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Optical Materials (09253467) 148
We report on the nonlinear properties of the series of deep eutectic solvents (DESs) which are prepared by a certain ratio of choline chloride as the base and lactic acid as additive materials. The z-scan technique is used to characterize the nonlinear index and absorption of the solvents. Obtained results indicated a negative nonlinear index of the order of about 10−9 cm2/W for the DES solvents at 808 nm of a ∼60-mW CW laser source. It is further found that while the different ratios of lactic acid are increasingly added to the choline chloride, the nonlinear index of solvents are accordingly changed by a factor of 1.2 in magnitude. The results of the open-aperture z-scan confirmed that neither the solvents nor the lactic acid responded to the nonlinear absorption. The represented experiment suggested that with a novel look at these series of DES liquids, it is possible to improve their nonlinear properties by engineering the ratio of choline chloride and lactic acid. © 2024 Elsevier B.V.
Journal of Chemometrics (08869383) (1)
In this study, the effect of different error structures on psedounivariate and multivariate analytical figures of merit in simulated data of hyphenated chromatographic systems was investigated. Different error structures (e.g., homoscedastic, heteroscedastic, and correlated) were investigated. For this purpose, five components systems at five concentration levels with three replicates were simulated. Different types of error were added to the data. Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) and Maximum Likelihood Principal Component Analysis (MLPCA-MCR-ALS) methods were used. After resolution, pseudo-univariate and multivariate analytical figures of merit were calculated and compared. As it expected, the detection limit for noisy datasets is higher than the noise-free datasets, whereas the slopes of the calibration curves are not significantly different. Comparing the results generally showed that the detection limit values in multivariable mode were better than the univariate mode. The LODs of data (pseudo-univariate and multivariate) with homoscedastic and correlated error structure by MCR-ALS and MLPCA-MCR-ALS were the same. The analysis of data with heteroscedastic error structure by MLPCA-MCR-ALS had a lower detection limit than analysis with MCR-ALS. The figures of merit obtained from WLS and OLS regression in heteroscedastic datasets were compared and better LODs were obtained after WLS method. © 2022 John Wiley & Sons Ltd.
Saeidi, Hamidreza ,
Mozaffari, Morteza ,
Ilbey, Serhat ,
Asanjarani, Neda ,
Saeidi, H. ,
Mozaffari, M. ,
Ilbey, S. ,
Dutz s., ,
Zahn d., ,
Azimi gandomani, G. ,
Bock, M. Nanomaterials (20794991) 13(2)
Magnetic nanoparticles (MNPs) have been widely applied as magnetic resonance imaging (MRI) contrast agents. MNPs offer significant contrast improvements in MRI through their tunable relaxivities, but to apply them as clinical contrast agents effectively, they should exhibit a high saturation magnetization, good colloidal stability and sufficient biocompatibility. In this work, we present a detailed description of the synthesis and the characterizations of europium-substituted Mn-Zn ferrite (Mn0.6Zn0.4EuxFe2-xO4, x = 0.00, 0.02, 0.04, 0.06, 0.08, 0.10, and 0.15, herein named MZF for x = 0.00 and EuMZF for others). MNPs were synthesized by the coprecipitation method and subsequent hydrothermal treatment, coated with citric acid (CA) or pluronic F127 (PF-127) and finally characterized by X-ray Diffraction (XRD), Inductively Coupled Plasma (ICP), Vibrating Sample Magnetometry (VSM), Fourier-Transform Infrared (FTIR), Dynamic Light Scattering (DLS) and MRI Relaxometry at 3T methods. The XRD studies revealed that all main diffraction peaks are matched with the spinel structure very well, so they are nearly single phase. Furthermore, XRD study showed that, although there are no significant changes in lattice constants, crystallite sizes are affected by europium substitution significantly. Room-temperature magnetometry showed that, in addition to coercivity, both saturation and remnant magnetizations decrease with increasing europium substitution and coating with pluronic F127. FTIR study confirmed the presence of citric acid and poloxamer (pluronic F127) coatings on the surface of the nanoparticles. Relaxometry measurements illustrated that, although the europium-free sample is an excellent negative contrast agent with a high r(2) relaxivity, it does not show a positive contrast enhancement as the concentration of nanoparticles increases. By increasing the europium to x = 0.15, r(1) relaxivity increased significantly. On the contrary, europium substitution decreased r(2) relaxivity due to a reduction in saturation magnetization. The ratio of r(2)/r(1) decreased from 152 for the europium-free sample to 11.2 for x = 0.15, which indicates that Mn0.6Zn0.4Eu0.15Fe1.85O4 is a suitable candidate for dual-mode MRI contrast agent potentially. The samples with citric acid coating had higher r(1) and lower r(2) relaxivities than those of pluronic F127-coated samples.
Chemosphere (00456535) 342
A photocatalytic adsorbent composed of carbon dots (CD) embedded in a metal-organic framework (MOF) of MIL-88 B(Fe) was prepared by solvothermal technique. The synthesized CD@MIL-88 B(Fe) was characterized by different X-ray-based microscopic and spectroscopic methods, as well as electrochemical impedance spectroscopy, UV–Vis, FT-IR, DRS, TGA, and photoluminescence (PL) analysis. The prepared adsorbent showed a remarkable photocatalytic activity for eliminating amphotericin B (AmB) and naproxen (Nap) from aqueous solutions under visible light, reaching up to 92% and 90% removal, respectively, with an RSD value of around 5%. The parameters affecting the degradation process of pharmaceuticals were investigated. The optimal conditions for the degradation process were determined, including pH values (3 and 4 for AmB and Nap), photocatalyst concentration (0.2 g L−1), and H2O2 concentration (40–50 mM). Reactive oxidative species were also identified (·OH, ·O2) by examination of different scavengers. The adsorption isotherm and kinetic studies reveal that the synthesized photocatalyst exhibits dual functionality as an effective adsorbent (with maximum adsorption capacities of 42.5 and 121.5 mg g−1 for AmB and Nap) and a photocatalytic agent for removal purposes. © 2023 Elsevier Ltd
Physical Chemistry Chemical Physics (14639084) 24(24)pp. 14898-14908
The quantum chemical computational method and Born-Oppenheimer (BO) dynamics simulation were employed to investigate the non-radiative relaxation mechanism of protonated 9H- and 7H-adenine (AH+). We located three conical intersections (CIs) between the first 1ππ* excite state and the S0 ground state potential energy surfaces for the two most stable protonated isomers of adenine. It was predicted that the barrier-free potential energy profile along the out-of-plane deformation coordinates of the six-member ring plays the most prominent role in the deactivation of the excited AH+ from 1ππ* to the ground state via ultrafast internal conversions. This ring deformation was predicted to provide a common deactivation pathway in protonated DNA/RNA bases, describing their high level of photostability, and corresponding neutral homologues. © 2022 The Royal Society of Chemistry.
Journal of Analytical Atomic Spectrometry (02679477) (5)
Determination of traces of Cd, Co, Cu, Mn and Pb elements in zirconium and its alloys by inductively coupled plasma optical emission spectrometry (ICP OES) suffers from severe spectral interferences from the matrix elements. Here we developed an interference-free analytical procedure for ICP OES determination of these elements in zirconium and zirconium-niobium alloys based on a simple and inexpensive on-line matrix separation method using a small amount of a strong cation exchange resin (∼0.4 g) in a microcolumn, which also serves to preconcentrate the elements. The conditions of adsorption and desorption of the above mentioned elements were optimized. The desorption of the elements was performed using a dilute aqueous solution (1%) of diethylenetriaminepentaacetic acid (DTPA). The developed method is free from spectral interferences caused by zirconium and niobium in the determination of the aforementioned elements by ICP OES. The results of the proposed method were compared with those of Japanese Industrial Standards (JIS) as reference methods, and by recovery tests performed by spiking standard reference solutions of the desired elements to the solution of the dissolved zirconium-niobium alloy samples. © 2021 The Royal Society of Chemistry.
