Analytical approach to the discoloration of edible laver "nori" in the Ariake Sea.

To understand the cause of discoloration of the sea laver "nori," which is found in the Ariake Sea, the concentrations of pigments and elements in the normal and discolored laver samples were determined. In the discolored samples, a decrease in all of the pigments, chlorophyll a and carotenoids, and proteinous pigments, phycobiliproteins, was clearly observed. This was accompanied by a decrease in the content of Fe, Zn, Mn, Cu, and P. Good correlations between these elements and chlorophyll a, as well as between these elements and phycobiliproteins, were confirmed, indicating that, in addition to the deficiency of nitrogen and phosphorus, the deficiency of trace elements (Fe, Zn, Mn, and Cu), which are specifically required for photosynthesis, could be a reason for the discoloration of nori. The cause of elemental deficiency is also discussed.     

Stability of porphyrin-calix[4]arene complexes analyzed by electrospray ionization mass spectrometry

The stability of some porphyrin-calix[4]arene sodium-ion complexes were determined by a collision-activated decomposition (CAD) method utilizing electrospray ionization mass spectrometry (ESI-MS). Comparing the values of E(1/2), the collision energy at which the relative intensity of the complex ion is 0.5, we found that the porphyrin-calix[4]arene complex with the higher value of E(1/2) corresponded to that with the larger association constant (Kass), as measured by 1H-NMR in CDCl3. Both our ESI-MS and NMR studies proved that the number of hydrogen bonds and the rigidity of the calix[4]arene stabilized the complex. The ESI-MS technique could be successful in screening the binding affinity in host-guest systems with a small amount of sample.     

A new stereoselective synthesis of 2-subsdtituted 1,3-bis(trimethylsilyl)propene derivatives and their conversion to cyclopentane and cyclohexane derivatives

Ester $\text{2}$ on treatment with sodium salt of sulfone or sulfoxide afforded 2-substituted 1,3-bis(trimethylsily)propene $\text{3}$ in good yield, from which cyclopentane and cyclohexane derivatives bearing a trimethylsilyl group in the molecules were synthesized.     

Reaction of 1-alkylthioisoquinolinium salts with active methylene compounds

2-Alkyl-1-alkylthioisoquinolinium salts were readily prepared from 2-alkyl-1(2H)-isoquinolones via 2-alkyl1(2H)-thioisoquinolones in two steps. Under mild conditions, the reaction of 2-alkyl-1-alkylthioisoquinolinium salts with active methylene compounds in the presence of sodium hydride afforded 2-alkyl-1-(substituted methylene)iso-quinolines in good yields. Pyrrolo[2,1-a]isoquinolines were synthesized by the cyclization of 2-benzyl-1-(substituted methylene)isoquinolines using acetic anhydride.     

Synthesis of acryloyl-type polymer fixing 5-fluorouracil residues through D-glucofuranoses and its antitumor activity

Acryloyl-type polymer fixing 1-β-carbonylethyl-5-fluorouracil residues through D -glucofuranoses via ester bonds was synthesized by means of polymerization of the corresponding monomer and polymer reaction. In order to provide the water-soluble objective polymer, the copolymerization of the acryloyl-type monomer with acrylamide was carried out. The extent of release of 5-FU residues from the copolymer was investigated in the enzyme or nonenzyme system in vitro. Furthermore, the antitumor activities of the water-insoluble homopolymer and water-soluble copolymer obtained were tested in vivo.     

Liquid chromatographic-mass spectrometric analysis for screening of patients with cystinuria, and identification of cystine stone.

Analyses of amino acids in the urine of a normal human and of patients with heterozygous and homozygous cystinuria have been carried out, using liquid chromatography-mass spectrometry with an atmospheric pressure ionization interface system. A kidney cystine stone was also analysed by this system. Very intense quasi-molecular ions ([M + H]+) of standard cystine, arginine, lysine and ornithine were observed on mass chromatograms as base peaks. Mass chromatograms of the urine samples from a normal human and from patients with heterozygous and homozygous cystinuria were easily distinguishable. The retention times in the mass chromatogram and mass spectrum of kidney stone cystine was almost the same as that of authentic cystine.     

