Preparation,characterization and catalytic activity studies of organoruthenium‐supported polyoxotungstates on SBA‐15

Organoruthenium‐supported polyoxometalates [(RuC₆H₆)XW₉O₃₄]^7? (XWRu; X = As, P) were selected as samples to study their catalytic activities towards the solvent‐free oxidation of n‐hexadecane. First of all, the XWRu were deposited on 3‐aminopropyltriethoxysilane‐modified SBA‐15 to prepare solid catalysts, which were characterized using powder X‐ray diffraction, nitrogen adsorption measurements, Fourier transform infrared reflectance spectroscopy and X‐ray photoelectron spectroscopy. Subsequently, their catalytic performances and stabilities were assessed through the oxidation of n‐hexadecane using air as the oxygen source without any additives and solvents, and the influences of the loading amount, catalyst amount, reaction time and reaction temperature on the catalytic activities were investigated. The results indicated the influence of the central heteroatoms X of XWRu on the catalytic activities. Copyright © 2014 John Wiley & Sons, Ltd.     

Syntheses,crystal structures,and properties of two molecular double-supporting polyoxotungstates

Two molecular double-supporting polyoxotungstates [SiW₁₂O₄₀{M(phen)₂H₂O}₂] · nH₂O (phen = 1,10′-phenanthroline, M = Mn 1, n = 2; M = Co 2, n = 3) were synthesized hydrothermally and characterized by elemental analyses, IR, TG, and X-ray single-crystal diffraction. The variable-temperature magnetic susceptibilities were measured at 2–300 K. The double-supporting polyoxotungstate molecule consists of a Keggin-type dodecatungstosilicate anion and a pair of transition metal complex fragments which are covalently linked to opposite sides of the Keggin anion. The transition metal ion locates in the center of a distorted octahedron. Multiple H-bonding interactions are observed between the coordinated waters of the transition metal complex fragments and terminal oxygen atoms of Keggin units and also between the bridging oxygen atoms of Keggin units and the lattice waters, which creates one-dimensional chains or two-dimensional layers. Between the layers or chains there are weak CH···O hydrogen bonding interactions and van der Waals forces. The molecular double-supporting polyoxotungstosilicate begins to decompose at ca. 500 °C. The variable-temperature magnetic behavior of 1 shows weak antiferromagnetic characteristics with a small value of θ = −0.289 K.     

Glycal-ruthenium carbonyl clusters: Syntheses, characterization, and anticancer activity

Four new chiral ruthenium carbonyl cluster complexes Ru₃(μ-H)₂(CO)₉(L-2H) (1), Ru₃(μ-H)₂(CO)₇(L-2H)(dppm) (2), Ru₃(μ-H)₂(CO)₇(L-2H)(PPh₃)₂ (3), Ru₃(μ-H)₂(CO)₇(L-2H)(dppe) (4) containing a dehydrogenated form (L-2H) of 3,4,6-tri-O-benzyl-d-galactal (L) as a chiral ligand have been prepared and characterized. The anticancer activity of five compounds 1-4 and Ru₃(μ-H)₂(CO)₉(L-2H) 5 (L = tribenzyl glucal) against six types of human cancer cell lines was studied and compared to cisplatin. Compound 1 was chosen to produce more detailed growth curves based on overall highest activity profile. The structure of compound 2 was established by a single-crystal X-ray diffraction analysis. The structure based on triangular metal framework contains a bridging dehydrogenated tribenzyl galactal ligand bonded in a parallel μ₃-η²-bonding mode and a bridging dppm ligand. Variable-temperature NMR studies show that the two hydride ligands in compounds 1 and 2 are dynamically active on the NMR time scale at room temperature.     

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.     

Syntheses,characterization and catalytic activity of Mannich aminomethylation products of bis(glycinato)metal(II) complexes

Mannich aminomethylation products have been prepared from one-pot template condensation of bis(glycinato)metal(II) complexes, M(gly)₂, with formaldehyde and nitromethane. The synthesized compounds were characterized by suitable spectroscopic and analytical methods such as UV–Vis, infrared spectroscopy, elemental analysis, FAB mass, ESR, cyclic voltammetry, TGA and NMR. One of the synthesized products has been used as catalyst in the hydrogen peroxide induced degradation of pyrocatechol violet (PCV) dye.     

