Organic functionalization of the surface of silica with arylsilanes. A new method for synthesizing organic-inorganic hybrid materials

Organic functionalization of a silica surface has been realized by employing arylsilanes. Grafting reactions of aryl(3-chloropropyl)dimethylsilanes (aryl = p-anisyl, p-tolyl, phenyl) with silica were carried out in heptane at 80 °C for 24 h. The ²⁹Si and ¹³C CP/MAS spectra of the obtained silica materials clearly showed that the 3-chloropropyldimethylsilyl moieties were cleanly grafted onto silica via a siloxane (Si-O-Si) bond accompanied by the release of the aryl groups. The loading amounts on FSM-type mesoporous silica (TMPS-4) with aryl(3-chloropropyl)dimethylsilanes were comparable to those with 2-propenylsilane and the most commonly used methoxysilane.     

Numerical analysis for a nematic droplet in polymer dispersed liquid crystals

Starting from the Landau-de Gennes free energy expression, the author has numerically analysed the director pattern in a nematic droplet of polymer dispersed liquid crystals. The nematic director has been understood as the eigenvector, which corresponds to the largest eigenvalue of the tensor order parameter. To investigate the droplet structure influence, all equations have been treated on the curvilinear coordinate system which is generated along the droplet boundary. In the case of spherical and spheroidal droplets with normal strong anchoring, the director exhibits an axial configuration and a disclination ring. The ring radius and the capactiance of the system change without hysteresis with the applied voltage.     

Novel High Precision Optoelectronic Device Fabrication Technique Using Guided Fluidic Assembly

High precision assembly of laser diodes (LDs) on silicon wafer substrates for use in advanced optoelectronic devices is an important issue from a mass production point of view. An acceptable alternative to replace an obsolete pick and place flip chip bonding robotic technology with a simple, low cost and high speed technique is desired for industrial applications. We have investigated a novel assembling technique with micrometer order accuracy for LDs and other microchips. Its feasibility for rapidly assembling a large number of high power edge emitting LDs is practically demonstrated. A 150 $mUm thick nickel metal mask is used to confine as well as guide the unassembled LDs into the recesses by its restricted displacements. This technique is based on guiding the LDs within a suitable fluidic medium and the assembling process is performed in two steps: (i) coarse precision with a confinement mask to bring LDs near the recesses to achieve high assembling efficiency and (ii) fine precision due to the electrode patterns on the base surface of LDs, under fluidic as well as gravitational force. The assembly of 80 red LDs of the same size and of 40 pairs of red and infrared LDs of two different sizes is successfully demonstrated within less than ±2 $mUm precision and 100% efficiency in a few seconds after transferring them into a confinement mask region.     

Rhodium-catalyzed nondecarbonylative addition reaction of ClCOCOOC2H5 to alkynes

Addition of ethoxalyl chloride (ClCOCOOEt) to terminal alkynes at 60 degrees C in the presence of a rhodium(I)-phosphine complex catalyst chosen from a wide range affords 4-chloro-2-oxo-3-alkenoates regio- and stereoselectively. Functional groups such as chloro, cyano, alkoxy, siloxy, and hydroxy are tolerated. The oxidative addition of ethoxalyl chloride to [RhCl(CO)(PR(3))(2)] proceeds readily at 60 degrees C or room temperature and gives [RhCl(2)(COCOOEt)(CO)(PR(3))(2)] (PR(3) = PPh(2)Me, PPhMe(2), PMe(3)) complexes in high yields. The structure of [RhCl(2)(COCOOEt)(CO)(PPh(2)Me)(2)] was confirmed by X-ray crystallography. Thermolysis of these ethoxalyl complexes has revealed that those ligated by more electron-donating phosphines are fairly stable against decarbonylation and reductive elimination. [RhCl(2)(COCOOEt)(CO)(PPh(2)Me)(2)] reacts with 1-octyne at 60 degrees C to form ethyl 4-chloro-2-oxo-3-decenoate. The catalysis is therefore proposed to proceed by oxidative addition of ethoxalyl chloride, insertion of an alkyne into the Cl--Rh bond of the resulting intermediate, and reductive elimination of alkenyl-COCOOEt.     

Retention of configuration on the oxidative addition of P-H bond to platinum (0) complexes: the first straightforward synthesis of enantiomerically pure P-chiral alkenylphosphinates via palladium-catalyzed stereospecific hydrophosphinylation of alkynes

The oxidative addition of pure (R(P))-menthyl phenylphosphinate 1 to a platinum (0) complex proceeds readily with retention of configuration at the chiral phosphorus center which was unambiguously confirmed by an X-ray analysis. In the presence of a catalytic amount of palladium, the hydrophosphinylation of a variety of alkynes with 1 also takes place stereospecifically, with retention of configuration, affording high yields of the corresponding vinylphosphinates bearing a single chirality at phosphorus.