A Convenient and Efficient Method for the Preparation of Unique Fluorophores of Lariat Naphtho‐Aza‐Crown Ethers

New naphtho‐aza‐crown ethers containing different phenolic side‐arms attached through the ortho‐position of the phenol have been prepared under solvent‐free conditions. The starting macrocyclic naphtho‐aza‐crown ether 2 was obtained by treatment of naphthalene dicarboxylic acid diester 1 with diethylenetriamine in EtOH at room temperature for two days without stirring in 77% yield (Scheme 1). Phenolic ligands ( 3 – 14 ) were synthesized by the Mannich reaction of the secondary macrocyclic amine 2 with the substituted phenols using nontoxic and inexpensive CaCl₂. This procedure was applied successfully for the synthesis of Mannich bases from simple secondary amines. The CaCl₂ powder can be reused up to three times after simple washing with dry acetone.     

First study of rhodium(I) complexes with chiral sulfur-containing terpenoids as catalytic systems for ketone hydrosilylation

Abstract

Using a “chiral pool” approach, a number of chiral thiolate and sulfide ligands based on natural terpenes and terpenoids have been synthesized in a few simple steps. Two new Rh-thiolate complexes with the formula [Rh(CO)₂(μ-SR)]₂ were obtained. The influence of these complexes and catalytic systems formed by combining the synthesized ligands with [Rh(CO)₂(μ-Cl)]₂ and [Rh(cod)(μ-Cl)]₂, on the reaction rate, chemoselectivity, stereoselectivity and formation of tetraphenyldisiloxane in Rh-catalyzed asymmetric hydrosilylation of acetophenone as a model reaction have been studied. Mechanistic aspects of formation of silyl enol ether as a side product in the presence of S-containing ligands are presented.     

Preparation, characterization and thermolysis of metal nitrate complexes with 4,4’-bipyridine

Two bis(bipyridine) polymeric metal nitrate complexes with 4,4’-bipyridine of simple formula like [M(bipy)₂](NO₃)2⋅xH₂O (where M=Co, Ni and Cu; x=4, 2 and 0, respectively) have been prepared and characterized. Their thermal decomposition has been undertaken using simultaneous TG-DTG-DTA and DSC in nitrogen atmosphere and non-isothermal TG in air atmosphere. Isothermal TG has been performed at decomposition temperature range of the complexes to evaluate the kinetics of decomposition by applying model-fitting as well as isoconversional method. Possible mechanistic pathways have also been proposed for the thermolysis. Ignition delay measurements have been carried out to investigate the response of these complexes under the condition of rapid heating.     

Icosahedral carboranes. XVI. Preparation of linear poly-m-carboranylenesiloxanes

The first members of the series of poly-m-carboranylenesiloxanes were synthesized by the ferric chloride-catalyzed condensation of methoxy- and chloro-terminated monomers and generally obtained as insoluble crosslinked gums It has now been discovered that long-chain, linear polymers can be prepared by simple hydrolytic condensation of m-B₁₀H₁₀C₂(SiMe₂OSiMe₂Cl)₂ and m-B₁₀H₁₀C₂(SiMe₂OSiMe₂OSiMe₂Cl)₂ at ice bath temperature, as well as by acid-catalyzed condensation of the corresponding silanols. In addition, phenyl-substituted copolymers have been obtained which show outstanding thermo-oxidative stability at elevated temperature. These linear polymers are soluble waxes and liquids with molecular weights between 16,000 and 30,000; they are potentially useful as high-temperature liquids and coatings and can be cured at room temperature to form elastomers.     

Potentiometric studies on mixed complexes of Ni(II) with taurine, -methionine and -ethionine in aqueous solution

The formation and stability of the simple and mixed complexes of Ni(II) with taurine, -methionine and -ethionine have been investigated by means of potentiometric measurement of hydrogen ion concentration at 25°C and in a 0.1 M NaClO₄ medium. Mixed complexes, [Ni(Met₂)Tau] and [Ni(Eth₂)Tau], have been considered, where Met = -methionine, Eth = -ethionine and Tau = taurine.     