Syntheses, characterization and catalytic reactivities of heteropolyanion-pillared clay of anions of Zn-Al type

Mono-substituted Keggin ions PW11O39Cr(H2O)4 , PW11TiO403 and PW11VO404 were intercalated between the layers of the clay of anions of Zn-Al type using the ion exchange method to obtain a new type of pillared layered microporous materials ZnAl-PW11Cr, ZnAl-PW11Ti and ZnAl-PW11V with basal spacing (1.48±0.02) run. On the basis of the MAS NMR results of 27A1 and 31P, a steric pillared layered structure model of orientation localization of PW11VO40,4- in the orientation in which the C2 axis of PW11VO404-is perpendicular to the host layer. It has been found that this kind of pillared layered microporous materials possess a higher catalytic activity for the esterification of acetic acid with n-butanol than H-type molecular sieves.     

Synthesis and catalytic properties of niobium indenyl peroxo complexes

Synthesis of four niobium sandwich peroxo complexes containing fragments of substituted indenes was performed and their structure was proved by NMR spectroscopy and ESI-MS mass spectrometry. Catalytic activity of the complexes in the oxidation of sulfides with hydrogen peroxide was studied, and a high selectivity in the oxidation of sulfides to sulfoxides and sulfones of the sandwich peroxo complexes was found.     

Preparation,characterization and catalytic activity of biomaterial-supported copper nanoparticles

Synthesis of copper nanoparticles was carried out with nanocrystalline cellulose (NCC) as a support by reducing CuSO₄·5H₂O ions using hydrazine. Ascorbic acid and aqueous NaOH were also used as an antioxidant and pH controller, respectively. The synthesized copper nanoparticles supported on NCC (CuNPs@NCC) were characterized by UV–vis, XRD, TEM, XRF, TGA, DSC, N₂ adsorption-desorption method at 77 K and FTIR. The UV–vis confirmed the formation and stability of the CuNPs, which indicated that the maximum absorbance of CuNPs@NCC was at 590 nm due to the surface plasmon absorption of CuNPs. Morphological characterization clearly showed the formation of a spherical structure of the CuNPs with the mean diameter and standard deviation of 2.71 ± 1.12 nm. Similarly, XRD showed that the synthesized CuNPs@NCC was of high purity. The thermal analysis showed that the CuNPs@NCC exhibited better thermal behaviors than NCC. BET surface area revealed that the N₂ adsorption–desorption isotherms of CuNPs@NCC featured a type IV isotherm with an H3 hysterisis loop. This chemical method is simple, cost effective, and environmentally friendly. Compared to NCC-supported CuNPs and unsupported CuNPs, the as-prepared CuNPs@NCC exhibit a superior catalytic activity and high sustainability for the reduction of methylene blue with NaBH₄ in aqueous solution at room temperature. The CuNPs@NCC achieved complete reduction of MB with completion time, rate constant and correlation coefficient (R ²) of 12 min, 0.7421 min^?1 and 0.9922, respectively.     

Syntheses,characterization and catalytic activities of half-sandwich ruthenium complexes with naphthalene-based Schiff base ligands

Four ruthenium(II) p-cymene complexes with naphthalene-based Schiff base ligands [Ru(p-cymene)LCl] (2a–2d) have been synthesized and characterized. The half-sandwich ruthenium complexes were characterized by ¹H and ¹³C NMR spectra, elemental analyses, and infrared spectrometry. The molecular structures of 2a, 2b, and 2c were confirmed by single-crystal X-ray diffraction. Furthermore, these half-sandwich ruthenium complexes are highly active catalysts for the hydrogenation of nitroarenes to anilines using NaBH₄ as the reducing agent in ethanol at room temperature.     

多核羰基钴配合物的合成及其催化活性的研究

多核羰基钴配合物对很多有机化学反应有良好的催化作用,从而引起人们很大关注.但这类配合物由高压反应得到,因此给实用带来不便. 我们通过各种含膦配体的氯化钴,在锌粉存在下,与一氧化碳在常温常压下反应,得到了一系列通式为:(PR_3)_mCo_n(CO)_x的多核羰基钴配合物,讨论了它们的结构,并对这些配合物在由十四碳烯羰基合成作为表面活性剂原料的十五碳伯醇反应中的催化性能进行了研究.     

