Stoichiometry and conformation of the azacrown moiety in sodium complexes of azacrown ethers. A Raman/IR spectroscopic study. Part I: Complexes of 4,13-Diaza-18-crown-6

Three sodium complexes (bromide, iodide and thiocyanate) of 4,13-diaza-18-crown-6 were studied using Raman and IR spectroscopy and normal coordinate calculations to probe the stoichiometry of the complexes and the variation in the conformation of azacrown moiety on complex formation. complex formation is accompanied by characteristic shifts of the bands, especially of those in the 800–900 cm^–1 region. Complexes of both 11 and 21 stoichiometry were observed. Normal coordinate calculations showed the reduction of symmetry of azacrown moiety toC _i , in contrast to theC _2h symmetry known for the parent azacrown and potassium thiocyanate complex.     

Reaction between rare earth elements and HFNO2 solution

Rare earth elements react with HFNO₂ solution to produce nitrosylium fluorometallates (NO)_xLnF_x+3. The value of x is 1.0 or 1.5 for light rare earth elements and 0.5 or 1.0 for heavy rare earths. Nitrosylium fluorometallates of rare earth elements can be decomposed into the simple fluoride and nitrosyl fluoride at low temperatures (46–68°C).     

Efficient photocleavage of DNA utilising water-soluble lipid membrane-incorporated [60]fullerenes prepared using a [60]fullerene exchange method

Various types of lipid membrane-incorporated C60 with high C60 concentrations can be prepared easily in several hours using the C60 exchange method and the photocleaving activity of cationic lipid membrane-incorporated C60 was appreciably higher than that of the C60.gamma-CDx complex.     

Scattering theory for threadlike micellar solutions

Association-dissociation equilibria and the static scattering function were formulated using precise thermodynamic functions for nonionic surfactant solutions including long, stiff, threadlike micelles. The present theory is applicable for micellar solutions with the surfactant concentration much higher than the critical micelle concentration and containing highly growing threadlike micelles. The scattering function formulated was compared with experimental light scattering data for aqueous solutions of a nonionic surfactant, penta(oxyethylene glycol) n-decyl ether (C12E5), at different surfactant concentrations and also temperatures.     

Novel and stereocontrolled synthesis of (+/-)-tetrodotoxin from myo-inositol

[reactions: see text] The novel and stereocontrolled synthesis of (+/-)-tetrodotoxin from myo-inositol is described. The key steps involve the stepwise oxidation of hydroxyl groups to the carbonyl function, followed by the addition of specific nucleophiles, including the successive spiro alpha-chloroepoxide formation and its ring-opening with the azide anion, to give the desired branched chain structures (5-->6, 17-->18-->19-->20 and 23-->24-->25) with the desired regio- and stereoselectivities in high yields. The stepwise conversion of the alpha-azido aldehyde 25 to the delta-lactone 29, followed by reduction of the azide, introduction of a guanidine moiety, aldehyde formation, and deprotection, produced the (+/-)-tetrodotoxin.     

Synthesis and biological evaluation of 3-chloro-1-carbacephem compounds

The 3-chloro-1-carbacephem nucleus was prepared for the first time from a 3H-1-carbacephem compound through a sequence of reactions involving addition of thiophenol, oxidation of sulfide to sulfoxide, and alpha-chlorination of the sulfoxide, followed by elimination of phenylsulfinic acid. The 2-beta-methyl analog was similarly prepared, but the 2 alpha-methyl analog was not obtained. Optical resolution of the 3-chloro-1-carbacephem compound was achieved by the employment of penicillin acylase. That is, the 7-phenylacetamido derivative was enantioselectively hydrolyzed to afford the optically active 7-amino-3-chloro-1-carbacephem compound. Carbacefaclor, the carbacephem analog of cefaclor, was directly and efficiently prepared by enzymatic phenylglycylation of the racemic 7-amino-3-chloro-1-carbacephem compound by using immobilized penicillin acylase. Carbacefaclor thus prepared exhibited comparable antibacterial activity against most gram positive bacteria tested and higher activity against typical gram negative bacteria as compared with cefaclor. Moreover, carbacefaclor possessed remarkably high chemical stability.     