Metal-organic deposition of YBa2Cu3Ox and Bi2Sr2Ca1Cu2Ox films on various substrates starting from different fluorine-free metallorganic compounds

YBa₂Cu₃O_x (Y-123) and Bi₂Sr₂Ca₁Cu₂O_x (Bi-2212) films on various substrates have been prepared by Metal-Organic Deposition starting from different metallorganic fluorine-free compounds and using a very simple instrumentation. The processing conditions include a rapid pyrolysis step in air and an annealing step in oxygen for Y-123 and in air for Bi-2212. The films obtained have been characterized by X-ray diffraction (XRD) and the formation of a superconducting phase of Y-123 or Bi-2212 was confirmed measuring the critical temperature (T _c) with Ac-susceptibility and resistive measurements. Microstructure and final cationic ratios have been studied by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS).     

ZrO2球的准气相反应合成

提出了一种工艺简单、成本低廉的准气相反应合成ZrO₂球的新方法. 通过对产物的SEM观测表明: 该方法制备的ZrO₂粒子为较好的球形, 球表面光滑; 其平均粒径1.71 μm, 标准偏差0.49 μm; 球有三种结构: 均匀致密结构、核心疏松外层致密结构和空心结构; 经600 ℃煅烧后, XRD分析确定ZrO₂球的相组成主要为立方相.     

The high-resolution mass spectra of aliphatic aldehydes

The mass spectra of the C₃ to C₉ n-alkanals and a number of branched aldehydes have been obtained at a resolution sufficient to resolve the O? CH₄ doublets. From the resolved spectra, a study of metastable transitions, and the spectrum of one deuterium-labelled alkanal, (n-hexanal-2,2-d₂) the major fragmentation reactions have been elucidated. Of particular interest are the γ-cleavage reaction, leading to [C₃H₅O]+ in the n-alkanals, which proceeds both by a simple cleavage and by cleavage preceded by hydrogen interchange, and the loss of C₂H₄, which involves loss of the C₂ and, probably C₃, carbons.     

Subduction coefficients for 〈2N/2–S, 12S〉 ↓ 〈2, 1〉 ⊗ 〈2, 1〉 of U(n) ↓ U(n1) ⊗ U(n2)

The determination of the subduction coefficients for states of the unitary group U(n) under the restrictions U(n) ↓ U(n₁) ? U(n₂) have been considered for the spin free states of many electron systems. Using the transformation properties of the tensor basis spanning the irreducible representation 〈2^N/2–S, 1^2S〉 of U(n) under the permutations of electron coordinates, a simple programmable procedure has been developed for the determination of these coefficients. The procedure has been illustrated using a simple example.     

CuO Nanoparticles as Effective Reusable Heterogeneous Catalyst for S‐Arylation Reactions

Copper(II) oxide nanoparticles have been synthesized from Cu(OAc)₂ via a simple hydrolysis route and were found to be an efficient and inexpensive catalyst for ligand free C? S cross‐coupling reactions of malononitrile? CS₂ adduct with various aryl halides. Aryl iodides and bromides, with electron‐withdrawing as well as electron‐releasing groups on the aromatic ring, undergo coupling reactions in good yields.     

The solvent dependence of the sorptive abilities of tetracyanocomplexes

The two different types of tetracyanocomplexes [ZnNi(CN)₄·nH₂O] and [Cd(en)Pd(CN)₄·2C₆H₆] have been examined as sorptive materials in a simple contact with benzene, after their modification with auxiliary solvents and their use in gas chromatographic experiments. All forms of sorption experiments show identical characteristics from the view of the sorption of aromatic compounds as exemplified by benzene. The tetracyanocomplexes exhibit a permanent capability of sorption, even when heated to a temperature of 260°C and show a separation ability towards sorbed materials depending on the solvent used and on the degree of thermal degradation of the tetracyanocomplex. The prducts of the modification and sorption (in static and dynamic) experiments have been characterized by IR spectroscopy, X-ray patterns and by thermal analysis.     