Physical Chemistry Chemical Physics (14639084) 23(14)pp. 8916-8925
Ab initioand surface-hopping nonadiabatic dynamics simulation methods were employed to investigate relaxation mechanisms in protonated thymine (TH+) and cytosine (CH+). A few conical intersections were located between1pp* and S0states for each system with the CASSCF (8,8) theoretical model and relevant contributions to the deactivation mechanism of titled systems were addressed by the determination of potential energy profiles at the CASPT2 (12,10) theoretical level. It was revealed that the relaxation of the1pp* state of the most stable conformer of both systems to the ground state is mostly governed by the accessible S1/S0conical intersection resulting from the barrier-free out-of-plane deformation. Interestingly, it was exhibited that the ring puckering coordinate driven from the C6position of the heterocycle ring in TH+and CH+plays the most prominent role in the deactivation mechanism of considered systems. Ourab initioresults are also supported by excited-state nonadiabatic dynamics simulations based on ADC(2), describing the ultrashort S1lifetime of TH+/CH+by analyzing trajectories leading excited systems to the ground. It was confirmed that the excited-state population mostly relaxes to the groundviathe ring puckering coordinate from the C6moiety. Overall, the theoretical results of this study shed light on the deactivation mechanism of protonated DNA bases. © the Owner Societies 2021.
RSC Advances (20462069) 10(56)pp. 33718-33730
Herein, the geometry, electronic structure, Fe-ligand bonding nature and simulated IR spectrum of α-Keggin, lacunary Keggin, iron(ii/iii)-substituted and the important oxidized high-valent iron derivatives of Keggin type polyoxometalates have been studied using the density functional theory (DFT/OPTX-PBE) method and natural bond orbital (NBO) analysis. The effects of different Fe oxidation states (ii-vi) and H2O/OH−/O2−ligand interactions have been addressed concerning their geometry and electronic structures. It has been revealed that the d-atomic orbitals of Fe and 2p orbitals of polyoxometalate's oxygen-atoms contribute in ligand binding. Compared with other high valent species, the considered polyoxometalate system of [PW11O39(FeVO)]4−, possesses a high reactivity for oxygen transfer. © The Royal Society of Chemistry 2020.
Journal of Physical Chemistry A (15205215) 124(25)pp. 5089-5097
We have conducted here a theoretical exploration, discussing the distinct excited state lifetimes reported experimentally for the two lowest lying protonated isomers of uracil. In this regard, the first-principal computational levels as well as the nonadiabatic surface hopping dynamics have been employed. It has been revealed that relaxation of the 1ππ∗ state of enol-enol form (EE+) to the ground is barrier-free via out-of-plane coordinates, resulting in an ultrashort S1 lifetime of this species. For the second most stable isomer (EK+), however, a significant barrier predicted in the CASPT2 S1 potential energy profile along the twisting coordinate has been proposed to explain the relevant long lifetime reported experimentally. © 2020 American Chemical Society.
Microchemical Journal (0026265X)
Combination of fast high-performance liquid chromatography–diode array detection (HPLC–DAD) technique and ultrasonic assisted emulsification micro-extraction (USAEME) as extraction method are used for simultaneous determination of sixteen polycyclic aromatic hydrocarbons (PAHs) in river samples. The optimum conditions of USAEME procedure are selected according to the literature. Due to presence of different chromatographic issues and the complexity of water matrices, multivariate curve resolution-alternating least squares (MCR-ALS) is a good resolution technique for simultaneous quantification of PAHs in standard and real samples. On this matter, region-based and whole chromatographic data analysis of 16 PAHs are done and the results are compared. Although the results of both methods were acceptable, region-based analysis had improvement regarding to the whole data analysis. Recoveries ranging from 81.80% to 105.86% and relative standard deviations (RSDs) less than 10% for all PAHs verified the precision and accuracy of this method. Also, the relative error of calibration curves (RE, %) were less than 14.69%. Also, analytical figures of merit using multivariate approach were used for whole and segment-based strategies. In this regard, the values of multivariate figures of merit in region-based analysis had better results compared to pseudo-univariate techniques and total analysis. These results confirmed that using second order calibration algorithms in USAEME–HPLC–DAD data is a powerful method for fast, cost effective and simple determination of PAHs in highly polluted samples. © 2019 Elsevier B.V.
International Journal of Quantum Chemistry (1097461X) 119(3)
New platinum(II) complex with picolinate (pic) and 2-phenyl naphtothiazole (pntl) ligand as the guest material has been designed and its capability for OLED applications have been examined. Also, we have studied the effects of different substitutions (ie, electron-withdrawing and electron donating groups) on naphtothiazole moiety on optovoltaic characters. We have employed density functional theoretical (B3LYP/DFT) methods to reveal the photophysical and structure properties relationships with the typical host material. The valence MO energies, vertical and adiabatic triplet energy, reorganization energy, and triplet exciton generation fraction (χT) have been extensively studied to exploring high phosphorescence efficiency in OLEDs. It has been predicted that substituted systems are good candidates for OLED applications as well as their parent system. © 2018 Wiley Periodicals, Inc.
Research in Pharmaceutical Sciences (17355362) (2)
Berberis integerrima Bonge. (Syn: Berberis densiflora Boiss. & Buhse) is a shrub widely distributed in Middle East and central part of Asia. An ethnobotanical study revealed that indigenous and tribal people in Iran use B. integerrima root decoction for treatment of brucellosis. Therefore, the aim of this study was bioassay directed isolation of antibacterial compounds from this plant based on their in vitro bactericidal activity against Brucella abortus. Briefly, the ethanol extract of B. integerrima was fractioned and subjected to preliminary antibacterial screening tests against Brucella. The more active fraction (Fr.3) was subjected to purification by repeated chromatography systems. Quaternary benzylisoquinoline alkaloids including columbamine, palmatine, berberine, and jatrorhizine were four main components identified in the selected active fraction. Except for berberine which is reported before, palmatine, columbamine and jatrorhizine are isolated for the first time from this plant. Anti-brucellosis properties of isolated compounds 1-4 were studied against B. abortus under different test conditions. In minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) results, jatrorhizine (4) showed more antibacterial activity with MIC and MBC of 0.78 and 1.56 μg/mL, respectively. In both agar well diffusion and disk diffusion ANOVA results showed that there were statistically significant differences between compounds 1-4 versus placebo in all of the tested concentration (P <0.001). In conclusion, all of four alkaloids showed potent antibacterial activity against B. abortus but jatrorhizine and columbamine with free hydroxyl group on C-3 or C-2 showed more activity than palmatine and berberine without any free hydroxyl group on their structures. The antibacterial effects of columbamine (15 μg/mL) and jatrorhizine (15 μg/mL) were comparative to streptomycin (10 μg/mL) as standard drug which candidate them for more pharmacological researches to find new antibacterial agents against brucellosis. © 2018 Medknow Publications. All rights reserved.
Chinese Journal of Chemical Engineering (10049541) 25(6)pp. 782-792
The main purpose of this work was the modification of NaX nanozeolite using copper oxide nanoparticles and various monovalent cations such as K+, Cs+, and Ag+ in order to make the negatively charged zeolite surface accessible for anionic forms of uranium which are the most dominant species of uranium in the contaminated radioactive waters at natural pH. Various methods such as the X-ray fluorescence (XRF), X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), and atomic absorption spectroscopy (AAS) were used to characterize the final synthesized absorbents. Batch technique was used to study the adsorption behavior of uranium ions from polluted drinking water by NaX nanozeolite and its modified forms. In order to better understand the performance of them, the results were compared with those that were obtained for synthesizing bulk NaX zeolite and Na-form of clinoptilolite natural zeolite. Preliminary results indicated that uranium sorption increased as the loading level of CuO nanoparticles on NaX nanozeolite increased from 2.1 wt% to 11.2 wt%. In addition, from the obtained data, an increase in uranium removal efficiency resulted as charge/ionic radius ratio of exchanged cation decreased. Also, the effect of contact time, solid–liquid ratio, initial concentration and temperature on the adsorption process was studied. It is worth mentioning that, in this study, the sorption of uranium was performed under natural conditions of pH and the presence of competing cations and anions which are available in drinking waters. © 2016 Elsevier B.V.
