JOURNAL OF THE IRANIAN CHEMICAL SOCIETY(JICS)
Year:2014 | Volume:11 | Issue:3|Papers Count:30

The complexation processes among Li+, Na+, K+, and NH4o+o cations with the macrocyclic ligand, 15-crown-5 (15C5) have been studied in acetonitrile–methanol binary mixtures at different temperatures using conductometric method. The stability constants of the resulting 1: 1 complexes were calculated from the computer fitting of the molar conductance–mole ratio data at various temperatures. The values of thermodynamic parameters (\unicodex0394H∘cand\unicodex0394S∘c) for the formation of the complexes were obtained from temperature dependence of the stability constants of complexes using van’t Hoff plots. In addition, a theoretical study has been carried out using density functional theory to obtain the stability of the complexes and the geometrical structure of the 15C5 and its complexes with Li+, Na+, K+ and NH4o+o cations in the gas phase. We compared the experimental data with those obtained by quantum chemistry calculations to investigate the effect of the solvent on complexation process.

A series of novel 2,3-dihydroquinazolin-4(1H)-ones was synthesized by a three-component reaction between dehydroabietylamine (DHA) diterpene, isatoic anhydride and different aromatic aldehydes in the presence of a catalytic amount of p-toluenesulfonic acid (13 mol%). Diastereomeric products were separated by preparative thin-layer chromatography and their structures were characterized by1H and 13C NMR, HMQC, IR and HR-ESI-MS. Antioxidant activities of the synthesized compounds were assessed by two different methods including DPPH and β-carotene-linoleic acid bleaching assays. Antibacterial activities of the compounds were also evaluated against two Gram-positive and one Gram-negative bacterial strains and in the case of Bacillus cereus a considerable inhibitory effect (MIC 4–16 mg/ml) was observed.

Formation of the complex of ethyl viologen in its cationic (Ev+) and neutral (Ev∘) forms with β-cyclodextrin (b-CD) was investigated by means of voltammetric technique in buffer solution of pH 7.00. The number of bCD (n or m) per viologen species (Ev+) or (Ev∘), bonding equilibrium constants as well as bonding rate constants was calculated. The calculated values ofK (1) eqandK (2) eq (pertaining to the bonding of Ev+and Ev∘ with bCD) are 13.6 M–n and 2.1×103 M−m , respectively, whereas the calculated values of n and m are 0.54 and 1.25, respectively. The bimolecular rate constant for the Ev∘−bCD inclusion complex formation is 3.03×103 M−1s−1. These results are supported by the simulation of the experimental cyclic voltammograms. This study also highlights the significance of the proposed electrochemical method as compared to earlier studies on viologen-Cyclodextrin systems

A facile and efficient one-pot three-component synthesis of the amino-spiroindene derivatives was achieved, via the reaction of ninhydrin, malononitrile or ethylcyanoacetate and various reagents including 1, 2- and 1, 3-dicarbonyl compounds/enols.

In the present work, three-component synthesis for novel khellactone-type compounds via the reaction of Meldrum’s acid, aryl aldehydes and 5, 7-dihydroxy benzopyrone derivatives was described. In this reaction 10-aryl substituted-9, 10-dihydropyrano [2, 3-h] benzopyrone-8-ones as new khellactone analogous in the presence of catalytic amount of potassium hydroxide as cheap and green basic catalyst were obtained in good to excellent yields under refluxing methanol.

Ti–Al/Al2O3 nanocomposite catalyzed green and efficient synthesis of 2-amino-4H-chromen-5 (6H) -ones via three-component condensation reaction of different aromatic aldehyde, malononitrile and dimedone in aqueous media. The reaction was preceded to completion within 30–90 min in 80–96 % yield at ambient temperature. The Ti–Al/Al2O3 nanocomposite was prepared by milling for 4 h and combustion synthesis at 800 °C in the air atmosphere. The catalyst was well characterized by X-ray diffraction; laser particle sizer and transmission electron microscopy. Its average particle size was found to be around 27 nm. Reusability of the system was assured carrying out multiple runs using the recycled catalyst.