Determination of some aliphatic carboxylic acids in anaerobic digestion process waters by ion-exclusion chromatography with conductimetric detection on a weakly acidic cation-exchange resin column

The determination of seven aliphatic carboxylic acids, formic, acetic, propionic, isobutyric, n-butyric, isovaleric and n-valeric acids in anaerobic digestion process waters was examined using ion-exclusion chromatography with conductimetric detection. The analysis of these biologically important carboxylic acids is necessary as a measure for evaluating and controlling the process. The ion-exclusion chromatography system employed consisted of polymethacrylate-based weakly acidic cation-exchange resin columns (TSKgel OApak-A or TSKgel Super IC-A/C). weakly acidic eluent (benzoic acid), and conductimetric detection. Particle size and cation-exchange capacity were 5 microm and 0.1 meq./ml for TSKgel OApak-A and 3 microm and 0.2 meq./ml for TSKgel Super IC-A/C, respectively. A dilute eluent (1.0-2.0 mM) of benzoic acid was effective for the high resolution and highly conductimetric detection of the carboxylic acids. The good separation of isobutyric and n-butyric acids was performed using the TSKgel Super IC-A/C column (150 mm x 6.0 mm i.d. x 2). The simple and good chromatograms were obtained by the optimized ion-exclusion chromatography conditions for real samples from mesophilic anaerobic digestors, thus the aliphatic carboxylic acids were successfully determined without any interferences.     

Leakage of immobilized IgG from therapeutic immunoadsorbents

In developing therapeutic immunoadsorbents (IAs), antibodies (IgG molecules) covalently immobilized on porous carriers, a leak of IgG was determined both in the storage test with buffers at 25 and 4 degrees C and in contact with plasma at room temperature (RT). The amount of antibody released from therapeutic IAs must be minimized to avoid side effects during treatment. The amount of IgG released was a. Dependent on the amount of IgG immobilized b. Much greater with CNBr-activated Sepharose 4B, or Formyl-Cellulofine as a support material than with aminopropyl CPG (controlled pore glass) c. Found to yield again during another storage in buffers after the IAs were washed and their buffers replaced with fresh ones and d. Decreased after the IAs were treated with glutaraldehyde (GA) solutions. Whereas treating the IAs with GA solutions significantly reduced the amount of IgG released, it caused some deterioration of the adsorption characteristics of the IAs. An irradiation dose of 2.5 Mrad as a crosslinking procedure also reduced the amount of IgG released; its effect was comparable to that of 0.025% GA, the lowest concentration used.     

The study of sensitivity and resolution of microautoradiography using Auger electrons

By using low energy beta emitter to microautoradiography, it is expected that high resolution microautoradiogram can be made. In this report, the authors pay attention to the use of monochromatic and low energy electron on the metallic samples, and used⁵¹Cr that emits Auger electrons with the energy of 4.5keV and⁶⁵Zn that emits Auger electrons with energy of 7keV in the study of the resolution of Auger electron microautoradiograph. From the results of the study, it was clearly confirmed that the resolution of the microautoradiograph using⁵¹Cr was better than 0.5 m and the resolution using⁶⁵Zn was better than 1 m.In order to make high resolution microautoradiograph, it is essentially important to know the sensitivity of the nuclear emulsion to the low energy electrons in advance, for securing the reasonable exposure to the nuclear emulsion. In this regard, the investigation on the sensitivities of those emulsions to the Auger electrons with the energy of 5.4keV from⁵⁵Fe and 7keV from⁶⁵Zn was made using Ilford and Fuji nuclear emulsions.     

Crystal field calculation of g values and zero-field splitting for high spin ferric complexes of rhombic character

For high spin ferric ions in rhombic symmetry, we have used a crystal field model to relate term splittings of the ⁴ T ₁, ² T ₂ and ⁴ T ₂ excited states to zerofield split energies and g values of the ⁶ A ₁ term. In this model five crystal field parameters were used, namely, one cubic parameter, two tetragonal parameters and second and fourth order rhombic parameters. In tetragonal symmetry with only three crystal field parameters, a simpler model including only the ⁴ T ₁ and ² T ₂ excited states is adequate to relate term energies to g values and zero-field split energies. However, we have demonstrated the importance of the ⁴ T ₂ state in rhombic crystalline fields. No higher lying terms other than ⁴ T ₂ can influence the ⁴ T ₁ term directly through the tetragonal or rhombic crystal field, Furthermore, we show that the fourth order rhombic crystal field parameter is a key parameter because the rhombic splitting of the dominant low lying ⁴ T ₁ term of high spin ferric complexes depends to first order on the fourth order crystal field potential. We have performed a computer diagonalization of the spin-orbit, electrostatic and crystal field perturbation matrix, and calculated g values and zero-field splittings in seventeen high spin ferric mixed crystalline species of varying rhombicities and for metmyoglobin and cytochrome P-450. The high spin and spin-mixed regions are developed completely to yield the crystal field term energies, zero-field splittings and basis functions together with g values.