دانشگاه تربيت مدرس
دانشگاه تربيت مدرس
گروه آموزشی شیمی
گروه آموزشی شیمی
In this study, a zirconium-based metal-organic framework (Zr-MOF), named UiO-66-OH, was synthesized by the solvo-thermal method and characterized by Fourier transform-infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), and scanning electron microscopy (SEM). This Zr-MOF was then employed as a sorbent for selective extraction and preconcentration of thorium ions after their complexation with 2 (2,4 dihydroxyphenyl) 3,5,7 trihydroxychromen 4 one (morin) from environmental water samples prior to its spectrophotometrical determination. The experimental parameters affecting extraction, such as pH of sample solution, amount of Zr-MOF, type and volume of eluting solvent, adsorption and desorption time, and concentration of complexing agent were evaluated and optimized. Under the optimized conditions, an enrichment factor of 250 was achieved. The limit of detection was calculated to be 0.35 μg·L−1 with a linear range between 10 and 2000 μg·L−1of thorium. Themaximumsorption capacity ofMOF toward thorium was found to be 47.5 mg·g−1. The proposed procedure was successfully applied to the analysis of real water samples.
A bioinspired iron(III)porphyrinic Zr-MOF, PCN-222(Fe), was modified by post-synthetic cluster metalation with iron(III) chloride, as a cheap, earth-abundant, and environmentally friendly metal precursor, towards formation a new multifunctional MOF, namely Fe@PCN-222(Fe). The MOF consists of bimetallic (Zr-oxo-Fe) nodes linked by Fe(III)porphyrin struts. The cluster metalation and pre-activation treatment of PCN-222(Fe) were performed cooperatively using the FeCl3. The respective MOF was characterized through various techniques, such as FT-IR, PXRD, ICP-AES, BET surface area, SEM, UV–Vis DRS, TGA/ DSC, PL, and XPS analyses. The solid showed catalytic activity for one-pot tandem synthesis of quinazolin-4(3H)-ones from alcohols and 2-aminobenzamide through a three-consecutive-step reaction (oxidation-cyclization-oxidation) under visible light irradiation using air or oxygen without adding any additive. In addition, its catalytic performance was superior to that of the bare PCN-222(Fe) and the corresponding homogeneous catalysts. The experiments indicate that the solid MOF acts as both a photoredox and Lewis acid catalyst. Hot-filtration and Fe-leaching tests as well as reusability experiments confirm that the nominal MOF acts as an efficient reusable heterogeneous catalyst for at least three runs without significant decrease in its activity. This work demonstrates the potential of using MOFs as supports for single-site metal species towards preparation of multifunctional MOFs for modern organic transformations combining photocatalysis and catalysis.
An amino-functionalized zirconium metal-organic framework was composed with a 3D urea-based porous organic polymer to give a hybrid material termed UiO-66-NH2/urea-POP. The material was characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, and Brunauer-Emmett-Teller surface area measurements. It is shown to be a viable sorbent for solid-phase extraction of uranium from water samples. Parameters such as the pH value of the sample, amount of adsorbent, type and volume of eluent, adsorption and desorption time, and sample volume were optimized. Uranyl ion was quantified by using UV-vis spectrophotometry by using 1-(2- pyridyl-azo)-2-naphthol as the indicator. Figures of merits include (a) a maximum sorption capacity of 278 mg g−1; (b) a detection limit of 0.6 μg L−1; and (c) intra-day and inter-day precisions (for n = 5 at a concentration of 100 μg L−1) of 4.8 and 1.9%, respectively. The sorbent can be recycled, and no significant change was observed in the capacity and repeatability of the sorbent after seven extractions. The high surface area, metal-binding sites, and stability of the sorbent makes it a most viable tool for efficient and fast extraction and removal of uranium.
