JOURNAL OF THE IRANIAN CHEMICAL SOCIETY(JICS)
Year:2015 | Volume:12 | Issue:4|Papers Count:20

When considering the importance of mesoporous materials as adsorbent for heavy metal ions, this study concerns on the preparation, characterization and application of a SBA-15 mesoporous silica material functionalized with a Schiff base ligand N-propylsalicylaldimine (SBA/SA). The properties of this adsorbent were compared with two SBA-15 mesoporous silica materials modified with aminopropyl (SBA/NH2) and ethylenediaminopropyl (SBA/En) groups. These materials were characterized by XRD, SEM, TEM, TGA techniques and FTIR spectroscopy. The potential of the prepared modified mesoporous materials, as metal ion adsorbents, was evaluated by their application for removal of Pb (II), Cd (II) and Ag (I) ions from aqueous solutions. The assessments were conducted by investigating the effect of sample aqueous pH, contact time, adsorbent dose and initial concentration of the metal ions in batch systems. Flame atomic absorption spectroscopy (FAAS) was used for metal ions measurements. It is found that after 4 h of mechanical agitation of the adsorbents and solution, under optimum conditions, lead ions can be quantitatively removed from 10 mg L−1 Pb (II) solution using 0.03 g of SBA/NH2, 0.005 g of SBA/En or 0.005 g of SBA/SA. Under same conditions, silver ions can be quantitatively removed from 10 mg L−1 Ag (I) solution using 0.04 g of SBA/SA. In addition, all the studied ions can be eliminated from solution (initial concentration 10 mg L−1) using 0.06 g of SBA/En adsorbent. Based on the calculated values from the Langmuir isotherm, the maximum adsorption capacities of the adsorbents SBA/NH2,SBA/En and SBA/SA for Pb (II), Cd (II) and Ag (I) were found to be 29.4, 111.1 and 100.0 mg g−1, 8.0, 14.0 and 5.6 mg g−1, and 7.3, 31.2 and 28.5 mg g−1, respectively. The equilibrium data were analyzed using the Langmuir and Freundlich isotherms. The proposed method was applied for removing Pb (II), Cd (II) and Ag (I) ions from real samples under selected experimental conditions.

Bi (OTf)3 was found to be an efficient, reusable and high yielding catalyst for the synthesis of dihydropyrano [3, 2-b] chromenediones via the three-component reaction of aromatic aldehydes, kojic acid and 1,3-diones. The catalyst could be separated and recovered easily, and was reused for several runs without significant loss of its activity.

Potential energy curves (PECs) of the lowest singlet and triplet states of the HCl2+ dication have been calculated using density functional theory with the B3LYP and HSE06 functionals and coupled cluster CCSD (T) method, all with 6-311G (3df,3pd) basis set. Analysis of the results of all three methods shows that the triplet state is a pure 3å− state, while the singlet state is a mixture of the 1D and 1å+ states. Spectroscopic constants and Franck–Condon factors corresponding to the transitions from the ground state neutral HCl to these dicationic states have been calculated and compared to the available experimental and computational data. While the calculated spectroscopic constants and equilibrium bond lengths of the PECs obtained by the HSE06 functional are in good agreement with the available data, the predicted vertical offset of the PECs differ significantly with those observed experimentally. Inclusion of a set of floating basis functions corresponding to the Li ghost atom does not improve the results within the available experimental resolution. Addition of centrifugal term to the potential energy decreases the well depth and well width at barrier and increases the barrier height.

In this work, a new and simple method is proposed to estimate the melting points of hazardous organic peroxide compounds including hydro peroxides, dialkyl peroxides, primary and secondary ozonides, peroxyacids, diacyl peroxides and alkyl peroxyesters compounds. This method can be applied for any peroxide compound with general formula CxHyOz to predict its melting point on the basis of elemental composition and specific structural moieties as additive and non-additive functions. It was applied for 104 different peroxide compounds including complex molecular structures. The predicted results give more reliable results in comparison to two of the best available methods. The average and maximum percent deviations of the new method are 6.8 and 21.1, respectively, which are lower than corresponding predicted values of Joback–Reid (24.1 and 101.9) and Jain–Yalkowsky (25.4 and 211.1).

In this article, we present a convenient and green method for synthesis of b-amino carbonyl compounds through ball-milling technique by using aqueous formic acid, which is an inexpensive and highly efficient catalyst. This multi-component reaction was done at room temperature with high anti-selectivity and easy workup. The use of solvent-free ball-milling technique helped to have high yields and more cleanness, besides omitting the need for solvent in this method.