Nanoflower structured a-Fe2O3 was synthesized by adding hexamine to an aqueous solution of ferrous sulphate followed by drying and annealing at 600°C for 6 h. X-ray diffraction analysis, Fourier-transformed infrared spectroscopy, Raman and DRS UV–visible absorption spectroscopy showed the formation of a-Fe2O3 with good crystalline nature. Field emission-scanning electron microscopy investigation revealed that the α-Fe2O3 has flower-like morphology, which is composed of nanorods. Cyclic voltammetry and chronoamperometry were used to investigate their electrochemical sensing property towards uric acid (UA). a-Fe2O3 exhibited enhanced sensing behavior with respect to that of bare GCE. Additionally, the a-Fe2O3 nanoflowers exhibit better photocatalytic activity of up to 71.7 % against rhodamine B (RhB) in short time of 60 min under visible light irradiation. It is found that the smaller crystallite size and flower-like morphology play a vital role in allowing an interaction between a-Fe2O3 and UA or RhB dye which enhances both the electrochemical sensing and photocatalytic activity.

1-Amidoalkyl-2-naphthols were prepared via one-pot multi-component reaction of 2-naphthol, aldehydes, and amides in the presence of nano silica phosphoric acid under solvent-free condition at 80°C. Short reaction times, high yields, and easy work-up are the advantages of this protocol.The manuscript has been presented at the "1st National Conference on Multi-Component Reaction" in Institute of Science and High Technology and Environmental sciences, Graduate University of Advanced Technology, Kerman, Iran, 2012.

An efficient synthesis of novel bis (1-(cyclohexylamino)-1-oxoalkyl or aryl) fumarates (4a–k), considering as organic building blocks for natural products and drugs, via the reaction of fumaric acid, various aldehydes and cyclohexyl isocyanide in water using one-pot three-component approach under mild condition and without catalyst is described. This rapid method produced the products in short reaction times (10–15 min) and excellent yields (85–95 %) at room temperature. The structures of the products were deduced from their elemental analyses and spectroscopic data.

MgO nanoparticles were prepared by an improved sol–gel technique which appeared to have narrow size distributions. The synthesized magnesium oxide nanoparticles were used as an efficient catalyst in aza-Michael reaction for addition of amines to a series of α, β-unsaturated carbonyl compounds and nitro olefins under solvent-free conditions at room temperature to afford high yields of the β-amino carbonyl and b-nitro amines. The catalyst can be recovered and reused at least five successive runs without loss of activity.

A novel, efficient, heterogeneous, and reusable multi-walled carbon nanotubes (MWCNTs), functionalized with phosphonic acid (MWCNTs–C–PO3H2) has been synthesized. The synthesized CNTs were characterized using some electron microscopic techniques such as scanning electron microscopy (SEM), atomic force microscopy (AFM), Energy dispersive X-ray spectroscopy (EDAX), and also some thermal and spectroscopic methods such as thermogravimetry (TG). The nitrogen adsorption behavior of the MWCNTs–C–PO3H2 catalyst was evaluated using the TG instrumentation system at 25°C. The catalyst was applied successfully for highly efficient and selective acetylation of alcohols, phenols, thiols and aromatic amines with acetic anhydride at room temperature under solvent-free conditions. The reusability of the catalyst was checked and the recovered catalyst was reused for five runs without significant loss in activity.

A highly diastereoselective catalyst-free multicomponent Mannich reaction between cyclohexanone, aromatic aldehydes and amines in cyclohexane is described. The double Mannich reaction of diamines and two equivalents of aldehydes and cyclohexanone gave the novel bis (b-aminocarbonyl) compounds. Reactions proceeded in good to high yields with an excellent diastereoselectivity. The best selectivity was obtained where there are weak electron donating and electron-withdrawing groups on the aldehyde. The rate formation of Mannich product is decreased when strong electron-withdrawing groups and/or electron-releasing groups are present on aldehyde. In these cases only the corresponding imines are obtained in moderate to high yields. Aromatic diamines are more suitable than aliphatic diamines in this reaction. Usually, aliphatic diamines only produce the corresponding imines albeit in high yields.

