Synthesis and characterization manganese oxide nanobundles from decomposition of manganese oxalate

The present investigation reports, the synthesis of manganese oxide (α-Mn₂O₃) nanobundles using thermal decomposition and its physicochemical characterization. The α-Mn₂O₃ nanobundles have been prepared using manganese oxalate dihydrate powders as precursor in the presence of oleylamine and triphenylphosphine as solvent and capping agent. Transmission electron microscopy (TEM) analysis demonstrated Mn₂O₃ nanobundles compose of nanospheres with diameter 30 nm. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) spectroscopy. Manganese oxide nanocrystals have been prepared under different condition. The controlled experimental results showed that the use of oleylamine and triphenylphosphine as the solvent and capping agent in the chemical process played important role in the formation of the final products.     

Synthesis, characterization and optical properties of tin oxide nanoclusters prepared from a novel precursor via thermal decomposition route

As a new precursor, [bis(2-hydroxy-1-naphthaldehydato)tin(II)]; ([Sn(HNA)₂]), complex was used in thermal decomposition process for the synthesis of tin oxide (SnO₂) nanoclusters. The steric hindrance of the precursor raises the need of using co-surfactant, therefore oleylamine (C₁₈H₃₇N) was applied as the only surfactant of the reaction. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) spectroscopy. Also the novel precursor was thermal treated in solid-state reaction in different temperature, 400, 500, and 600 °C. Synthesized tin dioxide nanoclusters with tetragonal phase, have average size of 1.5-4 nm. Finally, optical properties of the products were examined and investigated by photoluminescence spectra.     

Synthesis, characterization, and reactivity of organometallic Zr(IV) carboxylate complexes

A series of zirconium(IV) complexes, [ZrX₂(XDK)], where XDK is the constrained carboxylate ligand m-xylylenediamine bis(Kemp's triacid imide), were prepared and structurally characterized. The solid state structure of the mononuclear carboxylate alkyl complex [Zr(CH₂Ph)₂(XDK)] reveals that one benzyl group is bonded in an η²-fashion to the metal center. The reactivity of [Zr(CH₂Ph)₂(XDK)] displays its electrophilic character toward nucleophiles strong enough to displace the η²-benzyl group. Thus, weak sigma donor ligands such as CO, alkynes and anilines do not react, whereas strong sigma donors, such as pyridines and isocyanides, rapidly form the monoadduct [Zr(CH₂Ph)₂(4-tert-butylpyridine)(XDK)] and [Zr{η²-2,6-Me₂PhNCCH₂Ph}₂(XDK)], an η²-iminoacyl derivative, respectively. Attempts to prepare zirconium amido complexes with H₂XDK generally afforded the eight-coordinate [Zr(XDK)₂] complex but use of the small amido ligand precursorZr(NMe₂)₄ allowed [Zr(NMe₂)₂(4-tert-butylpyridine)(XDK)] to be isolated in good yield.     

Synthesis, characterization and crystal structure of zirconium complex containing amidinate, guanidinate and amide ligand sets

A new zirconium complex containing amidinate, guanidinate and amide ligand sets with formula Zr[(CyN)₂CMe][(CyN)₂CNMe₂](NMe₂)₂ (1) (Cy = cyclohexyl) was synthesized by the insertion of the 1,3-dicyclohexylcarbodiimide moiety into the bond of zirconium and dimethylamido group. Characterization of the complex 1 was achieved using elemental analysis, ¹H and ¹³C NMR spectra and single crystal X-ray diffraction. The molecular structure of the complex 1 revealed that the coordination geometry around the zirconium is a distorted pseudo-octahedron. The metal center is surrounded by the four nitrogen atoms of two bidentate amidinate and guanidinate ligands positioned cis to each other and two cis-NMe₂ groups.     

Synthesis and characterization of norbelladine,a precursor of Amaryllidaceae alkaloid,as an anti-inflammatory/anti-COX compound