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy (13861425) 182pp. 8-16
Kazemi, Z. ,
Amiri rudbari, H. ,
Mirkhani, V. ,
Sahihi, M. ,
Moghadam, M. ,
Tangestaninejad, S. ,
Mohammadpoor baltork, I. ,
Abbasi kajani, A. ,
Azimi gandomani, G. European Journal of Medicinal Chemistry (02235234) 135pp. 230-240
The reaction of a racemic mixture of Schiff base tridentate ligand with vanadium(V) affords homochiral vanadium complex, (VO(R-L))2O and (VO(S-L))2O due to ligand “self-recognition” process. The formation of homochiral vanadium complex was confirmed by 1H NMR, 13C NMR and X-ray diffraction. The HSA- and DNA-binding of the resultant complex is assessed by absorption, fluorescence and circular dichroism (CD) spectroscopy methods. Based on the results, the HSA- and DNA-binding constant, Kb, were found to be 8.0 × 104 and 1.9 × 105 M−1, respectively. Interestingly, in vitro cytotoxicity assay revealed the potent anticancer activity of this complex on two prevalent cancer cell lines of MCF-7 (IC50 value of 14 μM) and HeLa (IC50 value of 36 μM), with considerably low toxicity on normal human fibroblast cells. The maximum cell mortality of 12.3% obtained after 48 h incubation of fibroblast cells with 100 μM of the complex. Additionally, the specific DNA- and HSA-binding was also shown using molecular docking method. The synthesized complex displayed high potential for biomedical applications especially for development of novel and efficient anticancer agents. © 2017 Elsevier Masson SAS
Chemical Physics Letters (00092614) 679pp. 90-96
Microsolvation effect on geometry and transition energies of protonated serotonin has been investigated by MP2 and CC2 quantum chemical methods. Also, conductor-like screening model, implemented recently in the MP2 and ADC(2) methods, was examined to address the bulk water environment's effect on the isomer stability and electronic transition energies of protonated serotonin. It has been predicted that the dipole moment of gas phase isomers plays the main role on the isomer stabilization in water solution and electronic transition shifts. Also, both red- and blue-shift effects have been predicted to take place on electronic transition energies, upon hydration. © 2017
Dehkhodaei, M. ,
Khorshidifard, M. ,
Amiri rudbari, H. ,
Sahihi, M. ,
Azimi gandomani, G. ,
Habibi, N. ,
Taheri, S. ,
Bruno, G. ,
Azadbakht, R. Inorganica Chimica Acta (18733255) 466pp. 48-60
Four new Schiff base complexes (NiL2, CoL2, CuL2 and ZnL2) (HL: ((E)-2-((isopropylamino) methyl) phenol) were synthesized and characterized by CHN elemental analysis, FT-IR and single crystal X-ray diffraction technique. The crystallographic data reveal that in all complexes the metal centers are four-coordinated by two phenolate oxygen and two imine nitrogen atoms of two moles of Schiff base ligand HL and geometry around the metal center in all of them is distorted tetrahedral. In addition, 1H and 13C NMR techniques were employed for characterization of diamagnetic ZnL2 complex. The binding affinity of complexes with DNA (fish sperm DNA, FS-DNA) and Human Serum Albumin (HSA) were investigated using fluorescence quenching, chemometrics, UV–Vis spectroscopy, viscosity measurements and molecular docking methods. The obtained results revealed that the DNA and HSA affinity for binding to complexes are in the following order: CuL2 > ZnL2 > CoL2 > NiL2 and NiL2 > ZnL2 > CuL2 > CoL2. The distance between complexes and HSA was obtained based on the Förster's theory of non-radiative energy transfer. The computational molecular docking results showed that H-bond interactions, hydrophobic interactions, π-π stacking and π-cation interactions have dominant role in the stability of HSA-ML2 (M: Cu, Co, Ni and Zn). The computational docking and viscosity results suggest that all metal complexes interact with DNA presumably by the groove binding mechanism. © 2017 Elsevier B.V.
Journal of Materials Science (15734803) 51(22)pp. 9991-10004
In this study, a novel PAN/NaX/ZnO nanocomposite absorbent was introduced and its ability to remove of uranium anionic species, which are the most dominant species of uranium in water at natural pH, from contaminated waters was studied. In this regards, micro and nano sized NaX zeolite and PAN/NaX/ZnO nanocomposite were successfully synthesized and characterized using various methods, including X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transforms infrared spectroscopy (FT-IR), atomic absorption spectroscopy (AAS), and Brunauer–Emmett–Teller (BET) specific surface area analysis. Batch technique was used to study the adsorption behavior of uranium ions from contaminated water as a function of solid–liquid ratio, initial uranium concentration, contact time, and temperature. Results showed that although NaX nanozeolite due to its negative framework charge, showed low sorption capacity for adsorption of uranium anionic species but the composite of it with ZnO nanoparticles and polyacrylonitrile (PAN) effectively improved its uranium adsorption capacity. The novel PAN/NaX/ZnO nanocomposite could selectively remove uranium ions from contaminated water with removal efficiency of more than 98.65 % in the presence of all anions and cations which are available in waters. © 2016, Springer Science+Business Media New York.
Microporous and Mesoporous Materials (13871811) 234pp. 257-266
A novel PAN/AgX/ZnO nanocomposite was synthesized and used for the removal of uranium ions from contaminated waters. NaX nanozeolite was successfully synthesized using the hydrothermal technique. Ion exchange method was used to modify it by Ag+ cations. Then ZnO nanoparticles were loaded on the AgX nanozeolite by the ion exchange method which was followed by a calcinations process. Various characterization methods such as X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transforms infrared spectroscopy (FT-IR), and atomic absorption spectroscopy (AAS) were utilized to analyze the synthesized absorbents including bulk NaX zeolite, NaX nanozeolite, and PAN/AgX/ZnO nanocomposite. The experiments of uranium adsorption were conducted at different solution temperatures, contact times, initial uranium ion concentration and adsorbent dose by using batch method. Results showed that the novel PAN/AgX/ZnO adsorbent had a better adsorption performance rather than the micro and nano sized NaX zeolite. This demonstrated the immense potential of newly synthesized adsorbent as an alternative adsorbent for heavy metal ion remediation in polluted waters and wastewaters. © 2016 Elsevier Inc.
