on the interaction of copper porphyrazines and phthalocyanine with human telomeric G-quadruplex DNA", Biophys. Chem, 187, 7-13, (2014).|
The G-quadruplex DNA is a novel target for anticancer drug discovery and many scientific groups are investigating interaction of small molecules with G-quadruplex DNA to discover therapeutic agents for cancer. Here, interaction of a phthalocyanine (Cu(PcTs)) and two tetrapyridinoporphyrazines ([Cu(2,3-tmtppa)]4+ and [Cu(3,4-tmtppa)]4+) with Na+ and K+ forms of human telomeric G-quadruplex DNA has been investigated by spectroscopic techniques. The results indicated that interaction of the cationic porphyrazines is remarkably stronger than the anionic phthalocyanine and they presumably bind to the G-quadruplex DNA through end-stacking. Fluorescent intercalator displacement assay implied the displacement ability of the complexes with thiazole orange. In addition, circular dichroism spectra of both quadruplex forms converge to the Na+ isoform after binding to the porphyrazines. In conclusion, the porphyrazines as the complexes that bind to the G-quadruplex DNA, could be suitable candidates for further investigations about inhibition of telomerase enzyme.
|2- Sheykhi, H., Safaei, E., "A proline-based aminophenol ligand: Synthesis, iron complexation, magnetic, electronic and redox investigation", Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
, 118, 915-920, (2014).|
A new proline-based aminophenol ligand was synthesized by a convenient procedure. The ligand was characterized by 1H NMR, 13C NMR and IR spectroscopies, elemental analysis and optical activity measurements. Mononuclear iron(III) complex (FeLPro) of this ligand was synthesized and characterized by IR, UV–vis, ESI-MS, magnetic susceptibility studies and cyclic voltammetry techniques. The equilibrium formation constant of FeLPro and the pure UV–vis spectral profile of the complex was determined by multivariate hard modeling method. The molecular structure of FeLPro determined by ESI-MS consist of two aminophenolate ligands. The variation of magnetic susceptibility with temperature indicates paramagnetic iron(III) in the monomeric complex. FeLPro complex undergo metal-centered reduction, and ligand-centered oxidation.
|3- Hassani , L., Hakimian, F., Safaei, E., Fazeli, Z., "Antibacterial effect of cationic porphyrazines and anionic phthalocyanine and their interaction with plasmid DNA", J. Mol. Struct, 1052, 221-227, (2013).|
Resistance to antibiotics is a public health issue and identification of new antibacterial agents is one of the most important goals of pharmacological research. Among the novel developed antibacterial agents, porphyrin complexes and their derivatives are ideal candidates for use in medical applications. Phthalocyanines differ from porphyrins by having nitrogen atoms link the individual pyrrol units. The aza analogues of the phthalocyanines (azaPcs) such as tetramethylmetalloporphyrazines are heterocyclic Pc analogues. In this investigation, interaction of an anionic phthalocyanine (Cu(PcTs)) and two cationic tetrapyridinoporphyrazines including [Cu(2,3-tmtppa)]4+ and [Cu(3,4-tmtppa)]4+ complexes with plasmid DNA was studied using spectroscopic and gel electrophoresis methods. In addition, antibacterial effect of the complexes against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria was investigated using dilution test method. The results indicated that both porphyrazines have significant antibacterial properties, but Cu(PcTs) has weak antibacterial effect. Compairing the binding of the phthalocyanine and the porphyrazines to DNA demonstrated that the interaction of cationic porphyrazines is stronger than the anionic phthalocyanine remarkably. The extent of hypochromicity and red shift of absorption spectra indicated preferential intercalation of the two porphyrazine into the base pairs of DNA helix. Gel electrophoresis result implied Cu(2,3-tmtppa) and Cu(3,4-tmtppa) are able to perform cleavage of the plasmid DNA. Consequently, DNA binding and cleavage might be one of the antibacterial mechanisms of the complexes.
