Mohammad Hakimi

Catalytic Epoxidation Activity of Keplerate Polyoxomolybdate Nanoball toward Aqueous Suspension of Olefins under Mild Aerobic Conditions

Catalytic efficiency of a sphere-shaped nanosized polyoxomolybdate {Mo132} in the aerobic epoxidation of olefins in water at ambient temperature and pressure in the absence of reducing agent is exploited which resulted good-to-high yields and desired selectivity.

Fabrication and Characterization of Gelatin Stabilized Silver Nanoparticles under UV-Light

Silver nanoparticles (Ag-NPs) were successfully synthesized using the UV irradiation of aqueous solutions containing AgNO3 and gelatin as a silver source and stabilizer, respectively. The UV irradiation times influence the particles’ diameter of the Ag-NPs, as evidenced from surface plasmon resonance (SPR) bands and transmission electron microscopy (TEM) images. When the UV irradiation time was increased, the mean size of particles continuously decreased as a result of photoinduced Ag-NPs fragmentation. Based on X-ray diffraction (XRD), the UV-irradiated Ag-NPs were a face-centered cubic (fcc) single crystal without any impurity. This study reveals that the UV irradiation-mediated method is a green chemistry and promising route for the synthesis of stable Ag-NPs for several applications (e.g., medical and surgical devices). The important advantages of this method are that it is cheap, easy, and free of toxic materials.

Coordination geometries and crystal structures of cadmium(II) complexes with a new amino alcohol (NN′O) ligand

The new ligand 2-(2-(2-hydroxyethylamino)ethylamino)cyclohexanol, (HEAC), was prepared under microwave conditions through ring opening of cyclohexene oxide with 2-(2-amino-ethylamino)ethanol. Its cadmium(II) complexes [Cd2(HEAC)2(μ-Cl)2Cl2] (1) and [Cd(HEAC)2][CdI4] (2) were identified by elemental analysis, FT-IR, Raman, 1H NMR spectroscopies, and single-crystal X-ray diffraction. HEAC formed 1 : 1 M : L complexes with cadmium chloride and cadmium iodide. Complex 1 crystallized as a dimer with two asymmetrically bound bridging Cl− and a terminally coordinated Cl− on each metal. The geometry around the cadmiums in 1 with four five-membered chelate rings and four Cl− ligands is distorted octahedral for each Cd(II). The cyclohexanol OH of each ligand forms intramolecular hydrogen bonds. In 2, the coordination numbers for cadmium in [Cd(HEAC)2]2+ and [CdI4]2− moieties are six and four, respectively. In [Cd(HEAC)2]2+ each ligand coordinates through two N- and one O-donors, leading to a distorted octahedral geometry. The geometry of [CdI4]2− in 2 is slightly distorted tetrahedral. The protonation equilibrium constants of the two secondary amino groups in HEAC, determined by pH-potentiometry, were 6.26 and 9.26, respectively, at 25°C. Stability constants for this ligand with Ni(II), Cu(II), and Zn(II) (1 : 1 M : L), determined by glass-electrode potentiometry, were 7.13, 10.50, and 5.42, respectively.

Silver(I) coordination polymer and nine-coordinated cadmium(II) complex with dimethyl pyridine-2,6-dicarboxylate supported by solid state and electrochemical studies

Two complexes of dimethyl pyridine-2,6-dicarboxylate (L), [CdL3][CdI4] (1) and [Ag(L)NO3]n (2) were prepared and identified by elemental analysis, FT-IR, Raman and 1H NMR spectroscopy, cyclic voltammetry, and single-crystal X-ray diffraction. The crystal structure of 1 contains both complex cation and complex anion of the metal. Cadmium in [CdL3]2+, coordinated by three nitrogens and six oxygens, has a distorted tricapped trigonal prismatic geometry while [CdI4]2−, with four coordinated iodides, has a slightly distorted tetrahedral geometry. In the crystal structure of 2, silver has distorted tetrahedral geometry by coordination of nitrogen and three oxygens. One oxygen of nitrate in 2 bridges two silvers. Extension of these bridges forms a 1-D coordination polymer. Cyclic voltammetry of L reveals two reduction steps which are shifted after coordination in 1, while no significant shifts are observed in 2. Hydrogen bonds including C–H I, C–H O and C–H C and short interactions such as C I, , and O are compared with Cambridge Structural Database analogs . Two brief structural surveys on ligand coordination modes and silver polymers are also presented.