Synthesis of New Pyrano[2′,3′: 5,6]chromeno[4,3‐b]quinolin‐4‐ones via Aza‐DielsAlder Reaction

New pyrano[2′,3′: 5,6]chromeno[4,3‐b]quinolin‐4‐ones have been synthesized by intramolecular aza‐Diels? Alder reaction of the azadienes generated in situ from aryl amines and 8‐formyl‐7‐(prop‐2‐ynyl)2,3‐disubstituted chromones using CuFe₂O₄ nanoparticles as a catalyst in DMSO at 80–90° in good‐to‐excellent yields. Particularly valuable features of this methodology include simple implementation, inexpensive and reusable catalyst, and good yields. The structures were established by spectroscopic data and further confirmed by X‐ray diffraction analysis of one of the products.     

Studies on poly(iminomethylenes)

A variety of simple alkyl and aryl isocyanides have been polymerized using 0.5% NiCl₂ in ethanol as a catalyst. The resulting poly(iminomethylenes) have been characterized by carbon-13 NMR spectroscopy and their polystyrene-equivalent molecular weights have been determined by gel permeation chromatography. Straight chain aliphatic isocyanides having from three to ten carbon atoms in the chain form readily solyble polymers having molecular weights (M_w) in the general range 10,000 to 30,000. Neopentyl isocyanide unlike tert-butyl isocyanide forms an insoluble polymer. A number of new soluble aryl isocyanide polymers have been obtained. However, aryl isocyanides having a single alkyl substituent (CH₃, C₂H₅, CF₃) in the ortho position give only insoluble polymers, whereas aryl isocyanides having alkyl substituents in both ortho positions (e.g., 2,6-(CH₃)₂C₆H₃NC and 2,4,6-(CH₃)₃C₆H₂NC) fail to polymerize under these conditions. The highest molecular weight soluble aryl isocyanide homopolymer is obtained from 3-CH₃OC₆H₄NC(M_w = 26,000). The trimethylsilyl substituted isocyanide (CH₃)₃SiCH₂CH₂NC has been obtained from LiCH₂NC and (CH₃)SiCH₂Cl and gives a brown soluble homopolymer with a molecular weight (M_w) of 19,000.     

The mass spectra of benzamide and thiobenzamide

The mass spectra of benzamide, thiobenzamide and their N-d₂ analogues have been studied In addition to fragmenting by simple bond cleavages the molecular ions dissociate partly from their imide forms. Equilibration or ‘scrambling’ of ortho ring hydrogen atoms with amide hydrogen did not occur in benzamide but such exchange must take place in the thiocompound whose fragmentation behaviour is very complex. Neither labelled compound produced the label-retaining benzoyl (thiobenzoyl) cation which has been the subject of much interest in the mass spectrum of O-d₁ benzoic acid.     

An Exceedingly Mild,Green Synthesis of Substituted N‐3‐diaryl‐1,8‐naphthyridin‐2‐amine Derivatives and Their Antimicrobial Activity

An exceedingly and highly efficient procedure has been described for the synthesis of substituted N‐3‐diaryl‐1,8‐naphthyridin‐2‐amines by the reaction of 2‐chloro‐3‐aryl‐1,8‐naphthyridines with various anilines in the presence of N‐methyl‐2‐pyrrolidone and K₂CO₃ under thermal green solvent‐free conditions. The significant features of this green reaction include very good yields in purity, simple experimental, short reaction time, easy workability, and avoidance of toxic solvents. All synthesized compounds have been evaluated for their antibacterial activity.     

Bright Luminescent Platinum(II)-Biaryl Emitters Synthesized Without Air-Sensitive Reagents

Transition-metal complexes bearing biaryl-2,2′-diyl ligands tend to show intense luminescence. However, difficulties in synthesis have prevented their further functionalization and practical applications. Herein, a series of platinum(II) complexes bearing biaryl-2,2′-diyl ligands, which have never been prepared in air, were synthesized through transmetalation and successive cyclometalation of biarylboronic acids. This approach does not require any air- or moisture-sensitive reagents and features a simple synthesis even in air. The resulting (Et₄N)₂[Pt(m,n-F₂bph)(CN)₂] (m,n-F₂bph=m,n-difluorobiphenyl-2,2′-diyl) complexes exhibit intense green emissions with high quantum efficiencies of up to 0.80 at 298 K. The emission spectral fitting and variable-temperature emission lifetime measurements indicate that the high quantum efficiency was achieved because of the tight packing structure and strong σ-donating ability of bph.     

