Mandelate and prolinate ionic liquids: synthesis, characterization, catalytic and biological activity

A group of quaternary ammonium mandelates and l-prolinates, as ionic liquids, were synthesized and characterized. The prepared salts were soluble in water and showed high surface activity. The described synthesis of l-prolinate was simple and the obtained ionic liquid contained a chiral anion. l-Prolinate in CH₂Cl₂ was employed for the asymmetric Michael addition of a ketone to nitrostyrene. A yield of 60%, enantioselectivity (upto 50% ee), and good diastereoselectivity (syn/anti ratio of up to 90:10) were obtained for the asymmetric addition of cyclohexanone. These novel ionic liquids proved to be very effective anti-microbial and anti-fungal agents, especially didecyldimethylammonium l-prolinate. Additionally, it was found that phytotoxicity can be a useful tool in assessing the optical forms of ionic liquids.     

New palladium catalyst immobilized on epoxy resin: synthesis,characterization and catalytic activity

A new thiol‐functionalized epoxy resin as a support for palladium(II) complexes has been synthesized in good yields. A palladium catalyst was ‘heterogenized’ by anchoring [PdCl₂(PhCN)₂] complexes to these thiol‐functionalized polymers via ligand exchange reaction. These new palladium catalysts were tested in Mizoroki–Heck coupling and hydrogenation reactions. The activity of the complexes in terms of yield is comparable to that of homogeneous PdCl₂(PhCN)₂. The stability and a good recycling efficiency of these catalysts make them useful for prolonged use. The constant and good selectivity of the supported catalysts during recycling experiments indicate that they could be useful for practical application in many organic reactions. To characterize the heterogeneous complexes before and after use, X‐ray photoelectron spectroscopy, infrared spectroscopy, scanning electron microscopy, energy dispersive X‐ray microscopy, atomic absorption spectroscopy and time‐of‐flight secondary ion mass spectrometry were applied. Density functional theory calculations were also used to better understand the structures of the obtained palladium complexes. Polythiourethanes contain three atoms, oxygen, nitrogen and sulfur, capable of coordinating to transition metals. We examined the possibility of intra‐ and intermolecular binding for both cis and trans palladium complexes. Copyright © 2015 John Wiley & Sons, Ltd.     

Lanthanide bis(trifluoromethanesulfonyl)amides, synthesis, characterization and catalytic activity

The synthesis of lanthanum, neodymium and ytterbium bis(trifluoromethanesulfonyl)amides, named triflimidates, from acetates, carbonates and oxides is investigated. When the synthesis is performed in water, all the salts contain one molecule of water and the lanthanum and neodymium salts synthesized from the acetates also contain one molecule of acetic acid. After removal of the water and acetic acid in refluxing ethanol, the salts are obtained anhydrous but associated for lanthanum and neodymium, whereas the ytterbium salt is monomeric and volatile. When the synthesis is performed directly in ethanol, the neodymium salt contains two molecules of coordinated ethanol.In non-hazardous solvents, these triflimidates are better catalysts than the analogous triflates toward either Friedel-Crafts acylations, or Fries transpositions or Baeyer-Villiger oxidations. Unexpectedly, the cerium(IV) triflimidate catalyzes the oxidation of aromatic ketones to give the corresponding acids.     

A high activity photocatalyst of hierarchical 3D flowerlike ZnO microspheres: synthesis, characterization and catalytic activity