Gold nanowire networks: synthesis, characterization, and catalytic activity

Gold nanowire networks (AuNWNs) with average widths of 17.74 nm (AuNWN(1)) or 23.54 nm (AuNWN(2)) were synthesized by direct reduction of HAuCl(4) with sodium borohydride powder in deep eutectic solvents, such as ethaline or reline, at 40 °C. Their width and length were dependent on the type of solvent and the NaBH(4)/HAuCl(4) molar ratio (32 in ethaline and 5.2 in reline). High resolution transmission electron microscopy (HR-TEM) analysis of the gold nanowire networks showed clear lattice fringes of polycrystalline nanopowder of d = 2.36, 2.04, 1.44, and 1.23 ? corresponding to the (111), (200), (220), or (311) crystallographic planes of face centered cubic gold. The purified AuNWNs were used as catalysts for the chemical reduction of p-nitroaniline to diaminophenylene with sodium borohydride in aqueous solution. The reaction was monitored in real time by UV-vis spectroscopy. The results show that the reduction process is six times faster in the presence of gold nanowire networks stabilized by urea from the reline (AuNWN(2)) than in the presence of gold nanowire networks stabilized by ethylene glycol from ethaline (AuNWN(1)). This is due to a higher number of corners and edges on the gold nanowires synthesized in reline than on those synthesized in ethaline as proven by X-ray diffraction (XRD) patterns recorded for both types of gold nanowire networks. Nevertheless, both types of nanomaterials determined short times of reaction and high conversion of p-nitroaniline to diaminophenylene. These gold nanomaterials represent a new addition to a new generation of catalysts: gold based catalysts.     

Synthesis, structural and spectroscopic characterization, catalytic properties, and thermal transformations of new cyclic di- and trisiloxanediolato tantalum complexes

The reaction between Ta(OEt)5 and 1,1,3,3-tetramethyl-1,3-disiloxanediol, (HOSiMe2OSiMe2OH), leads to new siloxy complexes in which the dimeric nature of Ta(OEt)5 is maintained with both bridging ethoxide and disiloxanediolato bridges. With equal amounts of the reagents, two terminal OEt groups are replaced to form [Ta(OEt)2]2(mu-OEt)2(mu-OSiMe2OSiMe2O)2, 1, whereas with an excess of diol, the remaining terminal OEt groups are also replaced but with a trisiloxanediolato unit to form [Ta(OSiMe2OSiMe2OSiMe2O)]2(mu-OEt)2(mu-OSiMe2OSiMe2O)2, 2. Complexes 1 and 2 catalyze the transformation of HOSiMe2OSiMe2OH to polysiloxanes. Thermal treatment of 1 results in the formation of a 1:2 mixture of Ta2O5/SiO2; no new phases are observed. The molecular structures of 1 and 2 are confirmed by X-ray crystallography.     

Mononuclear ruthenium complexes containing chiral aminooxazolines: Syntheses, X-ray studies and catalytic activity

The synthesis and characterisation of three novel mononuclear ruthenium(II) complexes containing one of the following chiral auxiliary ligands: 2-amino-(4R)-phenyl-2-oxazoline (amphox), indanyl-2-amino-(4R,5S)-2-oxazoline (aminox) or indanyl-(2′-anilinyl)-(4R,5S)-2-oxazoline (aninox) is described using [Ru₂Cl₄(η⁶-p-cym)₂] (p-cym = 1-isopropyl-4-methylbenzene) as the Ru starting material. The new complexes have been identified as the neutral derivatives [RuCl₂(η⁶-p-cym)(amphox-κ¹N_ox)] (1), [RuCl₂(η⁶-p-cym)(aminox-κ¹N_ox)] (2) and the salt [RuCl(η⁶-p-cym)(aninox-κ²N,N′)]Cl (3). These materials have been fully characterised (elemental analysis, NMR, IR, conductance, MS, etc.) and, in the case of 2 and 3, structurally elucidated in the solid-state using single crystal X-ray diffraction methods. All three complexes show good catalytic activity (max. conversion >99%, TOF = 424 h⁻¹) but only modest enantio-selectivity (max. ee = 40%) for the transfer hydrogenation reaction of acetophenone with isopropyl alcohol. The complexes were also tested in an asymmetric Diels-Alder reaction involving cyclopentadiene and acrolein (max. conversion >99%, TOF = 42 h⁻¹). In this case, the diastereo-selectivity was good to moderate (max. de = 84%), but the ee values were poor (max. ee = 12%).     

Syntheses, structures and catalytic activity of copper(II) complexes with hydroxyindanimine ligands

A series of new hydroxyindanimine ligands [ArNCC₂H₃(CH₃)C₆H₂(R)OH] (Ar = 2,6-i-Pr₂C₆H₃, R = H (HL¹), R = Cl (HL²), and R = Me (HL³)) were synthesized and characterized. Reaction of hydroxyindanimine with Cu(OAc)₂ · H₂O results in the formation of the mononuclear bis(hydroxyindaniminato)copper(II) complexes Cu[ArNCC₂H₃(CH₃)C₆H₂(R)O]₂ (Ar = 2,6-i-Pr₂C₆H₃, R = H (1), R = Cl (2), and R = Me (3)). The complex 2′ was obtained from the chlorobenzene solution of the complex 2, which has the same molecule formula with the complex 2 but it is a polymorph. All copper(II) complexes were characterized by their IR and elemental analyses. In addition, X-ray structure analyses were performed for complexes 1, 2, and 2′. After being activated with methylaluminoxane (MAO), complexes 1-3 can be used as catalysts for the vinyl polymerization of norbornene with moderate catalytic activities. Catalytic activities and the molecular weight of polynorbornene have been investigated for various reaction conditions.     

