Unexpected Self‐Sorting Self‐Assembly Formation of a [4:4] Sulfate:Ligand Cage from a Preorganized Tripodal Urea Ligand

The design and synthesis of tripodal ligands 1 – 3 based upon the N‐methyl‐1,3,5‐benzenetricarboxamide platform appended with three aryl urea arms is reported. This ligand platform gives rise to highly preorganized structures and is ideally suited for binding SO₄^2? and H₂PO₄^? ions through multiple hydrogen‐bonding interactions. The solid‐state crystal structures of 1 – 3 with SO₄^2? show the encapsulation of a single anion within a cage structure, whereas the crystal structure of 1 with H₂PO₄^? showed that two anions are encapsulated. We further demonstrate that ligand 4 , based on the same platform but consisting of two bis‐urea moieties and a single ammonium moiety, also recognizes SO₄^2? to form a self‐assembled capsule with [4:4] SO₄^2?: 4 stoichiometry in which the anions are clustered within a cavity formed by the four ligands. This is the first example of a self‐sorting self‐assembled capsule where four tetrahedrally arranged SO₄^2? ions are embedded within a hydrophobic cavity.     

A Regio‐ and Stereoselective ω‐Transaminase/Monoamine Oxidase Cascade for the Synthesis of Chiral 2,5‐Disubstituted Pyrrolidines

Biocatalytic approaches to the synthesis of optically pure chiral amines, starting from simple achiral building blocks, are highly desirable because such motifs are present in a wide variety of important natural products and pharmaceutical compounds. Herein, a novel one‐pot ω‐transaminase (TA)/monoamine oxidase (MAO‐N) cascade process for the synthesis of chiral 2,5‐disubstituted pyrrolidines is reported. The reactions proceeded with excellent enantio‐ and diastereoselectivity (>94 % ee; >98 % de) and can be performed on a preparative scale. This methodology exploits the complementary regio‐ and stereoselectivity displayed by both enzymes, which ensures that the stereogenic center established by the transaminase is not affected by the monoamine oxidase, and highlights the potential of this multienzyme cascade for the efficient synthesis of chiral building blocks.     

Graphene materials preparation methods have dramatic influence upon their capacitance

Graphene related materials are widely expected to play a major role as materials for the construction of supercapacitors. We demonstrate here that graphene oxides prepared by various well-established methods exhibit dramatically different capacitances. We exfoliated graphite oxide sonographically to graphene oxide (GO) and we reduced GO by chemical or electrochemical means to chemically reduced graphene oxide (CRGO) and electrochemically reduced graphene oxide (ERGO); in addition, graphite oxide was thermally exfoliated leading to thermally reduced graphene oxide (TRGO). We found clear dependence of weight specific capacitance upon amount of oxygen containing groups presented on the surface of these graphenes. GO exhibits the lowest and TRGO the highest values of weight specific capacitance.     

Analysis of sexual assault evidence by desorption electrospray ionization mass spectrometry

Desorption electrospray ionization mass spectrometry (DESI‐MS) is employed in the forensic analysis of chemical components present in condoms and imaging of latent fingerprints as circumstantial evidence of sexual assault. Polymers such as nonoxynol‐9, polyethylene glycol, and polydimethylsiloxane, as well as small molecules additives such as N‐methylmorpholine, N‐octylamine, N,N‐dibutyl formamide, and isonox 132, commonly used in lubricated condom formulations, were successfully characterized by DESI. The results suggest that DESI‐MS is useful for identification of this type of evidence, and it has advantages over conventional extractive techniques, in terms of speed of analysis and ease of use. Copyright © 2013 John Wiley & Sons, Ltd.     

Lipase production byPenicillium restrictum in a bench-scale fermenter

A preliminary screening work selectedPenicillium restrictum as a promising micro-organism for lipase production. The physiological response of the fungus towards cell growth and enzyme production upon variable carbon and nitrogen nutrition, specific air flow rate (Qa) and agitation (N) was evaluated in a 5-L bench-scale fermenter. In optimized conditions for lipase production meat peptone at 2% (w/v) and olive oil at 1% (w/v) were used in a growth medium with a C/N ratio of 9.9. Higher C/N ratios favored cell growth in detriment of enzyme production. Low extracellular lipase activities were observed using glucose as carbon source suggesting glucose regulation. Final lipase accumulation of 13,000 U/L was obtained, using optimized specific air flow rate (Qa) of 0.5 wm and an impeller speed (N) of 200 rpm. Agitation showed to be an important parameter to ensure nutrient availability in a growth medium having olive oil as carbon source.     