A new series of pyrano [2, 3-f] chrome none derivatives were synthesized starting from resorcinol. Resorcinol reacted with 3-chloropropanoic acid to give 7-hydroxychroman-4-one and reaction of the later compound with 2-methylbut-3-yn-2-ol led to the formation of 7-((2-methylbut-3-yn-2-yl)oxy) chroman-4-one. The obtained compound tolerated the cyclization reaction through Claisen rearrangement by heating in DMF to afford 8,8-dimethyl-2,3-dihydro-4H,8H-pyrano [2,3-f] chromen-4-one. Reaction of the later compound with various aromatic aldehydes gave the title compounds in good yields. All products were evaluated for their cytotoxic activity on the blood tumor cell line K562 and compared to reference drug, etoposide. Most of them exhibited low inhibitory activity against tumor cell line and among them, the compound possessing three methoxy groups on aromatic ring showed better cytotoxic effect.

Today, fabrication of new materials in nano scale based on protein-polysaccharide for targeted drug delivery by oral way is unresolved question for researchers in drug delivery system field. In this work, nanoparticles were made by b-lacto globulin (b-LG), as a globular milk whey protein, complex with low methoxyl pectin (LMP) for chemotherapy agent (oxali-palladium) delivery. Affinity of b-LG to chemotherapy agent was investigated based on the intrinsic fluorescence intensity at 25°C, so that b-LG binds to chemotherapy agent with molar ratio of 1:1. Hence, the nanoparticles were synthesized at various pH at ambient temperature. The results indicated that the nanoparticles were fabricated smaller than 200 nm at optimal pH approximately close to isoelectric point of b-LG with stability and solubility properties at ambient temperature. Also, scanning electron microscopy results demonstrated that nanoparticles were formed spherical so that were homogeneously distributed. Moreover, the results of dissolution profiles of drug release from b-LG nanoparticle-LMP complex at 37°C show that in acidic conditions, nanoparticles are stable and there is no significant drug release but in alkaline conditions drug is released from nanoparticles. Therefore, we suggest b-LG nanoparticles-LMP complex are biodegradable and biocompatible and might be useful as targeted oral drug delivery system.

Three new hexaaza (N6) macro cyclic Schiff base ligands containing a phenanthroline moiety (L1-L3) have been synthesized and their coordination capability toward perchlorate salts of Mn(II) and Cd(II) have been investigated. The complexes are 18- and 19-membered hexaaza macro cycles, and incorporate a 1,10-phenanthroline unit as an integral part of their cyclic structure. All complexes have been characterized by a variety of methods such as IR, elemental analysis, EI-Mass, and conductivity measurements and in the case of cadmium complexes by 1H and 13C NMR spectroscopy. DFT (BP86) calculation on structures and molecular orbital of Mn (II) and Cd (II) complexes of latter ligands are also reported. Also the synthesized complexes were screened for their antibacterial activities against six bacterial strains and showed antibacterial effects

Trifluoroethanol as an efficient media for the domino Knoevenagel–hetero-Diels–Alder reaction of O-propargyloxy benz aldehydes as non-activated terminal alkynes with some active methylene compounds has been described. Short reaction time, easy work-up, good to high yields, and mild reaction conditions are advantages of this new media.

In the present work the removal of two azo dyes, methylene blue and methyl orange, from water using a synthesized hydrogel entitled poly (styrene-alt-maleic acid) is investigated. Superabsorbent hydrogel poly (styrene-alt-maleic anhydride) was prepared through a thermally initiated free-radical polymerization of styrene and maleic anhydride. The parameters affecting the adsorption of the studied dyes such as pH of the solution, hydrogel dose and contact time were investigated. The dye adsorption process was monitored spectrophotometri cally. For this purpose the spectrophotometric linear range of both dyes were obtained and the removal experiments were done at the middle of the linear range. At the optimum conditions, 80–95 % of the mentioned dyes could be removed in less than 10 min which provides strong evidence of the potential of synthesized hydrogel for the application in azo dyes removal from water.

N-Sulfonic acid modified poly (styrene-co-maleic anhydride) as a recyclable solid acid catalyst efficiently catalyzed the one-pot three-component synthesis of spiropyran derivatives through a simple, convenient, and cost-effective approach in good yields and selectivity.

