Interfacial deformation between an impacting water drop and a silicone-oil surface

Detailed observations have been conducted on the interfacial deformation of a silicone oil surface and a water drop falling on it. Eleven kinds of silicone oils with wide variations of kinematic viscosity, nu(T)=1-10(5) mm(2)/s, have been tested. The oil surface is disturbed by a water drop with a diameter d(L)=3.1 mm, which falls freely on it from a height of 100-1000 mm. Special attention has been directed to the maximum depth of the cavity formed on the oil surface D(M) and to the maximum diameter of the water drop spreading on the oil surface d(M). We have categorized the configurations of the oil cavity into seven patterns, and those of the water drop at the oil-water interface into five patterns. The maximum cavity depth D(M)/d(L) can be well correlated by a dimensionless group Re(TL)We(TL), where Re(TL) is Reynolds number based on d(L) and nu(T) and We(TL) is Weber number with the water density and surface tension of oil. The maximum diameter of the impacting water drop d(M)/d(L) can be correlated by the Reynolds number with a viscosity of water (Re(L)) and the Ohnesorge number (Oh). Moreover, the condition under which the impacting water drop is smashed into pieces has been also examined based on Re(L) and Oh.     

Design and synthesis of chiral 1,10-phenanthroline ligand,and application in palladium catalyzed asymmetric 1,4-addition reactions

Pd-catalyzed asymmetric 1,4-addition of phenylboronic acid to α,β-unsaturated carbonyl compounds was developed using chiral 1,10-phenanthroline derivative as ligand. Good yields (up to 97%), and high enantioselectivities (up to 97% ee) were achieved.     

Stereoselective formation of alpha-alkylidene cyclic carbonates via carboxylative cyclization of propargyl alcohols in supercritical carbon dioxide

Carboxylative cyclization of propargyl alcohols in supercritical carbon dioxide (scCO2) containing P(n-C4H9)3 as a catalyst proceeded smoothly to give alpha-alkylidene-1,3-dioxolan-2-ones. Internal propargyl alcohols afforded Z-alkyl-idene cyclic carbonates exclusively. CO2 incorporation was markedly promoted under supercritical conditions, possibly due to the facile formation of a putative P(n-C4H9)3-CO2 adduct as a key intermediate.     

Three new monoterpenoids from the fruit of Genipa americana

Three new monoterpenoids, called genipacetal, genipamide, and genipaol, were isolated from the fruit of Genipa americana L. (Rubiaceae), along with the four known iridoids genipin, gardendiol, deacetyl asperulosidic acid methyl ester, and shanzhiside. Their chemical structures were determined on the basis of spectroscopic data.     

Reaction of 2,4-di-t-butyl-6-methylphenylphosphonous dichloride with chloroform in the presence of lithium diisopropylamide

2,4-Di-t-butyl-6-methylphenylphosphonous dichloride reacted with chloroform in the presence of lithium diisopropylamide to give (2,4-di-t-butyl-6-methylphenyl) (dichloromethyl) (1,2,2-trichloroethenyl)phosphine. The structure of this phosphine was analyzed by X-ray crystallography. This phosphine further reacted with butyllithium to give (1-butylpentylidene)(2,4-di-t-butyl-6-methylphenyl)phosphine bearing a low-coordinated phosphorus atom. © 1996 John Wiley & Sons, Inc.     

Efficient visible/NIR light-driven uncaging of hydroxylated thiazole orange-based caged compounds in aqueous media

In photoactivation strategies with bioactive molecules, one-photon visible or two-photon near-infrared light-sensitive caged compounds are desirable tools for biological applications because they offer reduced phototoxicity and deep tissue penetration. However, visible-light-sensitive photoremovable protecting groups (PPGs) reported so far have displayed high hydrophobicity and low uncaging cross sections (εΦ < 50) in aqueous media, which can obstruct the control of bioactivity with high spatial and temporal precision. In this study, we developed hydroxylated thiazole orange (HTO) derivatives as visible-light-sensitive PPGs with high uncaging cross sections (εΦ ≈ 370) in aqueous solution. In addition, 2PE photolysis reactions of HTO-caged glutamate were achieved using a NIR laser (940 nm). Moreover, HTO-caged glutamate can activate N-methyl-d-aspartic acid receptors in Xenopus oocytes and mammalian cells with green-light illumination, thus allowing optical control of biological functions.

A hydroxylated thiazole orange (HTO)-caged glutamate efficiently releases a glutamate for temporal activation of ion channels under visible-to-NIR light in aqueous media.     

Monolayer/bilayer transition in Langmuir films of derivatized gold nanoparticles at the gas/water interface: an x-ray scattering study

The microscopic structure of Langmuir films of derivatized gold nanoparticles has been studied as a function of area/particle on the water surface. The molecules (AuSHDA) consist of gold particles of mean core diameter D approximately 22 angstroms that have been stabilized by attachment of carboxylic acid terminated alkylthiols, HS-(CH2)15-COOH. Compression of the film results in a broad plateau of finite pressure in the surface pressure versus area/particle isotherm that is consistent with a first-order monolayer/bilayer transition. X-ray specular reflectivity (XR) and grazing incidence diffraction show that when first spread at large area/particle, AuSHDA particles aggregate two dimensionally to form hexagonally packed monolayer domains at a nearest-neighbor distance of a = 34 angstroms. The lateral positional correlations associated with the two-dimensional (2D) hexagonal order are of short range and extend over only a few interparticle distances; this appears to be a result of the polydispersity in particle size. Subsequent compression of the film increases the surface coverage by the monolayer but has little effect on the interparticle distance in the close-packed domains. The XR and off-specular diffuse scattering (XOSDS) results near the onset of the monolayer/bilayer coexistence plateau are consistent with complete surface coverage by a laterally homogeneous monolayer of AuSHDA particles. On the high-density side of the plateau, the electron-density profile extracted from XR clearly shows the formation of a bilayer in which the newly formed second layer on top is slightly less dense than the first layer. In contrast to the case of the homogeneous monolayer, the XOSDS intensities observed from the bilayer are higher than the prediction based on the capillary wave model and the assumption of homogeneity, indicating the presence of lateral density inhomogeneities in the bilayer. According to the results of Bragg rod measurements, the 2D hexagonal order in the two layers of the bilayer are only partially correlated.     

Molten salts bearing anion receptor

A series of organoboron molten salts prepared by hydroboration of allyl imidazolium type molten salts with various hydroborating reagents such as monobromoborane dimethyl sulfide complex, 9-borabicyclo[3.3.1]nonane (9-BBN) and mesitylborane, and subsequent anion exchange reaction exhibited selective cation transporting property with ionic conductivity of 7.79 x 10(-5) - 6.25 x 10(-6) S cm(-1) at 323 K.