Preliminary experiment of fluorescent X-ray computed tomography to detect dual agents for biological study

The simultaneous observation of various information, such as blood flow, tissue metabolism and distribution of receptors, is quite important in order to understand the functional state of biomedical objects. The simultaneous detectability of contrast agents by fluorescent X-ray computed tomography (FXCT) with synchrotron radiation is examined in this study. The system consisted of a silicon (111) double-crystal monochromator, an X-ray slit system, a scanning table, a PIN diode, a highly purified germanium detector and an X-ray charge-coupled device (CCD) camera. The monochromatic X-ray beam energy was adjusted to 37.0 keV and collimated into a pencil beam of 1 x 1 mm. The fluorescent spectra of the K alpha lines for iodine and xenon were detected simultaneously. FXCT could image the distribution of both iodine and xenon agents in a phantom clearly and the contrast ratio was significantly better than that of transmission X-ray computed tomography images.     

Alkane oxidation via photochemical excitation of a self-assembled molecular cage

The photoexcitation of a self-assembled M6L4-type coordination cage accommodating photochemically inert alkane guests (e.g., adamantane and cyclooctane) led to the regioselective oxidation of the guest within the cage. Under anaerobic conditions, the guest oxidation was accompanied by the stable radical formation as indicated by ESR spectrometry (g = 2.002) and change in solution color (from colorless to blue). These phenomena were shown to be characteristic of the self-assembled molecular systems: i.e., from the M6L4 supersetGn assembly, none of the components (M, L, or G) can be eliminated for the unusual oxidation and/or radical formation.     

Accumulation of phenyl boronic acid-carrying telomers on a gold surface

By coupling two equivalents of N,N-diethyldithiocarbamoylmethylbenzoic acid succinimidyl ester with cystamine dihydrochloride, a disulfide-carrying compound (Cys-BDC) was prepared and used as iniferter (a compound which pursues initiation, chain transfer, and termination) in the telomerization of N,N-dimethylacrylamide and 3-acrylamidophenylboronic acid. The telomerization was carried out in the presence of N,N,N',N'-tetraethylthiuram disulfide under photoirradiation at 365 nm. An aqueous solution of the telomer obtained showed responsiveness to both temperature and sugars as confirmed by the turbidity measurements. The telomer formed a self-assembled monolayer (SAM) on a gold surface as confirmed by both cyclic voltammetry (CV) and ellipsometry. The recognition of sugar residues by the telomer SAM constructed on the gold electrode was detected by the CV measurements. The usefulness of the iniferter to prepare various telomer-carrying SAMs with bio-related functions was strongly suggested.     

Novel synthesis and properties of 1,6-methanocycloundeca[b]pyrimido[5,4-d]pyrrole-12,14-dione derivatives: autorecycling oxidation of some amines and alcohols

Novel 1,6-methanocycloundeca[b]pyrimido[5,4-d]pyrrole-12,14-dione derivatives 6a,b and 7a-c were synthesized in moderate to good yields by the enamine alkylation and dehydrating condensation reactions of 11-chloro-3,8-methano[11]annulenone (8) with 6-amino-3-substituted uracil derivatives and subsequent elimination of HCl. The (1)H NMR spectra clarified that compounds 6a,b and 7a-c are aromatic molecules having a diatropic pi-system, which is suggested by the chemical shifts of the bridge methylene protons and peripheral protons. The electrochemical reduction exhibited more positive reduction potentials as compared with those of the vinylogous compounds of cyclohepta[b]pyrimido[5,4-d]pyrrole derivatives. In a search for the oxidizing function of 6a,b and 7a-c, compounds 6a and 7b were demonstrated to oxidize benzylamines, cyclohexylamine, and benzyl alcohol to give the corresponding carbonyl compounds in more than 100% yield under aerobic and photoirradiation conditions, while only benzylamine was oxidized under aerobic and thermal conditions at 100 degrees C. Thus, compounds 6a and 7b oxidize amines and alcohols in an autorecyling process, and the efficiency is higher under photoirradiation as compared with the thermal process, suggesting the oxidation reaction probably proceeds via electron transfer from amine and alcohol to the excited and ground states of compounds 6a and 7b.