Three-component condensation reactions between azines (isoquinoline or phenanthridine) and acetylenic esters were undertaken in the presence of phenol derivatives (2, 6-di-tert-butyl-phenol, 2, 4-di-tert-butyl-phenol, 2, 6-dimethyl phenol and 2, 4-dimethyl phenol) for generation of C-arilation in good yields. The reactions proceeded smoothly at room temperature without using any catalyst. This method is very useful to functionalize aza-aromatic compounds in a one-pot operation.

Sulfonic acid functionalized SBA-15 (SBA-Pr-SO3H) as a new nanoporous solid acid catalyst was applied in the green one-pot synthesis of spiro [indole-tetrahydropyrano (2, 3-d) pyrimidine] derivatives via three-component reaction of isatins, malononitrile or cyanoacetic esters and barbituric acids under solvent-free conditions. SBA-Pr-SO3H was proved to be an efficient heterogeneous nanoporous solid acid catalyst with a pore size of 6 nm, which could be easily handled and removed from the reaction mixture by simple filtration and can be recovered and reused several times without any loss of activity. The advantages of this methodology are high product yields, being environmentally benign, short reaction times, and easy handling.

A new solid-phase extraction method for determination of palladium by atomic absorption spectrometry is described. Multiwalled carbon nanotube (MWCNT) modified with 1-butyl 3-methyl imidazolium hexafluorophosphate (MWCNT- [BMIM] PF6) and supported on sawdust was used as an adsorbent for preconcentration of palladium. Palladium ions are retained on (MWCNT- [BMIM] PF6) adsorbent as [PdI4]2− and eluted from the column with a thiosulfate–ammonia mixture. The optimum conditions for the adsorption were evaluated by changing various parameters such as pH, sample volume, concentration and volume of eluent, iodide concentration and interfering ions to achieve highest sensitivity and selectivity. The calibration graph was linear in the range of 2–120 ng mL−1 of palladium in the initial solution and the limit of detection based on 3Sb was 0.41 ng mL−1. The method was applied to the determination of palladium in water, wastewater and soil samples.

A green and atom-efficient one-pot protocol for the synthesis of some novel a-aminophosphonates using micron-particulate AlN/Al as a new reusable heterogeneous catalyst by the Kabachnik–Fields reaction under solvent-free conditions has been developed. The synthesized a-aminophosphonates were screened for several biological activities. They all were investigated to exhibit moderate to promising antioxidant, anti-inflammatory and cytotoxic properties.

Using density functional calculations, we have investigated the adsorption of a H2S molecule on the pristine and Si-doped BeO nanotubes (BeONT). It was found that the H2S molecule is physically adsorbed on the pristine BeONT with adsorption energies ranging from 3.0 to 4.2 kcal/mol. Substituting a Be or O atom of the tube by Si increases the adsorption energy to 6.9–17.2 kcal/mol. We found that substituting an O atom by Si makes the electronic properties of the BeONT strongly sensitive to the H2S molecule. Therefore, the process of Si doping provides a good strategy for improving the sensitivity of BeONT to toxic H2S, which cannot be trapped and detected by the pristine BeONT. Also, the emitted electron current density from the SiO–BeONT will be significantly increased after the H2S adsorption. Look.

A semi-automated cold column trapping-cloud point extraction (CCT-CPE) method was developed and applied to the determination of phenazopyridine in human serum. In the proposed technique, a mixture of sample (pH 8) and Triton X-100 (0.4 % v/v) was incubated at 90°C for 5 min in a heating sample cell. The developed turbid solution was then flowed through a CCT preconcentration column packed with C18 sorbent using a peristaltic pump. A pair of thermal electric cooler (TEC) plates was used for cooling the column. The surfactant-rich phase was retained on the CCT at 0°C and desorbed, subsequently, in an elevated temperature by ethanol. The analytical parameters such as pH, surfactant concentration, and temperature and incubation time were optimized by a central composite design (response surface) method. Six replicated analyses at the optimized conditions resulted in a recovery of 99.7 % and a relative standard deviation of 2.45 for phenazopyridine. The detection limit of the method (3σ) was 0.50 mg L−1 for the analyte. Compared to conventional CPE, the proposed CCT-CPE method required less sample handling eliminated the centrifugation step and was substantially faster. The method was successfully applied to the determination of phenazopyridine in some human serum and tablet samples.