Salting‐out assisted liquid/liquid extraction with acetonitrile: a new high throughput sample preparation technique for good laboratory practice bioanalysis using liquid chromatography–mass spectrometry

Acetonitrile, an organic solvent miscible with aqueous phase, has seen thousands of publications in the literature as an efficient deproteinization reagent. The use of acetonitrile for liquid–liquid extraction (LLE), however, has seen very limited application due to its miscibility with aqueous phase. The interest in LLE with acetonitrile has been pursued and reported in the literature by significantly lowering the temperature of the mixture or increasing the salt concentration in the mixture of acetonitrile and aqueous phase, resulting in the separation of the acetonitrile phase from aqueous phase, as observed in conventional LLE. However, very limited application of these methods has been reported. The throughput was limited. In this report, we report a new sample preparation technique, salting‐out assisted liquid–liquid extraction with acetonitrile, for high‐thoughput good laboratory practice sample analysis using LCMS, Two compounds from an approved drug, Kaletra^®, were used to demonstrate the extractability of drugs from human plasma matrix. Magnesium sulfate was used as the salting‐out reagent. Extracts were diluted and then injected into a reversed phase LC‐MS/MS system directly. One 96‐well plate was extracted with this new approach to evaluate multiple parameters of a good laboratory practice analytical method. Results indicate that the method is rapid, reliable and suitable for regulated bioanalysis. With minimal modification, this approach has been used for high‐throughput good laboratory practice analysis of a number of compounds under development at Abbott. Copyright © 2008 John Wiley & Sons, Ltd.     

The chemistry of chromium(V) oxide trichloride

Summary The recent upsurge of interest in chromium(V)^(1–8) has highlighted two features of especial interest in its chemistry. Firstly, the complexes of chromium(V) are considerably more stable than has generally been assumed in the past, as exemplified by the recent characterisation of a water soluble complex, potassium bis(2-hydroxy-2-methylbutyrato)oxochromate(V)⁽¹⁾. Secondly, the d1 electronic configuration of the complexes makes them ideal model systems for study by such techniques as electron paramagnetic resonance (²) and electronic absorption spectroscopy^(3,4) . Although chromium(V) oxide trichloride was first prepared in 1962, by the reaction between chromium(VI) oxide and SOCl₂ or SO₂Cl₂ ^{(9 10)}, and subsequently by the reaction between CrO₂Cl₂ and BCl₃ ⁽¹¹⁾, its chemistry and physical properties have remained virtually unstudied. We report here the first series of reactions of CrOCl₃, along with details of its i.r. and photoelectron spectra.     

New amphiphilic silicon(IV) phthalocyanines as efficient photosensitizers for photodynamic therapy: synthesis, photophysical properties, and in vitro photodynamic activities

A novel series of silicon(IV) phthalocyanines substituted axially with one or two 1,3-bis(dimethylamino)-2-propoxy group(s) have been prepared by ligand substitution and alkoxy exchange reactions. Two dicationic and tetracationic phthalocyanines have also been prepared by methylation of two of these compounds. The nonionic phthalocyanines are essentially nonaggregated in common organic solvents and show a weak fluorescence emission, while the methylated derivatives are also nonaggregated, even in aqueous media, and exhibit a strong fluorescence emission. These new phthalocyanines, in particular the unsymmetrical and amphiphilic analogues, are highly potent against HepG2 human hepatocarcinoma cells and J774 mouse macrophage cells with IC50 values down to 0.02 microM. The photodynamic activities are related to the cellular uptake and the efficiency to generate singlet oxygen. A higher positive charge at the phthalocyanine hinders the uptake, reflected by the lower intracellular fluorescence intensity. Fluorescence microscopic studies have also revealed that the unsymmetrical phthalocyanine SiPc[C3H5(NMe2)2O](OMe) (4) has a high and selective affinity to the mitochondria of HepG2 cells.     

A metabonomic investigation of hepatotoxicity using diffusion-edited 1H NMR spectroscopy of blood serum

It has been shown extensively, that chemometric investigations of 1H NMR spectra of rat urine taken from animals dosed with model toxins produce characteristic patterns of metabolic responses and that this permits the identification of biomarkers of toxic response and regeneration. To date, metabonomic methods have been mainly optimised for urine which contains mainly low molecular weight moieties, and thus a conventional 1-dimensional 1H NMR pulse sequence is an efficient means of obtaining information-rich data. In the case of biofluids such as blood plasma or serum, which contain a wide range of macromolecules the resonances of which can overlap with peaks from small molecule metabolites, the information giving rise to sample classification can be concealed in a conventional NMR spectrum andthis presents a different analytical challenge in terms of chemometric analysis of spectral profiles. Here, the use of other types of NMR data have been investigated and it is shown that by using spectra where the peak intensities are edited according to their molecular diffusion coefficients, it is possible to improve differentiation of control animals and those treated with the model hepatotoxin, alpha-naphthylisothiocyanate (ANIT). By using diffusion-edited spectroscopy, plasma lipid moieties are less attenuated than those from small endogenous metabolites and thus the toxin-induced changes to the lipoprotein profiles are more easily detectable.