Hydrogen-bond-directed 2-D sheet assemblies of sulfamide derivatives: formation of giant vesicles with patchwork-like surface pattern.

Sulfamide derivatives showed high ability to form hydrogen-bond-directed two-dimensional (2-D) sheet assemblies of nanometer thickness. Further, fine-tuning of the side chain structures and preparation conditions allowed for the formation of micrometer-sized giant vesicles of 4b in water by the simple injection method. IR and XRD studies indicated that 4b having tetradecyl and oxyethylene-terminated alkyl side chains formed hydrogen-bond-directed 2-D nanosheet pairs. SEM, AFM, and TEM observation of the dried vesicles revealed that the vesicle membrane was composed of several lamellar-stacked layers of 2-D nanosheets and showed a characteristic patchwork-like pattern on the surface.

Selective Intermolecular Coupling of Alkynes with Nitriles and Ketones via beta,beta' Carbon-Carbon Bond Cleavage of Zirconacyclopentenes.

Selective intermolecular coupling of alkynes with nitriles and ketones was performed by the reaction of a mixture of alkynes and Cp(2)ZrEt(2) with nitriles and ketones, respectively. Hydrolysis of the mixture gave alpha,beta-unsaturated ketones and allylic alcohols in good to excellent yields, respectively. These reactions proceeded via zirconacyclopentenes which were prepared by the reaction of alkynes with Cp(2)ZrEt(2). The structure of zirconacyclopentene, which was prepared from diphenylacetylene and Cp(2)ZrEt(2), was determined by X-ray analysis. It clearly indicated that there is a single bond between the beta- and beta'-carbons of the zirconacyclopentene. The reaction of zirconacyclopentenes with nitriles or ketones proceeded via the beta,beta' carbon-carbon bond cleavage of the zirconacyclopentenes. In a similar way, addition of PMe(3) to the zirconacyclopentene afforded a zirconocene-alkyne complex in 87% yield.

Adsorption of dimethyl silicone onto hair-surface models prepared with micro-phase separated monolayers.

The adsorption of dimethylsilicone (DMS) from its emulsion onto hair-surface models was investigated. The model surfaces were prepared on silicon wafers by utilizing a micro-phase separation in mixed Langmuir monolayers with a chemically adsorptive organosilane, n-octadecyltriethoxysilane (ODTES), as one component. The resulting surfaces consisted of hydrophobic micro-domains of polymerized ODTES and a surrounding hydrophilic surface silanol (SiOH) region of the silicon wafer, corresponding to the healthy and damaged regions of the hair surface, respectively, in terms of surface wettability. DMS preferentially adsorbed onto the high surface energy hydrophilic region of the model surface when the hydrophobic micro-domains were composed of fully condensed alkyl chains. The surface energy of the micro-domains could be controlled by using palmitic acid (PA) as the second component to form the micro-domains in the phase-separated Langmuir monolayers. The increase in the surface energy of the micro-domains induced the adsorption of DMS onto the intrinsically hydrophobic domain surface.

Amphiphilic sulfamide as a low-molecular-mass hydrogelator: A novel mode of 3-D networks formed by hydrogen-bond-directed 2-D sheet assemblies.

Asymmetrically substituted amphiphilic sulfamide, N-tetradecyl-N'-(6-dimethylaminohexyl)-sulfamide (3c) having a dimethylamino group at one end of the side chain, showed a strong ability to form two-dimensional (2-D) sheet-like assemblies by the 2-D hydrogen-bond networks between sulfamide moieties. Upon protonation of the amino group with acid, the cationic ammonium form of 3c induced effective hydrogelation (minimum gelation concentration: 0.5wt%) to yield a translucent, self-standing hydrogel. Infrared (IR) spectroscopy, X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) studies confirmed formation of the fibrous assemblies of the hydrogen-bond-directed 2-D nanosheets in the hydrogel. A novel mode of three-dimensional (3-D) networks was formed by branching and recombination of hydrogen-bond networks and knit-like linkages between the assemblies. The storage and loss moduli of the hydrogel (2wt%) were measured to be in the range of 10(2) and 10(3)Pa, showing relatively high mechanical stability.