In this work, the CO2 and N2 adsorption properties of MIL-101 metal-organic framework (MOF) and activated carbon (AC) were investigated using a standard gravimetric method within the pressure range of 0–30 bar and at four different temperatures (298, 308, 318 and 328 K). The dual-site Langmuir–Freundlich (DSLF) model was used to describe the CO2 adsorption behaviors on these two adsorbents. The diffusion coefficients and activation energy E a for diffusion of CO2 in the MIL-101 and AC samples were estimated separately. Results showed that the isosteric heat of CO2 adsorption on the MIL-101 at zero loading was much higher than that on the AC due to a much stronger interaction between CO2 molecule and the unsaturated metal sites Cr3+on MIL-101. Meanwhile, the dramatically decreased isosteric heats of CO2 adsorption on MIL-101 indicated a more heterogeneous surface of MIL-101. Furthermore, the adsorption kinetic behaviors of CO2 on the two samples can be well described by the micropore diffusion model. With the increase of temperature, the diffusion coefficients of CO2 in the two samples both increased. The activation energy E a for diffusion of CO2 in MIL-101 was slightly lower than that in AC, suggesting that MIL-101 was much favorable for the CO2 adsorption. The CO2/N2 selectivities on MIL-101 and AC were separately estimated to be 13.7 and 9.2 using Henry law constant, which were much higher than those on other MOFs.

The new copper (II) tetraphosphonate, [Cu3 (HO3PCH2) 2N–CH2C6H4CH2–N (CH2PO3H) 2) (H2O) 4] n (1) was hydrothermally synthesized from the reaction of Cu (NO3) 2 and (H2O3PCH2) 2N–CH2C6H4CH2–N (CH2PO3H2) 2, (H8L). Compound 1 was structurally characterized by means of X-ray single crystal diffraction. The structure of 1 showed a 3D structure constructed from two types of Cu (II) and chelating and bridging modes of (HO3PCH2) 2N–CH2C6H4CH2–N (CH2PO3H) 2, and features a (44.610.8) topological network. The 3D compound is further stabilized by hydrogen bonds. UV–Vis diffuse reflectance and infrared spectroscopy as well as elemental analysis of compound 1 are also presented.

A computational study was carried out by density functional theory (DFT) to investigate the relative stability and reactivity in three selected penicillins: penicillin-G, penicillin-V and carbenicillin. The geometry of the investigated molecules was optimized at the B3LYP/6-31G (d) level of theory. Then, the nuclear quadrupole resonance (NQR) parameters of 14N and 2H nuclei and natural bond orbital (NBO) analysis in these molecules were calculated on the geometrically optimized models at the B3LYP level using 6-311++G (d, p) basis sets in the gas phase. The NBO analysis shows that the occupancy of the LP (N) decreases with increasing p character of the lone pair of nitrogen. A comparison between the results obtained for these penicillins and related 6-APA structures of them indicates that the presence of a bulky side group in the acyl side chain can lead to more stability of the b-lactam ring. On the other hand, NBO analysis was applied to rationalize the 14N NQR parameters in the charge distribution around nitrogen atoms. Inspection of the present results illustrates that the largest component of EFG tensor (q zz), the nuclear quadrupole coupling constant, C Q, and the NQR frequency values of nitrogens decrease with decreasing occupancy values of LP (N). We suggest that the reason for this trend can be found in increasing contribution of delocalized electrons of nitrogen in the intramolecular interactions and hence stability of these structures increases in the order: PG < PV < CA. Finally, a good relationship is found between most of the calculated 2H NQR parameters and the related intramolecular hydrogen bonds.