Rising ROS and systemic inflammation is often a serious concern in many disease conditions including obesity. Therefore, compounds with both anti-oxidant and anti-inflammatory activities are considered beneficial in preventing/treating several human chronic diseases. Norbelladine is an amine compound, a precursor for Amaryllidaceae alkaloids (e.g., belladine, crinamine, lycorine, and galanthamine) found in plants traditionally used for treating a variety of human diseases. However, little information is available about its potential health effects. Therefore, the amine was first synthesized, and its anti-oxidant and anti-inflammatory activities were investigated in this study. Also, the potential effects of the amine on NF-κB activation were investigated due to the critical involvement of ROS in the activation. Norbelladine was synthesized with more than 60% yield, analyzed by a HPLC method, and verified using NMR spectroscopic method. Then, its radical scavenging activity was investigated using DPPH- and superoxide radical assays. At the concentration of 10 μM, norbelladine was a compound able to quench DPPH-radical by 31% (P < 0.05) and reduce superoxide radicals from xanthine oxidase by 33% (P < 0.05). At the concentration of 0.25 μM, the amine also inhibited both COX-1 and COX-2 enzymes by 51% and 25% (P < 0.05), respectively. Furthermore, at the concentration of 10 μM, norbelladine inhibited NF-κB activation by 23% (P < 0.05). In summary, the data suggests that norbelladine may be a compound to quench radicals, inhibit COX enzymes as well as suppress NF-κB activation at relatively lower concentrations.     

Controlled morphologies of copper oxide single crystalline nanostructures by wet chemistry and thermal decomposition processes

A wet-chemical method to synthesize CuO nanocubes (0D), nanorods (1D) and nanosheets (2D) is demonstrated with using Cu(OAc)₂ as an inorganic precursor and triethylammine as a basic source in the presence of tetraoctylammonium bromide in a H₂O-C₂H₅OH mixed-solvent. We found that the nanocubes spontaneously self-assembled into nanorods that could further self-assemble into nanosheets via oriented attachment of the nanorods. Based on the structural characterization, we found that the CuO nanosheets grow primarily along the [0 1 0] direction. A single phase of CuO nanostructures was observed. Another simple thermal decomposition method was also developed to prepare monodispersed single crystalline CuO nanocubes controlled by the decomposition of the inorganic Cu(OAc)₂ precursor with triethylammine and TOAB in H₂O-C₂H₅OH solution on a Si wafer and indium tin oxide conducting glass. The composition of the CuO was further confirmed by XRD and XPS analyses.     

Synthesis and characterization of cobalt oxide nanoparticles by thermal treatment process

The simple preparation of Co₃O₄ nanoparticles from a solid organometallic molecular precursor N-N′-bis(salicylaldehyde)-1,2-phenylenediimino cobalt(II); Co(salophen) has been achieved via two simple steps: firstly, the Co(salophen) precursor was precipitated from the reaction of cobalt(II) acetate and N-N′-bis(salicylaldehyde)-1,2-phenylenediimino; H₂salophen; in propanol under nitrogen condition; then, cubic phase Co₃O₄ nanoparticles with the size of mostly 30-50 nm could be produced by thermal treatment of the Co(salophen) in air at 773 K for 5 h. The as-synthesized products were characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and scanning electronic microscopy (SEM). These results confirm that the resulting oxide was pure single-crystalline Co₃O₄ nanoparticles. The optical property test indicates that the absorption peak of the nanoparticles shifts towards short wavelength, and the blue shift phenomenon might be ascribed to the quantum effect. The hysteresis loops of the obtained samples reveal the ferromagnetic behaviors the enhanced coercivity (H_c) and decreased saturation magnetization (M_s) in contrast to their respective bulk materials.     

Synthesis, spectral properties, and antitumor activity of a new axially substituted phthalocyanine complex of zirconium(IV) with citric acid

The new axially substituted phthalocyanine (pc) complex of zirconium(IV) with citric acid is reported. It has been shown that the replacement of two Cl-atoms with two citric acid fragments takes place as the result of the reaction between [ZrCl2(pc)] and citric acid. The complex [Zr(citrate)2(pc)] was formed. The spectroscopic properties of the synthesized compound in DMSO, RPMI 1640 medium with and without fetal calf serum (FCS), H2O, and buffer (Tris) solutions have been described. Antitumor activity of this compound has been studied. The cytostatic activity was observed in the concentration range of 6.1-9.0x10(9) molecules [Zr(citrate)2(pc)]/cell and occurred in 4-6 h after treatment with [Zr(citrate)2(pc)] solution.     

Synthesis and structural characterization of new one- and two-dimensional lead(II) coordination polymers; new precursors for preparation of pure phase lead(II) oxide nanoparticles via thermal decomposition

Two new lead(II) nitrate coordination polymers from ligand 1,2-di-(4-pyridyl)-ethylene (bpe), [Pb₂(μ-bpe)₃(μ-NO₃)₂(NO₃)₂]_n (1) and {[Pb(μ-bpe)(μ-NO₃)₂(NO₃)(H₂O)]·(Hbpe)·0.5(bpe)}_n (2), were synthesized. The compounds 1 and 2 were characterized by IR spectroscopy, elemental analyses and X-ray crystallography. The structures of 1 and 2 may be considered coordination polymers of lead(II) consisting of metallocyclic chains formed by bridging bpe ligands, making two- and one-dimensional array of Pb(NO₃)₂ and bpe, respectively. Pure phase PbO nano-particles were obtained by thermolyses of compounds 1-2 in oleic acid as surfactant at 180 and 200 °C under air atmosphere. The PbO nanoparticles were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM).     