Synthesis and characterization of copper(I) complexes from triphenylphosphine and isatin Schiff bases of semi- and thiosemicarbazide

The reaction of isatin-3-thiosemicarbazone (ITC, 1) or isatin-3-semicarbazone (ISC, 2) with nitrato bis(triphenylphosphine)copper(I) gave the four coordinate copper(I) complexes [Cu(PPh3)2(ITC)]NO3 (3) and [Cu(PPh3)2(ISC)]NO3 (4). The synthesized complexes were characterized by FT-IR, UV–VIS, Raman and elemental analysis. The crystal structure of 3 was investigated by single crystal X-ray diffraction. The ITC coordinates to the copper(I) ion in a bidentate fashion via the N(imine) and S atoms which along with two triphenylphosphine ligands form a tetracoordinate complex. The complex has a distorted tetrahedral coordination environment. Crystal data at 150.0 K: space group P21/c with a=12.5777(4), b=15.2062(5), c=21.9057(7) Å, β=95.628(3)o, Z=4, R 1=0.049.

Synthesis, characterization, and crystal structure of a tricadmium complex of 3,4-diamino-5-methyl-1,2,4-triazole

The ligand 3,4-diamino-5-methyl-4H-1,2,4-triazole (DAMT) and its trinuclear cadmium complex [Cd3(DAMT)2(DAMTH)2Cl8] have been prepared and identified by elemental analyses, infrared, Raman, 1H and 13C NMR spectroscopy, and single crystal X-ray diffraction. The protonation equilibria of the ligand have been studied by pH-potentiometry, with pK 1 13.29 and pK 2 5.40 determined. The free ligand consists of triazole cations (DAMTH) and chloride counter ions. The neutral cadmium compound is a complex of the cationic ligand in which three Cds are coordinated by two unidentate cation forms of the ligands (DAMTH), two ambidentate neutral forms of the ligand (DAMT), and eight chlorides. Cadmium ions have slightly distorted octahedral geometry.

Synthesis and Crystal Structure of Diaqua bis(4-amino-3-methyl-1,2,4-triazol-5- thione)cadmium(II) Nitrate

Abstract. The reaction of 4-amino-5-methyl-1,2,4-triazol-3(2H)-thione (HAMTT, 1 ) with cadmium(II) acetate in ethanol leads to[Cd(η 2 -AMTT) 2 (H 2 O) 2 ]( 2 ); the reaction of 2 with nitric acid inethanol produces the single-crystals of [Cd(η 2 -HAMTT) 2 -(H 2 O) 2 ](NO 3 ) 2 ( 3 ). 2 and 3 have been characterized by IR, Raman, 1 H NMR spectroscopy and elemental analyses; furthermore, 3 has Synthese und Kristallstruktur von Diaqua-bis(4-amino-3-methyl-1,2,4-triazol-5-thion)cadmium(II)-nitrat Inhaltsubersicht. Die Reaktion von 4-Amino-5-methyl-1,2,4-tria-zol-3(2H)-thion) (HAMTT, 1 ) mit Cadmiumacetat in Ethanol er-gibt [Cd(η 2 -AMTT) 2 (H 2 O) 2 ]( 2 ); die Reaktion von 2 mit Salpeter-saure in Ethanol ergibt Einkristalle von [Cd(η 2 -HAMTT) 2 -(H 2 O) 2 ](NO 3 ) 2 ( 3 ). 2 und 3 wurden mittels IR-, Raman- und 1 H-NMR-Spektroskopie sowie durch Elementaranalysen charakte- 1 Introduction The chemistry of N N C S linkage has been extensivelystudied and reviewed [1 3]. One class of such compoundsis the 4-amino-5-thio substituted 1,2,4-triazoles. Metal che-lates of these derivatives containing sulfur and nitrogencould be of interest from the viewpoint of chemical reactiv-ity and biological activity [4]. These compounds have beenreported to possess significant antifungal, antibacterial andinsecticidal properties [5 7]. Some of new triazole deriva-tives have been synthesized as potential antidepressants [8]and plant growth regulators [9]. Furthermore, metal com-plexes containing triazole ligands may also show biologicalactivity [10]. 4-amino-5-thio substituted 1,2,4-triazoles existin the two tautomeric forms as shown in Figure 1.