Nano-sized nickel ferrite (NiFe2O4) and cobalt ferrite particles (CoFe2O4) were successfully synthesized using a hydrothermal method. Techniques of X-ray diffraction, scanning electron microscope, Fourier transform infrared spectrometer, energy dispersive X-ray spectroscopy, vibrating sample magnetometer and transmission electron microscope have been used to characterize and study the as-synthesized NiFe2O4 and CoFe2O4 products. The results showed that the average size of the nickel and cobalt ferrite nanoparticles is smaller than 10 and 100 nm, respectively. The results of magnetic measurement showed that the synthesized NiFe2O4 and CoFe2O4 nanoparticles were superparamagnetic and soft ferromagnetic materials, respectively. Study of adsorption behavior showed that these nanoparticles can act as a good adsorbent for removing Pb2+.

Reaction pathways of ethylene and carbon monoxide on the singlet and triplet potential energy surfaces (PESs) have been calculated at B3LYP/6-311++G (3df, 3dp), G3B3 and CCSD (T)//B3LYP levels. Reaction mechanisms have been investigated by analysis of various structures. Suggested reaction mechanisms reveal that 3P3 (CH2CHCHO) and 3P4 (CH3CCHO) are thermodynamically stable adducts with the negative value in Gibbs free energies on the triplet PES. In addition, results show that one intersystem crossing exists between triplet and singlet PESs, which are obtained by scanning of the C-C bond length in 1IN3 and 3IN7 species.

Xanthenes and their derivatives as very important classes of organic compounds are key structural elements of many biologically active compounds. These materials are important heterocyclic nucleus of various dyes and drugs. Because of their wide range of pharmacological, industrial and synthetic applications, many methods for the preparation of xanthenes are reported in the literature. In recent years, among the other chemists, introduction of new methods for the preparation of these types of compounds has attracted the attention of Iranian chemists. The result of these efforts is the introduction of appropriate, effective and efficient methods. In this paper, we have a brief review on these methods and their main advantages and important applicabilities.

A series of binuclear copper (II) complexes of N-functionalized cyclam derivatives has been prepared by the Schiff base condensation of 1, 8-[bis (3-formyl-2-hydroxy-5-methyl) benzyl]-l, 4, 8, 11-tetraazacyclo-tetradecane (PC-a), 1, 8-[bis (3-formyl-2-hydroxy-5-bromo)benzyl]-l, 4, 8, 11-tetraazacyclo-tetradecane (PC-b) with appropriate aliphatic diamines, and copper (II) perchlorate. All the complexes were characterized by elemental, FT-IR, UV-Vis, ESI and ESR spectral analysis. The room temperature magnetic moment studies depicts the presence of an antiferromagnetic interaction in the binuclear complexes, which is also observed from the broad ESR spectra with a g value of 2.10-2.11. Variable-temperature magnetic susceptibility study of the complex [Cu2L2a] (ClO4)2 shows that the calculated -2J value is 219 cm-1, which conveys a spin–spin interaction between the two copper (II) ions. The catechol oxidation and hydrolysis of 4-nitrophenylphosphate were carried out by using the complexes as a catalyst. All the above metal complexes were screened for antimicrobial and human pathogenic fungal activity. The binding of the complexes to calf thymus DNA (CT-DNA) has been investigated with UV-Vis and fluorescence spectroscopy. All complexes display significant cleavage property of circular plasmid pBR322 DNA into linear form. Spectral, electrochemical, magnetic and catalytic studies support the distortion of the copper ion geometry that arises as the macrocyclic ring size increases.

