Enantioselective/anion-selective incorporation of tris(ethylenediamine) complexes into 2D coordination spaces between tripalladium(II) supramolecular layers with D-penicillaminate

The formation of a cocrystallized coordination compound, [Pd(3)(D-pen)(3)](2)·[M(en)(3)](ClO(4))(3) (D-H(2)pen = D-penicillamine; M = Co(III) or Rh(III)), from [Pd(3)(D-pen)(3)] and [M(en)(3)](ClO(4))(3) is reported. In this compound, only the Δ-configurational [M(en)(3)](3+) cations were incorporated when its racemic (Δ/Λ) isomer was employed. Besides this enantioselective incorporation of complex cations, this compound was found to show the selective incorporation of ClO(4)(-) as the anion species.     

Helical arrangement of a hydrogen‐bonded columnar liquid crystal induced by a centered triphenylene derivative bearing chiral side‐chains

A hydrogen‐bonded helical columnar liquid crystal was synthesized, in which the helical structure is induced by a centered triphenylene derivative bearing chiral side‐chains. The triphenylene derivative, 2,6,10‐tris(carboxymethoxy)‐3,7,11‐tris((S)‐(‐)‐2‐methyl‐1‐butanoxy)triphenylene ( TPC4(S) ), and a dendric amphiphile, 3,5‐bis‐(3,4‐bis‐dodecyloxy‐benzyloxy)‐N‐pyridine‐4‐yl‐benzamide ( DenC12 ), were mixed in a 1:3 ratio to obtain a complex, TPC4(S)‐DenC12 . Analyses by ¹H‐NMR spectroscopy, diffusion ordered spectroscopy (DOSY), CD spectroscopy, infrared (IR) spectroscopy, polarized optical microscopy (POM), differential scanning calorimetry (DSC), and X‐ray diffractometry revealed that TPC4(S)‐DenC12 self‐assembles to form helical columnar stacks in solution and a helical columnar liquid crystal in bulk. The hydrogen bonding between TPC4(S) and DenC12 is essential for the helical columnar organization, and the preference for a one‐handed helical conformation is likely derived from the steric interaction between the chiral side‐chains and the dendric amphiphiles in the packing of the hydrogen‐bonded columnar assemblies. Copyright © 2008 John Wiley & Sons, Ltd.     

Control of the Dynamic Motion of a Gel Actuator Driven by the Belousov‐Zhabotinsky Reaction

A novel self‐oscillating gel actuator with gradient structure, which generates a pendulum motion by fixing one edge of the gel without external stimuli was achieved. The gel was synthesized by copolymerizing the ruthenium catalyst for the Belousov‐Zhabotinsky reaction with N‐isopropylacrylamide and 2‐acrylamido‐2‐methylpropane sulfonic acid. Furthermore, we clarified that the period and amplitude for the self‐oscillating behavior of the gel actuator are controllable by changing the composition, temperature, and size of the gel. The maximum amplitude of the novel gel actuator is about a 100 times larger than that of the conventional self‐oscillating gel system.

     

Effects of temperature and anion species on CO2 permeability and CO2/N2 separation coefficient through ionic liquid membranes

The permeability of carbon dioxide (CO₂) through imidazolium-based ionic liquid membranes was measured by a sweep gas method. Six species of ionic liquids were studied in this work as follows: [emim][BF₄], [bmim][BF₄], [bmim][PF₆], [bmim][Tf₂N], [bmim][OTf], and [bmim][dca]. The ionic liquids were supported with a polyvinylidene fluoride porous membrane. The measurements were performed at T = (303.15 to 343.15) K. The partial pressure difference between feed and permeate sides was 0.121 MPa. The permeability of the CO₂ increases with temperature for the all ionic liquid species. Base on solution diffusion theory, it can be explained that the diffusion coefficient of CO₂ in an ionic liquid affects the temperature dependence more strongly than the solubility coefficient. The greatest permeability was obtained with the [bmim][Tf₂N] membrane. The membrane of [bmim][PF₆] presents the lowest permeability.The separation coefficient between CO₂ and N₂ through the ionic liquid membranes was also investigated at the volume fraction of CO₂ at feed side 0.10. The separation coefficient decreases with the increase of temperature for the all ionic liquid species. The membrane of [emim][BF₄] and [bmim][BF₄] gives the highest separation coefficient at constant temperature. The lowest separation coefficient was obtained from [bmim][Tf₂N] membrane which presents the highest permeability of CO₂.     

