Nanosized silver–palm pollen nanocomposite,green synthesis,characterization and antimicrobial activity

Palm pollen (PP) has been widely used in nutrition, pharmaceutical and cosmetic industries. In the present study, we explored the potential of PP in the synthesis of a silver nanoparticle (Ag NP). PP was used as both reducing and stabilizing agent. The Ag/PP nanocomposite was examined by field emission electron microscopy, X-ray diffraction, Fourier transform infrared (FT-IR) spectroscopy, ultraviolet spectroscopy and zeta potential measurement. The biosynthesized NPs showed surface plasmon resonance centered at 425 nm with an average particle size measured to be 23 nm and a zeta potential of ?30.9 mV. Prominent FT-IR signals were obtained and ascribed to phenolic and carbohydrate compounds involved in the formation of the Ag NPs, and proteins which participated in stabilization of the Ag NPs. The biologically synthesized Ag NPs were found to be extremely effective against E. coli (13.8 ± 0.25 mm) with a minimum inhibitory concentration of 20 µg/mL. Thus, such biosynthesized Ag NPs can be used in medicinal applications.     

Electrochemical synthesis and characterization of polydiphenylamine

Electrochemical oxidation of diphenylamine(DPA)in acetonitrile solution producedan adhesive conducting polydiphenylamine(PDPA)film on the electrode,which exhibited multiplecolour variation in a wide range of potential.The polymer was characterized by cyclic voltam-merry,FTIR and ESR.The results indicate that the electropolymerization of diphenylamine per-forms via the 4,4＇C—C phenyl-phenyl coupling mechanism.FTIR,ESR and conductivity mea-surements for the different states of PDPA show that polydiphenylamine can be reversibly dopedand dedoped either chemically or electrochemically.It is evidenced also that there are paramagneticspecies—polarons in PDPA supposed to be the current carrier.     

Photochemical synthesis and characterization of hydrogel–silver nanoparticle composites

Research on Chemical Intermediates - Hydrogels were synthesized by grafting polyacrylamide onto dextran using N,N′-methylene-bis-acrylamide as a cross-linker. The hydrogels were converted...     

Low-temperature synthesis and characterization of the Mn–Zn ferrite

Nanocrystalline ferrite with the composition: Mn_0.6Zn_0.4Fe₂O₄ was synthesized by two-stage route: the precipitation of Zn, Mn and Fe hydroxides from sulphates solution and the synthesis of a precursor by the sol–gel auto-combustion method. The ferrite powder obtained from the gel by ashing was sintered under air at a temperature of 720, 1150 and 1300 °C. The composition and morphology of the as-obtained phases were examined by ICP-AES, TG/DTA, XRD, FTIR, SEM and low-temperature nitrogen adsorption (BET). It was found that the spinel phase forms after gel combustion. The nanometric ferrite powder obtained as a result of the combustion is soft-agglomerated. The zinc content in the ferrite during ashing and auto-combustion is lower by about 21 mol% than the assumed one and the final product turn out to be Mn_0.68Zn_0.32Fe₂O₄.     

Electro organic synthesis and characterization of phenol–aniline based copolymers

A new series of copolymers of phenol and aniline poly(PHE-co-ANI) was synthesized at platinum electrode through electro-oxidative polymerization in acetonitrile in the presence of lithium perchlorate as supporting electrolyte. Electro-polymerization was studied by cyclic voltammetry. The resultant copolymers were characterized by UV–Vis, IR, ¹³C and ¹H NMR spectroscopy; surface morphology of the copolymers was investigated by scanning electron microscopy.     

Sol–gel synthesis and characterization of titania monolith with bimodal porosity

Monolithic titania materials with macro-mesoporosity bimodal texture have been prepared through a template-free sol–gel approach, based on the reaction of hydrolysis and polycondensation of titanium isopropoxide promoted by the slow released water from esterification between acetic acid and methanol under a strong acidic condition. With the coarsening of the titania oligomers, phase separation and sol–gel transition processes take place so as to form a homogeneous gel system that will change into a monolith after aging, drying and heat treatment. The synthesized titania monolith possesses a specific surface area of 77 m² g⁻¹ (calcined at 350 °C), an anatase with partly rutile crystallite structure and great mechanical strength. The synthesis method applied here is simple and easy to implement as no extra chemical modifier such as poly(ethylene oxide) (PEO) and formamide is needed to control the process. The properties of biomodal porous structure, satisfactory surface area and high mechanical strength will enable the monolith to be served as a chromatography column to separate phosphorus organo-compounds.     