Novel nucleoside analogs were synthesized, in which (3R,4R)-4-(hydroxymethyl) pyrrolidin-3-ol bears the nucleobase exploiting a 1-oxoethane-1,2-diyl group. Within this synthetic approach, cleavage of the N-phenyl ethyl group in the starting compound and introduction of the nucleobase-bearing amidic chain were accomplished with a one-pot procedure, simply using bromoacetyl bromide. Moreover, the benzyl carbonate protecting group was used to obtain easy to handle compounds and avoid deprotection of nucleobases occurring under basic conditions. Eventually, directed towards the preparation of short oligonucleotide sequences, both hydroxy functionalities of the iminosugar were orthogonally protected as benzyl carbonate and dimethoxytrityl ether, respectively. Then, exploiting selective orthogonal de protections and subsequent use of the phosphoramidite method, a dimer phosphite was synthesized, verifying the possibility of building oligomeric structures displaying these novel nucleoside analogs.

Carbon ceramic electrode (CCE), a new electrode substrate, was prepared by sol–gel procedure and used for the electro polymerization of aniline and dispersion of platinum nanoparticles into the resulting polyaniline (PANI) film. The microscopic structure and morphology of the CCE, CCE/PANI and CCE/PANI/Pt are characterized by scanning electron microscopy. The electrochemical and catalytic activities of the CCE/PANI/Pt were studied in 0.3 M H2SO4 solution. The electro catalytic oxidation of methanol at the CCE/PANI/Pt has been investigated using cyclic voltammetric and chronoamperometric methods. The catalytic activity of Pt-coated PANI film on the CCE surface was compared with glassy carbon and Pt polyaniline/platinum-modified electrodes.

In this work, molecular self-assembled monolayers (SAM) of 2-(2,3-dihydroxy phenyl) benzothiazole (HPB) on gold electrode are prepared for the first time and described by cyclic voltammetry (CV), electrochemical impedance spectroscopy, scanning electron microscopy (SEM) and quartz crystal microbalance techniques. The redox properties of the modified electrode were investigated by CV at various scan rates, and the apparent charge transfer rate constant (ks) and transfer coefficient (a) were calculated for HPB-SAM/Au. Then, electro oxidation of dopamine (DA) on a HPB-SAM-modified gold electrode has been studied by cyclic voltammetry, chronoamperometry and differential pulse voltammetry (DPV). The mediated oxidation of DA at the modified electrode in CV occurs at a potential of about 180 mV less positive than that of the unmodified gold electrode. The values of electron transfer coefficients (a), catalytic rate constant (k) and diffusion coefficient (D) were calculated for DA, using electrochemical methods. DPV exhibited a linear dynamic range over the concentration range of 0.1–500.0 mM and a detection limit (3 s) of 0.03 mM for DA in pH 7.0.

The direct electrochemistry of human adult and fetal hemoglobin on the surface of nano composite containing the carboxylated multi-walled carbon nanotubes (MWCNTs) and a hydrophilic room temperature ionic liquid (RTIL) has been reported. The voltammetric results showed that both types of hemoglobins entrapped in RTIL-MWCNTs nano composite displayed a pair of well defined, quasi-reversible redox peaks, corresponding to the Fe (III)/Fe (II) redox couple of heme prosthetic group, with the formal potentials of −0.234 and −0.232 V (vs. Ag/AgCl) for human adult and fetal hemoglobin, respectively. Immobilized human fetal hemoglobin on RTIL-MWCNTs nano composite relative to immobilized human adult hemoglobin showed slight differences in reversibility, electron transfer rate and protein-substrate affinity toward hydrogen peroxide.

The photo induced electron transfer reactions of three Ru(II) complexes with phenol ate ions of polyphenols (gallic acid, quercetin, p-coumaric acid, and ferulic acid) and thymol have been measured in 50 % aqueous acetonitrile at pH 11 and the observed quenching constant (kq) values are sensitive to the nature of the ligand and the structure of the phenol ate ion. The change of kq values with DG0 is in accordance with the Marcus semi classical theory of electron transfer. The static as well as dynamic nature of quenching is confirmed from the ground-state absorption studies. The reductive quenching of the Ru (II) complexes by the phenol ate ions has been confirmed from the transient absorption spectra. The formation of phenoxyl radical as a transient is confirmed by its characteristic absorption at 400 nm.

