5-O-(4-[125 I]Iodobenzyl)-L-ascorbic acid: electrophilic radioiodination and biodistribution in mice

As a part of our efforts to develop potential imaging agents for ascorbate bioactivity, 5-O-(4-[(125)I]iodobenzyl)-L-ascorbic acid ([(125)I]1) was prepared through a two-step sequence which involved radioiodo-destannylation of a protected tributylstannyl precursor 6, followed by hydrolysis in acidic methanol of the protecting groups in 61% overall radiochemical yield, with a radiochemical purity of over 98% and a specific activity of more than 15.4?GBq/μmol. Tissue distribution of [(125)I]1 in tumor-bearing mice showed signs of distribution profiles similar to the reported results for 6-deoxy-6-[(18)F]fluoro-L-ascorbic (6-(18)FAsA) acid and 6-deoxy-6-[(131)I]iodo-L-ascorbic acid (6-(131)IAsA) but with notable differences in the adrenal glands, in which considerably lower uptake of radioactivity and rapid clearance with time were observed. Pretreatment of mice with a known inhibitor of ascorbate transport, sulfinpyrazone, did not produce any significant change in the adrenal uptake of radioactivity after injection of [(125)I]1 compared to the control, suggesting that uptake in the adrenal glands is independent of the sodium-dependent vitamin C transporter 2 transport mechanism. Introduction of a bulky substituent at C-5 on AsA, such as an iodobenzyloxy group, may not be suitable for the design of analogs that may still be able to maintain characteristic distribution properties in vivo seen with AsA itself.     

PH-Dependent Water Structure at a Quartz Surface Modified with an Amino-terminated Monolayer Studied by Sum Frequency Generation

Sum frequency generation (SFG) is a second-order nonlinear optical process in which two photons at frequencies W₁ and w₂ generate a photon of sum-frequency at w₃=w₁+w₂. SFG does not occur in media with inversion symmetry and is only active on the surface or interface where the inversion symmetry is necessarily broken^[1]. In the IR-visible SFG measurement, a visible laser beam (w₁) and a tunable infrared laser beam (w₂ are overlapped at an interface and the SFG signal is measured by scanning w₂ while keeping w₂ constant. The SFG is enhanced when w₂ is equal to the vibration levels of molecules at the interface^[1].     

Syntheses and electrical conductivity of polyamides containing tetrathiafulvalene moieties in the main chain

Novel polyamides that contain tetrathiafulvalene (TTF) moieties were synthesized by direct polycondensation of Δ^2,2′ -bi-1,3-dithiole-4,4′(5′)-dicarboxylic acid with aromatic diamines in the presence of triphenylphosphine, hexachloroethane, and pyridine. Complexes of these polyamides with bromine were TTF cation radical () salts which resulted from the charge transfer of TTF moieties to bromine. The electrical conductivity of undoped polyamides increased with a decrease in diamine length. By doping the bromine the conductivity of the polyamides was enhanced by 3–5 orders of magnitude and reached 10^?5–;10^?9S cm^?1. Maximum conductivity was observed at the doping ratio of [Br]/[repeat unit] < 1. The electrical conduction in the bromine complexes may be attributed to the hopping of odd electrons of between TTF moieties.     

Selective separation of water–alcohol binary mixture through poly(maleimide-co-acrylonitrile) membrane

Separation of various alcohols and water through a membrane was carried out by means of a hydrogen-bonding interaction. A membrane obtained from poly(maleimide-co-acrylonitrile) was effective for a selective separation of water from aqueous alcohol solution by pervaporation technique. Spectroscopic analyses verified that this high selectivity was attributed to the hydrogen-bonding interaction between water and maleimide units in the membrane.     

Thermoosmosis of various electrolyte solutions through anion-exchange membranes

Thermoosmosis through anion-exchange membranes was measured for 10^-3 to 2 mol/kg of aqueous KCl, LiCl, and NH₄Cl and for 10^-3 to 3 x 10^-1 mol/kg of aqueous KIO₃ and K₂SO₄. For all electrolytes used the direction of thermoosmosis was from the cold side to the hot side over the whole range of concentrations. For KCl and LiCl the experimental results were analyzed with an extension of a previously published theory, using additional data for transport numbers of ions in membranes and for electroosmosis. The agreement between theory and experiment is satisfactory. The absolute value of thermoosmosis for KIO₃ is larger than that for other electrolytes because the pore volume fraction of the membrane for KIO₃ is larger than that for the other electrolytes.     

Stereoselective synthesis of the right-hand cores of 16-methylated oxazolomycins

The right-hand heterocyclic cores of oxazolomycins having either 16R or 16S-methyl group configurations on the β-lactones were stereoselectively synthesized from the common intermediate utilized for our previous syntheses of neooxazolomycin and oxazolomycin A. In addition, the right-hand segment required for the synthesis of KSM-2690 and lajollamycin members was also synthesized in a stereoselective manner.     

Room-temperature polycondensation of β-amino acid derivatives,I. Polyamide from amino alcohols and acrylates

Acrylates, such as ethyl acrylate, add with amino alcohol to form N-(hydroxyalkyl) β-alanine ester and room-temperature polycondensation follows, forming polyamide in the presence of a basic catalysts, such as alkali metal alkoxide. The reaction medium has an influence on the course of the polycondensation; that is, N-(hydroxyalkyl) polyamide is formed in methanol solution and polyamide ether in other solvents, such as tetrahydrofuran. These two courses of the room-temperature polycondensation have been studied, and the reaction mechanism is discussed in this paper.     

Synthesis of microtubes with a surface of "house of cards" structure via needlelike particles and control of their pore size

The conditions for synthesizing microtubes with a surface of "house of cards" structure via needlelike particles were examined in detail. Magnesium carbonate trihydrate was formed as a metastable phase in the reaction process using magnesium hydroxide and carbon dioxide as starting materials. Subsequently, in the formation of basic magnesium carbonate from magnesium carbonate trihydrate, microtubes with a surface of house of cards structure were obtained via needlelike particles of magnesium carbonate trihydrate under certain conditions where the temperature and added amount of sodium hydroxide were properly controlled. The pore size of the microtubes could be controlled within a range of 0.5-6 microm by adjusting the condition of needlelike particle formation. In addition, the sustainability of naphthalene release from the microtube was found to be about 6 times higher than that from naphthalene crystal.