This contribution reports the design, preparation, and characterization of nanostructured hybrid films of silver nanoparticles (AgNPs) and a tailored nitric oxide (NO) photodonor. They were achieved by exploiting effective interfacial interactions between an amino-terminated NO photodonor spread onto water surface and naked AgNPs dissolved in the water subphase. The morphology, the spectroscopic features, and the interaction between the two components in the floating films at the air/water interface were inspected by Brewster Angle Microscopy, UV-Vis reflection, and polarization-modulation infrared reflection-absorption spectroscopy. AgNPs and the NO photodonor were successfully transferred onto hydrophobized quartz substrates by horizontal lifting deposition and the resulting multilayer films were characterized by UV-Vis absorption spectroscopy and transmission electron microscopy, respectively. The results obtained showed the presence of both isolated AgNPs and assemblies of AgNPs having nanodimensional character in the films. The photochemical properties of the NO photodonor were well preserved in the hybrid multilayers. In fact, they were able to release NO under visible light excitation, as unambiguously demonstrated by the direct and in real-time monitoring of this transient species using an ultrasensitive electrode, and the transfer of the released NO to a protein such as myoglobin.     

New porphyrin-polyoxometalate hybrid materials: synthesis, characterization and investigation of catalytic activity in acetylation reactions

New hybrid complexes based on covalent interaction between 5,10,15,20-tetrakis(4-aminophenyl)porphyrinatozinc(ii) and 5,10,15,20-tetrakis(4-aminophenyl)porphyrinatotin(iv) chloride, and a Lindqvist-type polyoxometalate, Mo(6)O(19)(2-), were prepared. These new porphyrin-polyoxometalate hybrid materials were characterized by (1)H NMR, FT IR and UV-Vis spectroscopic methods and cyclic voltammetry. These spectro- and electrochemical studies provided several spectral data for synthesis of these compounds. Cyclic voltammetry showed the influence of the polyoxometalate on the redox process of the porphyrin ring. The catalytic activity of tin(iv)porphyrin-hexamolybdate hybrid material was investigated in the acetylation of alcohols and phenols with acetic anhydride. The reusability of this catalyst was also investigated.     

Unusual polybrominated polypyrazolylborates and their copper(I) complexes: synthesis, characterization, and catalytic activity

Five new homoscorpionate ligands were prepared and structurally characterized as their Tl complexes, three of which, Tl[TpBr,Ph,Br] (1) (Tp = hydrotris(pyrazolyl)borate, Tl[TpBr,p-Tomicronl,Br] (2), and Tl[TpBr,p-ClPh,Br] (3), are unique in being the first examples of an "atypical" B-N bond to the most sterically hindered pyrazole nitrogen. They contain bromine atoms on the central and outer carbons of the pyrazole ring, with all aryl substituents in the 5-position of the ligand, forming a protective pocket around the B-H bond. These complexes display a rather high B-H stretch frequency (above 2 600 cm-1) in the IR region. Two other ligands, Tl[Tpp-ClPh,4Br] (4) and Tl[TpPh,Me,Br] (5), containing no outer bromine substituents, have normal B-N bonding to the least-hindered nitrogen. These new ligands have been employed to prepare the series of complexes TpxCu(NCMe) (6-10), for which X-ray studies of two of them (7 and 10) have shown that the atypical or normal geometry of the ligands is maintained when complexed to the copper center. The new complexes have also been tested as the catalysts in carbene and nitrene transfer reactions providing moderate to high yields in the expected products.     

碳酸酐酶模型化合物的合成、表征及其催化性能研究

模拟碳酸酐酶的活性中心结构,以三(取代吡唑基)硼氢根[T~p^R^,^R^1]^-为配体,合成了一系列金属配合物[T~p^R^,^R^1]MX[R=Ph,2'-thie(2'-噻吩基),Me;R^1=Ph,2'-thie,Me;M=Co,Ni,Cu,Zn,Cd;X=Cl,NO~3,CH~3COO]共13个,均经元素分析,IR,^1HNMR谱表征。选取其中5个有代表性的配合物,采用Stopped-flow技术,研究了模型物催化CO~2可逆水合反应的动力学,结果表明具备酶促反应动力学的一般特征。详细考察了溶液pH值、模型物的结构(尤其是中心金属离子的电子结构)、浓度对该反应的影响,得出一些重要的结果。计算出该反应有、无催化剂时的活化能,从本质上阐明了反应活化能降低是模型物加速反应的根本原因。     