Journal of Separation Science (16159306) (2)
Comprehensive two-dimensional gas chromatography and flame ionization detection combined with unfolded-partial least squares is proposed as a simple, fast and reliable method to assess the quality of gasoline and to detect its potential adulterants. The data for the calibration set are first baseline corrected using a two-dimensional asymmetric least squares algorithm. The number of significant partial least squares components to build the model is determined using the minimum value of root-mean square error of leave-one out cross validation, which was 4. In this regard, blends of gasoline with kerosene, white spirit and paint thinner as frequently used adulterants are used to make calibration samples. Appropriate statistical parameters of regression coefficient of 0.996-0.998, root-mean square error of prediction of 0.005-0.010 and relative error of prediction of 1.54-3.82% for the calibration set show the reliability of the developed method. In addition, the developed method is externally validated with three samples in validation set (with a relative error of prediction below 10.0%). Finally, to test the applicability of the proposed strategy for the analysis of real samples, five real gasoline samples collected from gas stations are used for this purpose and the gasoline proportions were in range of 70-85%. Also, the relative standard deviations were below 8.5% for different samples in the prediction set. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Applied Radiation and Isotopes (09698043) 118pp. 43-55
In order to efficiently remove of uranium anionic species (which are the most dominant species of uranium in natural water at neutral pH) from contaminated waters, nano-NaX zeolite was synthesized and then modified using various divalent cations (Mg2+, Ca2+, Mn2+) and ZnO nanoparticles (from 1.7 to 10.3 wt%). Different characterization techniques of XRF, XRD, FE-SEM, TEM, FT-IR, and AAS were used to characterize the final synthesized absorbents. Sorption experiments by batch technique were done to study the effect of solid-liquid ratio, initial uranium concentration, contact time and temperature under neutral condition of pH and presence of all anions and cations which are available in the waters. Results showed that although nano-NaX zeolite due to its negative framework charge had a low sorption capacity for adsorption of uranium anionic species, but modification of parent nano-NaX zeolite with ZnO nanoparticles and various cations effectively improved its uranium adsorption capacity. Also, results showed that under optimum condition of pH=7.56, contact time of 60 min at 27 °C with solid-liquid ratio of 20 g/L a maximum uranium removal efficiency of 99.7% can be obtained in the presence of all anions and cations which are available in the drinking waters by NaX/ZnO nanocomposite. © 2016 Elsevier Ltd
Kazemi, Z. ,
Amiri rudbari, H. ,
Sahihi, M. ,
Mirkhani, V. ,
Moghadam, M. ,
Tangestaninejad, S. ,
Mohammadpoor baltork, I. ,
Azimi gandomani, G. ,
Gharaghani, S. ,
Abbasi kajani, A. Journal of Photochemistry and Photobiology B: Biology (18732682) 163pp. 246-260
A racemic mixture of a new chiral Schiff base ligand (HL: R/S-(1-phenylethylimino)methylnaphtalen-2-ol) has been utilized to prepare Pd(II) complex. Crystallization technique has been employed to separate diastereomeric pairs of Pd(II) complex: (meso PdL2) and (rac PdL2) that in this paper are known as PdL2 1 and PdL2 2, respectively. The synthesized complexes have been characterized by means of elemental analysis (CHN), FT-IR, 1H and 13C NMR spectroscopies. Moreover, PdL2 1 has been structurally characterized by single-crystal X-ray diffraction. The geometry around the metal center is square-planar. The interaction of two diastereomers of Pd(II) complex with FS-DNA has been explored, using UV–vis spectroscopy, fluorescence quenching, chemometrics and viscosity measurement methods. The PdL2 1 exhibited higher binding constant, about 10-fold, (1.0 × 106 M− 1) as compared to PdL2 2 (1.5 1.5 × 105 M− 1). Moreover, the human serum albumin (HSA) binding ability has been monitored by absorption, quenching of tryptophan fluorescence emission and circular dichroism (CD) studies. The slight difference is observed between HSA binding affinity with the complexes: PdL2 1 (6.2 × 104 M− 1) and PdL2 2 (3.3 × 104 M− 1). Also, the thermodynamic parameters were determined at three different temperatures (298, 308 and 318 K). In this study, molecular docking was also carried out to confirm and illustrate the specific DNA- and HSA-binding of the Pd(II) complexes. In the PdL2 1-HSA system a T-shaped π-π interaction with PHE206 was observed. While in the PdL2 2-HSA system there are a hydrogen bond, a π-cation and two T-shaped π-π interactions with ASB324, LYS212 and PHE228, respectively. The groove binding mode of DNA interaction has been proposed for both diastereomers. © 2016 Elsevier B.V.
RSC Advances (20462069) 5(118)pp. 97619-97628
The second order approximate Moller-Plesset (MP2) and coupled cluster (CC2) methods have been employed to investigate the geometry, electronic transition energies and photophysics of the isoindole-pyridine and quinoline-pyrrole complexes. The most stable geometry of both isoindole-pyridine and quinoline-pyrrole complexes has been predicted to be a perpendicular structure. It has also been found that the first electronic transition in both complexes is responsible for UV absorption owing to its 1ππ∗ nature, while a charge transfer 1ππ∗ state governs the nonradiative relaxation processes of both complexes. In this regard, excited state intermolecular hydrogen/proton transfer (ESHT/PT) via the charge transfer electronic states plays the most prominent role in non-radiative deactivation. In the HT/PT reaction coordinate, the minimum potential energy profile of the lowest CT-1ππ∗ state predissociates the local 1ππ∗ state, connecting the latter to a curve crossing with the S0 state. At the region of this curve crossing, the S0 and CT state become degenerate, enabling the 1ππ∗ state to proceed as the predissociative state and finally direct the excited system to the ground state. © 2015 The Royal Society of Chemistry.
Journal of Physical Chemistry A (15205215) 119(25)pp. 6650-6660
The RI-MP2 and RI-CC2 methods have been employed to determine the potential energy profiles of neutral and protonated α-naphthol, in their individual forms and microhydrated with 1 and 3 water molecules, at different electronic states. According to calculated results, it has been predicted that dynamics of nonradiative processes in protonated α-naphthol is essentially different from that of its neutral homologue. In protonated α-naphthol, the calculations reveal that 1σπ∗ state, is the most important photophysical state, having a bound nature with a broad potential curve along the OH coordinate of isolated system, while it is dissociative in monohydrated homologue. In neutral system, similar to phenol, the 1πσ∗ state, plays the fundamental relaxation role along the O-H stretching coordinate. Moreover, microhydration strongly affects the photophysical properties of α-naphthol, mostly by alteration of the 1ππ∗ PE profile, from a bound state in an isolated analogue to a dissociative state in hydrated systems. Furthermore, it has been found that three water molecules are necessary for ground state proton transfer between protonated α-naphthol and water; with a small barrier; (E< 0.1 eV). © 2015 American Chemical Society.
RSC Advances (20462069) 5(37)pp. 29032-29039
The potential energy (PE) profiles of neutral and protonated phenylalanine, as the simplest aromatic amino acid, at different electronic states have been investigated extensively using RI-MP2 and RI-CC2 methods. The PE profiles have been determined, considering the Cα-Cβ and Cα-C(COOH) bond stretching following proton transfer to the aromatic ring and CO group, respectively, as well as the hydrogen detachment reaction coordinate. The calculated results reveal that a low-barrier proton transfer process from ammonia to the aromatic chromophore, leading the excited system to Cα-Cβ bond cleavage, plays the most prominent role in the deactivation mechanism of excited PheH+ at the origin of the S1-S0 electronic transition. On the contrary, for excited neutral phenylalanine at the band origin of the S1-S0 transition, a large barrier in the S1 profile along the Cα-Cβ bond-stretching hinders the excited system from approaching the dissociative part of PE curve. This barrier may explain the large lifetime of the S1 excited phenylalanine (nanosecond range), while a low barrier in the S1 PE profile of the protonated species along the PT process explains the short-range lifetime of the protonated species (in the picosecond range). © 2015 The Royal Society of Chemistry.
Analytical Methods (17599660) (6)
The present work demonstrates that the simultaneous determination of epinephrine (EPI) and acetaminophen (ACT) can be performed using a glassy carbon electrode (GCE) modified with a novel multi-walled carbon nanotubes (MWCNTs), nickel hydroxide nanoparticles (NHNPs) and Mg-Al layered double hydroxide (LDH) composite (MWCNTs-NHNPs-LDH/GCE). The electro-oxidations of EPI and ACT were investigated using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and chronoamperometry (CA) methods. Under optimum conditions, DPV indicated linear relationships between oxidation peak current and EPI and ACT concentrations in the ranges of 0.04-60 μM and 0.02-40 μM with detection limits of 11 and 5 nM, respectively. The proposed method was successfully applied to the determination of these compounds in human urine and blood serum samples. © The Royal Society of Chemistry 2015.
Photochemical and Photobiological Sciences (1474905X) 14(2)pp. 457-464
Excited state hydrogen transfer in hydroquinone- and catechol-ammonia clusters has been extensively investigated by high level ab initio methods. The potential energy profiles of the title systems at different electronic states have been determined at the MP2/CC2 levels of theory. It has been predicted that double hydrogen transfer (DHT) takes place as the main consequence of photoexcited tetra-ammoniated systems. Consequently, the DHT processes lead the excited systems to the 1πσ∗-S0 conical intersections, which is responsible for the ultrafast non-radiative relaxation of UV-excited clusters to their ground states. Moreover, according to our calculated results, the single hydrogen detachment or hydrogen transfer process essentially governs the relaxation dynamics of smaller sized clustered systems (mono- and di-ammoniated). This journal is © The Royal Society of Chemistry and Owner Societies.
