Crystal Structures of Methyl and Ethyl N-(2,3-Dimethoxybenzyl)-N-(p-toluenesulfonyl)-2-phenylglycinates

The crystal structures of methyl and ethyl N-(2,3-dimethoxybenzyl)-N-(p-toluenesulfonyl)-2-phenylglycinates 4a and 4b respectively, have been determined by X-ray diffraction analysis. The presence of different alkyl ester groups in both molecules does not affect the geometry retaining a synclinal conformation for the N atom and the O atom of the C=O group [N—C17—C18—O5 38.1(5)° for 4a and 33.3(4)° for 4b ].     

Determination of orbifloxacin in rabbit plasma by high-performance liquid chromatography with fluorescence detection.

A simple and sensitive high-performance liquid chromatography method is developed for the determination of orbifloxacin (ORB) in rabbit plasma. Sample preparations are carried out by adding phosphate buffer (pH 7.4, 0.1 M) and extracting with trichloromethane. ORB and the internal standard, norfloxacin (NOR), are separated on a reversed-phase column using an aqueous phosphate buffer-acetonitrile (80:20, v/v) mobile phase. The concentrations of ORB and NOR eluting from the column with retention times of 2.16 and 3.09 min, respectively, are monitored by fluorescence detection at 338 (excitation) and 425 nm (emission). The method is shown to be linear from 4 to 1500 ng/mL (regression coefficient r2 = 0.999). The quantitation and detection limits are 4 and 9 ng/mL, respectively. Mean recovery is determined as 92% by the analysis of plasma standards containing 150, 750, and 1500 ng/mL. Inter- and intra-assay precisions were 4 and 3%, respectively.     

Influence of a mixed ionic/nonionic surfactant system and the emulsification process on the properties of paraffin emulsions

Paraffin emulsions are important in technological applications such as coating in the food packaging industry or to provide waterproof properties to particleboard panels. Small particle size (about 1.0 μm) and low polydispersity are required to form stable paraffin emulsions for these applications. In this context, the main objective of the present work is to study the influence of the surfactant system and the emulsification process on the properties of paraffin emulsions. A high pressure homogenizer was used to prepare the emulsions and its characterization was made by means of optical microscopy, laser diffraction and electrophoretic mobility measurements. Emulsions were prepared as a function of the ionic/nonionic surfactant ratio, the total surfactant concentration and the homogenization pressure. A simple theoretical model to predict the minimum particle size was used, assuming that surfactant is either at the oil-water interface or as monomer in the external phase. Experimental and theoretical data are on good agreement and the formation of stable emulsions is explained according to such model. This result could be of prime importance in order to formulate new paraffin emulsions.     

A singular noninterpenetrating coordination polymer with the Pt3O4 structure containing naked [Na+]4 units

The homoleptic low-spin complex [Fe(L)3]2+ where L is the bisbidentate ligand 1,10-phenanthroline-5,6-dione, coordinates Na+ ions via exo-oriented dione groups defining a three-dimensional cationic network {[Fe(L)3]4Na3}11+}n with Pt3O4 topology. The large volume generated by the network is filled with 11 perchlorate ions, 7 "NaClO4" ionic pairs, and 9 H2O molecules. Singular [Na+]4 units, in which the Na+ ions are practically uncoordinated, are formed.     

Oil-in-alcohol highly concentrated emulsions as templates for the preparation of macroporous materials

New oil-in-alcohol highly concentrated emulsions were formulated and were used as a templates to obtain macroporous poly(furfuryl alcohol) monoliths by a one-step method. The oil-in-alcohol highly concentrated emulsions were prepared by stepwise addition of the oil phase to the surfactant-alcohol solution and were characterized by optical microscopy and by laser diffraction. The typical structure of highly concentrated emulsions, with close-packed polyhedral droplets, has been observed. Poly(furfuryl alcohol) monoliths were obtained by polymerizing in the external phase of these emulsions. These materials are mainly macroporous and retain the size distribution and morphology from the highly concentrated emulsions. The internal structure of the monoliths was observed by scanning electron microscopy. The images showed an interconnected network with pore size similar to the droplet size of the highly concentrated emulsions used as templates.     

Highly diastereoselective one-pot synthesis of spiro[cyclopenta[a]indene-2,2'-indene]diones from 1-indanones and aromatic aldehydes

Treatment of 1-indanones with aromatic aldehydes and NaOEt in THF affords complex spiropolycyclic compounds through a four-component reaction in which two molecules of each starting compound are combined with formation of four new carbon-carbon bonds, leading to the elaboration of a new five-membered ring that bears five contiguous stereogenic centers with a well-defined relative configuration. Different amounts of a minor epimer of the main product are also formed. The presence of methoxy substituents in the indanone component and the use of aldehydes derived from pi-excedent heterocycles make the dimerization step a slower transformation. In these cases, better yields of spirodimers are obtained starting from the preformed enones. The reaction seems to take place by cross-aldol condensation, dehydration, and dimerization of the thus formed enones. The molecular mechanism of the dimerization reaction of enone 5g has been studied using DFT methods at the B3LYP/6-31G level. The dimerization takes place through a process involving a Michael addition of a carbanion, obtained by deprotonation of 5g at the 3-position, to a second molecule of 5g, followed by an intramolecular Michael addition in the corresponding intermediate. The final protonation of the resulting anion accounts for the formation of the cis-fused pentacyclic system.     

