Sharif Digital Repository

Oxygen evolution was observed upon mixing solid manganese(III) bidentate Schiff base complexes with aqueous solutions of cerium(IV) ammonium nitrate. However, oxygen evolution was not observed upon mixing solutions of the complexes (in acetonitrile) with Ce(IV). Electron-withdrawing substituents on the Schiff base ligands (NO2, Br) enhanced the reactivity of the manganese complexes toward oxygen evolution. Oxygen evolution was also affected by R groups on the ligands, in the order Me > Et Bz. © 2009 Springer Science+Business Media B.V  

The title complex [Mn(tptz)(CH3COO)(OH2) 2]NO3 was synthesized through the reaction of tptz (2,4,6-tris(2-pyridyl)-1,3,5-triazine), nitric acid and manganese(II) acetate. The molecular structure was characterized by X-ray diffraction, elemental analysis, electrochemistry, EPR, IR, fluorescence and UV-Vis spectroscopy and its oxygen evolving activity has been studied. X-ray structure analysis shows that each Mn(II) ion is seven coordinated by a bidentate acetate, three nitrogen atoms of tptz and two oxygen atoms from two water ligands, which are coordinated in axial positions. The complex acts as an oxygen evolving complex with oxone (2KHSO5·KHSO4·K 2SO4) as primary oxidant in aqueous... 

A polymeric manganese(II) complex with the general formula [Mn(O 2CCH2NH2CH2CO2) 2(H2O)2]n from reaction of iminodiacetatic acid and manganese(II) perchlorate under nitrogen in water, was synthesized and characterized. The structure of the complex was determined using single-crystal X-ray diffraction, elemental analysis, IR and UV-vis spectra. This complex exhibited excellent catalytic activity and selectivity for oxidation of various alcohols and sulfides to the corresponding aldehydes/ketone and sulfoxides using urea hydrogen peroxide and oxone (2KHSO 5·KHSO4·K2SO4), respectively, as oxidants under air at room temperature. The easy preparation, mild reaction conditions, high yields of the... 

A manganese(II) complex of 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tptz) has been synthesized and characterized by single-crystal X-ray diffraction, elemental analyses, IR, and UV-Vis spectroscopic techniques. Oxidation of alcohols to their corresponding aldehydes and ketones was conducted by this catalyst using oxone (2KHSO5KH-SO4K2SO4) as an oxidant under biphasic reaction conditions (CH2Cl2/H 2O) and tetra-n-butylammonium bromide as phase transfer agent under air at room temperature. Easy preparation, mild reaction conditions, high yields of the products, short reaction times, no further oxidation to the corresponding carboxylic acids, high selectivity and inexpensive reagents make this... 

Nano-sized particles of manganese oxides have been prepared by a very simple and cheap process using a decomposing aqueous solution of manganese nitrate at 100 °C. Scanning electron microscopy, transmission electron microscopy and X-ray diffraction spectrometry have been used to characterize the phase and the morphology of the manganese oxide. The nano-sized manganese oxide shows efficient catalytic activity toward water oxidation and the epoxidation of olefins in the presence of cerium(iv) ammonium nitrate and hydrogen peroxide, respectively  

Ultra-small and highly dispersive (< 10 nm) iron oxide hydroxide is characterized by some methods. The compound is an efficient and stable catalyst for alcohol oxidation, organic sulfide oxidation, and epoxidation of alkenes in the presence of H2O2. The electrochemical oxygen-evolution reaction of the iron oxide hydroxide is also tested under acidic, neutral, and alkaline conditions. In the presence of the iron oxide hydroxide, excellent conversions (75–100%) and selectivities of substrates (92–97%), depending on the nature of the sulfide, were obtained. Benzylalcohols having electron-donating and-withdrawing substituents in the aromatic ring were oxidized to produce the corresponding... 

Activated layered manganese oxides with deposited nano-sized gold or silver were synthesized and characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction spectrometry, atomic absorption spectroscopy and energy-dispersive X-ray mapping. Here, we report that Au or Ag nanoparticles deposited on layered Mn oxides improve the catalytic activity of the Mn oxides toward the epoxidation of olefins in the presence of H2O2 and NaHCO3  

The mononuclear complex [Mn(tptz)(CH3COO)(OH2)2]NO3 (1) was investigated by electrospray ionization mass spectrometry in aqueous solution at pH 4.5. Electrospray ionization mass spectrometry shows that mononuclear and dinuclear manganese cationic species are present in solution, probably in equilibrium with neutral 1. An experiment showed that the most important reaction in the presence of oxone (2KHSO5·KHSO4·K2SO4) is decoordination  

In the title compound [systematic name: 2-(3,4-dihydroxy-phen-yl) ethanaminium perchlorate], C8H12NO2 +·ClO4 -, the cations and anions are linked into three-dimensional structure via inter-molecular N - H⋯O and O - H⋯O hydrogen bonds. © 2008  

Two new silver(I) complexes ((tptz)Ag2(NO3) 2 and [Ag5(tptz)4](NO3)5) with 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tptz) have been synthesized and characterized by X-ray diffraction, elemental analysis, 1H NMR, IR, fluorescence, UV-Vis spectroscopy and electrochemistry. Oxidation of alcohols to their corresponding aldehydes and ketones was conducted with one of the Ag complexes as a catalyst, soluble enough in organic solvent, using oxone (2KHSO5·KHSO4·K2SO4) as an oxidant under biphasic reaction conditions (CH2Cl 2/H2O) and tetra-n-butylammonium bromide as phase transfer agent under air at room temperature  

A polymeric phenolato-bridged potassium compound, K(2-bromo-4,6 dinitrophenolate) (H2O), was obtained by reaction of methylammonium 2-bromo-4,6-dinitrophenolate and potassium chloride in water. 2-bromo-4,6 dinitrophenolate co-ordinates to the metal ion by phenolic O atom, Br, and O atoms of the nitro groups. K+ ion is eleven-coordinate in the compound. Single-crystal X-ray diffraction for methylammonium 2-bromo-4,6-dinitrophenolate and single-crystal X-ray diffraction, elemental analysis, IR, UV-Vis spectra, and fluorescence emission spectra for the complex have also been determined. Methylammonium 2-bromo-4,6-dinitrophenolate was solved in the monoclinic system, space group P21/c, with the... 