Synthesis, characterization and crystal structure of manganese (IV) complex derived from salicylic acid

The binuclear manganese (IV) [Mn₂(Hsal)₄(OH)₄] (H₂sal = salicylic acid) complex has been obtained from a complex reaction mixture in methanol consisting of Mn(II)(OAc)₂ · 4H₂O, GS ( a reagent obtained by refluxing glycine and salicylaldehyde in 1:1 molar ratio in methanol), monosodium salicylate and pyridine. The compound contains a distorted octahedral MnO₆ coordination unit of potential importance to high oxidation state manganese bimolecules.     

Synthesis, isolation, spectroscopic and structural characterization of a new pH complex structural variant from the aqueous vanadium(V)-peroxo-citrate ternary system

In a pH-specific fashion, V₂O₅, citric acid and H₂O₂ reacted at pH 5.5-6.0 and afforded a red crystalline product at 4 °C. Elemental analysis pointed to the molecular formulation . Complex 1 was further characterized by UV/Vis, FT-IR, NMR, cyclic voltammetry, and X-ray crystallography. The X-ray structure of 1 reveals two dinuclear vanadium-peroxo-citrate subunits, A and B, linked through a hydrogen bond. In both A and B, the citrate ligands have different protonation states, ultimately affording a pentagonal bipyramidal geometry around each V(V) ion. The peroxide ligands bind V(V) in a side-on fashion. pH-Dependent, non-thermal and thermal transformations of 1 unravel its connection with key participants in the vanadium-peroxo-citrate ternary system and project its association with other non-peroxo binary complexes of variable vanadium oxidation state, geometry, citrate binding mode and state of protonation. Overall, the surprising twist in the aqueous synthetic chemistry of the investigated ternary system: (a) projects a new pH structural variant (species A) as a component of the speciation; (b) provides an in-depth look at that speciation under specific pH conditions; and (c) offers significant insight into the aqueous structural speciation of vanadium with peroxide and citrate, and its potential relevance to biological processes.     

Synthesis,characterization and in vitro cytotoxicity of new organotin(IV) derivatives of N-methylglycine

The synthesis and characterization of new coordination compounds of some diorganotins(IV) with N-methylglycine (sarcosine) are reported; all these derivatives mainly tend to assume a chelate structure. As single crystals were not obtained, a large number of experimental techniques were used to accomplish a definitive characterization and determination of their structure. Results obtained by (1)H/(119)Sn NMR, FT-IR and (119)mSn-M?ssbauer spectroscopy and thermogravimetric analysis allow us to deduce the pentacoordination for 1:1 (Sn/sarcosine) derivatives [R(2)SnCl(2)(Sar)](+)Cl(-) (R=Me, n-Bu) in a trigonal-bipyramidal structure, and the hexacoordination for 1:2 complexes [R'(2)Sn(Sar)(2)](2+)2Cl(-) (R'=Me, n-Bu, Ph) in an octahedral structure; however, the probability of partially or totally non-chelate structures for some adducts increases with the steric hindrance of the R/R' groups and the number of the sarcosine molecules bound to the tin atom, so that they give rise to fluxional equilibria in solution. Finally, the synthesized compounds have been tested for in vitro cytotoxic activity against human adenocarcinoma HeLa cells showing, in some cases, strong activity even at low concentration.     

Preparation of trimethylsilyl alkyne complexes of bis(pentamethylcyclopentadienyl)zirconium, (η-C5Me5)2Zr(RC≡CSiMe3), and their regioselective reactions with nitrous oxide

