Synthesis of polysulfonamides from aromatic disulfonyl bromides and diamines

Solution polycondensations of aromatic disulfonyl bromides with diamines in tetramethylene sulfone at room temperature by the use of organic or inorganic acid acceptors yielded polysulfonamides with moderately high molecular weights. Preferred acid acceptors were 2-methylpyridine and propylene oxide and lead oxide. The high activity of lead oxide was discussed in relation to the principle of hard and soft acid and bases.     

Photoisomerization of 1,2-diphenylcyclopropane sensitized by polypeptides containing naphthalene groups in their side chain

Poly(γ-1-naphthylmethyl L - and DL -glutamate) (PNLG and PNDLG) and copolypeptides of γ-1-naphthylmethyl L -glutamate and γ-benzyl-L -glutamate were used as sensitizers for isomerization of trans-1,2-diphenylcyclopropane. Quantum yields relative to that of 1-methylnaphthalene were measured in dichloroethane (DCE) and dichloroacetic acid (DCA). The relative quantum yield in DCE was smaller than unity for PNLG, but greater than unity for PNDLG and copolypeptides. The result is discussed in terms of increased effective collisional radius and energy trapping by excimer formation. The relative quantum yields in DCA were close to unity except for the copolypeptides of higher γ-benzyl L -glutamate content. This suggests that the naphthalene groups act in the same manner as their monomeric counterparts in the random conformation and that the greater proportion of γ-benzyl L -glutamate in the copolypeptides lowers the quantum efficiency because trans-1,2-diphenylcyclopropane must penetrate through the polymeric medium in order to encounter the excited naphthalene.     

Synthesis and chiral recognition ability of optically active poly{N‐[(R)‐α‐methoxycarbonylbenzyl]methacrylamide} with various tacticities by radical polymerization using Lewis acids

The radical polymerization of an optically active methacrylamide, N‐[(R)‐α‐methoxycarbonylbenzyl]methacrylamide, was carried out in the absence and presence of Lewis acids such as yittribium trifluoromethanesulfonate [Yb(OTf)₃] and scandium trifluoromethanesulfonate [Sc(OTf)₃]. Catalytic amounts of the Lewis acids significantly affected the stereoregularity of the obtained polymers. The polymerization with Yb(OTf)₃ in tetrahydrofuran afforded isotactic polymers (up to mm = 87%), whereas the conventional radical method without the Lewis acid produced polymers rich in syndiotacticity (up to rr = 88%). The radical polymerization in the presence of MgBr₂ proceeded in a heterotactic‐selective manner (mr = 63%). Thus, the isotactic, syndiotactic, and heterotactic poly(methacrylamide)s were synthesized by the radical processes. The chiral recognition abilities of the obtained optically active poly(methacrylamide)s were affected by the stereoregularity. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3354–3360, 2003     

Simulation and Experimental Study of Wavefront Measurement Accuracy of the Pencil-Beam Method

Ultra-bright and high-coherence X-rays are now being used in synchrotron radiation facilities and X-ray free electron laser facilities. X-ray focusing techniques are essential to take full advantage of these excellent X-ray light sources. To meet the strong demand, high-quality X-ray focusing optics have been developed owing to the advancement of ultraprecision machining and measurement. State-of-the-art refractive lenses [1 C.G. Schroer, Applied Physics Letters 87, 124103 (2005).[Crossref], [Web of Science ®] , [Google Scholar]], zone plates [2 T. Chen, Optics Express 19, 19919 (2011).[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]], and Laue lenses [3 H. Yan, Optics Express 19, 15069 (2011).[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]] can be used to achieve X-ray focusing to a spot a few tens of nanometers.     

Iron films deposited on porous alumina substrates

Iron films were deposited on porous alumina substrates using an arc plasma gun. The pore sizes (120 – 250 nm) of the substrates were controlled by changing the temperature during the anodic oxidation of aluminum plates. Iron atoms penetrated into pores with diameters of less than 160 nm, and were stabilized by forming γ-Fe, whereas α-Fe was produced as a flat plane covering the pores. For porous alumina substrates with pore sizes larger than 200 nm, the deposited iron films contained many defects and the resulting α-Fe had smaller hyperfine magnetic fields. In addition, only a very small amount of γ-Fe was obtained. It was demonstrated that the composition and structure of an iron film can be affected by the surface morphology of the porous alumina substrate on which the film is grown.     

Formation of chiral 21-helical columnar host system with phenylacetylene unit by using (1R,2S)-2-amino-1,2-diphenylethanol

A tunable supramolecular phenylacetylene host system with a chiral channel-like cavity is developed by using (1R,2S)-2-amino-1,2-diphenylethanol. This host system possesses a chiral 2₁-helical columnar structure; chiral cavities are constructed by the self-assembly of the 2₁-helical column, and guest molecules are included by varying the packing of this column.     

Aqueous noncovalent functionalization and controlled near-surface carbon doping of multiwalled boron nitride nanotubes

Noncovalent functionalization of boron nitride nanotubes (BNNTs) in aqueous solution was achieved by means of pi-stacking of an anionic perylene derivative, through which carboxylate-functionalized BNNTs were prepared for the first time. Starting from the functionalized nanotubes, an innovative methodology was designed and demonstrated for the controlled near-surface carbon doping of BNNTs. As a result of such delicate doping, novel B-C-N/BN coaxial nanotubes have been fabricated, and their p-type semiconducting behaviors were elucidated through gate-dependent transport measurements.     

Templating route for mesostructured calcium phosphates with carboxylic acid- and amine-type surfactants

Mesostructured calcium phosphates constructed by ionic frameworks were synthesized using carboxylic acid- and amine-type surfactants in mixed solvent systems of ethanol and water. A lamellar mesostructured calcium phosphate was prepared using palmitic acid as an anionic surfactant, as in the case using n-alkylamines. A wormhole-like mesostructured calcium phosphate can be obtained using dicarboxyl N-lauroyl- l-glutamic acid, whose headgroup is larger than that of palmitic acid. Similar mesostructured product was obtained using 4-dodecyldiethylenetriamine with a large headgroup containing two primary amine groups. Interactions of carboxyl and primary amino groups in the surfactant molecules with inorganic species are quite important for the formation of mesostructured calcium phosphates. The Ca/P molar ratio of mesostructured calcium phosphates was strongly affected by the molecular structure of surfactants containing carboxyl and primary amino groups. Ca-rich materials can be obtained using carboxylic acid-type surfactants (Ca/P approximately 1.7) rather than amine-type surfactants (Ca/P approximately 1.0).