Stability and vibrational spectra of toroidal isomers of C 240

To study the thermodynamic and mechanical stability of toroidal isomers of C ₂₄₀, we use a semi-empirical tight-binding theory and calculate their electronic structure, cohesive energy and vibrational spectra within the harmonic approximation. From these, we deduce their free energy at temperatures up to 1500K. The results are also compared to the isomer with icosahedral symmetry. Finally, we discuss within this approach, their stability and abundance.     

Cyclopalladation of the indole ring in palladium(II) complexes of 2N1O-donor ligands and its dependence on the O-donor properties

Synthetic, structural, spectroscopic, and kinetic studies have been carried out on the Pd(II) complexes of new 2N1O-donor ligands containing a pendent indole, 3-(N-2-pyridylmethyl-N-2-hydroxy-5-methoxybenzylamino)ethylindole (HMeO-iepp), 3-(N-2-pyridylmethyl-N-2-hydroxy-5-nitrobenzylamino)ethylindole (HNO2-iepp), and (N-2-pyridylmethyl-3-indolylethylamino)acetic acid (Hiepc) (H denotes a dissociable proton). [Pd(MeO-iepp)Cl] (2), [Pd(NO2-iepp)Cl] (3), and [Pd(iepc)Cl] (4) were prepared and revealed by X-ray analysis to have a pyridine nitrogen, an amine nitrogen, a phenolate or carboxylate oxygen, and a chloride ion in the coordination plane. UV absorption and 1H NMR spectral changes indicated that all the complexes could be converted to the indole-binding complexes where the O donor was replaced by the indole C2 atom by cyclopalladation in DMSO or DMF in the temperature range of 40-60 degrees C. Formation of the indole-binding complex species obeyed the first-order kinetics, from which the activation parameters were estimated. The formation rate was dependent on the properties of the O-donor group, a lower pKa value of its conjugate acid causing faster conversion to the indole-binding species in the order 2 (methoxyphenolate) < 3 (nitrophenolate) < 4 (carboxylate). On the other hand, the ratio of the indole-binding complex to the O-donor complex as a result of the conversion was greater for the complexes with a higher pKa value of the ligand OH group, the order being 2 > 3 > 4.     

Characterization of the non-stoichiometric and isomorphic hydration and solvation in FK041 clathrate

FK041 crystallizes as a non-stoichiometric hydrate or as solvated hydrates which were characterized as isomorphic clathrates by powder X-ray diffractometry. Moisture and organic solvent vapor sorption studies, differential scanning calorimetry and thermogravimetric analysis revealed that FK041 monohydrate forms a physically stable host crystal, which has lattice channels for guest water and/or organic solvent molecules. The hydration state varies non-stoichiometrically between dihydrate and tetrahydrate depending on the relative humidity and the mol content of the co-existing organic solvent, that is 2-propanol, ethanol, or acetone. These organic solvents are thought to replace a part of originally present water with a mol ratio of 1:3. 2-Propanol exhibited the most stable solvation, indicating that the size and shape of 2-propanol are the most preferable to the lattice channels.     

Synthesis, structure, and physical properties of 1,11-o-benzeno[2]orthocyclo[2](1,2)tropyliophane

The title compound (2) has been synthesized, the structure and the physical properties of which are investigated by X-ray, spectroscopic analyses, and MO calculations. There exists charge transfer (CT) interaction between the tropylium ion and the facing phenyl ring. From the pK_R⁺ value of 2, it can be clear that the cation 2 is stabilized by the CT interaction. In spite of the presence of bond weakening σ-π orbital mixing, the cation 2 withstands retro[4+4]type bond cleavage, which is quite interesting when compared to a facile cleavage for the congener with anthracene photodimer type structure.