A 3D urea-based porous organic polymer (Urea-POP) was prepared via the reaction of tetrakis(4-aminophenyl)methane and 1,4-Phenylene diisocyanate. The polymer was subsequently reacted with 2D layered nanosheets of graphene oxide (GO) to prepare Urea- POP/GO as a novel and highly efficient sorbent for pre-concentration and extraction of serum albumin samples, prior to spectrophotometric determination. The hybrid material combines advantages of both POP and GO such as hydrophilicity, high dispersion stability, porosity, and having a large number of nitrogen- and oxygen-containing functional groups. Parameters which influence the extraction efficiency such as the amount of the adsorbent, pH of sample solution, ionic strength, adsorption and desorption time were investigated and optimized. For the method, detection limit of 0.068 mgL-1 and determination coefficient (R2) of 0.9991 were obtained. The intra- and inter-day was calculated with five replicates in the same day and seven consecutive days, respectively. Intra-day and interday precisions were 1.7% and 5.9%, respectively. The maximum sorption capacity was 357.1 mg g-1, which is higher than the other reported sorbents. The proposed method was demonstrated to be sensitive enough for determination of serum albumin from biosamples.
This study describes the preparation of zinc oxide nanoparticle–chitosan as a solid-phase adsorbent for separation and preconcentration of trace amount of chromium and nickel from environmental water samples and their determination by inductively coupled plasma optical emission spectrometry. Important factors including pH, amount of adsorbent, amount of 1-(2-pyridylazo)-2-naphthol, sample volume, eluent concentration and extraction time were investigated and optimized. The equilibrium data according to the Freundlich’s and Langmuir models were processed. The results showed that the equilibrium data were well fitted with Langmuir isotherm model. The best fit of adsorption kinetics was attained with a secondorder equation. Under the optimum conditions, the detection limits for chromium and nickel were 0.041 and 0.039 μg L−1, respectively, and the relative standard deviations (RSD %) were 1.5% and 1.3% (n = 10, c = 50 μg L−1) for chromium and nickel, respectively. This procedure was then used for preconcentration and determination of target compounds from environmental water samples.
Herein, a comparative study focusing on the effects of measuring atmosphere on ultraviolet (UV) photodetection performance of ZnO nanostructures is presented. Various morphologies of ZnO nanostructures were synthesized by changing the hydrothermal temperature within 343e423 K. The ultraviolet photodetection performance of the samples was studied against dark ultraviolet light (360 nm, 800 mW/cm2) under 200 sccm gas flows of argon and oxygen. The nanoflowers grown at 373 and 393 K showed the best photosensitivity and photoresponsivity under both argon and oxygen flows. Concerning the importance of active surface area, it was shown that the sample grown at 393 K serves higher accessible surface-to-volume ratio (qualitatively observable by SEM and confirmed by BET), higher concentration of freed electron due to oxygen vacancies (confirmed by PL) and consequently, the best UV photosensitivity. The comparative study between photodetection parameters in argon and oxygen atmospheres showed that although higher partial pressure of oxygen is favorable for all photodetection parameters like photosensitivity, photoresponsivity and decay time, it has adverse effects on rising time because rising time is directly coupled with the density of desorbed oxygen atoms.
determination of gold from water samples prior to UV-Vis spectrophotometry. An artificial neural network (ANN) combined with imperialist competitive algorithm (ICA) has been applied to optimize the EME. The effective parameters including pH of acceptor phase, extraction time (t), volume of sample solution (V), stirring rate (S), and voltage (E) were chosen as input variables and the extraction recovery of gold was considered as output variable. The mean of squared error (i.e., 0.0009) and determination coefficient (i.e., 0.9821) were applied to estimate the performance of the ANN model. The limit of detection was 4.5 μg L
New trans-A2B2-porphyrins substituted at phenyl positions were synthesized from 4-methylphthalic acid as a starting material through sequential multistep reactions. These macrocycles were characterized by 1H NMR, 13C NMR, 19F NMR, 1H–1H COSY NMR, and MALDI-TOF mass spectrometry. Computational studies were performed on the porphyrins to investigate various factors such as structural features, electronic energy, energy gaps, and aromaticity. Energy band gap values of these compounds especially N-hydroxyphthalimide-functionalized porphyrins were small that makes them as good candidates for solar cell systems and photocatalysis. Relationships between electronic energies and aromaticity of the compounds were then investigated. The data indicated that the aromaticity features at the center of two series of these compounds (fluorinated and non-fluorinated porphyrins) were in the opposite manner.