Journal of Analytical Chemistry (10619348) (2)
A method for simultaneous spectrophotometric determination of Ga(III) and Tl(III) based on their complexes with 4-(2-pyridylazo)-resorcinol (PAR) is proposed. The results of simultaneous determinations in mixture were obtained by using partial least squares regression (PLS) and genetic algorithm-partial least squares regression (GA-PLS). Moreover, the comparison between them has been conducted. The relative errors of prediction for Ga(III) and Tl(III) were calculated to be 4.98, 8.84 from PLS and 4.83, 4.82 due to running GA-PLS respectively. The pH effect on the sensitivity and selectivity was studied according to the net analyte signal (NAS) approach. The pH was selected at 5.5 as the optimum value to compromise the sensitivity and selectivity of these metal ions. As a consequence, the GA-PLS shows better prediction ability over full spectrum of PLS. © 2015, Pleiades Publishing, Ltd.
International Journal of Thermal Sciences (12900729)
Water self-diffusion coefficient and tracer diffusion coefficient of tert-butanol in water-based silica nanofluids were measured by using pulsed field gradient nuclear magnetic resonance (PFG-NMR) method for silica nanoparticle volume fractions ranged from 0.005% to 1% at three different temperatures (15, 25 and 35 °C). In this work, formation of dye-nanoparticle complexes was minimized and undesirable primary advection effects induced by solute injection were also eliminated. Insignificant enhancement (mostly less than 10% increase) in both water self-diffusion coefficient and tracer diffusion coefficient of tert-butanol in nanofluids was observed. These results indicate that probably Brownian motion of nanoparticles and induced micro-convection tend to enhance mass transfer but the obstruction effect of solid nanoparticles limits this enhancement by reducing the free volume face to diffusion path of molecules. © 2014 Elsevier B.V. All rights reserved.
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy (13861425) 122pp. 337-342
The second-order approximate coupled-cluster (CC2) method was performed to investigate the excited state hydrogen-bonding properties of Glyoxal (C 2H2O2, Gl) dimers. Since the strengthening and weakening of hydrogen bonds can be investigated by monitoring the vibrational absorption spectra of some hydrogen-bonded groups in different electronic states, the infrared spectra of the hydrogen-bonded GlGl complexes in both of the ground state and the S1 electronically excited state are calculated using the MP2/CC2 methods respectively. We demonstrated that the intermolecular hydrogen bond COâ̄HC between two glyoxal molecules is significantly strengthened in the electronically excited S1 state upon photoexcitation of the hydrogen-bonded GlGl complexes. © 2013 Elsevier B.V. All rights reserved.
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy (13861425)
The nanostructure of γ-alumina was used as an effective adsorbent for simultaneous removing of a mixture of alizarin red and alizarin yellow from aqueous solutions. The Taguchi design and principle component analysis were applied to explore effective parameters for achieving a higher adsorption capacity and removal percentage of the binary mixture containing alizarin red and alizarin yellow. Seven factors including temperature, contact time, initial pH value, the shaker rate, the sorbent dose, and initial concentrations of alizarin red and alizarin yellow in three levels were considered through the Taguchi technique. A L27 orthogonal array was used to determine the signal-to-noise ratio. Then, the removal percentage (R%) and adsorption capacity (q) of the above-mentioned dyes were transformed into an accurate S/N ratio. The Taguchi method indicates that the solution pH has the most contribution in controlling the removal percentage of alizarin red and alizarin yellow. Under optimal condition, the maximum removal percentages of 99% and 78.5%, and the capacity uptake of 54.4 and 39.0 mg g-1 were obtained for both alizarin red and alizarin yellow, respectively. Isotherm modeling and kinetic investigations showed that Langmuir, modified Langmuir, and pseudo-second-order models describe both the adsorption equilibrium and kinetic behavior well. The Fourier transform infrared analysis also firmly confirmed the involving active sites of nano γ-alumina in the adsorption process. © 2014 Elsevier B.V. All rights reserved.
Separation Science and Technology (Philadelphia) (01496395) (5)
This study introduces a novel and highly efficient biosorbent called Platanus Carpinifolia tree leaves to remove Methyl violet from aqueous solution. A Box-Behnken design of experiment based on three main factors (initial concentration (C d), sorbent amount (S), and pH) through the response surface methodology approach was chosen to model the removal efficiency (R%) of Methyl violet. The optimum conditions were found from the obtained model as C d = 500 mg/L and S = 0.11 g/L with no pH significant influences. Langmuir, Freundlich, and Temkin isotherms were applied to scrutinize the equilibrium aspect of biosorption by fitting the adsorption experimental data with isotherms. The adsorbent's maximum capacity uptake (q max) was obtained to be 555.5 mg/g from the Langmuir model, which has shown better description of the equilibrium process. Kinetic of biosorption was studied with making use of the pseudo-first order and pseudo-second order models along with intra-particle diffusion. The results showed that the adsorption process behaves in accordance with the pseudo-second order model, and intraparticle diffusion is not solely the rate-limiting step. Regarding the thermodynamical investigation, Δ G°, ΔH ○, and ΔS°respectively, were predicted to be 1.96, 37.34 kJ/mol, and 132 J/mol. This implies that chemisorption is the predominant portion of adsorption mechanism.© 2014 Taylor & Francis Group, LLC.
Chemical Physics Letters (00092614) 555pp. 19-25
The low-lying electronic excited states of protonated phenol and para-Fluorophenol have been investigated extensively by RI-MP2/RI-CC2 methods. Although, protonation of phenol leads to a small red-shift-effect on the S 1-S0 (ππ) electronic transition in respect to its neutral homologue, a large red-shift-effect, on the same electronic transitions of para-substituted phenol has been predicted. The ππ excited state of protonated phenol stays in the UV range (4.34 eV), while its πσ state lies in the VUV region (8.3 eV). The S1 excited-state geometry optimization of protonated phenol predicted unstable S1 state owing to the strong out-of-plane deformation in the benzene ring. © 2012 Elsevier B.V. All rights reserved.
Journal of Chemometrics (08869383) (10)
In most three-dimensional quantitative structure-activity relationship studies, default SYBYL parameters for comparative molecular field analysis (CoMFA) have been used to derive the models. In this work, a genetic algorithm has been employed for the first time to select the best set of parameters. Three-dimensional quantitative structure-activity relationship analysis of a set of 33 analogues of α-aminosuberic acid as a new generation of histone deacetylase inhibitors was performed. Contrary to the ordinary and region focusing CoMFA models, in genetic algorithm optimized model, H-bond was the preferred field type. Genetic algorithm optimized model showed a better predictive ability (r2pred=0.982, q2LOO=0.828, and q2LMO=0.795) compared with ordinary (r2pred=0.937, q2LOO=0.629, and q2LMO=0.537) and region focusing (r2pred=0.954, q2LOO=0.665, and q2LMO=0.564) models derived by CoMFA default set of parameters. © 2013 John Wiley & Sons, Ltd.
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy (13861425)
A new 1,2,4-triazole-based Schiff base hydrazone with N, O, S donor set of atoms, H4L, has been prepared by condensation reaction of N,N′-bis(3-formyl-5-methylsalicylidene)ethane-1,2-diamine, H2L, with 4-amino-3-(4-pyridyl)-5-mercapto-1,2,4-triazole. The structure of H 4L was characterized by using FT-IR, UV-Vis and 1H NMR spectroscopic methods as well as elemental analysis data. The formation constants of copper(II), cadmium(II), mercury(II) and silver(I) complexes of H4L in DMSO were calculated using a hard model chemometrics method applying the spectrophotometric data. The protonation constants of H 4L were also measured in DMSO-water (1:10) mixture. Furthermore, 1H chemical shifts of H4L were studied by the gauge independent atomic orbital (GIAO) and continuous set of gauge transformations (CSGTs) methods at the level of density functional theory using B3LYP/6-311++G- basis sets in gas phase. The computed chemical shifts are in reasonably good agreement with the experimental data. © 2012 Elsevier B.V. All rights reserved.
