Optimization of microwave and infrared drying process of nettle leaves using design of experiments

Journal of Thermal Analysis and Calorimetry - Optimization of microwave and infrared drying processes of nettle leaves was investigated using dependent variables of drying time and phenolic...     

Rapid magnetic solid phase extraction with in situ derivatization of methylmercury in seawater by Fe3O4/polyaniline nanoparticle

A new Fe(3)O(4)/polyaniline nanoparticle (PANI) material has been successfully developed as magnetic solid-phase extraction sorbent in dispersion mode for the determination of methylmercury (MeHg) in aqueous samples, via quantification by gas chromatography/mass spectrometry (GC-MS). The resultant core-shell magnetic solid-phase extraction nanoparticle (MSPE-NP) sorbent was characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS) and Fourier transform-infrared (FTIR) spectroscopy. Fe(3)O(4)/PANI composites showed fibrous structure with diameters between 50 and 100 nm for fibers. The MSPE-NP process involved the dispersion of the Fe(3)O(4)/PANI nanoparticles in water samples with sonication, followed by magnetic aided retrieval of the sorbent and then, solvent (hexane) desorption of extracted MeHg for GC-MS analysis. The extraction, derivatization and adsorption conditions were optimized by selecting the appropriate extraction parameters including the amount of sorbent, extraction time, derivatizing reagent volume and extraction solvent. The calibration graph was linear in the concentration range of 0.5-300 ng mL(-1) (R(2)>0.993) with detection limit of 0.1 ng mL(-1) (n=3), while the repeatability was 4.1% (n=5). Enrichment factor was obtained as 91. Seawater sample was analyzed as real sample and good recoveries (>98%) were obtained at different spiked values.     

Mercury(II) complexes of new bidentate phosphorus ylides: synthesis,spectra and crystal structures

The reaction of dppm (1,1-bis(diphenylphosphino)methane) with 2-bromo-4-phenylacetophenone and benzyl bromoacetate in chloroform produces new phosphonium salts, [Ph₂PCH₂PPh₂CH₂C(O) C₆H₄Ph]Br (I) and [Ph₂PCH₂PPh₂CH₂COOCH₂Ph]Br (II). By allowing the phosphonium salts to react with the appropriate base, the bidentate phosphorus ylides, Ph₂PCH₂PPh₂=C(H)C(O)C₆H₄Ph (III) and Ph₂PCH₂PPh₂=C(H)C(O)OCH₂Ph (IV), were obtained. The reaction of these ligands with mercury(II) halides in dry methanol led to the formation of the mononuclear complexes {HgX₂[(Ph₂PCH₂PPh₂C(H)C(O)C₆H₄Ph)]} (X = Cl (V); X = Br (VI); X = I (VII)) and {HgX₂[(Ph₂PCH₂PPh₂C(H)COOCH₂Ph)]} (X = Cl (VIII); X = Br (IX); X = I (X)). The FTIR and ¹H, ³¹P and ¹³C NMR spectra were studied. The structure of compound III was unequivocally determined by the single-crystal X-ray diffraction technique. Single-crystal X-ray analysis of the {HgBr₂[(Ph₂PCH₂PPh₂C(H)C(O)C₆H₄Me)]} complex (XI) revealed the presence of a mononuclear complex containing the Hg atom in a distorted tetrahedral environment. In all complexes, the ylides referred to above were coordinated through the ylidic carbon and the phosphine atom.     