The Amadori product is a stable intermediate in the glycation process, and its increased formation is a marker of hyperglycemia in diabetes mellitus. Its accumulation in the body contributes to pathological complications of diabetes including diabetic nephropathy and retinopathy, and cardiovascular diseases. In this study the effect of 3-b-hydroxybutyrate on the production of Amadori products and structural changes of human serum albumin (HSA) after incubation with glucose was investigated using FT-IR, circular dichroism (CD), and UV-visible and fluorescence spectroscopy. Our results showed that the production of Amadori products in HSA incubated with glucose was decreased in the presence of 3-b-hydroxybutyrate. The glycation-mediated alterations in HSA secondary and tertiary structures were also reduced in the presence of 3-b-hydroxybutyrate. These changes were attributed to reduced formation of glucose covalent bonds with the HSA lysine residues in the presence of 3-b-hydroxybutyrate. Thus, 3-b-hydroxybutyrate reduced the production of Amadori products by reacting with lysine residues and decreasing HSA covalent modifications by glucose.
The objective of the present study was to investigate the effects of dietary supplementation with zinc oxide (ZnO) and chitosan–zinc nanoparticles (chitosan– ZnO NPs) on biochemical, immunological, and antioxidant biomarkers in blood of juvenile belugas (Huso huso). The beluga juveniles with initial weight of 287 ± 46 g were fed with eight experimental diets containing 0 g kg−1 ZnO (the control diet); 10, 20, and 40 mg kg−1 ZnO; and 10, 20, and 40 mg kg−1 chitosan– ZnO NPs and 36 mg kg−1 chitosan. After 28 days of culture, the fish were fed with ZnO and chitosan–ZnO NP–supplemented diets showed a more significant increase in total antioxidant capacity (TAC), superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), glutathione peroxidase (GPX), and glutathione S-transferase (GST) activity (p < 0.05) compared to the control group. There were no significant differences (p > 0.05) in malondialdehyde (MDA) and glucose level in all treatment groups. The results showed that with increasing levels of ZnO and chitosan–ZnO NPs, alternative complement activity (ACH50), and total immunoglobulin, total protein, albumin, and lysozyme had a significant increase in fish fed with ZnO and chitosan–ZnO NP–supplemented diets compared to the control group (p < 0.05). ALP, ALT, and AST enzyme activities showed significant difference between control and treatment groups (p > 0.05),while the levels of LDH enzyme activity, urea, and creatinine decreased by increasing both ZnO and chitosan–ZnO NP levels. These results demonstrated that dietary chitosan–ZnO NPs could improve the health status, immune function, and antioxidant capacity of the cultured beluga juvenile
Three-dimensional graphene foam (GF) with different layer numbers was synthesized by a chemical vapor deposition method. The number of GF layers was controlled by adjusting the feed gas ratio. The average number of layers was calculated by means of Raman spectra and found to be 2, 4, 6, 11 and 25 layers by changing the methane flow at 0.5 sccm, 0.6 sccm, 0.7 sccm, 1 sccm and 1.5 sccm, respectively. ZnO nanorods were grown on each sample by a hydrothermal method. The samples were characterized by scanning electron microscopy, energy-dispersive x-ray spectroscopy, x-ray diffraction and Raman spectroscopy techniques. Photocatalytic degradation of methylene blue (MB) by GF/ZnO composites under visible light was studied. The results showed that the photocatalytic degradation of MB is related to the number of the graphene layers in the composite. In fact, it was concluded that the electronic structure of low-layer graphene indicates a higher capturing performance for photo-assisted electrons of ZnO nanorods.