Mixed-addenda vanadium-substituted polyfluorooxometalates: synthesis, characterization, and catalytic aerobic oxidation

For the first time, mixed-addenda vanadium-substituted polyfluorooxometalates, PFOMs, have been synthesized. Depending on the workup procedure used, two types of compounds were prepared. The first PFOM was a quasi Wells--Dawson type compound, [H2F6NaVVW17O56]8-, and the second a mixture of vanadium-substituted polyfluorooxometalates of the Keggin structure, XVIVW11FnO40 - n (X = H2, V, W; n = 1-4). From the X-ray diffraction analysis, [H2F6NaVVW17O56]8- has an elliptic (egg) shape with a central sodium atom surrounded by six fluorine atoms in a trigonal prism coordination. One may differentiate between two types of addenda atoms to be found in belt and capped positions. According to 1H, 19F, and 51V NMR analysis, it is concluded that vanadium is isomorphically substituted in both the belt and capped position of [H2F6NaVVW17O56]8-. The mixture of vanadium-substituted PFOMs of the Keggin structure was shown, by HPLC and ESR, to contain at least two species of different charge and of a different vanadium environment. The [H2F6NaVVW17O56]8- PFOM was active for the catalytic aerobic oxidation of alkyl aromatic compounds in biphasic (water-catalyst and substrate) media. The reaction selectivity (autoxidation versus oxydehydrogenation) depended on the substrate and reaction conditions such as temperature and oxygen pressure. The selectivity to oxydehydrogenation was significantly higher compared to the prototypical cobalt acetate catalytic system.     

Rhodium dinaphthocyclooctatetraene complexes: synthesis, characterization and catalytic activity in [5+2] cycloadditions

Rh COT in the act: a Ni(0)-catalyzed [2+2+2+2] cycloaddition provides a high-yielding, scalable synthesis of the ligand dinaphtho[a,e]cyclooctatetraene (dnCOT). dnCOT complexation with Rh(I) gives [Rh(dnCOT)(MeCN)(2)]SbF(6), an excellent catalyst for [5+2] cycloadditions of vinylcyclopropanes and π-systems with impressive functional group compatibility.     

Copper(II) complexes with 18-membered decaaza macrocycles: synthesis,characterization and catalytic activity

New square-planar copper(II) complexes of 18-membered decaaza macrocyclic ligands: 5,6,14,15-tetramethyl-1,3,4,7,8,10,12,13,16,17-decaazacyclooctadecane (Me₄[18]aneN₁₀); 1,10-dimethyl-(Me₂Me₄[18]aneN₁₀); 1,10-diethyl-(Et₂Me₄[18]aneN₁₀); 1,10-dipropyl-(Pr₂Me₄[18]aneN₁₀); 1,10-dibutyliso-(Bu₂Me₄[18]aneN₁₀) and 1,10-dibenzyl-5,6,14,15-tetramethyl-1,3,4,7,8,10,12,13,16,17-decaazacylooctadecane [(Benzyl)₂Me₄[18]aneN₁₀)] have been prepared by a one-pot template condensation of formaldehyde and 2,3-butanedihydrazone with alkyl and benzylamine in the presence of copper(II) ion. The complexes of the decaaza macrocycle have been characterized by elemental analyses, i.r., u.v.–vis., conductometric and magnetic measurements. The spectra of [Cu(R₂Me₄[18]ane N₁₀)](ClO₄)₂shows that the four nitrogen (α-diimine) atoms are coordinated to the copper(II) ion. These complexes are found to be effective catalysts for the selective oxidation of tetrahydrofuran to yield the corresponding tetrahydrofuran-2-one and a small amount of tetrahydrofuran-2-ol and 4-hydroxybutyraldehyde, using diluted H₂O₂ as the oxidant.     