Synthesis of CdTe Quantum Dots with Tunable Photoluminescence Using Tellurium Dioxide as Tellurium Source

A simple and convenient method has been developed for synthesis of water‐soluble CdTe quantum dots (QDs) under ambient atmospheric conditions. In contrast to the traditional aqueous synthesis, green to red emitting CdTe QDs were prepared by using TeO₂ to replace Te or Al₂Te₃ as tellurium source in this method. The influences of experimental variables, including pH value, 3‐mercaptopropionic acid (MPA)/Cd and Te/Cd molar ratios, on the emission peak and photoluminescence (PL) quantum yield (QY) of the obtained CdTe QDs have been systematically investigated. Experimental results indicate that green to red emitting CdTe QDs with a maximum photoluminescence quantum yield of 35.4% can be prepared at pH 11.3 and n_(Cd):n_(Te):n_(MPA)=1:0.1:1.7.     

Simple fast preparation of neutral palladium(II) complexes with SnCl− 3 and Cl− ligands

A new method for preparing neutral trichlorostannate complexes of Pd^II, based on the interaction between solid [PdCl₂(MeCN)₂] and SnCl₂ suspension and a solution of an appropriate ligand in CH₂Cl₂, has been developed. The analogous method can be used to prepare complexes without tin, as well as compounds containing mixed anionic ligands. A number of complexes (including several new compounds) with amines, phosphines and diene ligands have been obtained by these methods. The procedures are simple and fast – the total preparation time (without recrystallisation) is ca. 30 min.     

The Effect of Doping Different Heteroatoms on the Interaction and Adsorption Abilities of Fullerene

Density functional method has been employed to compare the interaction and adsorption abilities of simple and doped fullerenes with various heteroatoms (Al, B, Si, N, P, and S). Three sulfur‐containing molecules (H₂S, SO₂, and thiophene) were selected to study of their interactions with fullerenes. These interactions will be important in the design of new sensor, adsorption, and elimination of pollutants and chemical reactions. The calculated adsorption energies (E_ad) in the gas phase and solvents (water, using the polarized continuum model) showed that all adsorbates have exothermic interaction with all fullerenes. The maximum E_ad values were calculated for aluminum‐doped fullerene (AF) and nitrogen‐doped fullerene (NF), and the adsorption energies in solvent are not so different with those in the gas phase. Natural Bond Orbitals (NBO) calculations showed the complexes of AF and then boron‐doped fullerene (BF) have the highest E2 interaction energies, whereas simple fullerene (F) and phosphorus‐doped fullerene (PF) have the least E2 energies. Population analyses showed that doping by heteroatoms bearing extra electrons reduces the energy gap and this decrease is more than the decrease observed from doping by heteroatoms with electron defect. Moreover, the change in the energy gaps of the complexes, obtained from the density of states (DOSs) plots, showed that these structures could be used in sensor devices. All calculated data confirmed the better adsorption of SO₂ by fullerenes versus H₂S and thiophene and among all fullerenes, AF and then BF and NF are the best adsorbent for these structures.     

Ab initio quantum chemical studies of the reactions of CF3CFHO2 with HO2

The potential energy surface (PES) for the CF₃CFHO₂+HO₂ reaction has been theoretically investigated using the DFT [B3LYP/6‐311G(d,p)] and B3LYP/6‐311++G(3df,3pd)//B3LYP/6‐311G(d,p) levels of theory. Both singlet and triplet PESs are investigated. The reaction mechanism on the triplet surface is simple. It is revealed that the formation of CF₃CFHOOH+³O₂ is the dominant channel on the triplet surface. On the basis of the ab initio data, the total rate constants for the reaction CF₃CFHO₂+HO₂ in the T = 210–500 K range have been computed using conventional transition state theory with Wigner's tunneling correction and have been fitted by a rate constant expression as k = 1.04 ×10^?12(cm³ molecule^?1 s^?1) exp (700.33/T). Calculated transition state rate constants with Wigner's tunneling correction for the reaction CF₃CFHO₂+HO₂ are in good agreement with the available experimental values. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007