Single molecular multianalyte sensor: jewel pendant ligand

[structure: see text] The jewel pendant ligand has multiple chromogenic units combined in a single molecule with the dyes linked to a semiselective binding site by three heteroatoms (O, N, S) having different HSAB characteristics, to indicate diverse response to individual transition metal ions. Using a single-molecular multianalyte sensor, multiple analytes could be determined with a minimal sensing system.     

Chemical trend of Ln-M exchange couplings in heterometallic complexes with Ln = Gd, Tb, Dy, Ho, Er and M = Cu, V

The 4f-3d exchange couplings were definitively and precisely determined in the dinuclear complexes (Ln-M) involving double μ-oxo-bridges, by means of combined high-frequency electron paramagnetic resonance and pulsed-field magnetization techniques, revealing a monotonic decrease of ferromagnetic J(Ln-Cu) in the order of the atomic number, (64)Gd to (68)Er.     

Computer-aided structure elucidation methods

Computer-aided structure elucidation methodology is discussed. Major processes involved in computer-aided structure elucidation systems are partial-structure elucidation, structure generation, and structure examination. For the three representative systems CONGEN, CASE, and CHEMICS, these processes are examined. There are four necessary conditions for automated chemical structure elucidation systems: reliability, width of application, ease of modification and portability.     

Synthesis of [1]benzopyrano[2,3,4-kl]acridin-3-ol and its analogues as pentacyclic compounds

A new heterocyclic compound, [1]benzopyrano[2,3,4-kl]acridin-3-ol was synthesized by cyclization of xanthone derivatives. The key compound, 1-(3'-methoxyanilino)-xanthone, was prepared from 1-aminoxanthone. [1]benzopyrano[2,3,4-kl]acridin-3-ol analogues, [1]benzothiopyrano[2,3,4-kl]acridin-3-ol, pyrido[3',2':5,6]pyrano[2,3,4-kl]acridin-3-ol and pyrido[3',2':5,6]thiopyrano[2,3,4-kl]acridin-3-ol were synthesized by the same method.     

Electronic polarizability and crystallization of K2O-TiO2-GeO2 glasses with high TiO2 contents

Some K₂O-TiO₂-GeO₂ glasses with a large amount of TiO₂ contents (15-25 mol%) such as 25K₂O-25TiO₂-50GeO₂ have been prepared, and their electronic polarizability, Raman scattering spectra, and crystallization behavior are examined to clarify thermal properties and structure of the glasses and to develop new nonlinear optical crystallized glasses. It is proposed that the glasses consist of the network of TiO₆ and GeO₄ polyhedra. The glasses show large optical basicities of Λ=0.88-0.92, indicating the high polarizabity of TiO_n (n=4-6) polyhedra in the glasses. K₂TiGe₃O₉ crystals are formed through crystallization in all glasses prepared in the present study. In particular, 20K₂O-20TiO₂-60GeO₂ glass shows bulk crystallization and 18K₂O-18TiO₂-64GeO₂ glass exhibits surface crystallization giving the c-axis orientation. The crystallized glasses show second harmonic generations (SHGs), and it is suggested that the distortion of TiO₆ octahedra in K₂TiGe₃O₉ crystals induces SHGs.     

An indication of magnetic-field-induced superconductivity in a bifunctional layered organic conductor,kappa-(BETS)(2)FeBr(4)

Hybrid systems consisting of the conducting layers of organic donor molecules and the magnetic layers of inorganic anions have been focused on as possible bifunctional materials, whose conducting properties can be tuned by controlling the magnetic state of the anion layers on an application of magnetic field. Here we report the magnetoresistance of the antiferromagnetic organic superconductor, kappa-(BETS)2FeBr4 [BETS = bis(ethylenedithio)tetraselenafulvalene], consisting of the two-dimensional superconducting layers of the BETS semications and the insulating layers of the FeBr4- anions. Due to the metamagnetic nature of the Fe3+ spin system, characteristic resistivity decrease was observed just below the antiferromagnetic superconductor-to-ferromagnetic metal transition at 1.6 T. Furthermore, an indication of the onsets of the magnetic-field-induced superconductivity was discovered around 12.5 T.     

