Study on the Solute–Solvent Interactions Using the Solubility of Asymmetric Metal Complex, CoX2(R-py)2, as a Probe of Interaction

The solubility of some cobalt(II) chloride and bromide complexes of pyridine bases was determined in 10 inert organic solvents. The measured solubilities were analyzed using two different solvent parameters, i.e., Hildebrand's solubility parameter and Richard's E _T(30). These contributions to solubility are interpreted in terms of the asymmetric structure of the probe metal complex.     

Two new meroterpenoids, penisimplicin A and B, isolated from Penicillium simplicissimum

In the course of our research for new antifungal agents, two new meroterpenoids, penisimplicin A (1) and B (2), were isolated from Penicillium simplicissimum. The absolute structures of 1 and 2 were established by spectroscopic and chemical investigation. Penisimplicin A (1) and B (2) are rare examples of D-ring seco-meroterpenoids. Since compounds 1 and 2 showed no antifungal activities, the isolation of the compounds with antifungal activity will be attempted.     

Preparation of samples for gas chromatography/mass spectrometry analysis of phthalate and adipate esters in plasma and beverages by steam distillation and extraction

Phthalate and adipate esters are present in relatively large amounts in the environment, resulting in their large blank values at analysis and making precise analysis difficult. We developed a highly sensitive analytical method for phthalate and adipate esters in plasma and beverages by lowering the blank values that interfere with analysis. The method uses a closed distillation cleanup system in which steam distillation and extraction are performed simultaneously. The recoveries from beverages and plasma were both satisfactory, ranging from 90.2 to 118.3%, relative standard deviation (RSD) = 2.8-5.3%, and 96.2-134.4%, RSD = 2.2-6.5%, respectively. The detection limits of dibutyl phthalate and di-2-ethyl hexyl phthalate were 5 ng/mL, and those of diethyl phthalate, butyl benzyl phthalate, and di-2-ethyl hexyl adipate were 10 ng/mL in rabbit plasma and beverages.     

Solubilities of rare earth lodates in aqueous and aqueous alcoholic solvent mixtures

The solubilities of thirteen iodates of rare earth metals in aqueous and aqueous alcoholic solvent mixtures at 25°C were measured. Methanol and ethanol were used as the alcoholic components, and the alcohol concentrations in solvent mixtures were between 0–40 mass percent. From the solubilities measured in this study and the published data, the recommended solubility values of eleven iodates of rare earth metals [Ln(IO₃)₃: Ln=Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb] in water at 25°C were decided by applying the guidelines of the IUPAC Solubility Data Project, and the solubilities of two iodates [Ln(IO₃)₃: Ce and Lu] are designated as tentative values. The change in solubility of lanthanide iodates in aqueous and aqueous alcoholic solvent mixtures as a function of lanthanide atomic number is discussed. The logarithm of the solubility decreases almost linearly with the reciprocal of the dielectric constant of the solvent mixture, as expected from Born's equation and its modifications.Presentation to First International Symposium on Solubility Phenomena, University of Western Ontario, London, Ontario, August 21–23, 1984.     

Radiation-induced polymerization of tetraoxane in the solid state

The radiation-induced polymerization of tetraoxane in the solid state has been investigated in air and in vacuo. The polymerization rate was higher in air than in vacuo, whereas the molecular weight of the polymer obtained at high conversion in air was considerably lower than in vacuo. A large decrease in the molecular weight with increasing polymer yield observed in air may be explained mainly by degradation during polymerization.     

Total Synthesis of (±)-Hirsutene via Pd-Promoted Cycloalkenylation Reaction

Beginning with trans-2-methyl-4-cyclohexenecarboxylic acid (9), a total synthesis of linear triquinane sesquiterpene (±)-hirsutene (1) has been accomplished. An acid catalyzed intramolecular conjugate addition (7→6a) and a Pd²⁺-promoted highly stereocontrolled cyclization (5→4) were utilized for the key step of the sequence. Interestingly, some synthetic intermediates exhibited cytotoxicity.     

The influence of light sources on sunitinib measurements with photoisomerization

Sunitinib is an orally administered tyrosine kinase inhibitor. Therapeutic drug monitoring is an important component of the follow‐up of patients because of high interpatient variability in the pharmacokinetics of sunitinib and large variabilities in its efficacy and toxicity. The aim of the present study was to examine the light stability of sunitinib and confirm the effects of light exposure on sunitinib measurements by LC–MS/MS. Sunitinib and its active metabolite, SU12662, convert Z isomers to E isomers with exposure to light. The Z–E photoisomerization ratio reached a plateau at 35% for both E isomers in methanol within 15 min of normal light exposure (700 lx). However, the Z isomer of the sunitinib and SU12662 peak area ratios in plasma decreased by 10% within 15 min. These results suggest that sunitinib samples need to be handled without light exposure in all sample preparation steps. Alternatively, it should be measured sunitinib and SU12662 after the sample has reached photoisomerical equilibrium. These results suggest that the sunitinib therapeutic range changes depending on light conditions during sample handling in sunitinib and SU12662 measurements.     

Guest-dependent flexible coordination networks with fluorinated ligands

Guest-dependent flexible coordination networks are formed from 1,4-bis(4-pyridylmethyl)tetrafluorobenzene (bpf), 4,4'-bis(4-pyridylmethyl)octafluorobiphenyl (bpfb), 2,6-bis(4-pyridylmethyl)hexafluoronaphthalene (2,6-bpfn), and 2,7-bis(4-pyridylmethyl)hexafluoronaphthalene (2,7-bpfn) with Cd(NO3)2 in the presence of various organic compounds. The reaction of bpf affords one-dimensional cyclic chains, two-dimensional rhombus grid sheets, and three-dimensional diamond frameworks with threefold interpenetration. The reaction of bpfb mainly affords two-dimensional rhombus grid sheets with twofold parallel interpenetration. The reaction of 2,6-bpfn affords a one-dimensional ladder and two-dimensional rhombus grid, twisted grid, and herringbone sheets. The reaction of 2,7-bpfn affords two-dimensional rhombus grid sheets and grid sheets with dumbbell-shaped cavities. This diversity of network topologies is induced by interactions between the guest molecules and the flexible ligand frameworks.     

Design of a practical fluorescent probe for superoxide based on protection-deprotection chemistry of fluoresceins with benzenesulfonyl protecting groups

A strategy for designing probes based on protection-deprotection chemistry involving fluoresceins and their benzenesulfonyl (BES) derivatives has led to the development of a much more practical superoxide (O(2) (-.)) probe than the previously reported bis(2,4-dinitro-BES) tetrafluorofluorescein (6 a). Examination of various BES derivatives, developed from the starting point of the prototype probe 6 a, yielded 4,5-dimethoxy-2-nitro-BES tetrafluorofluorescein (BESSo; 7 j) as the optimal reagent. A microtiter plate assay with BESSo showed a tenfold improved detection limit for O(2) (-.) compared with such an assay based on 6 a. BESSo showed markedly better specificity for O(2) (-.) than for GSH or other reactive oxygen species, and this specificity was significantly higher than that of Fe(2+) and some reducing enzymes. These features have resulted in the development of an assay based on BESSo that is capable of providing more unambiguous results for O(2) (-.) release from neutrophils, with or without stimulation by phorbol myristate acetate, as compared with an assay based on 6 a. Intracellular generation of O(2) (-.) in human Jurkat T cells stimulated by butyric acid has been measured by using flow cytometry and fluorescence microscopy utilizing the acetoxymethyl derivative of BESSo.