Sol–gel template synthesis and characterization of VO2 nanotube arrays

In this paper, we report on the obtention of highly ordered VO₂ nanotube arrays synthesized by the simple sol?Cgel template method. Techniques of transmission electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy were used to characterize the morphology and structure of the as-synthesized nanotube arrays. It is found that the size of the as-obtained nanotubes has the dimension of 180?C220?nm in outer diameter, 110?C140?nm in inner diameter and up to 10???m in length. The results show that as-synthesized sample is assigned to VO₂ (B) phase in expected V/O ratio with V existing in the +4 oxidation state.     

Design,synthesis, and characterization of fullerene–peptide–steroid covalent hybrids

The present study reports the synthesis, spectral characterization, self-assembly properties, and preliminary in vitro study of antioxidant capacity of two triple covalent hybrids consisting of fullerene C₆₀, peptide, and steroidal moiety. Previously synthesized fulleropyrrolidinic acid and pregnenolone were connected by peptide linker using a multistep DCC/DMAP and/or EDC/HOBT esterification/amidation procedure. The hybrids were characterized by comparative analysis of spectroscopic data obtained from FTIR, UV–vis, HRMS, and extensive NMR experiments (¹H, ¹³C, COSY, HSQC, and HMBC). The self-assembling properties and morphology of triads samples prepared by drop-drying method were examined by scanning electron microscopy (SEM). Preliminary in vitro antioxidant activity was studied by Ferrous ion Oxidation-Xylenol orange (FOX) method.     

Sol–gel combustion synthesis and characterization of nanostructure copper chromite spinel

Nanocomposite copper chromite spinel was fabricated by sol–gel process using copper nitrate trihydrate, chromium nitrate nonahydrate, ethylene glycol, diethyl ether, and citric acid. The thermoanalytical measurements (TG–DTG), X-ray powder diffractometry (XRD), field emission scanning electron microscopy (FESEM), and energy dispersive X-ray analysis were used to characterize the structural and the chemical features of the nanocomposites. TG–DTG results showed that the major mass loss for copper(II) nitrate, chromium(III) nitrate as precursors occur at 258 and 140 °C, respectively. The major mass loss for dried gel of copper chromite occurs at 310 °C. XRD data revealed the formation of pure copper chromite after thermal decomposition at 1,000 °C for 2 h. The observation of XRD patterns reveals the presence of single-phase tetragonal spinel CuCr₂O₄. FESEM analysis of calcined composite was found to be in the range of 20–30 nm.     

Sol–gel synthesis,optical and structural characterization of ZrOS nanopowder

In this paper, we report the synthesis of tetragonal zirconium oxysulfide t-ZrOS nanopowder by the sol–gel method using water solution of a precursor containing thiourea [CS(NH₂)₂] and zirconium in the form of an anionic oxalate complex [Zr(C₂O₄)]^4?. The tetragonal t-ZrOS structure with space group P4/nmm revealed by X-ray patterns showed preferred orientation along (101) plane. For surface morphology, compositional and optical absorption studies, scanning electron microscopy, energy dispersive X-ray and ultraviolet–visible spectroscopy were employed for characterization of the powder respectively. A nearly constant value of the refractive index at higher wavelength λ ≥ 1,100 nm was found to be 2.19. High indirect and direct optical band gap of ~2.0 and 2.50 eV with absorbance <40 % were obtained for the powder.     

One-pot synthesis of phosphate diesters and phosphonate monoesters via a combination of microwave-CCl3CN–pyridine coupling conditions

Simple and convenient one-pot synthesis of a phosphorus–oxygen bond in phosphate diesters and phosphonate monoesters using trichloroacetonitrile as an activating agent and pyridine as a solvent under microwave irradiation conditions was described. This method is useful for the preparation of various biologically interesting glycophospholipids and also phosphate diesters or phosphonate monoesters containing diverse moieties such as alkyl, prenyl, and benzyl substituents.     

Hydrothermal synthesis and structural characterization of two inorganic–organic composite sandwich-type tungstogermanates

Two new inorganic–organic hybrid polyoxotungstates [enH₂][C₈N₄H₂₂]₃H₂[Co₄(enH)₂(GeW₉O₃₄)₂] · 6H₂O (1) and [Co(en)₃]₂H₆[Co₄(enH)₂(GeW₉O₃₄)₂] · 14H₂O (2) (en = ethylenediamine) have been synthesized by hydrothermal methods and characterized by IR, TG, XRD, XPS, elemental analysis, and single-crystal X-ray analysis. The polyoxoanion frameworks of the two compounds consist of two classical tetra-Co sandwiched polyoxoanions [Co₄(H₂O)₂(GeW₉O₃₄)₂] in which two organic ligands substitute two water molecules. The tetra-Co clusters in 1 and 2 exhibit the familiar structural type of a β-junction at the sites of metal incorporation. Compound 1 is of interest owing to its C₈N₄H₂₀ ligands resulting from the reaggregation of triethylenetetramine which occurs under 160°C.     