Journal of Physical Chemistry A (15205215) 117(4)pp. 718-725
Excited state reaction coordinate and the consequent energy profiles of a new Schiff base, N-salicylidene-2-bromoethylamine, have been investigated at the CC2 level of theory. The electron-driven proton transfer and torsional deformation have been identified as the most important photochemical reaction coordinates. In contrast to the ground state, the excited state potential energy profile shows a barrierless dissociation pattern along the O-H stretching coordinate, which verifies the proton transfer reaction along the O-H coordinate at the S1 state. The calculations showed that the PT is electron driven and that the S1 transition has charge transfer character. The keto-type S1 state attained by barrierless proton transfer is found to be unstable via a torsional motion, which provides fast access to a S 1-S0 conical intersection. From the conical intersection, a barrierless reaction path directs the system back to the enol-type minimum of the S0 potential energy surface, thus closing the photocycle. © 2013 American Chemical Society.
Journal of Solution Chemistry (00959782) (11)
The effect of solvent on the stability and reactivity of methyltrioxorhenium (MTO) for activation of hydrogen peroxide (H 2O2) was investigated theoretically. The possible geometries for all Re complexes present in this system, MTO, monoperoxo complexes [A: MeReO2(η 2-O2) and A·H 2 O: MeReO2(η 2-O2)(H 2O)], and bisperxo complexes [B: MeReO(η 2-O 2)2 and B·H 2 O: MeReO(η 2-O2)2(H2O)] were calculated. Based on the theoretical calculations, species A lacks coordinated water while species B·H 2 O definitely has water coordinated to the Re. The changes of thermodynamic parameters (ΔH and ΔG) for six reactions in the MTO/H2O2, system including formation of mono- and bisperoxo complexes, were determined. © 2013 Springer Science+Business Media New York.
Journal of Organometallic Chemistry (0022328X) (21)
Three metal square planar complexes of the type [M(CH3) 2(NH3)2] (M = Ni, Pd, Pt), with a systematic variation in the metals, are chosen to investigating their SN2-type oxidative addition reactions with methyl iodide by using the B3LYP levels of theory. The oxidative addition was found to take place via a transition state with a nearly linear arrangement of the I-CH3-M moiety. Solvation effects in these oxidative addition reactions were also investigated. Considering the nature of the metal centre and solvation effects, the following conclusions emerge: (i) addition of MeI is exothermic for all three metals, and Pt is predicted to react with a much lower barrier than either Pd or Ni. The results describe that the MeI addition would be expected to be more favourable with the complex bearing the third-row metal (platinum) as compared to the other triad metals, nickel or palladium, in which case a more strongly bound MeI adduct is formed with a lower activation barriers and the reaction being more exothermic; (ii) the reaction is very difficult to occur in low polar solvents, such as benzene, due to the high barrier which is induced by dissociation of iodide anion from methyl group, but the reaction easily occurs in polar solvents, such as acetonitrile; this is attributed to the ability of polar solvents to solvate and therefore stabilize the related polar intermediate ion pair. Ethane reductive elimination from the M(VI) complexes fac-[M(CH 3)3(NH3)2I] were also studied, indicating that the Ni(IV) and Pd(IV) complexes are very prone to undergo the reductive elimination while the Pt(IV) analogous is less reactive towards the reductive elimination. The results indicate that in contrast to the Me-Me reductive elimination, the SN2 oxidative addition reaction of MeI to M(II) is much less sensitive to the nature of the metal centre, suggesting that the nucleophilicity of M(II) in [M(CH3)2(NH 3)2] does not change significantly as one moves from M = Ni to Pt. © 2011 Elsevier B.V. All rights reserved.
Simple and efficient microwave-assisted acid hydrolysis (MAAH) of proteins was used for rapid quantification of α-aminoadipic semialdehyde (AAS) and γ-glutamic semialdehyde (GGS) as major protein oxidation markers. The precursor amino acid residues corresponding to AAS and GGS in oxidized proteins were derivatized by reductive amination with sodium cyanoborohydride (NaCNBH3) and p-aminobenzoic acid (ABA) followed by MAAH to generate the marker derivatives AAS-ABA and GGS-ABA. The quantification was performed using electrospray ionization liquid chromatography-mass spectrometry (ESI LC-MS). The important parameters for hydrolysis were optimized, which include the temperature, the reaction time, the acid concentration and volume as well as the microwave power. Compared to the conventional acid hydrolysis of 18-24 h using 6-12 M HCl at 110 °C applied commonly in the literature and also in this work, MAAH of proteins can be completed as fast as in only 2-10 min and, additionally, with a 3-5 times higher yield of the final derivatization products. Furthermore, a better agreement between the ratio of the detected derivatization products and the theoretical yields from the studied protein has also been achieved, which indicates that MAAH may serve as a more reliable method of acid hydrolysis for this purpose than that with conventional thermal heating. The MAAH method is demonstrated to be a time-saving, reproducible and efficient technique for studying AAS and GGS as protein oxidation markers using LC-MS. © 2011 Elsevier B.V. All rights reserved.
Journal of Raman Spectroscopy (03770486) (3)
A sensitive and efficient method for the determination of acidity constants of salicylaldoxime (SALO) (2-hydroxybenzaldehyde oxime), using both Raman spectroscopic and potentiometric methods, at 30 °C in 50% (wt/wt) of ethanol-water mixture and at the constant ionic strength I = 0.1 M is proposed. The effect of pH on the Raman spectra has also been studied. The Raman spectroscopic technique allows the identification of compounds in different molecular and molecular ionic structures. The limit of detection (LOD) was determined to be 0.05 mol dm-3 for SALO by means of Raman peak area. © 2010 John Wiley & Sons, Ltd.
Analytical Sciences (09106340) (8)
A quantitative structure activity relationship (QSAR) study of 8-azaadenine, as antagonists for the A1 receptor, is described. A genetic algorithm (GA) method was used as the feature selection tool, and an adaptive neuro-fuzzy inference system (ANFIS) was employed for feature mapping. The best descriptors (GATS4v and BELv7) were applied to train the ANFIS model. The optimum number and shape of related functions were obtained through a subtractive clustering algorithm. The ability and robustness of the GA-ANFIS model in predicting the affinity of 8-azaadenine derivatives (pKi) are illustrated by validation techniques of Leave One Out, heuristic and randomized methods. The results have indicated that the proposed model of ANFIS in this work is superior over two other methods, radial basis function (RBF) and multiple linear regression (MLR). 2010 © The Japan Society for Analytical Chemistry.
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy (13861425) (5)
Molecular speciation of organic compounds in solution is essential for the understanding of ionic complexation. The Raman technique was chosen because it allows the identification of compounds in different states, and it can give information about the molecular geometry from the analysis of the vibrational spectra. The effect of pH on organic compounds can give information about the ionisation of molecule species. In this study the ionisation steps of salicylic acid and paracetamol have been studied by means of potentiometry coupled with Raman spectroscopy at 30.0 °C in a solution of ionic strength 0.96 mol dm-3 (KNO3) and 0.04 mol dm-3 (HNO3). The protonation and deprotonation behaviour of the molecules were studied in different pH regions. The abundance of the three different species in the Raman spectra of aqueous salicylic acid have been identified satisfactorily, characterised, and determined by numeric treatment of the data using a multiwavelength curve-fitting program and confirmed with the observed spectral information. © 2010 Elsevier B.V. All rights reserved.
Analytical Sciences (09106340) (5)
A new modified silica gel doped with 5-(4-dimethylaminobenzylidene)-rhodanine was prepared for separation, preconcentration and determination of silver ion by atomic absorption spectrometry. This new modified silica gel was used as an effective adsorbent for the solid phase extraction of Ag+ from aqueous solutions. The variables that influence the adsorption/desorption of trace levels of Ag+ were optimized in the column process. The preconcentration factor and capacity of the adsorbent at optimum conditions were found as 220 and 420 μg Ag+ per gram of adsorbent, respectively. The relative standard deviation and the detection limit for measurement of Ag+ in our experiments were less than 1.5% (n = 10) and 0.02 μg L-1, respectively. Common coexisting ions did not interfere with the separation and determination of silver ion. The proposed method was successfully applied for preconcentration and determination of silver ion in some spiked water samples. 2009 © The Japan Society for Analytical Chemistry.