NIR spectroscopic study of the dissolution process in pharmaceutical tablets

In this study, water penetration and the interaction between water and a pharmaceutical excipient in a tablet were investigated using near-infrared (NIR) spectroscopy and perturbation-correlation moving-window two-dimensional correlation spectroscopy (PCMW-2DCS). The penetration rate of water into a tablet was mainly dependent on the porosity of the tablet and was less dependent on the type of excipient. This behavior was well described by the Lucas–Washburn theory. The PCMW-2DCS technique revealed that there are two-staged interaction changes in NIR spectra of the water–powder interactions. The first and second changes corresponded to the water–solid interaction and the dissolution of the solid, respectively. The diffusion-controlled dissolution model by Nernst well explained these results.     

Development and validation of a hydrophilic interaction chromatography–tandem mass spectrometry for quantification of nicotine and its metabolites in human maternal and cord sera

A selective and sensitive HILIC‐MS/MS method for the simultaneous quantification of nicotine and its metabolites in human maternal and cord sera was developed and validated. After solid‐phase extraction, LC separation was achieved on a hydrophilic interaction chromatography. The validated method is capable of selective identification as well as accurate and sensitive quantification. Analyte recovery ranged from 86.2 to 107.7% and intra‐ and inter‐day assay precision were less than 15% relative standard deviation. This sensitive HILIC‐MS/MS method can be used to determine nicotine and its metabolic profile in smokers. This validated method is useful for the determination of nicotine and its metabolites in human serum in future studies of the effects of nicotine exposure on neonatal outcome. Copyright © 2010 John Wiley & Sons, Ltd.     

Compounds having thiourea moiety as derivatization reagents in liquid chromatography/electrospray ionization–tandem mass spectrometry (LC/ESI‐MS/MS): synthesis of derivatization reagents for carboxylic acids

The derivatization reagents for carboxylic acids, N‐(Pyridin‐3‐yl)hydrazinecarbothioamide, N‐[4‐(dimethylamino)phenyl]hydrazinecarbothioamide, 1‐(2‐aminoethyl)‐3‐(pyridin‐3‐yl)thiourea, 1‐(2‐aminoethyl)‐3‐[4‐(dimethylamino)phenyl]thiourea and 4‐(2‐aminoethyl)‐N‐phenylpiperazine‐1‐carbothioamide were synthesized. These reagents reacted with carboxylic acids at 60°C for 45 min in the presence of the condensation reagents. The generated derivatives were favorably separated on the reversed‐phase column and sensitively detected by electrospray ionization tandem mass spectrometry. These reagents enhanced the electrospray ionization response of the analyte and generated a particular product ion efficiently by collision‐induced dissociation, and thus they were suitable for MS/MS detection. Copyright © 2010 John Wiley & Sons, Ltd.     

Nb2O5·nH2O as a heterogeneous catalyst with water-tolerant Lewis acid sites

Niobic acid, Nb(2)O(5)·nH(2)O, has been studied as a heterogeneous Lewis acid catalyst. NbO(4) tetrahedra, Lewis acid sites, on Nb(2)O(5)·nH(2)O surface immediately form NbO(4)-H(2)O adducts in the presence of water. However, a part of the adducts can still function as effective Lewis acid sites, catalyzing the allylation of benzaldehyde with tetraallyl tin and the conversion of glucose into 5-(hydroxymethyl)furfural in water.