JOURNAL OF THE IRANIAN CHEMICAL SOCIETY(JICS)
Year:0 | Volume:10 | Issue:5|Papers Count:25

Quercetin belongs to the flavonol family. It is most abundant among the flavonoid molecules. A method was developed for quantification of quercetin in apple and onion using differential pulse voltammetry at graphene modified glassy carbon electrode (GR/GCE) and UV spectrophotometry as reference method. The electrochemical behavior of quercetin at the GR/GCE was investigated, and the results indicated that the electrode reaction was controlled by adsorption. The anodic peak current almost stops increasing after 280 s accumulation. This indicates that the accumulation of quercetin at the electrode surface nearly reaches a saturation state after 280 s. The accumulation potential was analyzed between −0.6 and 0.3 V, a maximum peak was achieved at 0.2 V. Under the optimal conditions, the peak currents of DPV increased linearly with the quercetin concentration in the range from 0.006 to 10 and 10 to 100 mmol L-1 with limit of detection 3.6 nmol L-1. The proposed method was successfully applied in the detection of quercetin in foods.

A new, practical and efficient method for the synthesis of furo [3,4-c] coumarins via the one-pot reaction of salicylaldehydes, b-ketoesters and isocyanides in the presence of piperidine in toluene has been reported. Reaction of 2-hydroxynaphthalene-1-carboxaldehyde, ethyl acetoacetate and cyclohexyl isocyanide resulted in the formation of benzo [f] furo [3,4-c] coumarin.

Tautomeric mixtures of 4-aryl substituted 5-acetyl-2-methoxydihydropyrimidines undergo oxidation by exposing to the UV-light under formation of sole pyrimidines. The nature of the 4-substitution and solvent, and the ratio of tautomeric mixtures affect the rate of reaction. A proposed electron transfer-induced photo-dehydrogenation supports the obtained results in this study.

Extremely facile and efficient procedures have been developed for the synthesis of highly functionalized piperidines and dihydro-2-oxypyrroles via one-pot multi-component reactions in the presence of Al (H2PO4)3 as a heterogeneous and eco-friendly catalyst under mild conditions. The multi-component reaction of aromatic aldehydes, aromatic amines, and b-keto esters catalyzed by Al (H2PO4)3 in EtOH at room temperature provides highly functionalized piperidines in good to excellent yields. The structure as well as the relative stereochemistry of these functionalized piperidines was confirmed by single X-ray crystallographic analysis. The same catalyst was found useful for the synthesis of polyfuntionalized dihydro-2-oxypyrroles using a four-component reaction of amines, dialkyl acetylenedicarboxylates and formaldehyde in MeOH at ambient temperature. It is found that the catalyst is recyclable and can be used up to five times without significant loss of its activity.

Compounds with both aromatic and perfluoro aromatic moieties often assemble in the form of p-stacks with alternating arene perfluoroarene arrangements. The 1,4 and 1,3-diamines of N-(2,3,5,6-tetrafluoropyridin-4-yl) benzene (1) and (2), C11H7F4N3, however, show a behavior more commonly observed for diblock perfluoro alkyl derivatives: the fluorinated and the hydrocarbon moieties of the molecules segregate from each other and form fluoro and hydrocarbon microdomains with parallel layers of p-stacked tetrafluoropyridine rings and diamino-phenyl moieties. The structural features of the two derivatives are, despite the different substitution patterns and cell settings, strikingly similar. The main feature in the non-fluorinated domains of 1 and 2 is a set of N–H···H and N–H···p interactions that connect the amino groups of four molecules with each other, which are augmented by some weaker C–H···p and C–H···F interactions, but no p–p stacking is observed. The fluoro microdomains in both 1 and 2 are characterized by extremely short interplanar distances between the tetrafluoropyridine rings of only about 3 °A. The molecules in the layers are shifted sideways against each other by half a pyridyl ring thus bringing the fluorine atoms to atop of the aromatic carbon atoms and vice versa.