A study on sol–gel synthesis and characterization of SiC nano powder

Nano sized β-SiC particles were synthesized from sol–gel process. Mono dispersed β-SiC nano particles with semi spherical morphology were obtained by employing APC as a dispersant agent and adjusting pH in the range of 2.5–4. Phenolic resin and TEOS were employed as precursors and heat treatment was conducted up to 1500 °C. Different techniques such as XRD, DTA, FTIR, PSA, SEM and TEM were used to characterize the formation of β-SiC. The (Si–O-C) bonds were formed by hydrolysis and condensation reactions in the gel while the nucleation of crystalline β-SiC was found to be initiated at 1400 °C. The primary particles in the sol were found to be (< 10 nm) while the size distribution in the final product was recorded in the range of 30–50 nm.     

Preparation and characterization of N–Ti-MCM-22 mesoporous molecular sieve and investigation of its photocatalytic properties

Nanocrystalline N-doped and Ti-containing MCM-22 catalyst was synthesized by the static hydrothermal method, using sodium azide as nitrogen source for doping, and tetra-n-butyl titanate [Ti(OC₄H₉)₄] as precursor for TiO₂. The catalysts were characterized by X-ray diffraction, transmission electron microscopy, and energy-dispersive spectroscopy. The results showed that a mesoporous region with ca. 3-nm pore size was created by expansion between lamellar crystalline sheets in Ti-MCM-22. Nitrogen was substituted for some of the lattice oxygen atoms. During liquid phase photocatalytic degradation of methylene blue under high-pressure Hg arc lamp irradiation, the as-prepared N-doped Ti-MCM-22 exhibited much higher activity than the undoped Ti-MCM-22, attributed to the effect of the nitrogen dopant. The effects of N-doping amount, catalyst concentration, initial solution pH, and initial concentration of MB on the photocatalytic activity were investigated.     

Total synthesis and cytotoxicity of (−)-jorumycin and its analogues

(?)-Jorumycin and its 15 C-22 analogues were prepared employing l-tyrosine as the chiral starting material via 21 steps. These analogues, along with (?)-jorumycin itself, were evaluated in vitro for cytotoxicity against HCT-8, BEL-7402, Ketr3, A2780, MCF-7, A549, BGC-823, Hela, HELF, and KB cells. The IC₅₀ values of the cytotoxicity of most of these analogs were at the level of nM, which was similar to that of (?)-jorumycin. Among these analogs including (?)-jorumycin, hippuric acid ester derivative 23 exhibited the most potent and broad-spectrum cytotoxic activity against the ten cell lines with an average IC₅₀ of 2.12 nM.     

Sol–gel synthesis and characterization of SiO2–Tac nanocomposites with controlled volume fraction

Nanocrystalline tantalum carbide (TaC) particles of average size ~15 nm dispersed in silica matrix, have been synthesized by the carbothermal reduction of Ta₂O₅ over a range of temperature 1,100–1,360 °C in Ar atmosphere. Investigation of the stability diagram of carbon saturated Ta–O–N system suggests that the TaC phase can be successfully synthesized within the SiO₂ matrix when the partial pressure of O₂ and N₂ are restricted to approximately lower than 1.25 and 0.0001 atm. respectively. Two different synthesis routes are investigated in the present study which differ fundamentally in the order of addition of the precursors, tetraethyl orthosilicate (TEOS) and tantalum isopropoxide (Ta-iso). Rietveld refinement analyses of the powder X-ray diffraction data are carried out for the quantitative estimation of the two phases in the samples. The yield of TaC increases from 18 to 52 % when both TEOS and Ta-iso are added simultaneously to the water compared to the process where TEOS is added first to the water followed by the delayed addition of Ta-iso. Samples are further characterized by field emission scanning electron microscopy and high resolution transmission electron microscopy.     

In-situ green synthesis of highly active GSH-capped Pt–Au–Ag-hybrid nanoclusters

Recently much attention has been paid to the application of metal hybrid nanoparticles in industrial catalytic fields because of their super-efficient catalytic activity and attractive properties. We explored a novel strategy to prepare GSH-capped Pt–Au–Ag-hybrid nanoclusters through the synergistic effect between ascorbic acid(VC) and glutathione(GSH) with chloroplatinic acid, chloroauric acid, and silver nitrate as precursors. The potential utilization of as-prepared GSH-capped Pt–Au–Aghybrid nanoclusters for catalytic applications has been evaluated through the reduction of 4-nitrophenol(4-NP) with NaBH4; we obtained the kinetic data by monitoring with UV-Vis spectroscopy. Our results illustrate that GSH-capped Pt–Au– Ag-hybrid nanoclusters could facilitate the process of reduction of 4-NP in a way that is unprecedented. This approach may offer a novel, non-cytotoxicity, efficient catalyst for industry.