New antifungal 1,2,4-triazoles with difluoro(substituted sulfonyl)methyl moiety

New 1,2,4-triazoles (2) having a difluoro(substituted sulfonyl)methyl moiety were designed and synthesized via alpha,alpha-difluoro-alpha-(substituted thio)acetophenones (3). Compounds (2) showed potent antifungal activities against C. albicans, C. krusei, A. flavus and A. fumigatus in vitro and against C. albicans in vivo for oral and i.v. administrations. Especially, (-)-2a, (-)-2b and (-)-2d showed potent antifungal activities.     

Thin-layer chromatographic behavior of rare earths on silica gel with aqueous alkaline earth metal nitrate solutions as mobile phases

The TLC behavior of all the rare earths except Pm has been surveyed on silica gel (pH 7.0) pretreated with 0.1 mol L^–1 tris(hydroxymethyl)aminomethane and 0.1 mol L^–1 HCl with aqueous nitrate solutions of alkaline earth metals as mobile phases. The R_F values of the lanthanides varied in a regular and characteristic way accompanied by the tetrad effect with increasing atomic number, and when the mobile phases were changed the R_F values of each metal decreased in the order Mg²⁺ > Ca²⁺ > Sr²⁺ > Ba²⁺, as the crystal ionic radii of the alkaline earth metals increased. This adsorption sequence was not observed with alkali metal nitrate and alkali metal chloride mobile phases. A brief discussion concerning the effect on R_F values of the solvent cations and the adsorption mechanism is included; also presented are typical chromatograms for the separation of multi-component mixtures containing adjacent lanthanides. Received: 9 October 2000 / Revised: 20 February 2001 / Accepted: 26 February 2001     

Adsorption and emission enhancement behavior of 4,4′-bipyridine on dispersed montmorillonite nano-sheets under aqueous conditions

The adsorption and photochemical behavior of 4,4′-bipyridine (BPy) on an exfoliated single montmorillonite nano-sheet (MtNS) was investigated in water. Under the appropriate conditions, BPy was adsorbed on the MtNS as a monomer state. BPy exhibited a relatively large red shift by 30?nm in the absorption spectrum, and showed significant emission enhancement in the fluorescence spectrum, contrary to the non-fluorescent property of BPy in water without MtNS. From the investigation using protonated BPy (BPyH₂²⁺) under acidic conditions, it was turned out that BPy was adsorbed as BPyH₂²⁺ on MtNS even under neutral conditions. From the analysis based on the Langmuir adsorption isotherm, the saturated adsorption amount of BPy on MtNS was calculated to be 3.2?×?10^?2 molecule nm^?2.     

Synthesis of Anisotropic Hydrogels and Their Applications

Owing to their water‐rich structures, which are similar to those of biological tissues, hydrogels have long been regarded as promising scaffolds for artificial tissues and organs. However, in terms of the structural anisotropy, most synthetic hydrogels are substantially different from biological systems. Synthetic hydrogels are usually composed of randomly oriented three‐dimensional polymer networks whereas biological systems adopt anisotropic structures with hierarchically integrated building units. Such anisotropic structures often play essential roles in biological systems to exhibit particular functions. In this context, anisotropic hydrogels provide an entry point for exploring biomimetic applications of hydrogels. Reflecting these aspects, an increasing number of studies on anisotropic hydrogels have been reported recently. This Minireview highlights the use and perspectives of these anisotropic hydrogels, particularly focusing on their preparation, structures, and applications.     

2‐Arylsilacyclobutane as a Latent Carbanion Reacting with CO2

An electronically neutral 2‐arylsilacyclobutane generates a nucleophilic carbanion at room temperature through cleavage of the benzylic C?Si bond when simply dissolved in polar aprotic solvents such as N,N‐dimethylformamide (DMF). The nucleophilic species is capable of capturing carbon dioxide to furnish a silalactone. The carboxylation reaction is unique in that no additional activating agents are required.     

Molecular inclusion in calixarenes. XVIII. Crystal and molecular structure of thep-tert-butylcalix[7]arene 1 : 3 pyridine complex/clathrate

The structure of thep-tert-butylcalix[7]arene 1:3 pyridine complex/clathrate (C₇₇H₉₈O₇ · 3 C₅H₅N) has been determined by X-ray crystallography. The crystal data are as follows: monoclinic, space groupP2₁/c,a = 37.790(4),b = 9.423(2),c = 29.075(4)Å; = 112.74(2)°;V = 8285(3)ų;Z = 4;D _calc = 1.10 g·cm^–3. The hostp-tert-butylcalix[7]arene links one pyridine molecule through a hydrogen bond between one of the seven hydroxy groups and the nitrogen of the pyridine. Two other guest molecules have been found in the crystal lattice, so the title compound may be defined as a complex/clathrate hybrid. The unambiguous conformation of the macrocycle is described by an alternative method, which avoids the use of dihedral angles (and the ambiguities in their values).Part XVII. Ref. [2].     

Effect of phosphorylated organic compound on the adsorption of bovine serum albumin by hydroxyapatite.

The amount of adsorption of bovine serum albumin (BSA) by hydroxyapatite (HAP) increased with a concentration of CaCl2 due to the bridging effect of Ca2+ between adsorbate BSA and adsorbent HAP. On the other hand, it decreased remarkably with a concentration of K2HPO4. This was explained in terms of the effects of ionic strength and competitive adsorption between inorganic phosphate anion (Pi) and BSA, because BSA is in negatively charged over the examined pHs. A similar effect was observed in the presence of phosphorylated compounds such as phosphoserine, phytate, and phosphorylated polyvinylalcohol. The inhibiting effect of these compounds was stronger than that of their mother compounds (serine, inositol, and polyvinylalcohol). This result shows that phosphate groups bound to the mother compounds interfere with the adsorption of BSA by HAP in the same manner that Pi does. Although the adsorption of BSA was almost irreversible with respect to dilution with water, desorption was performed when these organic phosphorylated compounds were added after the accomplishment of the adsorption of BSA. However, the effective concentration of the phosphorylated compounds for the desorption of BSA was fairly higher than that for the competitive inhibition against the BSA adsorption.     

Determination of prednisolone and prednisone in plasma by liquid chromatography with fluorescence detection

After a single-step extraction from plasma (250 μl) with dichloromethane, the drugs and dexamethasone (internal standard) are oxidized by copper(II) acetate to the corresponding glyoxal and converted into the fluorescent quinoxalines by reaction with 1,2-diamino-4,5-methylenedioxybenzene. The quinoxalines are separated within 55 min by reversed-phase liquid chromatography with isocratic elution. The detection limits for prednisolone and prednisone added to plasma are 3 ng ml^?1 in plasma (signal-to-noise ratio=3).     

1:2 Complexes of chloranilic acid with pyrazole and imidazole,and the aceto­nitrile solvate of a 1:1 complex with imidazole

2,5‐Di­chloro‐3,6‐di­hydroxy‐1,4‐benzo­quinone (chloranilic acid) forms X—H?Y (X, Y = N or O) and C—H?Cl hydrogen bonds with pyrazole and imidazole to afford bis­(pyrazolium) di­chloro­anilate and bis­(imidazolium) di­chloro­anilate, (I) and (II), both 2C₃H₅N₂⁺·C₆Cl₂O₄^2?, and imidazolium chloro­anilate aceto­nitrile solvate, C₃H₅N₂⁺·­C₆HCl₂O₄^?·C₂H₃N, (III). Their crystal structures demonstrate three novel supramolecular architectures based on supramolecular synthons to build a ladder, (I), a two‐dimensional network, (II), and a flat ribbon, (III).