Metallat‐Ionen [Al(OR)4]— als Chelatliganden für Übergangsmetall‐Kationen

Metalat Ions [Al(OR)₄]^— as Chelating Ligands for Transition Metal Cations Waterfree CoCl₂ can be reacted with [{Li(Diglyme)}{Al(O^tBu)₄}] in THF to the complex [Li(THF)₄][{CoCl₂}{Al(O^tBu)₄}]. Addition of diglyme to the reaction mixtures gives the blue compound [Li(diglyme)₂][{CoCl₂}{Al(O^tBu)₄}] ( 1 ). According to this procedure the Fe^II complex [Li(Diglyme)₂][{FeCl₂}₂{Al(O^tBu)₄}] ( 2 ) was formed by treatment of FeCl₂ with Li[Al(O^tBu)₄]. [{Li(diglyme)}{Al(O^tBu)₄}] in THF/diglyme can be used as alkoxide transfer reagent on TiCl₄ to give the neutral complex [TiCl₂(O^tBu)₂(diglyme)] ( 3 ). The sky‐blue salt [Li(THF)₄]₂[{CoCl₂}₃{Al(OCH₂Ph)₄}₂] ( 4 ) was obtained by reaction of Li[Al(OCH₂Ph)₄] with CoCl₂ in THF. By treatment of 4 with diglyme ligand redistribution was observed giving the sky‐blue compound [Li(Diglyme)₂]₂[{CoCl₂}₃{Al(OCH₂Ph)₄}₂] ( 5 ) and the violet salt [Li(Diglyme)₂]₂[Co₂Cl₅(OCH₂Ph)] ( 6 ). A similar salt can be synthesized also directly from Li[Al(O^tBu)₄] and CoCl₂ in diglyme to give [Li(Diglyme)₂]₂[Co₂Cl₅(O^tBu)] ( 7 ). 1 — 7 were characterized by IR spectroscopy, partly by mass spectrometry and X‐ray analyses. UV‐VIS spectra were recorded from 1 and 5 . According to the X‐ray analyses the M^II ions as well as the Al^III ions are coordinated distorted tedrahedrally. In 1 , 2 , 4 und 5 the unit [Al(OR)₄]^— acts a chelating ligand as desired.     

Morpholin als ambidenter Ligand

Morpholine as Ambident Ligand The reaction of MeInCl₂ with Li‐morpholinate [Li(Morph)] at 20 °C in THF gave after work‐up and recrystallization from diglyme the salt [Li(Diglyme){In₃Me₂Cl₄(Morph)₄}]·Diglyme ( 1 ). The treatment of the reaction mixture of MesInCl₂/Li(Morph) with wet THF yield as only isolated compound the coordination polymer [Li₆Cl₆(HMorph)₃] ( 2 ). Under similar conditions the reaction of InCl₃ with Li(Morph) led after work‐up in wet THF to [Li(Diglyme)₂][InCl₄(HMorph)₂] ( 3 ). 1 – 3 were characterized by NMR and IR spectroscopy as well as by X‐ray analysis. According to this, 1 contains the trinuclear anion [In₃Me₂Cl₄(Morph)₄]^? in which one of the morpholinate ligands is coordinated via N atom to the In³⁺ ions, while the O atom belongs to the coordination sphere of the Li⁺ ion. In 2 , LiCl forms a hexagonal heteroprismn, in which the morpholine molecules are responsible for a 3d network via coordination of both Lewis‐basic heteroatoms. 3 contains trans‐[InCl₄(Hmorph)₂]^? ions, connected by hydrogen bonding along [011].     

β‐Aminoacrolein: An ab initio,AIM and NBO study

The molecular structure and the intramolecular hydrogen bonding of β‐aminoacrolein and its simple derivatives were investigated at the MP2 and B3LYP levels of theory using the standard 6‐311++G(d, p) basis set. The “atoms in molecules” or AIM theory of Bader which is based on topological properties of the electron density (ρ), was used. Additionally, an analysis of the critical points was performed to study the nature hydrogen bonding in these systems. Natural bond orbital (NBO) analysis was also carried out for to better comprehend the nature of the intramolecular interactions in β‐aminoacrolein and its derivatives. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008     

Photoluminescence and electrochemical investigation of curcumin-reduced graphene oxide sheets

This paper reports on a novel low-temperature method for preparing curcumin-reduced graphene oxide (Cur-rGO) from graphene oxide (GO) and investigates their cyclic voltammetry (CV) and photoluminescence (PL) properties. GO sheets were synthesized using modified Hummers’ method and then were chemically reduced using polyphenol curcumin into graphene sheets. Atomic force microscopy, transmission electron microscopy and x-ray photoelectron spectroscopy were used to confirm the formation of Cur-rGO and revealed their functionalization with polyphenol curcumin. The electrochemical and optical properties of the Cur-rGO sheets were investigated using CV and PL spectroscopy. According to the PL and CV characterization for the Cur-rGO sheets, charges and resonant energy were transferred from curcumin molecules to the GO sheets’ surfaces. This arises from the bonding of the fluorescence curcumin molecules to the Cur-rGO surfaces, through π–π stacking of their aromatic rings. It should be noted that curcumin molecules act as electron donors, suppressing the fluorescence of the GO sheets while improving their electrochemical activities.     