The density jump on an inclined surface is analyzed using an integral method by applying mass and momentum conservation equations. The jump occurs in a two-layered fluid flow in which the upper layer is stagnant and very deep. A relation is derived, which gives the conjugate depth ratio as a function of inlet densimetric Froude number, inlet concentration ratio, bed slope and entrainment. A set of experiments are performed to verify the relation. The theory and the measurements are in good agreement. The analysis reveals that increasing the surface inclination results in a decrease in the conjugate depth ratio. This analysis also shows that the densimetric Froude number just after the jump... 

Fibrous biomaterials have received much attention in tissue engineering and regenerative medicine due to their morphology, resembling extracellular matrix. In comparison to synthetic fibers, cellulose based fibers have interesting properties for cellular applications such as biodegradability, biocompatibility, simple preparation and their potential for chemical modification. Among cellulose derivatives, carboxymethyl cellulose and quaternized cellulose are the most important and valuable cellulose ethers which have anionic and cationic surface charge. In this research, we report the fabrication of multifunctional cellulose microfibrous and nanofibrous scaffolds and the comparison of adhesion... 

A new manganese complex of the formula [Mn(tptz)(OH 2) 3](CF 3SO 3) 2·EtOH, (1, where tptz = (2,4,6-tris(2-pyridyl)-1,3,5-triazine) is presented, exhibiting an excellent catalytic activity and selectivity in oxidation of various sulfides to the corresponding sulfoxides with UHP (urea hydrogen peroxide) as oxidant under air at room temperature. A modified preparation procedure produces another new manganese complex of the formula [Mn(tptz)(CH 3COO)(OH 2) 2](CF 3SO 3)·3H 2O (2). X-ray structures of both Mn(II) complexes, properties (elemental analysis, electrochemistry, EPR, IR, Raman, and UV-Vis spectra), as well as DFT studies results are reported  

A new di-manganese complex with "back-to-back" 1,4-bis(2,2′:6,2′′-terpyridin-4′-yl) benzene ligation has been synthesized and characterised by a variety of techniques. The back-to-back ligation presents a novel new mononuclear manganese catalytic centre that functions as a heterogeneous catalysis for the evolution of oxygen in the presence of an exogenous oxidant. We discuss the synthesis and spectroscopic characterizations of this complex and propose a mechanism for oxygen evolution activity of the compound in the presence of oxone. The di-manganese complex also shows efficient and selective catalytic oxidation of sulfides in the presence of H2O2. Density functional theory calculations were... 

In this study, numerical computations are performed with the main purpose of shedding light on the mixing characteristics in an innovative T-shaped micromixer equipped with a twisted structure. A 3-D model is presented and verified to mix two miscible fluids in a single phase. By considering different geometrical cases, the proposed T-mixer is compared using the standard T-mixer (Base case) running in the same operational conditions. Furthermore, the impacts of variation in the geometry of twisted design are scrutinized for Re (Reynolds number) in the extent of 1≤Re≤500 with the focus of obtaining a significant mixing quality for flow through the micromixer. MI (Mixing index), PI... 

Wind erosion raises mineral dusts from dry and semidry lands and produces dust storms. Such dust masses have created numerous health and economic problems for the residents of southern, southwestern, and central parts of Iran. The main sources, movement, spread, and settlement of dust masses can be determined by solving the governing equations for aerosol transmission. Such information will be certainly useful in managerial decision-making. In this study, the dust event in Tehran on 20–22 February 2016 was studied using numerical model, Moderate Resolution Imaging Spectroradiometer satellite data, and data of ground-based stations. A comparison between the numerical results and in situ... 

In recent years, the city of Tehran, Iran's capital, has encountered numerous dust events so that the dust concentration of PM10 has reached even more than 800 μg m−3. This emphasizes the importance of the statistical study of dust in Tehran and the development of correlations for estimating dust concentration of PM10. In the present study, by evaluating the data measured during dust observations over the years 2013–2016 in Tehran, new statistical models are established for estimating PM10 concentration in terms of horizontal visibility and MODIS AOD. Firstly, simple nonlinear regression models between dust concentration of PM10 and horizontal visibility as well as MODIS AOD are developed.... 

Condensation heat transfer on stainless steel tube utilizing superhydrophobic coatings was investigated. The electrophoretic deposition and spraying methods were employed to coat the tubes’ outer surface. The mixture that was synthesized for spray coating was a hybrid paint. It incorporated polyurethane matrix and a colloidal suspension containing organic nanoparticles. The hybrid paint had a proper adhesion to the substrate which caused more durability compared to the electrophoretic coating. The agglomeration of nanoparticles in the hybrid paint caused the formation of particles with larger size compared to the particles in the electrophoretic coating. Consequently, contact angle...