Convenient and environmentally benign procedures have been reported for the synthesis of 1,4,5-trisubstituted-1,2,3-triazoles by the reaction of aryl azides with active methylene compounds in ionic liquid [bmim] BF4 in the presence of l-proline as a catalyst and also in task-specific basic ionic liquid [bmim] OH. The methodologies defined herein avoid the severe conditions as posed by earlier existing methods and proved to be efficient in terms of good yields, operational simplicity, easy workup and short reaction time.

Interaction of atenolol (ATE), as an electron donor, with iodine (I2), as a typical s-electron acceptor, has been studied. This interaction occurs in several remarkable steps. The first step is the initial formation of the ATE–I2 outer charge transfer (CT) complex, meanwhile this interaction ends with the formation of the solid CT complex which has the stoichiometric ratio 4:2 (ATE:I2). The synthesized solid CT complex has a novel and amazing structural formula in which hydrogen bonds exist side by side with the CT binding. Formation constants, molar absorption coefficients, and thermodynamic properties, DH, DS, and DG, of this ATE/I2 interaction have been determined and discussed. The different structural forms of the ATE/I2 complexes which occur in each of the different formation steps, involving their stoichiometric ratios, have been determined and confirmed. Several techniques involving UV/Visible, FT-IR, 1H NMR, and Mass spectra have been used in this study. In addition, morphology of the synthesized solid complex has been investigated by the scanning electron microscope.

A total of 11 new a,a-dioxoketene- N,S -acetals (2a–2k) and two new a,a-dioxoketene- N,N -acetals (3j and 3k) have been synthesised by treating 3-[bis(methylthiol)methylene]pentane-2,4-dione (1) with increasing mole ratios of secondary aliphatic amines at room temperature, in either toluene or ethanol. Eight non-cyclic N -methylalkyl and N -ethylalkyl amines and the azacyclopentane of pyrrolidine yielded exclusively mono-substituted N,S -acetals (2a–2i), while the azacyclohexanes of piperidine and morpholine yielded the mono-substituted N,S -acetals 2j and 2k and the double-substituted N,N -acetals 3j and 3k. The conversion yields for the reactions in ethanol are considerably higher than those in toluene. Furthermore, the secondary aliphatic amines with an N -methylalkyl moiety, which have one primary a-carbon and less steric crowding around the nucleophilic nitrogen, appear to be more reactive towards 1 than those with the N -ethylalkyl group, which have two primary a-carbons; further, the latter amines are more reactive than the amines with secondary a-carbons.

Prolyl hydroxylase domain 2 containing protein (PHD2) is a central protein in regulation of cellular response to hypoxia. This protein controls the responses of cell to oxygen level via the regulation of hypoxia inducible factor (HIF) stability. HIF induces the expression of many genes, especially ones orchestrate angiogenesis. There are some reports that mentioned in some tumor types the level of HIF is high in spite of the presence of wild-type PHD2 and normoxic environment. Therefore, the possibility of PHD2 misfolding in some cancer cells arises. Studying such important protein unfolding pathway is insightful for possible therapeutic approaches. In this study, the unfolding pathway of PHD2 illustrates utilizing molecular dynamics simulation of protein thermal denaturation. Based on current study results, we represent the possible mechanisms of PHD2 unfolding in detail. The possible intermediates of PHD2 thermal unfolding are characterized, and the most venomous state of its unfolding pathway is introduced.

The present work deals with the first attempt to study the effect of l-tyrosine on the characteristics of the peroxyoxalate chemiluminescence. Berberine was applied as an efficient fluorophore. The investigated parameters include rise and fall rate constant for the chemiluminescence burst, theoretical and experimental maximum intensity, the time needed to reach maximum intensity and the total light yield emission, which is theoretically evaluated using the pooled intermediate model by a computerized non-linear least-squares curve fitting program (KINFIT). Furthermore, based on the observed quenching effect of tyrosine, the Stern–Volmer plot with KQ value of 7.7×104 M-1 in the quencher concentration range 4×10-6 –5×10-5 M. Moreover, this method is applied to determinate tyrosine in biological samples successfully.