Copper(I) complexes with trispyrazolylmethane ligands: synthesis, characterization, and catalytic activity in cross-coupling reactions

Three novel Cu(I) complexes bearing tris(pyrazolyl)methane ligands, Tpm(x), have been prepared from reactions of equimolar amounts of CuI and the ligands Tpm, (HC(pz)(3)), Tpm*, (HC(3,5-Me(2)-pz)(3)), and Tpm(Ms), (HC(3-Ms-pz)(3)). X-ray diffraction studies have shown that the Tpm and Tpm(Ms) derivatives exhibit a 2:1 Cu:ligand ratio, whereas the Tpm* complex is a mononuclear species in nature. The latter has been employed as a precatalyst in the arylation of amides and aromatic thiols with good activity. The synthesis of a Tpm*Cu(I)-phthalimidate, a feasible intermediate in this catalytic process, has also been performed. Low temperature (1)H NMR studies in CDCl(3) have indicated that this complex exists in solution as a mixture of two, neutral and ionic forms. Conductivity measurements have reinforced this proposal, the ionic form predominating in a very polar solvent such as DMSO. The reaction of Tpm*Cu(I)-phthalimidate with iodobenzene afforded the expected C-N coupling product in 76% yield accounting for its role as an intermediate in this transformation.     

Spinel copper ferrite nanoparticles: Preparation,characterization and catalytic activity

The magnetic CuFe₂O₄ nanoparticles have been synthesized and characterized by various spectroscopic methods, including X‐ray diffraction (XRD), O K, Cu and Fe K ‐edge X‐ray absorption near edge structure (XANES), energy dispersive X‐ray analysis (EDX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The azide‐alkyne cycloaddition by the reaction of various phenylacetylenes with a mixture of benzyl halides and NaN₃ and also three component (A³) coupling reaction of aldehyde, alkyne and amine catalyzed by CuFe₂O₄ nanoparticles under aerobic conditions led to the formation of the 1,4‐disubstituted‐1,2,3‐triazoles and propargylamines in excellent yields. The catalyst can be recovered by applying an external magnetic field for the subsequent cycloaddition reactions and reused without any tangible loss in catalytic efficiency.     

Mesoporous nanotubes of iron phosphate: synthesis, characterization, and catalytic property

Iron phosphate nanotubes with mesoporous walls are solvothermally synthesized using sodium dodecyl sulfate (SDS) as a template. With different template concentrations, various shapes of nanosized iron phosphates can be obtained. When the concentration of SDS is set at the transition regions between the lamellar and the hexagonal mesophases, according to its phase diagram, the coassembly of iron phosphate precursor and SDS forms a flake-type mesoporous iron phosphate. Otherwise, nanoparticles or bulky sheets of iron phosphates are obtained. The followed solvothermal treatments on the mesoporous iron phosphate flakes produce iron phosphate nanotubes with mesoporous walls. The removal of the surfactant by acetate exchange and heat treatment results in the clean mesoporous nanotubes of iron phosphate with diameters of 50-400 nm and lengths of several microns. The nanotubular and mesoporous iron phosphate possesses a specific surface area of 232 m2/g and a bimodal distribution of pore sizes, corresponding to the size of mesopores in the walls and the diameter of the nanotubes, respectively. The novel nanotubular iron phosphate with composite meso-macroporous structure, in favor of the diffusion of reactive molecules, has been tested for direct hydroxylation of benzene with hydrogen peroxide and has shown better catalytic performance compared with the conventional particulate mesoporous iron phosphate.     

Sol–gel synthesis, characterization, and catalytic activity of Fe(III) titanates

Nanostructured iron–titanium mixed oxides with different Fe/Ti ratios were prepared by sol–gel methods under different preparative conditions. When equal molar amounts of Fe and Ti ions were employed, the product calcined at 500 °C showed an X-ray diffraction pattern that resembles Fe₂Ti₃O₉. On the other hand, lower Fe/Ti ratios favored the formation of Fe₂TiO₅ while higher ratios resulted in free α-Fe₂O₃ and TiO₂. Besides the effect of the Fe/Ti ratio, the composition of the final product was dependent on the preparative conditions and the calcination temperature. Enhancing the gelation process by heating or by employing an acid catalyst favored the formation of Fe₂TiO₅ at relatively low temperatures. Compared with the corresponding pure oxides, the prepared iron–titanium mixed oxides showed modified textural characteristics which were also dependent on the composition and the calcination temperature. The mixed oxides showed higher catalytic activity in the oxidation of methanol than their corresponding pure oxides with a noticeable enhanced oxidation potential forming methyl formate and carbon dioxide.     