Analytical Sciences (09106340) (10)
A new spectrophotometric reagent for the determination of trace amounts of fluoride has been introduced. This method is based on the decolorization of a complex of Al(III) with xylenol orange (XO) as an ultra-sensitive colored reagent. Since the Al-XO complex plays an important role in this method, the protonation and complexation of XO with Al(III) at an ionic strength of 0.1 mol L-1 at 25°C has been studied by a spectrophotometric global analysis method. The EQUISPEC program was used to evaluate the protonation constants of XO and the stability constants of the formed complexes with Al(III). The protonation and the stability constants of the major complex species such as ML, MLH and MLH2, were determined. Finally, a spectrophotometric method for the assay of fluoride based on a decrease of the color intensity of the Al-XO complex, in an aqueous solution has been designed. The effects of some important variables on the determination of fluoride based on the proposed method were investigated. The method was applied to the determination of fluoride under the optimum conditions (pH 5.2, ionic strength 0.1 mol L-1, 25°C). The determination of fluoride in the range of 0.08 - 1.4 μg mL-1 (SD = 1.2%) was successfully performed. Interferences of Fe(III) were easily eliminated by using ascorbic acid. The proposed method was applied to the determination of trace amounts of fluoride content of some real water sample. 2009 © The Japan Society for Analytical Chemistry.
Separation Science and Technology (15205754) (11-12)
The facilitated transport of Au(III) through a chloroform bulk liquid membrane containing potassium-dicyclohexyl-18-crown-6 as a selective ion carrier was designed. Au(III) as [AuBr4]-, quantitatively transported across the liquid membrane. In the receiving phase, L-cysteine acts as a specific stripping agent. The amount of Au(III) transported through the liquid membrane after 120 minutes was (96.2 ± 1.3)%. The type of halide and its concentration, pH of source and receiving phase and also the type of stripping agents were optimized. The selectivity and efficiency of gold(III) transport from aqueous solutions containing various metal ions were investigated. The presence of EDTA in the source phase diminished drastically the competitive effect of interfering metals ion.
Journal of Chemical and Engineering Data (00219568) (8)
The acid-base properties of 4-benzyl-5-(pyridin-2-yl)-4//-1,2,4-triazole- 5(4H)-thione, (4-benzyl-5-(pyridin-3-yl)-4H-1,2,4-triazole-5(4H)-thione, and 4-benzyl-5-(pyridin-4-yl)-4H-1,2,4-triazole-5(4H)-thione in ethanol/water mixtures have been studied at 25°C and for an ionic strength of 0.1 M by a multiwavelength spectrophotometric method. For evaluation of the pH-absorbance data, a resolution method based on the hard modeling was used. The acidity constants of each dissociation equilibria were estimated by fitting the whole spectral collected data to an established factor analysis model. The EQUISPEC program was used for determination of acidity constants. The corresponding pKa values in ethanol-water mixtures were determined. There is a linear relationship between acidity constants and the mass fraction of ethanol in the solvent mixtures. The effect of solvent on acid-base behavior was discussed. © 2008 American Chemical Society.
Sangi, Mohammad Reza ,
Shahmoradi, Ali ,
Zolgharnein J. ,
Azimi gandomani, G. ,
Ghorbandoost, Morteza Journal of Hazardous Materials (03043894) (3)
Ulmus carpinifolia and Fraxinus excelsior tree leaves, which are in great supply in Iran, were evaluated for removal of Pb(II), Cd(II) and Cu(II) from aqueous solution. Maximum biosorption capacities for U. carpinifolia and F. excelsior were measured as 201.1, 172.0 mg/g for Pb(II), 80.0, 67.2 mg/g for Cd(II) and 69.5, 33.1 mg/g for Cu(II), respectively. For both sorbents the most effective pH range was found to be 2-5 for Pb(II), 3-5 for Cd(II) and 4-5 for Cu(II). Metal ion biosorption increased as the ratio of metal solution to the biomass quantity decreased. Conversely, biosorption/g biosorbent decreased as the quantity of biomass increased. The biosorption of metal ions increased as the initial metal concentration increased. Biosorption capacities of metal ions were in the following order: Pb(II) > Cd(II) > Cu(II). The equilibrium data for Pb(II) and Cu(II) best fit the Langmuir adsorption isotherm model. Kinetic studies showed that the biosorption rates could be described by a second-order expression. Both the sorbents could be regenerated using 0.2 M HCl during repeated biosorption-desorption cycles with no loss in the efficiency of the Cu(II) removal observed. Biosorption of Pb(II), Cd(II) and Cu(II) was investigated in the presence of Na, K, Mg and Ca ions. The results from these studies show a novel way of using U. carpinifolia and F. excelsior tree leaves to remove Pb(II), Cd(II) and Cu(II) from metal-polluted waters. © 2007 Elsevier B.V. All rights reserved.
Separation Science and Technology (15205754) (10)
Potassium-dicyclohexyl-18-crown-6 was used as a selective and efficient carrier for the uphill transport of thallium (III) ion as [TlCl4]- complex ion through a chloroform bulk liquid membrane. By using oxalate anion as a metal ion acceptor in the receiving phase, the amount of thallium (III) transported across the liquid membrane after 120min was 962%. The selectivity and efficiencies of thallium transport from aqueous solutions containing Cu2+, Zn2+, Ni2+, Cd2+, Pb2+, Co3+, Mn2+, Cr3+, Mg2+, Ca2+, K+, Na+, and Fe3+ ions were investigated. In the presence of Na3PO4 (0.01M) at pH=3 as a suitable precipitation agent in the source phase, the interfering effect of Pb2+ ion were diminished drastically.
Arca, Massimiliano ,
Azimi gandomani, G. ,
Demartin, Francesco ,
Devillanova, Francesco A. ,
Escriche, Lluis Inorganica Chimica Acta (00201693) (7)
The macrocycles L1-L3 having N2S 2O-, N2S2-, and N2S 3-donor sets, respectively, and incorporating the 1,10-phenanthroline unit interact in EtOH and MeCN solutions with CuII to give 1:1 [M(L)]2+ complex species. The compounds [Cu(L1)(ClO 4)]ClO4 (1), [Cu(L2)(ClO4)]ClO 4·1/2H2O (2) and [Cu(L3)](ClO 4)2 (3) were isolated at the solid state and the first two also characterised by X-ray diffraction studies. The conformation adopted by L1 and L2 in the cation complexes reveals the aliphatic portion of the rings folded over the plane containing the heteroaromatic moiety with the ligands encapsulating the metal centre within their cavity by imposing, respectively, a square-based pyramidal and a square planar geometry. In both complexes, the metal ion completes its coordination sphere by interacting with a ClO4- ligand. The compound [Cu(L3) 2](PF6)2 (4) containing a 1:2 cation complex was also isolated at the solid state: EPR spectroscopy measurements suggest the presence of a CuN4 chromophore in this complex. The EPR and electronic spectral features of 1-4 have been studied and their redox properties examined in comparison with those observed for Type-1 blue copper proteins. The reactivity of L1-L3 has also been tested toward stoichiometric amounts of the CuI salt [CuCl(PPh3) 3]. © 2005 Elsevier B.V. All rights reserved.
Chemical Physics Letters (00092614) (1-3)
The hydrogen bonds formed between the hydroperoxyl radical and formamide, acetamide, and urea were characterized using geometric, energetic, along with the AIM analyses of the MP2 densities with the UMP2(full)/6-311G(d,p) method. Energetic analysis at G2MP2 level proved that the studied complexes are stable. The fundamental anharmonic OH vibrational frequencies calculated at this level of theory were 2840, 2749, and 2825 cm -1 for the complexes of HO 2 with formamide, acetamide and urea, respectively. The results allowed the characterization of the hydrogen bonds formed in the complexation of the amides with the hydroperoxyl radical. © 2004 Elsevier B.V. All rights reserved.
Chemical Physics Letters (00092614) (4-6)
The electronic structure and thermochemical stability of the HOO-SO 3 complex is studied using both second-order Møller-Plesset perturbation theory (MP2) and the B3LYP density-functional theory (DFT) method. The calculated dissociation energies of the complex are 10.25 and 11.51 kcalmol-1 at the G3(MP2) and G3 levels, respectively. Anharmonic OH stretching frequencies of the HO2 moiety along with the frequency shifts upon complex formation are calculated at the MP2/6-311++G(2df,2p) and B3LYP/6-311++G(2df,2p) levels, and also AIM analyses of the MP2 and Kohn-Sham densities were performed. Theoretical data strongly encourage performing of matrix-isolation studies of the title complex and its spectroscopic identification. © 2004 Elsevier B.V. All rights reserved.
