Aerobic oxidative acylation of nitroarenes with arylacetic esters under mild conditions: facile access to diarylketones.

A facile and regioselective base-mediated aerobic oxidative acylation of nitroarenes to access diarylketones under mild conditions has been developed. It features the use of bench-stable and readily available arylacetates as acyl surrogates, and the absence of transition-metals and synthetic oxidants. This protocol involves a cascade CDC/oxidative decarboxylation process.

Adsorption of lead(II) from aqueous solution onto Hydrilla verticillata.

The adsorption of Pb(II) onto Hydrilla verticillata was examined in aqueous solution with parameters of pH, adsorbent dosage, contact time and temperature. The linear Langmuir and Freundlich models were applied to describe equilibrium isotherms, and both models fitted well. The monolayer adsorption capacity of Pb(II) was found as 104.2 mg/g at pH 4 and 25 degrees C. Dubinin-Radushkevich (D-R) isotherm model was also applied to the equilibrium data. The mean free energy of adsorption (15.81 kJ/mol) indicated that the adsorption of Pb(II) onto H. verticillata may be carried out via chemical ion-exchange mechanism. Thermodynamic parameters, free energy (DeltaG (0)), enthalpy (DeltaH (0)) and entropy (DeltaS (0)) of adsorption were also calculated. These parameters showed that the adsorption of Pb(II) onto H. verticillata was a feasible, spontaneous and exothermic process in nature. The influence of Cd(2+), Cu(2+) and Ni(2+) on adsorption of Pb(2+) onto H. verticillata was studied, too. In the investigated range of operating conditions, it was found that the existence of Cd (2+), Cu (2+) and Ni (2+) had no impact on the adsorption of Pb(2+).

N-tert-Butyl-3-hydr-oxy-5-androstene-17-carboxamide monohydrate.

In the title compound, C(24)H(39)NO(2)·H(2)O, the A and C rings of the pregnolene derivative sterol adopt chair conformations, with the B ring in a flattened chair conformation and the five-membered ring in an envelope conformation twisted about the C/D ring junction. The N-tert-butyl-carboxamide substituent is equatorial. The 3ß-hydr-oxy H atom and one H atom of the water mol-ecule are disordered over two positions with equal occupancies. In the crystal structure, O-H⋯O hydrogen bonds between the 3ß-hydr-oxy groups of neighbouring mol-ecules form dimers in the bc plane and these dimers are stacked along the a axis by additional O-H⋯O hydrogen bonds involving the water mol-ecules. The steric effect of the bulky tert-butyl substituent in the carboxamide chain precludes hydrogen-bond formation by the N-H group.

1,3-Dimethyl-1H-indole-2-carbonitrile.

The title compound, C(11)H(10)N(2), crystallizes with two mol-ecules in the asymmetric unit, both of which are essentially planar (r.m.s. deviations = 0.014 and 0.016 Å). In the crystal, aromatic π-π stacking inter-actions occur [shortest centroid-centroid separation = 3.5569 (11) Å].

2-(2,6-Dichloro-benz-yl)pyrrolidine-1,3-dione.

In the title compound, C(11)H(9)Cl(2)NO(2), the dihedral anngle between the mean planes of the aromatic ring and the twisted pyrrolidinedione ring is 79.98 (9)°.

9-Benzyl-3-bromo-9H-carbazole.

The title compound, C(19)H(14)BrN, was synthesized by the N-alkyl-ation of (chloro-meth-yl)benzene with 3-bromo-9H-carbazole. The carbazole ring system is essentially planar (r.m.s. deviation = 0.013 Å) and forms a dihedral angle of 87.1 (2)° with the phenyl ring.

An Immunosensing System Using Stilbene Glycoside as a Fluorogenic Substrate for an Enzymatic Reaction Model.

A natural product, stilbene glycoside (2,3,5,4'-tetrahydroxydiphenylethylene-2-O-glucoside, TBG), has been evaluated for the first time as a potential substrate for horseradish peroxidase (HRP)-catalyzed fluorogenic reactions. The properties of TBG as a fluorogenic substrate for HRP and its application in a fluorometric enzyme-linked immunosensing system were compared with commercially available substrates such as p-hydroxyphenylpropionic acid (pHPPA), chavicol and Amplex red using Brucella melitensis antibody (BrAb) as a model analyte. The immunosensing body based on HRP-BrAb was constructed by dispersing graphite, BrAg and paraffin wax at room temperature. In a competitive immunoassay procedure, the BrAb competed with HRP-BrAb to react with the immobilized BrAg. In the enzymatic reaction, the binding HRP-BrAb on the sensing body surface can catalyze the polymerization reaction of TBG by H2O2 forming fluorescent dimers and causing an increase in fluorescence intensity. TBG showed comparable ability for HRP detection and its enzyme-linked immunosensing reaction system, in a linear detection ranging of 3.5´10-8~7.6´10-6g/L and with a detection limit of 1.7´10-9 g/L. The immobilized biocomposite surface could be regenerated with excellent reproducibility (RSD=3.8%) by simply polishing with an alumina paper. The proposed immunosensing system has been used to determine the BrAb in rabbit serum samples with satisfactory results.