From the reaction of ZnCl2 and HgCl2 metal salts with (E)-4-chloro-N-(pyridine-2-ylmethylene) benzeneamine (L) in methanol solution, two binuclear Schiff base complexes were prepared. Both complexes were characterized by elemental analysis, UV–Vis, and IR spectrophotometry. X-ray crystal structure analysis showed that metal ion in the resulting centrosymmetric dinuclear ML2Cl4 complexes is in a distorted trigonal bipyramidal and a distorted square pyramidal coordination environment in the case of Zn (II) and Hg (II) metal ions, respectively. Three types of reaction between MCl2 salts and ligand L producing three different types of products-ML22+, MLCl2, and M2L2Cl4-were simulated in both the gas phase and solution. The gas phase calculations at DFT (B3LYP) level of theory using SDD, CEP-121G, and LanL2DZ basis sets showed that the binuclear M2L2Cl4 complexes are more stable than corresponding mononuclear MLCl2 complexes. Furthermore, both the gas phase and solution studies showed that the formation of M2L2Cl4 complexes from the metal cations, chloride anion, and ligand molecule is energetically more favored than that of MLCl2 and ML22+ complexes.

The reaction of diaminoglyoxime with aldehyde and ketone derivatives in the presence of p-toluene sulphonic acid in H2O-MeOH mixture at room temperature afforded nitrone derivatives in high yields within 10-140 min. The applicability of ketones in this reaction for the preparation of novel nitrones has been verified. The effect of the temperature on the stability of the structural isomers of the products has been studied by NMR as well. The results showed that, at high temperatures only one product could be observed. The nature of solvent and catalyst were evaluated and found that the strong acids H2SO4 and CF3SO3H in protic solvent CH3OH work well while neither CH3SO3H in protic solvent nor p-toluene sulphonic acid in aprotic solvents toluene and THF perform the same reactions.

Plant non-specific lipid-transfer proteins (nsLTPs) are small basic proteins which transport phospholipids between different cell membranes. They are classified, based on their molecular weight, into two subfamilies: nsLTP1 (9 kDa) and nsLTP2 (7 kDa). These proteins have received an increasing research interest as efficient drug carriers in drug delivery systems. However, there have been few studies conducted on their drug-binding characteristics. The present study aims to comparatively evaluate binding of amphotericin B (AmB, an antifungal drug) to the native and modified forms of rice nsLTP1 and to assess possible applications in drug delivery methods. The LTP1 was purified and then interaction of AmB with the native and modified forms of protein was investigated with various spectroscopic methods. The results showed that the AmB–LTP binding is associated with quenching of the protein intrinsic fluorescence. Furthermore, as temperature of the medium increased, the stability of the AmB–native LTP complex decreased, whereas the stability of the AmB–modified LTP increased. Analysis of the thermodynamic parameters of the AmB–protein complexes and extrinsic fluorescence data indicated that the lysine modification caused a change in the intermolecular interactions between the protein and AmB as well as in the protein surface hydrophobicity (PSH). Furthermore, Dixon plot showed that AmB inhibits ANS binding especially in the AmB–modified RLTP binding. Findings of the current study highlighted the drug-binding characteristics of the modified form of LTP necessitating further studies to profoundly evaluate the characteristics of its mutant forms.

In the present investigation, we have decided to study the interaction between the bovine whey carrier protein of b-lactoglobulin (BLG) with a newly synthesized Pt (II) complex (bipyridine ethyl dithiocarbamate Pt (II) nitrate), as an anti-cancer compound using fluorescence and circular dichroism (CD) spectroscopic methods at two different temperatures of 25 and 37oC. Also, cytotoxicity and apoptotic activity of this complex have studied against cancer model cell line of K562. Results of intrinsic fluorescence of BLG represent that Pt (II) complex has strong ability to quench the intrinsic fluorescence of protein through dynamic quenching procedure. The values of binding constant (0.21 and 0.27 mM-1 at 25 and 37oC, respectively) and number of binding site calculated according to the quenching methods at different temperatures. Also, thermodynamic parameters data suggested that hydrophobic interaction plays a major role in the interaction of complex with BLG. In addition, far-UV-CD results show that Pt (II) complex did not induce any significant changes in the secondary structure of BLG. Cytotoxicity and apoptotic effects of the complex toward the cancer cell line of K562 were measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and 4,6-diamidino-2-phenylindole staining methods. From above results, it can be concluded that the bovine whey carrier protein of BLG could bind to be a suitable transfer for this new anti-cancer compound and may be suggested that the anti-tumor activity of this complex reveals typical morphological features of apoptotic death.

