1H NMR and Calorimetric Studies of the Inclusion of Trimethylammonium Cations into Water Soluble Calixresorcinarenes

Abstract

The complexation of tetramethylammonium (TEMA), benzyltrimethylammonium (BTMA), p-nitrobenzyltrimethylammonium (BTMAN) and N, N, N-trimethylanilinium (TMA) by the tetrasulphonate derivative of the resorcinol cyclic tetramer (1), was studied in aqueous solution by ¹H NMR and calorimetry. Host 1 specifically recognizes the—N⁺ (CH₃)₃ group of TEMA, BTMA and BTMAN, whereas it binds TMA unselectively; TMA is included both via the charged group and the aromatic moiety. The binding constants of all four guests with 1, as determined by both ¹H NMR and calorimetric titrations, show that all inclusion processes are almost equally stabilised.

ΔHΔ and ΔSΔ values, determined by direct calorimetry, reveal specific interactions that are not expressed in the ΔGΔ terms and indicate that we are dealing with “non-classical hydrophobic effects”. The effects of the structural, conformational and electronic properties of the guests on the forces driving the inclusion processes are discussed.     

Chiral spherical molecule constructed from aromatic amides: facile synthesis and highly ordered network structure in the crystal

A novel chiral spherical molecule composed of aromatic amide was synthesized in short steps. The molecule is constructed from four benzene rings connected by six amide bonds and has multiple functionalizable points and an asymmetric structure. The racemic spherical molecule constructed channel network structures in the crystalline state.     

Evaluation of diffusional anisotropy and microscopic structure in skeletal muscles using magnetic resonance

The pulsed-gradient spin-echo (PGSE) nuclear magnetic resonance (NMR) method is used for detecting the diffusion of water molecules in biological tissues. Because tissues generally have diffusional anisotropy, their diffusion properties are denoted by a tensor. In this study, we evaluated the diffusional anisotropy and microscopic structure in atrophied skeletal muscles using the PGSE NMR method. The left sciatic nerve was severed in twelve 9-week-old rats. Neurotomy caused neurogenic muscular atrophy at the left gastrocnemius. At 2, 4 and 8 weeks after neurotomy, magnetic resonance signals were selectively acquired from a 2 x 2 x 2 mm(3) voxel, which was located on the left gastrocnemius. The diffusion tensor, the mean diffusivity (MD) and the fractional anisotropy (FA) were calculated from the signals. A theoretical model of the diffusion in muscles was derived from Tanner's equation. The muscle fiber diameter was estimated by fitting the model to the measured signals. The measurements were also performed for normal rats as controls. No significant difference was found in the MD and the estimated intracellular diffusion coefficient between the control group and the denervated group. The denervated group had significantly higher FA compared with the control group (P<.05). The estimated muscle fiber diameter of the denervated group was significantly smaller than the estimated value of the control group (P<.05). These differences were found at 8 weeks after neurotomy. The proposed method is effective for evaluating changes in the microscopic structure of skeletal muscles.     

Four different types of hydrogen bonds observed in 1,2-bis(N-benzenesulfonylamino)benzenes due to conformational properties of the sulfonamide moiety

The crystal structures of 1,2-bis(N-benzenesulfonylamino)benzenes with secondary and/or tertiary sulfonamide groups were determined by X-ray crystallographic analysis. Every Ar-sulfonamide group existed in synclinal conformation in the crystals even though it was secondary or tertiary. Each compound showed different types of hydrogen bonds in the crystal structure. 1,2-Bis(N-benzenesulfonylamino)benzene (1) formed two double hydrogen bonds connected to the next molecules, 1-(N-benzenesulfonylamino)-2-(N-benzenesulfonyl-N-methylamino)benzene (2) contained double hydrogen bond involved by both the sulfonamide moieties, 1,2-bis(N-4-toluenesulfonylamino)benzene (3) had both intra- and intermolecular hydrogen bonds, and 1-(N-methyl-N-4-toluenesulfonylamino)-2-(N-4-toluenesulfonylamino)benzene (4) had one double hydrogen bond involved by only one sulfonamide moiety. Sulfonamides 1 and 3 formed infinite arrays of the molecules, and sulfonamides 2 and 4 formed racemic dimer of their conformational enantiomers via the hydrogen bonds.     

Biosensing using lipid bilayers suspended on porous silicon

We demonstrate for the first time the formation of a fluid lipid bilayer membrane on mesoporous silicon substrates for bioapplications. Using fluorescence recovery after photobleaching, the diffusion coefficients for the bilayers supported on oxidized, amino-, and biotin-functionalized mesoporous silicon were determined. The biodetection of a single human umbilical vein endothelial cell was accomplished using confocal microscopy and exploiting Foerster resonance energy transfer effects after the incorporation of RGD covalently linked lipid soluble dyes, with fluorescence donor and acceptor components, within the fluid membrane. A signal response of greater than 100% was achieved via the clustering of RGD peptides binding with areas of high integrin density on the surface of a single cell. These results are a testament to the usefulness of such functional molecular assemblies, based on mobile receptors, mimicking the cell membrane in the development of a new generation of biosensors.     