Modular Molecules: Site‐Selective Metal Substitution,Photoreduction, and Chirality in Polyoxometalate Hybrids

The first members of a promising new family of hybrid amino acid–polyoxometalates have emerged from a search for modular functional molecules. Incorporation of glycine (Gly) or norleucine (Nle) ligands into an yttrium‐tungstoarsenate structural backbone, followed by crystallization with p‐methylbenzylammonium (p‐MeBzNH₃⁺) cations, affords (p‐MeBzNH₃)₆K₂(GlyH)[As^III₄(Y^IIIW^VI₃)W^VI₄₄Y^III₄O₁₅₉(Gly)₈‐ (H₂O)₁₄] ? 47 H₂O ( 1 ) and enantiomorphs (p‐MeBzNH₃)₁₅(NleH)₃ [As^III₄(Mo^V₂Mo^VI₂)W^VI₄₄Y^III₄O₁₆₀(Nle)₉(H₂O)₁₁][As^III₄(Mo^VI₂W^VI₂)‐ W^VI₄₄Y^III₄O₁₆₀(Nle)₉(H₂O)₁₁] (generically designated 2 : L ‐Nle, 2 a ; D ‐Nle, 2 b ). An intensive structural, spectroscopic, electrochemical, magnetochemical and theoretical investigation has allowed the elucidation of site‐selective metal substitution and photoreduction of the tetranuclear core of the hybrid polyanions. In the solid state, markedly different crystal packing is evident for the compounds, which indicates the role of noncovalent interactions involving the amino acid ligands. In solution, mass spectrometric and small‐angle X‐ray scattering studies confirm maintenance of the structure of the polyanions of 2 , while circular dichroism demonstrates that the chirality is also maintained. The combination of all of these features in a single modular family emphasizes the potential of such hybrid polyoxometalates to provide nanoscale molecular materials with tunable properties.     

Essential oil composition and antioxidant activity of different extracts of Nepeta betonicifolia C.A. Meyer and Nepeta saccharata Bunge

Aerial parts essential oil of Nepeta betonicifolia and N. saccharata were obtained by hydrodistillation and analysed by GC-FID and GC-MS. Thirty-three and eighteen components represented 97.9% and 98.2% of the total oils identified, respectively. Main compounds of the oil of N. betonicifolia were 4aα,7β,7aα-nepetalactone (42.0%), germacrene D (6.0%), triplal (5.2%), 1-nor-bourbonanone (4.0%) and 1,8-cineole (3.2%). The principal constituents of the essential oil of N. saccharata were found to be 4aβ,7α,7aβ-nepetalactone (66.9%), germacrene D (12.9%), sabinene (6.5%) and trans-caryophyllene (3.3%). The radical scavenging capacity (RSC) of methanol extracts and chloroform, butanol and water subfractions of aerial parts of N. betonicifolia and N. saccharata were evaluated by using DPPH, FRAP and ABTS assays. TPC of each extract was measured using Folin-Ciocalteau. The antioxidant activity of the butanolic subfractions of both plants was higher than other extracts examined.     

Efficient Synthesis of β‐Acetamido Ketones and Esters Using Aluminum Chloride as an Inexpensive and Green Catalyst

Aluminum chloride (AlCl₃) efficiently catalyzes one‐pot multicomponent condensation of enolizable ketones or alkyl acetoacetates with aldehydes, acetonitrile and acetyl chloride to afford β‐acetamido ketone or ester derivatives in high to excellent yields and in relatively short reaction times. Moreover, by this synthetic method, some novel β‐acetamido ketones and esters (i.e. one complex structure) are prepared.     

Some exact solutions of F(R) gravity with charged (a)dS black hole interpretation

In this paper we obtain topological static solutions of some kind of pure F(R) gravity. The present solutions are two kind: first type is uncharged solution which corresponds with the topological (a)dS Schwarzschild solution and second type has electric charge and is equivalent to the Einstein-Λ-conformally invariant Maxwell solution. In other word, starting from pure gravity leads to (charged) Einstein-Λ solutions which we interpreted them as (charged) (a)dS black hole solutions of pure F(R) gravity. Calculating the Ricci and Kreschmann scalars show that there is a curvature singularity at r = 0. We should note that the Kreschmann scalar of charged solutions goes to infinity as r → 0, but with a rate slower than that of uncharged solutions.