Inclusion polymerization of various diene monomers in apocholic acid canals

The inclusion polymerization of diene monomers with different sizes and shapes in apocholic acid canals was studied under -ray irradiation. It was found that the sizes and shapes of monomers profoundly influenced the microstructures of the corresponding polymers obtaied. Thus, polybutadiene contained a significant amount of 1,2-units like usual radical polymerization in solution. Polyisoprene consisted of a mixture of head-to-tail and head-to-head (tail-to-tail) addition. The introduction of two methyl groups into butadiene led to the synthesis of polymers with almost exclusively head-to-tail, 1,4-trans structure.     

Funktionelle Monomere und Polymere. 26. Mitt Synthese und Polymerisation von Vinylcholat und Vinyldehydrocholat

Ohne Zusammenfassung     

Selective growth of InP by MOCVD around dry-etched mesas having various patterns for photonic integrated circuits

We have investigated the selective growth ofpnp- InP by metalorganic chemical vapor deposition (MOCVD) around mesas. The mesas were formed by reactiveion-etching using SiO₂ masks having various patterns. The patterns include stripes along different crystallographic orientations, Y-bifurcations, and X-crossings. The behavior of the growth, and that of the mass transport before the growth, were found to depend remarkably on the crystallographic direction of the mesa stripe. The most notable mass transport, which transforms a nearly vertical mesa wall to a sloped one, was observed for a stripe misoriented by about 30° from the [011] direction. The growth was observed to proceed preferentially on the sloped planes, planarizing the crystal surface, for a mesa stripe directed between the [011] and [010] directions. However, for the stripe direction near [01-1], the growth was observed to creep up a nearly vertical plane on the mesa wall, and sloped planes are reluctant to form. Selective growth with sufficient planarity has been obtained for various waveguides including the Y-bifurcations and the X-crossings, which are used as the waveguide components in photonic integrated circuits, when the stripes are almost along the [011] direction.     

Novel technique for connecting waveguides and fibers

A practical technique with low coupling loss has been developed for connecting waveguides and fibers by adjusting and fixing them one by one. A thin strip of glass is permanently cemented on the side of the fiber near the tip to be joined. This strip is used as a manipulator, after which it is cemented to the substrate.     

Vinyl polymerization by metal complexes. III. Vinyl polymerization initiated by oligoamide and cupric ion system

Polymerization of methyl methacrylate and other vinyl monomers was studied in the presence of oligoamide (?-aminocaproic acid, its dimer, trimer, tetramer, and pentamer) and cupric ion in aqueous media. The polymerization was found to be of free-radical character and selective for the type of vinyl monomer. Carbon tetrachloride can accelerate the polymerization. The initiation mechanism of the polymerization is discussed. Spectroscopic measurements were indicative of formation of 1:1 complex between oligoamides and cupric ion in aqueous NaClO₄ solution. Some chemical and physical properties of the resulting polymers were measured.     

Asymmetric synthesis of macrolactin analogue

Total asymmetric synthesis of macrolactin A analogue was accomplished by the convergent strategy. Rapid access to advanced intermediate 16 through isomerization of ynone to (E,E)-conjugated dienone is a key step of this synthesis. Overall, control of all of the four stereocenters was achieved by means of asymmetric and diastereoselective reactions without using any chiral natural sources.     

Photoinduced reactions—LXXI: Photorearrangement of 3-hydroxyflavones to 3-aryl-3-hydroxy-1,2-indandiones

3-Hydroxyflavones (1) were found to undergo a novel photorearrangement to 3-aryl-3-hydroxy-1,2-indandiones (2) which were characterized as o-phenylenediamine adducts, 1-aryl-1-hydroxy-11H-indeno[1,2-b]quinoxalines (3). To the contrary, 3-methoxyflavone underwent photochemical intramolecular hydrogen transfer. Photochemical reactivities of several other flavonoids were examined. It appears that the 5-hydroxyl H-bonded to the 4-carbonyl causes photoresistance in flavonoids.