The heme-imidazole–sodium dodecyl sulfate (SDS) ternary complex has been designed as a peroxidase-like nano-artificial enzyme, in which the imidazole moiety functions like the histidine ligand in the native horseradish peroxidase (HRP) and increases the reactivity and catalytic efficiency of the designed artificial enzyme by promoting the heterolytic cleavage of hydrogen peroxide. In the present study, three different ligands were used as the imidazole-based ligands in the heme–ligand–SDS ternary system: (1) 1-methylsulfonyl-1H-imidazole, (2) 1-(benzensulfonyl)-1H-imidazole, and (3) 1-tosyl-1H-imidazole (TsIm). The three different ligands gave variable reactivity in the system studied, and the enzymatic activation parameters, using spectrophotometric measurements, showed that the TsIm ligand had a higher catalytic efficiency at 26.38 % of the native HRP efficiency. To investigate the increase in catalytic activity, its mechanism was explored based on the original mechanism of HRP and the structure of its first catalytic intermediate (compound I). Based on the mechanism of HRP and the structure of compound I, a suggested mechanism for Tslm is as follows: the TsIm cation radical makes up part of the compound I structure, which is stabilized in the enzymatic process by charge distribution that is induced via phenyl and methyl groups. Suicide inactivation of heme–TsIm–SDS and heme–imidazole–SDS models was also compared to each other. Suicide inactivation was less exhibited in the presence of TsIm than imidazole in this system unless high concentrations of hydrogen peroxide were used.

In this work, a series of triazene derivatives in which the substituents have a wide range of electronic characters were synthesized to understand the effect of the substituent identity in controlling the changes in their electronic absorption spectra and NMR chemical shifts, as well as their tendency for interaction with some heavy metals. Elemental analysis and 1H NMR, 13C NMR, and FT-IR spectroscopies were used to elucidate the chemical structures of the new compounds. Thermal analysis and protolysis of these triazenes were evaluated. The thermodynamic parameters were calculated from thermal data using Coats-Redfern method. Complexation of these compounds with mercury (II) ion in acetonitrile and deuterated dimethylsulfoxide (DMSO-d6) solution were studied by UV–vis and 1H NMR spectroscopy, respectively. Stoichiometry and formation constants of the complexes were calculated by the mole ratio titration method. The effects of the nature of the substituents on the formation constants were discussed.

A simple and efficient method for the selective oxidation of alcohols to ketones using trans-3,5-dihydroperoxy-3,5-dimethyl-1,2-dioxolane at room temperature is developed. The reactions were smoothly proceeded under catalyst-free conditions to provide ketones in quantitative yields within short reaction times. Also, this method is compatible with many functional groups including aldehydes, olefins, halogens, amines and esters.

Structural, bonding and electronic characteristics of complexes of anthraquinone and 1-arylazo-2-naphtol dyes and cellulose Ib are studied using B3LYP density functional method with 6-31G** basis set based on the partially and fully optimized structures. Results reveal that for both partially and fully optimized complexes, there is a stabilizing attraction between dyes and cellulose surface. The hydrazone (Hy) tautomer in anionic state (Hy-SO3-) shows the strongest interaction with the cellulose surface. Natural bond orbital (NBO) and atoms-in-molecules (AIM) analyses have been carried out to study the nature of azo dyes-cellulose bonds in detail. According to NBO analysis, a remarkable charge transfer occurs between the –SO3-and -SO3H functional groups of the dye and the cellulose surface which can be regarded as the main source of the large dye–cellulose interaction energy. AIM analysis confirms the existence of hydrogen and van der Waals bonds between the azo dyes and cellulose. Furthermore, a very good agreement is observed between the number of hydrogen bonding sites and dye–cellulose interaction energies.

