Soluble and film-formable homopolymer tethering side-opened cage silsesquioxane pendants

Cage silsesquioxane, denoted as polyhedral oligomeric silsesquioxane (POSS) has high crystallinity to readily cause aggregation when it is induced into polymer side chain. In this work, side-opened POSS was employed to construct a bifunctional monomer for cyclopolymerization. The collapsed symmetry of the POSS core effectively reduced the crystallinity to realize homogeneous films, while a traditional POSS homopolymer formed turbid and brittle films. The obtained film showed high transparency and thermal stability.     

Circularly Polarized Luminescence of a Stereogenic Curved Paraphenylene Anchoring a Chiral Binaphthyl in Solution and Solid State

A curved stereogenic [6]paraphenylene ([6]PP), anchoring a chiral binaphthyl scaffold at 7,7’-positions, was prepared and investigated for its properties as a solid-state circularly polarized luminescence (CPL) dye. X-ray analysis revealed a helically twisted structure of PP units induced by axial chirality of binaphthyl framework. The curved [6]PP exhibits fluorescence in powder and polymethyl methacrylate (PMMA) film as well as solution. A significant increase in quantum yield was observed for a non-fluid PMMA film owing the suppression of the molecular motion. The g_CPL values of the dye in solution and as PMMA film were almost the same (4.3–4.4×10⁻³) and lager than that in powder. TD-DFT calculations in the excited state suggest that the exciton can be delocalized into a twisted PP unit to produce a larger magnetic transition dipole moment.     

Visible-Light-Induced Synthesis of 1,2,3,4-Tetrahydroquinolines through Formal [4+2] Cycloaddition of Acyclic α,β-Unsaturated Amides and Imides with N,N-Dialkylanilines

1,2,3,4-Tetrahydroquinolines should be applicable to the development of new pharmaceutical agents. A facile synthesis of 1,2,3,4-tetrahydroquinolines that is achieved by a photoinduced formal [4+2] cycloaddition reaction of acyclic α,β-unsaturated amides and imides with N,N-dialkylanilines under visible-light irradiation, in which a new Ir^III complex photosensitizer, a thiourea, and an oxidant act cooperatively in promoting the reaction, is reported. The photoreaction enables the synthesis of a wide variety of 1,2,3,4-tetrahydroquinolines, while controlling the trans/cis diastereoselectivity (>99:1) and constructing contiguous stereogenic centers. A chemoselective cleavage of an acyclic imide auxiliary is demonstrated.     

Triplet Diradical-Cation Salts Consisting of the Phenothiazine Radical Cation and a Nitronyl Nitroxide

The spin–spin and magnetic properties of two (nitronyl nitroxide)-(di-p-anisylamine-phenothiazine) diradical cation salts, ( DAA-PTZ ) ⁺ -NN⋅ MBr₄⁻ (M=Ga, Fe), have been investigated. These diradical-cation species were prepared by the cross-coupling of iodophenothiazine DAA-PTZ-I with NN-AuPPh₃ followed by oxidation with the thianthrenium radical cation ( TA⁺⋅ MBr₄⁻). These salts were found to be highly stable under aerobic conditions. For the GaBr₄ salt, large ferromagnetic intramolecular and small antiferromagnetic intermolecular interactions (J₁/k_B=+320 K and J₂/k_B=−2 K, respectively) were observed. The magnetic property of the Fe³⁺ salt was analyzed by using a six-spin model assuming identical intramolecular exchange interaction (J₃/k_B=+320 K) and the other exchange interactions (J₄/k_B=−7 K and J₅/k_B=−4 K). A significant color change was observed in the UV/Vis/NIR absorption spectra upon electrochemical oxidation of the doublet DAA-PTZ-NN to the triplet ( DAA-PTZ ) ⁺ -NN .     

Neutron spin rotation and P-violation

A new apparatus to measure the neutron spin rotation due to interaction with matter has been developed at KEK. The present apparatus enables us to measure the parity violating neutron spin rotation in the p-wave resonance in the energy region of eV.On leave from Tohoku University.     

Benzoin reaction in water as an aqueous medium catalyzed by benzimidazolium salt

Benzoin reactions are catalyzed by N,N-dialkylbenzimidazole to yield α-hydroxy ketones; the reaction proceeds in water as an aqueous medium under mild conditions. The utility of these salts as pre-catalysts in these reactions has been demonstrated.     

Inhibition of acyl coenzyme A: cholesterol acyltransferase by 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors

Relatively high concentrations of MK-733 (simvastatin) and MK-803 (lovastatin, mevinolin), which are 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, were found to inhibit acyl coenzyme A: cholesterol acyltransferase (ACAT) of rabbit intestinal microsomes with IC50's of 2.0 x 10(-5) and 3.6 x 10(-5) M, respectively. Dihydroxy acid forms of both MK-733 and MK-803 did not inhibit ACAT activity. A kinetic analysis using a Lineweaver-Burk plot indicated that MK-733 is a competitive inhibitor of ACAT, with a Ki value of 1.2 x 10(-5) M.     

Fundamental studies on thyroid stimulating hormone immunoradiometric assay kit (TSH RIABEAD II)

We have reported fundamental studies on the TSH immunoradiometric assay, using TSH RIABEAD II kit (Dainabot). The sensitivity of the assay was 0.03 mu IU/ml and its C.V. was 27.2%. Intra- and inter-assay C.V. were less than 5%. Dilution test and recovery test were good. Serum TSH level was 0.3-4.0 mu IU/ml in normal subjects, less than 0.03 mu IU/ml in untreated Graves' disease and subacute thyroiditis. Therefore, it was found that the clear difference exist in serum TSH levels between normal subjects and patients with untreated Graves' disease. There was a well correlation on the serum TSH levels between this method and TSH radioimmunoassay kit (Amerlex TSH, r = 0.983). Especially, the measurement of serum TSH levels, using immunoradiometric assay kit, was useful for the diagnosis of patients with Graves' disease.