Gold and gold-iron oxide magnetic glyconanoparticles: synthesis, characterization and magnetic properties

The preparation, characterization and the magnetic properties of gold and gold-iron oxide glyconanoparticles (GNPs) are described. Glyconanoparticles were prepared in a single step procedure in the presence of aqueous solution of thiol functionalized neoglycoconjugates and either gold salts or both gold and iron salts. Neoglycoconjugates of lactose and maltose disaccharides with different linkers were used. Iron-free gold or gold-iron oxide GNPs with controlled gold-iron ratios were obtained. The average core-size diameters are in the range of 1.5-2.5 nm. The GNPs are fully characterized by (1)H NMR spectrometry, transmission electron microscopy (TEM), and UV-vis and X-ray absorption (XAS) spectroscopies. Inductive plasma-atomic emission spectrometry (ICP) and elemental analysis gave the average number of neoglycoconjugates per cluster. The magnetic properties were measured in a SQUID magnetometer. The most remarkable results was the observation of a permanent magnetism up to room temperature in the iron-free gold GNPs, that was not present in the corresponding gold-iron oxide GNPs.     

Two palladium(II) complexes based on Schiff base ligands: synthesis, characterization, luminescence, and catalytic activity

Two Pd(II) complexes involving Schiff base ligands, namely, [Pd(L1)₂] (1), [Pd₂(L₂)Cl₂] (2) [HL1 = 2-((2,6-diisopropylphenylimino)methyl)-4,6-dibromophenol, L2 = N-(4-isopropylbenzylidene)-2,6-diisopropylbenzenamine] have been synthesized using solvothermal methods and characterized by elemental analysis, IR-spectroscopy, thermogravimetric analysis, powder X-ray diffraction, UV–vis absorption spectra, and single-crystal X-ray diffraction. Complex 1 is a mononuclear cyclometalated Pd(II) complex, whereas complex 2 is a μ-chloro-bridged dinuclear. Both 1 and 2 display photoluminescence in the solid state at 298 K and possess fluorescence lifetimes (τ ₁ = 86.40 ns, τ ₂ = 196.21 ns, τ ₃ = 1,923.31 ns at 768 nm for 1, τ ₁ = 69.92 ns, τ ₂ = 136.40 ns, τ ₃ = 1,714.26 ns at 570 nm for 2). The Suzuki reactions of 4-bromotoluene with phenylboronic acid by complexes 1–2 have also been studied.     

Gold(I)-dithioether supramolecular polymers: synthesis, characterization, and luminescence

A series of discrete compounds and supramolecular polymers were synthesized by self-assembly of dithioether building blocks and HAuCl4.3H2O. In complexes 1 {[AuL(1-Me)Cl], where L(1-Me) is bis(methylthio)methane} and 2 {[Au2L(2-Ph)Cl2], where L(2-Ph) is 1,2-bis(phenylthio)ethane}, adjacent units are connected via aurophilic interactions. Complex 1, a one-dimensional (1D) supramolecular polymer, and complex 2, a two-dimensional supramolecular network, both feature nearly linear [Au-Au-](infinity) chains. Complexes 4a, 4b, and 4c, all of which contain 1,3-bis(phenylthio)propane (L(3-Ph)), are polymorphs having the composition [Au2L(3-Ph)Cl2]. Complex 3 {[Au2L(1-Ph)Cl2], where L(1-Ph) is bis(phenylthio)methane}and complexes 4a and 4b consist of nearly identical 1D supramolecular polymers formed through Au-Au interactions. The third polymorph, 4c, is a molecular complex, as it does not have metal-metal interactions. Complex 5 {[Au2L(4-Ph)Cl2], where L(4-Ph) is 1,4-bis(phenylthio)butane} is also molecular. UV-vis spectra showed that the absorption bands of these complexes are allowed ligand-centered transitions between 230 and 260 nm. Complexes 1, 2, and 6 {[AuL(3-Me)Cl], where L(3-Me) is 1,3-bis(methylthio)propane} exhibited solid-state luminescence at 5 K with vibronic progressions and band maxima at approximately 570 nm. It is suggested that complex 6 contains [Au-Au-](infinity) chains.     