|4- Heidari, S., Safaei, E., Wojtczak, A., Cotič, P., "Oxalate-bridged binuclear iron(III) complexes of two pyridine-based aminophenol ligands", Inorg. Chim. Acta
, 405, 134-139, (2013).|
Two oxalate-bridged binuclear iron(III) complexes, [(FeLAPMe)2(μ-ox)] (1) and [(FeLAPOMe)2(μ-ox)] (2), in which H2LAPMe and H2LAPOMe are pyridine-based di-methyl and tert-butyl methoxy substituted aminophenol ligands respectively, were prepared. Both compounds have been characterized by X-ray crystallography, infrared spectroscopy, UV–Vis spectroscopic techniques, cyclic voltammetry analysis, and magnetic susceptibility studies. In both crystals, each iron(III) is coordinated by the oxygen atoms of an oxalate bridging ligand, two phenolate oxygen atoms, and amine nitrogens of ligands. The variable temperature magnetic susceptibility indicates antiferromagnetic coupling between iron centers in both complexes. Cyclic voltammograms of 2 in CH2Cl2 at low temperature showed quasi-reversible peaks corresponding to ligand-centered oxidations.
|5- Karimpour, T., Safaei, E., Wojtczak, A., Jagličić, Z., "Models for enzyme–substrate adduct of non-heme iron-containing enzymes, synthesis and characterization", Inorg. Chim. Acta
, 405, 309-317, (2013).|
Mononuclear iron(III) complexes of (HNEt3)[FeLNEC(TBC)], (HNEt3)[FeLNEB(TBC)] and (HNEt3)[FeLNEM(TBC)] as new models for enzyme–substrate adducts of catechol dioxygenases have been prepared and characterized, where H2LNEC, H2LNEB and H2LNEM are amine bis(phenolate) ligands with chlorine, bromine and methyl substituted phenol groups and TBC is a tetrabromo catecholate dianion. These complexes were characterized by IR, UV–vis, elemental analysis and magnetic measurements. X-ray structure analysis of complexes has revealed that the iron(III) core in the model compounds is a distorted octahedral coordination sphere and surrounded by two phenolate oxygen atoms, two amine nitrogens and two oxygen atoms of TBC. UV–vis spectroscopy exhibits two intense absorption bands in the range of 450–650 nm in dichloromethane. These bands are assigned to the catecholate and ligand to Fe(III) charge-transfer bands. The electrochemical features of the adduct complexes were investigated in dichloromethane solution by employing cyclic voltammetry (CV).
|1- Hassani , L., Fazeli , Z., Safaei , E., Hakimian, F., "comparative study on the interaction of water soluble zinc porphyrazine with G and C-rich strands and the complete c-MYC silencer element
", 1st Tabriz International Life Science Conference and 12th Iran Biophysical Chemistry Conference, 241-241, (2013).|
|2- Safaei , E., "A spectroscopic studty on the interaction of a water soluble tetra-methyl metallo-porphyrazine to calf thymus DNA
", 1nd International Conference of Chemistry and it,s applications, Doha, Qatar , (2013).|
|3- Balaghi, S. E., Safaei, E., "Highly Efficient and Aerial Alcohol Oxidation by a Chloro
Bridged Cu(II)-Cu(II) Complex of an Aminophenol Ligand", 14th Iranian Inorganic Chemistry Conference, Sharif University of Technology , 1-1, (2012).|
Many biological reactions are controlled by metalloenzymes containing one or more metal atoms and their coordinated ligands such as histidine and tyrosine holding them.Copper is one of these metal ions which serves as cofactor in many fundamental reactions mediated by copper enzymes. Galactose oxidase (GOase) best characterized member of radical-copper oxidase family has the ability to catalyze the oxidation of a wide range of primary alcohols to aldehydes. Hemocyanines and tyrosinases are type III multi-copper proteins which their active sites contain binuclear copper complexes. As well as galactose oxidase, these two enzymes are responsible for catalyzing some biological process associated with redox reactions. Significant efforts have also been made to provide multinuclear copper complexes containing chloro, hydroxo and oxo bridged complexes as models for active sites of multi-copper enzymes and their effective role in catalytic enzymatic reactions such as oxidation of alcohols to aldehydes. Although there are some reports about chloro bridged binuclear copper complexes as structural models for catechol oxidase, however according to our best knowledge there is not any report of these complexes as oxidase functional models.