This study investigated the use of ultrasound-assisted extraction (USAE) to improve the extraction efficiency of the classical solvent extraction techniques such as maceration and Soxhlet extraction to extract three coumarin compounds (osthol, isoimperatorin and oxypeucedanin) from dried roots of Prangos ferulacea (L.) Lindl. Separation was accomplished on a reverse-phase C18 column with the mobile phase of methanol–water (70:30) and detection of the analytes was performed with UV variable detector at a wavelength of 322 nm. Under the optimum conditions, the extracted amounts of osthol, isoimperatorin and oxypeucedanin were 157.66, 172.54 and 79.27 mg g−1 dry herb, respectively. The results also indicated that compared with Soxhlet at 8 h and maceration extraction method at 3 days, ultrasound-assisted extraction increased the extraction yield of the total coumarin compounds about 17 and 31 %, respectively, at only 30 min. Therefore, USAE was preferred as the most efficient method which consumed less amount of a nontoxic solvent at a short time in comparison with conventional methods for extraction of coumarin compounds.

Understanding the interaction between protein and manganese (II) Diamine sarcophagine (Mn (II)-DiAmsar) has significant implications for biological applications of Mn (II)-DiAmsar. To this aim, at first, Mn (II)-DiAmsar was synthesized and characterized. In the next step, the interaction between Mn (II)-DiAmsar and protein [human serum albumin (HSA) and bovine serum albumin (BSA)] was investigated by Fourier transform infrared (FT-IR), UV–Visible (UV–Vis), fluorescence spectroscopies, and cyclic voltammetry (CV) under the physiological conditions in Tris buffer solution adjusted to pH 7.4. FT-IR spectra revealed that the conformation and microenvironment of HSA and BSA were changed in the presence of Mn (II)-DiAmsar. Mn (II)-DiAmsar could strongly quench the intrinsic fluorescence of HSA and BSA by static quenching. The hydrogen bonding and weak van der Waals interaction plays a major role in stabilizing the Mn (II)-DiAmsar–HSA (BSA) complex. The binding site number n apparent binding constant Ka, and corresponding thermodynamic parameters DG°, DH° and DS° at different temperatures were calculated. The distance R between the donor (HSA and BSA) and acceptor (Mn (II)-DiAmsar) has been obtained utilizing fluorescence resonance energy transfer (FRET). Finally, the molecular docking was performed to explore the possible binding sites and assess the microenvironment around the bounded Mn (II)-DiAmsar with HSA and BSA. Our results clarified that Mn (II)-DiAmsar complex could bind to HSA and BSA effectively and could be a useful guideline for further biological applications.

The present work describes the sorption behavior of a newly synthesized calix [4] arene impregnated XAD-4 resin, i.e., (IV) for the amputation of As (III) from aqueous environment. Resin IV was characterized by using FT-IR spectroscopy, scanning electron microscope, elemental and thermo gravimetric analyses techniques. As (III) sorption was achieved through static method to assess the As (III) removal competency of impregnated resin IV under various conditions. Batch experiments were carried out to optimize several parameters such as effect of sorbent dosage, pH effect, contact time, initial arsenic concentration and temperature effect. From results it was observed that % sorption of As (III) is highly dependent on pH of solution. The maximum sorption was achieved at pH 4.5. Equilibrium was achieved in 45 min. From different isotherm models it has been deduced that As (III) sorption behavior of resin IV can be better explained by Langmuir with Q of 100 mmol/g and Temkin isotherm models. Furthermore, thermal study reveals that sorption process is temperature dependent. Kinetic studies found to follow second order and more appropriately Moris–Weber diffusion kinetic model. Besides this, resin IV has been utilized for the removal of arsenic from surface water samples. The field studies reveal that resin IV is an effective sorbent to treat and purify As (III) contaminated water.

The presented study investigates the application of new magnetic core–shell silica nanoparticles as a selective sorbent for magnetic solid phase extraction and determination of europium (Eu) in environmental water samples. Separation was performed by using a small amount of sorbent with high extraction capacity according to the special properties of magnetic nanoparticles. The elution step was performed by 1.5 mL nitric acid (1 mol L−1) and the desorbed analyte was introduced to ICP-OES. The effect of different parameters such as pH, extraction and desorption time, type and concentration of eluent,… were investigated and optimized. Under the optimized conditions the detection limit for determination of Eu was 0.04 µg L−1 and the relative standard deviation (RSD, C = 200 mg L−1, n = 6) was 3.2 %. The linearity of the method was obtained within the range of 0.5–1,000 mg L−1 and the extraction efficiency was 93.5 %. The accuracy of the method was evaluated by calculating the relative recovery by analyzing real water samples and good recoveries (95–106.5 %) were achieved, showing the reliability of the method for determination of europium in real samples.