Cyclophosphamides from aminosugars and aminonucleosides

Condensation of bis-(2-chloroethyl)phosphoramidic dichloride with 3′-amino-3′-deoxy-N,N-dimethyladenosine afforded the 2′,3′-cyclicphosphorodiamidate (III). By an improved synthesis, methyl 3-amino-3-deoxy-β-D-ribofuranoside was obtained as a model compound for conversion to the analogous 2,3-cyclicphosphorodiamidate (XII). Existence of the latter as two diastereomers due to phosphorus asymmetry was shown by nmr analysis, using comparison with the 5-(O-p-nitrobenzoate) (XIII) as a basis for assignments.     

The synthesis of 1H-benzimidazole derivatives containing a 9H-xanthene or 9H-thioxanthene ring

2-(9H-Xanthen-9-ylmethyl)-1H-benzimidazole ( 2a ) was prepared by condensing 9H-xanthene-9-acetic acid ( 1a ) with 1,2-benzenediamine. Similarly, 2-(9H-thioxanthen-9-ylmethyl)-1H-benzimidazole ( 2b ) and its S,S-dioxide ( 2d ) were obtained. Compound 2d was also prepared by oxidizing 2b with hydrogen peroxide in acetic acid. Heating of 9H-thioxanthene-9-acetic acid 10-oxide ( 1c ) with 1,2-benzenediamine gave 9-methylene-9H-thioxanthene ( 3 ). 2-(9H-Thioxanthen-9-ylmethyl)-1H-benzimidazole S-oxide ( 2c ) was obtained by oxidizing 2b with m-chloroperbenzoic acid in acetone.     

Medicinal flowers. XV. The structures of noroleanane- and oleanane-type triterpene oligoglycosides with gastroprotective and platelet aggregation activities from flower buds of Camellia japonica

The methanolic extract from the flowers buds of Camellia japonica L. (Theaceae) were found to exhibit potent inhibitory activities on ethanol- or indomethacin-induced gastric mucosal lesions in rats. Through bioassay-guided separation, 28-noroleanane-type triterpene oligoglycosides, camelliosides A, B, and C, and an oleanane-type triterpene oligoglycoside, camellioside D, were isolated from the methanolic extract together with five known compounds. The absolute stereostructures of camelliosides were determined on the basis of chemical and physicochemical evidence, which included the structure revision of the nortriterpene aglycons (camellenodiol and camelledionol). The principal oligoglycosides, camelliosides A and B, showed platelet aggregation activity in addition to the gastroprotective effects on ethanol- or indomethacin-induced gastric mucosal lesions in rats.     

Rapid determination of 89Sr and 90Sr in radioactive waste using Sr extraction disk and beta-ray spectrometer

A rapid determination method in which beta-ray spectrometry was combined with solid phase extraction using Sr Rad Disk was developed for the determination of ⁸⁹Sr and ⁹⁰Sr in low-level radioactive waste. Various amounts of ⁸⁹Sr, ⁹⁰Sr, and ⁹⁰Y retained by the Sr Rad Disk was measured by a beta-ray spectrometer, and it was found that both ⁸⁹Sr and ⁹⁰Sr were simultaneously determined with <30% error (2σ) at ⁸⁹Sr/⁹⁰Sr radioactivity ratio of 0.3 to 45. The present method was successfully applied to actual radioactive liquid waste samples arising from nuclear facilities in Japan Atomic Energy Agency. Strontium was simply separated from interfering nuclides such as ¹³⁷Cs and ¹⁵⁴Eu, and matrix components by the Sr Rad Disk, and the results obtained by beta-ray spectrometry was in good agreement with that of the conventional analysis.