The two water-soluble designed palladium (II) complexes, [Pd(bpy)(pip-Ac)] NO3 and [Pd(bpy)(mor-Ac)]NO3, (where bpy is 2,2’-bipyridine, pip-Ac is 1-piperidineacetato and mor-Ac is 4-morpholineacetato) have been synthesized and characterized by elemental analyses, molar conductivity measurements and spectroscopic methods (FT-IR, 1H NMR, UV–Vis). The complexes have been tested for in vitro cytotoxic activity against human breast cancer cell line, T47D. The binding of these complexes with DNA has been investigated by absorption spectroscopy, fluorescence titration spectra, EB displacement and gel chromatography. The results suggest that the complexes can bind to DNA cooperatively through a static mechanism at low concentrations (~0.57 mM). The thermodynamic parameters indicated that the van der Waals and hydrogen binding might play a major role in the interaction of these complexes with DNA.

The reaction of dichlorostannanes R2SnCl2 (R=Me 1, Bun 2) with piperazine ligand in molar ratio 1:2, in dry methylene dichloride, in an inert atmosphere leads to the synthesis of R2Sn (C4H9N2)2(R=Me 1, Bun 2). In a similar manner, The reaction between Ph2SnCl2 and piperazine in dry ethanol in molar ratio 1:1 produces [Ph2Sn (C4H8N2)]2 (3). The yields of these new products were excellent and they have been fully characterized by FT-IR, UV–Vis, multinuclear (1H, 13C, 119Sn) NMR spectroscopy and mass spectrometry, as well as elemental analysis. The spectroscopic results indicate that the piperazine ligand is coordinated to tin atom of organotin moieties, through the nitrogen atoms. Furthermore, the ligand behaves as a bidentate fashion in (1) and (2) and gives 1:2 substitution products, while in the complex (3) the two six-membered rings bind in bidentate-chelate forms between the two Sn atoms.

Prolinium triflate (ProTf) was easily prepared by addition of triflic acid to an aqueous solution of l-proline. The latter is employed as a catalyst for the condensation of indoles with aldehydes or ketones in aqueous media to form a series of bisindolyl methanes in high yields.

A novel modified glassy carbon electrode with ytterbium fluoride nanoparticles (YFNPs)-multiwalled carbon nanotubes (MWCNTs) was fabricated and then successfully used for the simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA). YFNPs were successfully coated on the MWCNTs via the intermediate of noncovalent hydrophobic interactions of the MWCNTs surface with sodium dodecyl sulfate. The YFNPs and immobilization of YFNPs on MWCNTs were confirmed by transmission electron microscopy. The particle size of YFNPs was measured to be around 45 nm. The catalytic peak currents for AA, DA and UA were linearly dependent on their concentrations in the range of 2.0–600.0, 2.0–560.0 and 1.8–640.0 mM, respectively, with the corresponding detection limits of 0.77, 0.22 and 0.17 mM. The modified electrode provided good sensitivity and stability, and was successfully applied for the simultaneous determination of AA, DA and UA in human blood serum and urine samples.

A simple and efficient method has been developed for the synthesis of b-amino alcohols by regioselective ring opening of epoxides with amines in the presence of CuFe2O4 nanoparticles as a heterogeneous recyclable catalyst at room temperature in high yields.

An efficient procedure has been developed for one-pot synthesis of N-acyle-2-aryl-1,2-dihydro-(4H)-3,1-benzoxazin-4-ones in the presence of Preyssler-type heteropolyacid acid modified nano-sized TiO2 as catalyst. The reactions proceed smoothly at 25oC to afford the products in high yields. The catalyst is easily separated and re-used for the next successive reactions without significant loss of its activity.

A green and efficient method for the synthesis of various 4H-benzo[b]pyrans and Spirooxindoles in the presence of FeNi3–SiO2 as the nanocatalyst at room temperature is reported. High catalytic activity and ease of recovery from the reaction mixture using an external magnet, and several reuse times without significant losses in performance are additional eco-friendly attributes of this catalytic system.