Self-assembly of charged Bodipy dyes to form Cassettes that display intracomplex electronic energy transfer and accrete into liquid crystals

Red- and blue-absorbing boron dipyrromethene dyes, bearing opposite electronic charges, associate in solution to form a 1:2 complex having a stability constant of ca. 10(17) M(-2). The complex can be dismantled by addition of a large excess of tetra-N-butylammonium cations. The same complex displays liquid crystalline properties on heating from rt to above 150 °C, as characterized by various experimental techniques. Highly efficient electronic energy transfer from the red to the blue dye occurs in both the initial complex and the subsequent mesomorphic state.     

New mono- and binuclear Pd(II) complexes containing 1,2,4-triazole moieties

The reaction of AMTT (AMTT = 4-amino-3-methyl-1,2,4-triazol-5-thione, HL1) with palladium(II) chloride and triphenylphosphane as a co-ligand in acetonitrile afforded the mononuclear Pd^II-complex [(PPh₃)Pd(HL1)Cl]Cl·2CH₃CN (1). The complex [(PPh₃)Pd(HL1)I]Cl·1/2H₂O (2) was prepared via halogen exchange between 1 and sodium iodide in methanol/acetonitrile. The first binuclear palladium(II) complex containing singly deprotonated HL1, [(PPh₃)₂ClPd(L1)Pd(PPh₃)Cl]Cl·1/3H₂O·CH₃OH (3), was prepared by the reaction of HL1 with palladium(II) chloride and triphenylphosphane in the presence of sodium acetate in methanol.     

Extended integer rank reduction formulas and Smith normal form

We present an integer rank reduction formula for transforming the rows and columns of an integer matrix A. By repeatedly applying the formula to reduce rank, an extended integer rank reducing process is derived. The process provides a general finite iterative approach for constructing factorizations of A and A ^T under a common framework of a general decomposition V ^T AP?=?Ω. Then, we develop the integer Wedderburn rank reduction formula and its integer biconjugation process. Both the integer biconjugation process associated with the Wedderburn rank reduction process and the scaled extended integer Abaffy–Broyden–Spedicato (ABS) class of algorithms are shown to be in the integer rank reducing process. We also show that the integer biconjugation process can be derived from the scaled integer ABS class of algorithms applied to A or A ^T . Finally, we show that the integer biconjuagation process is a special case of our proposed ABS class of algorithms for computing the Smith normal form.     

Development and Validation of a Stability Indicating HPLC Method for Determination of Granisetron

The aim of this study was to study the stress degradation of granisetron and analysis of the drug in the presence of its degradation products. Forced degradation studies were conducted on bulk sample using acidic, alkaline, oxidative, heat and photolytic conditions. Granisetron was relatively unstable under acidic, alkaline and oxidative conditions. Separation of granisetron and degradation products was achieved using a Nova‐Pak C₈ column and acetonitrile‐KH₂PO₄ 25 mM (75:25, v/v) as mobile phase with UV detection at 305 nm. The method was linear over the range of 0.2‐15 μg/mL granisetron (r² > 0.999). The within‐day and between‐day precision values were also in the range of 0.5‐4%. The proposed method was successfully applied for quantitative determination of granisetron in tablets and in vitro dissolution studies.     

Electrochemical determination of piroxicam on the surface of pyrolytic graphite electrode modified with a film of carbon nanoparticle-chitosan

The electrochemical behavior of the anti-inflammatory drug piroxicam is studied at the surface of a plain pyrolytic graphite electrode modified with chitosan-doped carbon nanoparticles. An electroactive surface was produced by drop-casting a suspension of the modifier and characterized by atomic force microscopy. A remarkable enhancement is found in studies on the cyclic voltammetric response towards piroxicam. This is described on the basis of the thin-layer mass transport regimes within the porous films, which leads to a considerable increase in the active surface area of the electrode. The electrode shows a linear response to piroxicam in the range of 0.05–50 μM, with a detection limit of 25 nM (at S/N of 3). The electrode was successfully applied to the determination of piroxicam in pharmaceutical and clinical preparations with satisfactory accuracy and precision.     

Simultaneous study of cure kinetics and rheology of montmorillonite/vinyl ester resin nanocomposites

In this work, the effect of quaternary ammonium salt containing nanoclay content (1–5 wt%) on phase morphology, rheology, cure kinetics, and mechanical properties of the vinyl ester resin (VER)‐based nanocomposites was studied. The morphological characterization including d‐spacing measurement, microscopy observation and phase‐height image processing were performed on the prepared nanocomposites using small angel X‐ray scattering (SAXS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). According to the results obtained from these techniques, it was concluded that an intercalated morphology existed for all the nanocomposites. The kinetic analyses of the isothermal curing followed by storage modulus obtained from the rheometry experiments are shown to be an affective rheological characteristic to investigate the cure behavior of VER/clay nanocomposites. In addition, the most important finding regarding the effect of nanoclay on the cross‐linking behavior of VER systems lays on the chemisorption and physisorption of the reacting monomers and initiator molecules on the nanoclay platelets surface which is found to be responsible for the retardation of the cure reaction caused by organoclay. Eventually, the mechanical characterizations were performed through the tensile, flexural and impact analysis tests. In this case, a considerable improvement of the bulk mechanical responses such as tensile and flexural strengths and also the corresponding moduli were observed for the nanocomposites. Copyright © 2011 John Wiley & Sons, Ltd.