Benzene solutions of Cp^*₂ZrCl₂ (1) (Cp^* = η⁵-C₅Me₅) react with the alkynes Me₃SiC≡CPh, Me₃SiC≡C(c-C₅H₉) and Me₃SiC≡CCMe₃ in the presence of Na/Hg amalgam to afford high yields of the respective alkyne complexes Cp^*₂Zr(Me₃SiC≡CPh) (2), Cp^*₂Zr{Me₃SiC≡C(c-C₅H₉)} (3) and Cp^*₂Zr(Me₃SiC≡CCMe₃) (4) as crystalline compounds. Complex 2 crystallizes in the triclinic space group with a = 9.791(6), b = 10.466(6), c = 15.756(12) Å, = 86.09 (5), β = 72.09(5), γ = 72.06(4)° and Z = 2. The least-squares refinement converged to R(F) = 0.0604 and R(wF) = 0.0628 for the 3655 unique data with F_o > 4σ (F_o). Salient metrical parameters of the bound alkyne include the following: C(30)-C(31) = 1.340(9) Å; Zr-C(30) = 2.178(6) Å; Zr-C(31) = 2.219(5) Å; C(30)-C(31)-Si = 141.0(5)°; C(31)-C(30)-C(26) = 135.5(5)°. Nitrous oxide reacts with 2 or 3 to afford ((5) R = Ph; (6) R = c-C₅H₉) and 1 equiv. of N₂ via an intermediate, , which is unstable with respect to loss of dinitrogen to give the oxametallacyclobutene derivatives 5 and 6. The oxygen-atom insertion is regiospecific for the Zr-C bond that is attached to the carbyl (Ph or c-C₅H₉) substituent. Under similar conditions, complex 4, in which the alkyne is particularly labile, gives a myriad of products in its reaction with N₂O.     

Sonochemical synthesis of nano-sized metal-organic lead(II) polymer: A precursor for the preparation of nano-structured lead(II) iodide and lead(II) oxide

Nanoparticles of a new Pb^II metal-organic polymer, [Pb(μ-pyr)(μ-I)₂]_n (1), with a net-like morphology have been synthesized by the reaction of pyrazine with Pb(NO₃)₂ and NaI via sonochemical irradiation. Nano-structured PbI₂ and PbO were synthesized from compound 1 by calcination at argon and air atmospheres, respectively. The structure of 1 was determined by single crystal X-ray crystallography and the nano-structures were characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The thermal stability of nano-sized and single crystalline samples of 1 were studied and compared.     

Preparation, spectral characterization, cytotoxic and thermal studies of platinum (IV) thiohydrazone complexes

Platinum (IV) complexes of type [Pt(L)₂Cl₂] [where, L=benzaldehyde-N,N-diphenyl-N-thiohydrazone (L¹), salicylaldehyde-N,N-diphenyl-N-thiohydrazone (L²), acetaphenone-N,N-diphenyl-N-thiohydrazone (L³) and cyclohexanone-N,N-diphenyl-N-thiohydrazone (L⁴)] have been synthesized. The thiohydrazones can exist as thione–thiol tautomer and coordinates as a bidentate N–S ligand. The ligands found to act in monobasic bidentate fashion. Analytical data reveals that metal to ligand stoichiometry is 1:2. The complexes have been characterized by elemental analysis, IR, mass, electronic, ¹H NMR spectroscopic studies, and TG/DTA study. Various kinetic and thermodynamic parameters like order of reaction (n), activation energy (E_a), apparent activation entropy (S^#) and heat of reaction (ΔH) have also been carried out for one complex. Cytotoxic study has also been carried out for one complex.     

Cellulose nanocrystals as a reinforcing material for electrospun poly(methyl methacrylate) fibers: Formation, properties and nanomechanical characterization

Uniform fibers composed of poly(methyl methacrylate) (PMMA) reinforced with progressively increasing contents of cellulose nanocrystals (CNCs), up to 41 wt% CNCs, have been successfully produced by electrospinning. The morphological, thermal and nanomechanical properties of the composite sub-micron fibers were investigated. The CNCs derived from wood pulp by sulfuric acid hydrolysis were well dispersed in solutions of PMMA and the processing solvent N,N-dimethylformamide prior to fiber formation. Well-formed fibers with controllable diameters were generated reproducibly at all CNC contents investigated including 41 wt%. The orientation of the CNCs along the fiber axis was facilitated by the electrospinning process and observed directly from microscopy examination. Shifts in thermal transitions of PMMA with increasing CNC content suggest hydrogen bonding interactions between CNC hydroxyl groups and carbonyl groups on the PMMA matrix. Nanoscale dynamic mechanical analysis (nano-DMA) was performed using nanoindentation on single fibers perpendicular to the fiber axis. Many of the current challenges associated with single fiber nanoindentation are addressed, such as fiber diameter range and minimum, depth to diameter ratio, and valid depth range under these experimental conditions. Fibers that contained 17 wt% CNCs showed a modest increase of 17% in the storage modulus of PMMA, a high modulus polymer of interest for transparent composite applications.     