Oil/water droplet formation by temperature change in the water/c(16)e(6)/mineral oil system

Droplet sizes of oil/water (O/W) nanoemulsions prepared by the phase inversion temperature (PIT) method, in the water/C16E6/mineral oil system, have been compared with those given by a theoretical droplet model, which predicts a minimum droplet size. The results show that, when the phase inversion was started from either a single-phase microemulsion (D) or a two-phase W+D equilibrium, the resulting droplet sizes were close to those predicted by the model, whereas, when emulsification was started from W+D+O or from W+D+Lalpha (Lalpha = lamellar liquid crystal) equilibria, the difference between the measured and predicted values was much higher. The structural changes produced during the phase inversion process have been investigated by the 1H-PFGSE-NMR technique, monitoring the self-diffusion coefficients for each component as a function of temperature. The results have confirmed the transition from a bicontinuous D microemulsion at the hydrophile-lipophile balance (HLB) temperature to oil nanodroplet dispersion in water when it is cooled to lower temperatures.     

A new 2D network built from potassium sandwiches {K[Cu(II)3(bdap)3]2} and {(micro(1,3)-SCN)3Cu(I)(NCS)} anions: structure and magnetic behaviour

The addition of a solution of excess K(SCN) to an aqueous solution containing Cu(NO3)2.6H2O and 1,3-bis(amino)-2-propanol (bdapH) yields a novel 2D mixed Cu(I)-Cu(II) complex; X-ray diffraction and magnetic studies are reported herein.     

Complementarity and countercomplementarity in polynuclear copper(II) complexes with R2NCH2CH(OH)CH2NR2 (R = H, CH3): crystal structures and magnetic study

The syntheses, structural characterization and magnetic behavior of five new copper(II) polynuclear compounds with formulae [Cu4(mu2-CH3COO)2(mu-bdmap)2(micro(1,5)-dca)2(dca)2(H2O)2] 1, [Cu2(mu2-CH3COO)(mu-bdap)(mu(1,1,5)-dca)(mu(1,3)-dca)]n 2, [Cu4(mu2-CH3COO)2(mu-bdmap)2(mu(1,1)-NCS)2(NCS)2] 3, [Cu2(mu2-CH3COO)(mu-bdap)(NCS)2] 4 and [Cu2(mu(1,3)-N3)(mu-bdmap)(N3)2]n 5 in which bdmapH is 1,3-bis(dimethylamino)-2-propanol, bdapH is 1,3-bis(amino)-2-propanol and dca is the anionic dicyanamide ligand, are reported herein. Tetranuclear complex 1 crystallizes in the monoclinic system, space group P2(1)/n, with unit cell parameters a = 8.284(8), b = 21.52(1), c = 11.432(3) A, beta = 105.19(2) degrees , Z = 2. Bi-dimensional complex 2 crystallizes in the triclinic system, space group P1, with unit cell parameters a = 8.184(5), b = 8.792(2), c = 10.887(2) A, alpha = 75.65(2), beta = 76.55(3), gamma = 74.36(3) degrees , Z = 2. Tetranuclear complex 3 crystallizes in the triclinic system, space group P1, with unit cell parameters a = 8.455(4), b = 9.114(9), c = 12.744(8) A, alpha = 104.62(8), beta = 99.86(6), gamma = 106.10(8) degrees, Z = 1. Dinuclear complex 4 crystallizes in the triclinic system, space group P1, with unit cell parameters a = 8.15(1), b = 8.18(2), c = 11.44(1) A, alpha = 69.39(2), beta = 80.36(2), gamma = 80.37(2) degrees , Z = 2. One-dimensional complex 5 crystallizes in the orthorhombic system, space group P2(1)2(1)2(1), with unit cell parameters a = 20.45(4), b = 11.36(3), c = 6.43(1) A, Z = 4. The magnetic behavior of all the complexes has been checked giving a bulk antiferromagnetic coupling in all the cases with |J| values in the range 109-144 cm(-1) for 1-4. Compound 5 is diamagnetic in the 2-300 K range of temperatures. The found J values 1-5 for can be justified from the structural data taking into account the orbital countercomplementarity for 1-4 and the orbital complementarity for 5.     

DETERGENT EFFICIENCY OF WATER/NONIONIC SURFACTANT/HYDROCARBON SYSTEMS. PART II: INFLUENCE OF ELECTROLYTES

Washing efficiency of water/nonionic surfactant/hydrocarbon systems under the presence of different types of electrolytes has been evaluated, The influence of different parameters such as pH value, washing time, electrolyte concentration, etc., have also been considered. The results showed that the enhancement on washing efficiency promoted by alkaline electrolytes was higher than that promoted by neutral electrolytes.