A series of six organotin (IV) carboxylates [Me2SnL2] (1), [n-Bu2SnL2] (2), [n-Oct2SnL2] (3), [Me3SnL] (4), n-Bu3SnL (5) and [Ph3SnL] (6), where L = 3-(4-cyanophenyl) acrylic acid have been synthesized and characterized by elemental analysis, FT-IR and NMR (1H, 13C). The complex (4) was also analyzed by single crystal X-ray analysis which showed distorted trigonal bipyramidal geometry with polymeric bridging behavior. The complexes 1–6 were screened for antimicrobial activities and cytotoxicity. The results showed significant activity with few exceptions. The catalytic activity of complexes was assessed in transesterification reaction of Brassica campestris oil (triglycerides) to produce biodiesel (fatty acid methyl esters). The results showed that triorganotin (IV) complexes exhibited good catalytic activity than their di-analogues.

A new compound of [Cu8 (Metz) 9] (OH)·xH2O (x »3) (1) (Metz = 5-Methyltetrazole) has been prepared and characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. The crystal is of hexagonal, space group P63/m with a = b = 13.988(1) Å, c = 16.309 (2)Å, a = b = 90o, g= 120o, V = 2 763.5 (4) Å3, Mr = 1327.13, Dc = 1.595 g cm−3, Z = 2, F(000) = 1 316, m= 3.076 mm−1, the final R = 0.0494 and wR = 0.1532 for 1,731 observed reflections (I > 2 s(I)). In this compound, the [(CuII) 2 (CuI) 6 (Metz) 9]+ cationic clusters are connected together through CuI cations and Metz ligands and result in a three-dimensional framework. Remarkable, three-dimensional intersecting channels exist in it. The variable temperature magnetic investigations indicate that 1 exhibits typical antiferromagnetic behaviors. N2 gas adsorption measurements at 77 K showed that compound 1 possesses permanent porosities.

Two novel 1D and 3D Sm (III) coordination polymers involving the 2-pyridin-4-yl-4,5-imidazoledicarboxylic acid (H3PIDC) ligand have been characterized by infrared spectroscopy, elemental analysis and single-crystal X-ray diffraction. The coordination polymers were synthesized under hydrothermal conditions. Coordination polymer 1 gave a 1D zigzag chain, then forming 3D supramolecular structure through  p…p stacking interactions and hydrogen bonds. Coordination polymer 2, in which oxalate was introduced as the second ligand gave a 3D framework with a 3,3-connected (4.85) (4.82) topology structure. But the luminescence of the coordination polymers has significant quenching.

Geometries, relative stabilities, and hydrogen bonds of l-ascorbic acid (LAA) and d-Erythroascorbate (DEAA) dimers as well as their S- and Se-substituted isomers in gas phase and water solvent are studied using density functional method. Furthermore, the hydrogen bond lengths in LAA and DEAA dimers are generally increased along with the binding dissociation energy of the dimers being decreased as apex O atoms in the five-membered C5 rings of LAA and DEAA dimers are substituted by S and Se atoms in gas phase and water solvent. Interestingly, one LAA dimer and its S- or Se-substituted isomer with four hydrogen bonds in gas and water solvent are the three-centers structures. In addition, the chemical bonding and charge distributions of all the dimers are discussed. A good agreement with available experimental results is reached.

Diatomic dications and dianions are attractive species for quantum chemists and spectroscopists. In comparison with neutral diatomics, these species show a wealth of potential behaviors arising mainly from the presence of residual Coulomb repulsion at the separated ions limit. Due to the stability of dications, numerous reports have been published on their potential curves, vibrational states, stability, and spectroscopic properties. In contrast, there are only a few reports on the stability and potential curves of dianions, since the strong correlation effects in dianions introduce some difficulties in the calculations of their potentials and properties, and perhaps, because they have not been observed in the laboratory due to their short lifetimes. In this review article, interesting subjects related to dications and dianions, the methods used to study their characteristics, and the achievements of these studies are described. Furthermore, the present research topics open on dications and dianions are reviewed. This report would thus serve researchers interested in the examination of quantum dynamical treatment on reactive scattering of ions and the laser–matter interactions and their subsequent phenomena such as vibrational wavepacket evolution, tunneling dissociation, vibronic coupling, and tunneling ionization for which dianions and dications can be regarded as prototypical species.