Synthesis, characterization and molecular structure of 1,1′ bis(diphenylphosphino ferrocene)dioxide complex of uranyl nitrate

A 1,1′ bis(diphenylphosphino ferrocene)dioxide complex of uranyl nitrate was synthesized and characterized by IR, ¹H and ³¹P{¹H} NMR spectroscopic and X-ray diffraction methods. The structure of the compound shows that the uranium atom is surrounded by eight oxygen atoms in a hexagonal bi-pyramidal geometry. Two oxygen atoms from 1,1′ bis(diphenylphosphino ferrocene)dioxide ligand and four oxygen atoms from the nitrate groups form a planar hexagon. The two uranyl oxygen atoms occupy the axial position. The 1,1′ bis(diphenylphosphino ferrocene)dioxide ligand acts as a bidentate chelating ligand with a bite angle of 71.56(8)° around the uranium(VI) atom, which is much smaller in value compare to any of the previously reported values (90.1°-154.0°) for this ligand.     

Synthesis, characterization and DNA modification induced by a novel Pt(IV)-bis(monoglutarate) complex which induces apoptosis in glioma cells

Programmed cell death or apoptosis is a mechanism for the elimination of cells that occurs not only in physiological processes but also in drug-induced tumor cell death. Thus, because cisplatin, cis-diamminechloroplatinum (II), produces important damages on the DNA inducing apoptosis in several cell lines it has become a widely used antitumor drug. However, cisplatin possesses some dose-limiting toxicities mainly nephrotoxicity. Pt(IV) complexes, such as iproplatin, ormaplatin, and JM216 are a new class of platinum complexes that exhibits less toxicity than cisplatin. Some of these complexes have shown significant antitumor activity and a low cross-resistance to cisplatin. In the present paper, we have analyzed the DNA binding mode and the cytotoxicity of a novel Pt(IV)-bis (monoglutarate) complex. The data show that this novel complex produces DNA interstrand cross-links to a higher extent and with a faster kinetics than cisplatin. Also the Pt(IV)-bis (monoglutarate) complex kills glioma cells at drug concentrations significantly lower than those of cisplatin. Interestingly, this Pt(IV) complex produces in the glioma cells characteristic features of apoptosis such as 'DNA laddering' and fragmented nuclei. Moreover, the p53 protein accumulates early in glioma cells as a result of Pt(IV)-bis (monoglutarate) treatment. These data indicate that the Pt(IV)-bis (monoglutarate) complex induces apoptosis in glioma cells through a p53-dependent pathway.     

Hydrothermal synthesis and structural characterization of a network oxide constructed from {Mo12O34(O3AsC6H5)4} clusters and {Cu(terpy)} subunits

The hydrothermal reaction of MoO₃, [Cu(CH₃CO₂)₂] · H₂O, 2,2^′:6^′,2″-terpyridine (terpy), H₂O₃AsC₆H₅, H₂O and H₂SO₄ yields aqua colored crystals of [{Cu(terpy)}₂Mo₁₂O₃₄(O₃AsC₆H₅)₄] · 2.25H₂O (1 · 2.25H₂O). The two-dimensional structure of 1 is constructed from {Mo₁₂O₃₄(O₃AsC₆H₅)₄}⁴⁻ clusters linked through {Cu(terpy)}²⁺ subunits. Each Cu(II) site exhibits {CuN₃O₂} coordination geometry and links two adjacent clusters. In turn, each cluster is associated with four Cu(II) sites through {MoO · Cu} interactions.     

Synthesis, crystal structure, luminescence and thermal decomposition kinetics of Eu(III) complex with 2,4-dichlorobenzoic acid and 2,2′-bipyridine

The complex of [Eu(2,4-DClBA)₃(bipy)]₂ (2,4-DClBA = 2,4-dichlorobenzoate; bipy = 2,2′-bipyridine) was obtained and characterized by elemental analysis, IR spectra, UV spectra, luminescence spectra, ¹H NMR spectra, single crystal X-ray diffraction and TG-DTG techniques. Two Eu³⁺ ions are connected by four carboxylate groups through bridging bidentate and bidentate chelating-bridging mode. The coordination number of europium ion is nine. The thermal decomposition behavior of the title complex under a static air atmosphere can be discussed by TG-DTG, SEM and IR techniques. The non-isothermal kinetics was investigated by using double equal-double steps method and Starink method. The mechanism function of the first decomposition step was determined. Meanwhile, the thermodynamic parameters (ΔH^≠, ΔG^≠ and ΔS^≠) and kinetic parameters (activation energy E and the pre-exponential factor A) were also calculated.