Template-directed synthesis of macrocyclic copper(II) complexes of diazacyclam, 1,3,6,10,12,15-hexaazatricyclo[13.3.1.16,10]eicosane

Template reaction of copper(II) nitrate with N-(2-aminoethyl)-1,3-diaminopropane and formaldehyde yields a macrocyclic copper(II) complex of 1,3,6,10,12,15-hexaazatricyclo[13.3.1.16,10]eicosane (L), [CuL(NO3)2] (1). Replacement of nitrate with perchlorate gives [CuL(ClO4)2] (2). These complexes have been characterized by FT-IR and Raman spectroscopies, electronic absorption, cyclic voltammetry, and X-ray crystallography. The crystal structure of 1 shows that copper has distorted octahedral geometry with two secondary and two tertiary amines of the macrocycle and two oxygen atoms from nitrate coordinating the axial positions. The copper in 2 has the same geometry with axial positions occupied by one oxygen atom of perchlorate. Copper lies on the plane of four coordinated nitrogen atoms and there is no rms deviation from this plane. Cyclic voltammetry of 1 and 2 gives two one-electron waves corresponding to CuII/CuIII (−0.75, −0.72) and CuII/CuI (0.48, 0.24) processes. For understanding of geometry parameters in diazacyclam-based copper(II) complexes, a survey on complexes from CSD structures is presented. In this study the macrocycle hole size was estimated by ionic radii of metal ions located inside of it.

Preparation, characterization, and antibacterial activity of γ-irradiated silver nanoparticles in aqueous gelatin

Colloidal silver nanoparticles (Ag-NPs) were obtained through γ-irradiation of aqueous solutions containing AgNO3 and gelatin as a silver source and stabilizer, respectively. The absorbed dose of γ-irradiation influences the particle diameter of the Ag-NPs, as evidenced from surface plasmon resonance (SPR) and transmission electron microscopy (TEM) images. When the γ-irradiation dose was increased (from 2 to 50 kGy), the mean particle size was decreased continuously as a result of γ-induced Ag-NPs fragmentation. The antibacterial properties of the Ag-NPs were tested against Methicillinresistant Staphylococcus aureus (MRSA) (Gram-positive) and Pseudomonas aeruginosa (P.a) (Gram-negative) bacteria. This approach reveals that the γ-irradiation-mediated method is a promising simple route for synthesizing highly stable Ag-NPs in aqueous solutions with good antibacterial properties for different applications.

Clean and Heterogeneous Condensation of 1,2-Diamines with 1,2-Dicarbonyls Catalyzed by {Mo132} Giant Ball Nanocluster

Catalytic efficiency of Keplerate {Mo132} nanoball in the condensation of 1,2-diketones and 1,2-diamines in ethanol under heterogeneous conditions is exploited. Quinoxaline and bipyrazine derivatives were produced safely in high yields and isolated easily from the reaction mixture by filtration. The recovery of the nanocatalyst was easy and efficient and its structure and activity preserved after recovering.Graphical Abstract