Analytical Sciences (09106340) (6)
Potassium-decyl-18-crown-6 was used as a highly selective and efficient carrier for uphill transport of silver as AgBr2- complex ion through a chloroform bulk liquid membrane. When thiosulfate anion was used as a metal ion acceptor in the receiving phase the amounts of silver transported across the liquid membrane after 120 and 180 min were 87.0 ± 1.8% and 96.0 ± 1.9%, respectively. The selectivity and efficiency of silver transport from aqueous solution containing Cu2+, Zn2+, Ni2+, Cd2+, Pb2+ and Fe3+ ions were investigated. In the presence of EDTA at pH = 4 as suitable masking agent in the source phase, the interfering effects of Pb2+ and Fe3+ ions were diminished drastically.
Shamsipur, M. ,
Kazemi, Sayed Yahya ,
Azimi gandomani, G. ,
Madaeni, Sayed Siavash ,
Lippolis, Vito Journal of Membrane Science (03767388) (1-2)
A new supported liquid membrane (SLM) system for the selective transport of silver ion is introduced. The SLM used is a thin porous membrane impregnated with a recently synthesized mixed aza-thioether crown containing a 1,10-phenanthroline sub-unit dissolved in nitrophenyl octyl ether. In the presence of thiosulfate as a metal ion acceptor in the strip solution, the transport of silver occurs almost quantitatively after 3h. The selectivity and efficiency of silver transport from aqueous solution containing excess amounts of Mg2+, Ca2+, Sr2+, Ba2+ Co2+, Ni2+, Cu2+ Zn2+, Pb2+, Cd2+ and Hg2+ ions were investigated. © 2003 Elsevier Science B.V. All rights reserved.
Simultaneous determination of total iron and vanadium by H-point standard addition method (HPSAM) and partial least squares (PLS) is described. Gallic acid (GA) in a cationic micellar solution of CTAB was used for determination of iron and vanadium in different oxidation states at pH 5. The presence of a micellar system enables total iron and vanadium to be determined with improved sensitivities. The total relative standard error for applying the PLS method to 15 synthetic samples in the ranges 0.20-15.00 μg ml-1 iron and 0.20-8.00 μg ml-1 vanadium was 2.2%. The results of applying the H-point standard addition method showed that iron and vanadium can be determined simultaneously with the concentration ratios of iron to vanadium from 10:1 to 1:20 in the mixed sample. Both HPSAM and PLS methods showed suitable abilities to resolve accurately overlapped absorption spectra of the compounds. Both proposed methods were successfully applied to the determination of Fe and V in several synthetic alloy solutions. © 2003 Elsevier Science B.V. All rights reserved.
Separation and Purification Technology (13835866) (2)
The transport of Hg2+ ions through a chloroform bulk liquid membrane containing tetrathia-12-crown-4 (TT12C4) as a specific ion carrier was studied. Mercury ion is quantitatively transported across the liquid membrane in the presence of ethylenediaminetetraacetic acid (EDTA) as a suitable stripping agent in the receiving phase, the amount of mercury transported across the liquid membrane after 2 h is 99.0 ± 1.0%. Excellent mercury ion selectivities relative to a wide variety of alkali, alkaline earth, transition and heavy metal ions were observed. © 2002 Elsevier Science B.V. All rights reserved.
The H-point standard addition method (HPSAM) for simultaneous determination of Fe(II) and Fe(III) is described. The method is based on the difference in the rate of complex formation of iron in two different oxidation states with Gallic acid (GA) at pH 5. Fe(II) and Fe(III) can be determined in the range of 0.02-4.50 μg ml-1 and 0.05-5.00 μg ml-1, respectively, with satisfactory accuracy and precision in the presence of other metal ions, which rapidly form complexes with GA under working conditions. The proposed method was successfully applied for simultaneous determination of Fe(II) and Fe(III) in several environmental and synthetic samples with different concentration ratios of Fe(II) and Fe(III). © 2002 Elsevier Science B.V. All rights reserved.
Analytical Letters (00032719) (10)
Optical sensors have been developed for high-acidity ([H+] = 1-9 M) measurements. The indicators Rhodamine B and Safranine T were entrapped in porous silica glass films prepared by the sol-gel method. The entrapped indicators were nonleachable and respond to high acid concentrations in a reversible manner. The influences of different experimental parameters such as the catalyst concentration, the water/tetraethoxy silane ratio, the amount of co-solvent, and the amount of surfactant on the chemical and mechanical stabilities of the sol-gel films were investigated. The optical sensors possess a short response time of <5 s and are stable for a period of at least 3 months. The relative standard deviation of the absorbance measurements is <2%. The interfering effect of different alkali, alkaline earth and transition metal salts on the response behavior of the sensors was studied.
Analytical Sciences (09106340) (4)
A facile supported liquid membrane (SLM) system for the selective and efficient transport of silver ion is introduced. The SLM used is a thin porous polyvinyldifluoride membrane impregnated with hexathia-18-crown-6 (HT18C6) dissolved in nitrophenyloctyl ether. HT18C6 acts as a specific carrier for the uphill transport of Ag+ ion as its picrate ion paired complex through the SLM. In the presence of thiosulfate ion as a suitable stripping agent in the strip solution, transport of silver occurs almost quantitatively after 4 h. The selectivity and efficiency of silver transport from aqueous solutions containing other Mn+ cations such as Mg2+, Ca2+, Co2+, Ni2+, Cu2+, Zn2+, Pb2+, Cd2+, Hg2+, Fe3+ and Cr3+ ions were investigated.
Main Group Metal Chemistry (21910219) (8)
The dissociation rates of the Ba 2+-C222 cryptate in different dimethylsulfoxide-acetonitrile mixtures have been studied spectrophotometrically using murexide as a suitable metallochromic indicator. The activation parameters E a, ΔH ‡ and ΔS ‡ for the dissociation of the cryptate were determined from the temperature dependence of the dissociation rate constants (ka). The correlation of the dissociation rate constant with the stability constant (K s) of the barium cryptate was investigated. There is a linear relationship between log K s and the activation parameters E a, ΔH ‡ and ΔS ‡ and the mole fraction of acetonitrile in the mixed solvent.
Journal of Membrane Science (03767388) (2)
A new supported liquid membrane (SLM) system for the selective transport of zinc ion is described. The SLM used is a thin porous polyvinyldifluride membrane impregnated with dicyclohexyl-18-crown-6 dissolved in nitrophenyloctyl ether. Potassium-dicyclohexyl-18-crown-6 acts as a highly efficient carrier for the uphill transport of zinc as Zn(SCN)42- through the SLM. In the presence of L-Cysteine as a metal ion acceptor in the strip solution, transport of zinc occurs almost quantitatively after 5h. The selectivity and efficiency of zinc transport from aqueous solution containing different mixtures of Co2+, Ni2+, Cu2+, Pb2+, Cd2+, Hg2+, Fe3+ and Cr3+ ions were investigated. In the presence of citrate ion and thiourea as suitable masking agents in the feed solution, the interfering effects of Pb2+ and Cu2+ ions were completely eliminated. Copyright (C) 2000 Elsevier Science B.V.
Journal of Coordination Chemistry (00958972) (4)
The dissociation and the formation rates of the Sr2+-C222 cryptate in different dimethylsulfoxide-acetonitrile mixtures have been studied spectrophotometrically using murexide as a metallochromic indicator. In all solvent mixtures used, the ratio of the rate constants for dissociation and formation of the cryptate was found to be in agreement with the formation constants obtained by an independent equilibrium spectrophotometric technique. The activation parameters Ea, ΔH‡ and ΔS‡ for the formation and dissociation of the cryptate were determined from the temperature dependence of the corresponding rate constants, and found to be strongly solvent dependent. There is a linear relationship between the logarithm of the formation constant as well as the activation parameters and the mol fraction of acetonitrile in the mixed solvent.