Syntheses,structures and catalytic activity for Friedel-Crafts reactions of substituted indenyl rhenium carbonyl complexes

The complexes [(η⁵-C₉H₆R)Re(CO)₃] [R = ⁿBu (8), ^tBu (9), CH(CH₂)₄ (10), Ph (11), Bz (12), 4-methoxyphenyl (13), 4-chlorophenyl (14)] were synthesized by refluxing substituted indenyl ligands [C₉H₇R] [R = ⁿBu (1), ^tBu (2), CH(CH₂)₄ (3), Ph (4), Bz (5), 4-methoxyphenyl (6), 4-chlorophenyl (7)], and Re₂(CO)₁₀ in decalin. The molecular structures of 9, 10, 12, and 13 were determined by X-ray diffraction analysis. These four crystals have similar molecular structures of the mononuclear carbonyl complex. In each of these molecules, Re is η⁵-coordinated to the five-membered ring of the indenyl group. Complexes 8–14 have catalytic activity for Friedel-Crafts reactions of aromatic compounds with a variety of alkylation and acylation reagents. Compared with traditional catalysts, these mononuclear metal carbonyl complexes have obvious advantages such as high activities, mild reaction conditions, high selectivity, and environmentally friendly chemistry.     

四氢呋喃聚合介孔催化剂Zr-PHTS合成、表征及反应性能

在水-有机溶剂复合体系中,以P123为结构导向剂水热直接合成了锆掺杂介孔固体酸催化剂(Zr-PHTS),运用XRD、TEM、N2吸附-脱附以及NH3-TPD、Py-FTIR等手段对催化剂进行了表征.结果表明,在硅锆摩尔比20-100考察范围内,所得Zr-PHTS样品均显示有序二维六方晶相结构,具有以L酸为主的中等强度的酸性中心;随着锆引入量的变化Zr-PHTS的比表面积仅显示少量的变化,孔径维持在9.8 nm;在四氢呋喃聚合反应中Zr-PHTS显示出较好的催化活性,硅锆摩尔比30的样品表现出最佳的催化性能,聚合物收率达到40.4%,数均分子量2 135,推测催化剂表面酸性和孔结构决定了催化剂对四氢呋喃的聚合性能.     

新型层柱化合物合成、表征及催化活性

将含过氧铌一、三取代钨硅、钨磷过氧杂多阴离子利用离子交换法嵌入Zn2Al类水滑石中制得层柱化合物,利用XRD,IR,UV等方法对产物的结构进行了表征。结果表明在层柱化合物中过氧杂多阴离子仍然保持Keggin结构,并且过氧键没被破坏。层柱化合物在酯化反应中显示优良的催化性能。     

过氧杂多阴离子型层柱化合物的合成、表征及催化活性

通过离子交换法,将含Zr过渡金属离子1,3取代钨硅、钨磷过氧杂多酸盐嵌入Zn2Al类水滑石中,获得了层柱化合物,并用XRD,IR,UV等手段对产物的结构进行了表征.结果表明过氧杂多阴离子进入水滑石层间后,水滑石的层间距从0.92增大到1.47 nm,且过氧链没被破坏.层柱化合物在酯化反应中显示优良的催化性能.     

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.     

Preparation, characterization, and catalytic activity of rare earth metal oxide nanoparticles

In present study, a series of rare earth metal oxide (CeO₂, Pr₂O₃, and Nd₂O₃) nanoparticles have been prepared by sol–gel route using Ce(NO₃)₃·6H₂O, Pr(NO₃)₃·6H₂O and Nd(NO₃)₃·6H₂O, and citric acid as precursor materials. Powder X-ray diffraction, scanning electron microscopy, and transmission electron microscopy are employed to characterize the size and morphology of the nano oxide particles. The particles are spherical in shape and the average particle size is of the order of 11–30 nm. Their catalytic activity was measured on the thermal decomposition of ammonium perchlorate and composite solid propellants (CSPs) by thermogravimetry (TG), TG coupled with differential thermal analysis (TG–DTA), and ignition delay measurements. The ignition delays and activation energies are found to decrease when rare earth metal oxide nanoparticles were incorporated in the system. Addition of metal oxide nanoparticles to AP led to shifting of the high temperature decomposition peak toward lower temperature and the burning rate of CSPs was also found to enhance. However, E _a activation energy for decomposition was also found to decrease with each catalyst.