Gold nanoparticles functionalized with deep-cavity cavitands: synthesis, characterization, and photophysical studies

In this report, we present methods of functionalization of AuNP's with deep-cavity cavitands that can include organic molecules. Two types of deep-cavity cavitand-functionalized AuNP's have been synthesized and characterized, one soluble in organic solvents and the other in water. Functionalized AuNP soluble in organic solvents forms a 1:1 host-guest complex where the guest is exposed to the exterior solvents. The one soluble in water forms a 2:1 host-guest complex where the guest is protected from solvent water. Phosphorescence from thiones and benzil included within heterocapsules attached to AuNP was quenched by gold atoms present closer to the guests included within deep-cavity cavitands. During this investigation, we have synthesized four new deep-cavity cavitands. Of these, two thiol-functionalized hosts allowed us to make stable AuNP's. However, AuNP's protected with two amine-functionalized cavitands tended to aggregate within a day.     

Formation,characterization and catalytic activity of PD-polyheteroarylenes complexes

High molecular weight polybenzimidazoles, poly[(N-phenyl)benzimidazoles], polynaphthoylenebenzimidazoles and poly(naphthoylene-s-triazoles) were obtained using well-known polycyclodehydration processes as well as new reactions for their preparation -reductive polyheterocyclization and “activated” poly-cyclocondensation. Treatment of polymers obtained with PdCl₂ led to the formation of Pd-containing polyheteroarylenes complexes. Pd^II bound to the polymers was reduced to Pd° by treatment with hydrogen or NaBH₄. Pd-polyheteroarylenes complexes obtained may be used as catalysts for the hydrogenation of alkenes and alkynes, for the selective hydrogenation of the triple bonds of unsaturated hydrocarbons in the presence of double bonds etc. Of especially great interest is the utilization of Pd-polybenzimidazole as catalyst for carbonylation of nitrobenzene and different halogen-substitited nitrobenzenes in the presence of alcohols leading to the formation of carbamates.     

Design, synthesis, and characterization of novel nanowire structures for photovoltaics and intracellular probes

Semiconductor nanowires (NWs) represent a unique system for exploring phenomena at the nanoscale and are expected to play a critical role in future electronic, optoelectronic, and miniaturized biomedical devices. Modulation of the composition and geometry of nanostructures during growth could encode information or function, and realize novel applications beyond the conventional lithographical limits. This review focuses on the fundamental science aspects of the bottom-up paradigm, which are synthesis and physical property characterization of semiconductor NWs and NW heterostructures, as well as proof-of-concept device concept demonstrations, including solar energy conversion and intracellular probes. A new NW materials synthesis is discussed and, in particular, a new "nanotectonic" approach is introduced that provides iterative control over the NW nucleation and growth for constructing 2D kinked NW superstructures. The use of radial and axial p-type/intrinsic/n-type (p-i-n) silicon NW (Si-NW) building blocks for solar cells and nanoscale power source applications is then discussed. The critical benefits of such structures and recent results are described and critically analyzed, together with some of the diverse challenges and opportunities in the near future. Finally, results are presented on several new directions, which have recently been exploited in interfacing biological systems with NW devices.