In this work, we describe a highly efficient, selective and eco-friendly oxidation of alcohols to aldehydes with air or oxygen as oxidant and [LAphCuCl]2 copper complex of a newly synthsized [N-O]-donor aminophenol ligand (HLAph, 2,4-di-tert-butyl-6-(pyridine-2-ylmethylamino)phenol) as catalyst.
|4- Balaghi, S. E., Safaei, E., "Synthesis, Molecular and Electronic Structures of a Six-Coordinate Cobalt Complex with an Oxazoline Ligand", 14th Iranian Inorganic Chemistry Conference, Sharif University of Technology , 1-1, (2012).|
Metalloenzymes often feature redox-active ligands. These ligands are very interesting due to their easily redox processes by one or more electrons, and affecting the reactivity and selectivity of metal ions in the active site of enzymes. Often these ligands transform into ligand radicals upon binding to transition metals. Metal complexes exhibiting intra-molecular electron transfer between a metal center and a redox-active ligand have attracted much attention in coordination chemistry due to their switchable magnetic and optical properties in molecular electronic devices and catalytic systems.
In this work the geometric and electronic structure of a redox-active cobalt complex ([Co(LBAIQ)2]; HLBAIQ = (E)-2,4-di-tert-butyl-6-((2-(5,7-di-tert-butylbenzo[d]oxazol-2-yl) phenyl) imino) cyclohexa-2,4-dienone) with an oxazoline-based o-aminophenol ligand has been investigated. X-ray crystallography analysis revealed an octahedral monomer complex in which cobalt(II) ion has been surrounded by two LBSQ. Based on the X-ray analysis the complex consists of a Co(II) centre and two semiquinone radical ligands. Frozen solution EPR a single isotropic signal at g = 1.995. The g-value is however lower than the free electron value and thus this seems to indicate some interaction between Co(II) center and two LBSQ ligands. Electrochemical redox reaction of cobalt complex show a quasi-reversible oxidation peak related to cobalt(III)/cobalt(II) redox process.
|5- Balaghi, S. E., Safaei, E., "Copper(II) Complexes with Benzoxazole Based Ligand, Synthesis, Magneto-Structural Study and Galactose Oxidase Activity", 14th Iranian Inorganic Chemistry Conference, Sharif University of Technology , 1-1, (2012).|
The research field of redox-active ligands and transition metal ions in metalloenzyme sites has enormously developed to biomimetics research area. Researchers learned the easy oxidation of tyrosine ligands of metalloenzymes from nature to develop catalysts with redox active ligands for catalytic applications. Complexes based on these ligands, which can be easily oxidized or reduced by one or more electrons are used as catalysts for energy storage/conversion, electrosynthesis, biomimetic transformations. In this work, two copper(II) complexes of newly synthesized aminophenol benzoxazole based ligand, namely LBSQCuIIX where X is acetate group in LBSQCuIIOAc, or chlorine atom in LBSQCuIICl were synthesized. LBSQ represents the deprotonated forms of HLBSQ, where HLBSQ stands for the (E)-2,4-di-tert-butyl-6-((2-(5,7-di-tert-butylbenzo[d]oxazol-2-yl) phenyl) imino) cyclohexa-2,4-dienone).
The copper complexes were characterized by X-ray, IR, EPR and UV/vis spectroscopies and magnetic susceptibility studies. LBSQCuIICl has a distorted tetrahedral geometry while LBSQCuIIOAc is square pyramidal. The structure of both complexes involves one ligand molecule coordinated to the copper ion and acetate or chloride groups in LBSQCuIIOAc, or LBSQCuIICl respectively. Both complexes are diamagnetic and EPR silent due to antiferromagnetic interaction between ligand semiquinone electron and copper(II) center. In addition, highly efficient, and eco- friendly oxidation of alcohol to aldehyde was achieved with molecular oxygen as oxidant and [LBAIQCuCl]-Cs2CO3 or [LBAIQCu(OAC)]-Cs2CO3 system as catalyst.