Spontaneous resolution of aromatic sulfonamides: effective screening method and discrimination of absolute structure

An effective screening method combining parallel synthesis and solid-state CD measurements was established to identify achiral aromatic sulfonamides that show spontaneous resolution with rapidity. We found that 4 of the 12 achiral sulfonamides crystallized as chiral crystals through this method. The chirality of each sulfonamide was discriminated by solid-state CD spectra and Flack parameter in an X-ray analysis. Correspondence between the observed Cotton effect and the absolute configuration could be confirmed by time-dependent DFT calculations. [structure: see text]     

Protective effects of a neutral polysaccharide isolated from the mycelium of Antrodia cinnamomea on Propionibacterium acnes and lipopolysaccharide induced hepatic injury in mice

Mycelia of Antrodia cinnamomea were extracted with chloroform and hot water. A neutral polysaccharide named ACN2a separated from the water extract was purified using 10% CCl3COOH, and repeated column chromatography on HW-65 and DE-52 cellulose. Its structure was determined by chemical and spectroscopic analyses. ACN2a was composed of Gal, Glc, Fuc, Man and GalN (in the ratio 1:0.24:0.07:0.026:faint), in which an alpha-D-(1-->6)-Gal linkage accounted for 73% of all linkages. The ratio of branch points was about 16% of the total residual numbers, and branches were attached to C-2 of galactosyl residues of the main chain. ACN2a had an average molecular weight of 12.9x10(5) Daltons, [alpha]D25=+115 degrees (c=0.44, H2O); [eta]=0.0417dl.g-1, Cp=0.2663 cal/(g. degrees C). The hepatoprotective effect of ACN2a was evaluated using a mouse model of hepatic injury that was induced by Propionibacterium acnes (P. acnes) and lipopolysaccharide (LPS). The administration of ACN2a (0.4, 0.8 g/kg/d, p.o.), significantly prevented increases in serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) enzyme activities in mice treated with P. acnes-LPS, indicating hepatoprotective activity in vivo.     

Miscibility of calcium chloride and sodium dodecyl sulfate in the adsorbed film and aggregates

The adsorption, micelle formation, and coagel-particle formation of sodium dodecyl sulfate in the presence of calcium chloride were studied from the viewpoint of mixed adsorption and aggregate formation of inorganic salt and surfactant. Judging from the phase diagrams of adsorption and aggregate formation, negative azeotropy takes place in the mixed adsorption and aggregate formation of calcium chloride and sodium dodecyl sulfate due to electrostatic attraction between calcium and dodecyl sulfate ions. The miscibility of calcium chloride and sodium dodecyl sulfate in the oriented states increases in the order, particle > adsorbed film > micelle. The difference in the miscibility was ascribed to the difference in geometry between the adsorbed film and micelle and to the interaction between bilayer surfaces in the particle. The particle-micelle equilibrium was thermodynamically considered by using the equilibrium composition of aggregates.     

Structural and optical properties of Zn(Mg,Cd)O alloy films grown by remote-plasma-enhanced MOCVD

We report the structural and optical properties of wurtzite-structure Zn(Mg,Cd)O ternary alloys. Wurtzite (0 0 0 1) Zn_1−xCd_xO and Mg_yZn_1−yO films were grown on (11–20) sapphire substrates using remote-plasma-enhanced metalorganic chemical vapor deposition. The large bowing parameters of Zn_1−xCd_xO and Mg_yZn_1−yO ternary alloys are 3.0 and 3.5, respectively, which reflects the large difference of each binary’s electronegativity. We have analyzed the broadening of photoluminescence (PL) in Zn(Mg,Cd)O alloys on alloy content by taking into account the statistical alloy fluctuation and the localization of the exciton, and have clarified that the localization of the exciton strongly affects to PL full-width at half-maximum (FWHM) in Zn(Mg,Cd)O alloys. The alloy broadenings in steady-state PL of Zn(Mg,Cd)O alloys are in good agreement with the calculated tendency by the theoretical model based on the statistical alloy fluctuation, while PL FWHM of Zn_1−xCd_xO is three times larger than the calculated results. Moreover, as another way to confirm alloy broadening, we also have done time-resolved PL measurements and derived the localized depth of the exciton in ZnO-based system, indicating a good agreement with the tendency of PL FWHM broadening.