Synthesis of 2-acylindole-3-acetic acids: a novel base-mediated indole synthesis

An efficient and expedient synthetic route to 2-acylindole-3-acetic acids is described. This work first demonstrates a one-pot room-temperature indole ring construction via the in situ generation of indoline intermediate.     

Speciation of small molecules and inorganic ions in salmon egg cell cytoplasm by surfactant-mediated HPLC/ICP-MS.

The speciation of diverse elements in salmon egg cell cytoplasm was performed by a surfactant-mediated HPLC/ICP-MS hyphenated system. In the present experiment, an ODS column coated with CHAPS (3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate), which is a zwitterionic bile acid derivative, was employed as a surfactant-mediated separation column, and ICP-MS was used as an element-selective detector. The present surfactant-mediated HPLC allowed us to separate large and small molecules within 10 min; large molecules, such as proteins, were eluted within 2.5 min, while small molecules were eluted after 2.5 min, but within 10 min. In the present experiment, Fe, Cu, and Zn in egg cell cytoplasm were observed mostly in species with large molecular weights, indicating that these elements are contained as metalloproteins or metalloenzymes in egg cell cytoplasm. On the contrary, it was found that P, S, Mo, and halogens in egg cell cytoplasm were contained as small molecules or inorganic ions. The major species of P in egg cell cytoplasm was identified as the phosphate ion (PO4(3-)). Molybdenum, Cl, and Br in egg cell cytoplasm were molybdate (MoO4(2-), chloride (Cl-), and bromide (Br-) ions, respectively.     

Performance of fast multipole methods for calculating electrostatic interactions in biomacromolecular simulations

The fast multipole method proposed by Greengard and Rokhlin (GR) is applied to large biomacromolecular systems. In this method, the system is divided into a hierarchy of cells, and electric field exerted on a particle is decomposed into two parts. The first part is a rapidly varying field due to nearby cells, so that it needs rigorous pairwise calculations. The second part is a slowly varying local field due to distant cells; hence, it allows rapid calculations through a multipole expansion technique. In this work, two additional possibilities for improving the performance are numerically examined. The first is an improvement of the convergence of the expansion by increasing the number of nearby cells, without including higher-order multipole moments. The second is an acceleration of the calculations by the particle–particle and particle–mesh/multipole expansion (PPPM/MPE) method, which uses fast Fourier transform instead of the hierarchy. For this purpose, the PPPM/MPE method originally developed by the authors for a periodic system is extended to a nonperiodic isolated system. The advantages and disadvantages of the GR and PPPM/MPE methods are discussed for both periodic and isolated systems. It is numerically shown that these methods with reasonable costs can reduce the error in potential felt by each particle to 0.1–1 kcal/mol, much smaller than the 30-kcal/mol error involved in conventional simple truncations. © 1994 by John Wiley & Sons, Inc.     

Temperature effect on the selective hydration of sodium ion in nitrobenzene.

The effect of the temperature on the co-extraction of water molecules with Na+ from water to nitrobenzene (NB) in the presence of dipicrylaminate ion has been studied. The number (n) of water molecules co-extracted with a Na+ ion, as measured by the Karl Fischer method, increased from 3.1 to 5.2 with increasing temperature (6-65 degrees C). This observation is in apparent contradiction to the expectation from simple thermodynamics because hydration is generally an entropically unfavorable process. Additional 1H NMR experiments for the selective hydration of Na+ in deuterated NB have confirmed that the association constants of water with Na+ indeed decrease with increasing temperature. On the other hand, however, it has been shown that water solubility into NB substantially increases with temperature. We conclude that the latter effect overwhelms the former unfavorable entropy effect, which results in a net increase of the n-value, as observed.     

A study to control chemical reactions using Si:2p core ionization: site-specific fragmentation

In an aim to create a "sharp" molecular knife, we have studied site-specific fragmentation caused by Si:2p core photoionization of bridged trihalosilyltrimethylsilyl molecules in the vapor phase. Highly site-specific bond dissociation has been found to occur around the core-ionized Si site in some of the molecules studied. The site specificity in fragmentation and the 2p binding energy difference between the two Si sites depend in similar ways on the intersite bridge and the electronegativities of the included halogen atoms. The present experimental and computational results show that for efficient "cutting" the following conditions for the two atomic sites to be separated by the knife should be satisfied. First, the sites should be located far from each other and connected by a chain of saturated bonds so that intersite electron migration can be reduced. Second, the chemical environments of the atomic sites should be as different as possible.     

Spectroscopy of HF and HF-containing clusters in solid parahydrogen

We report measurements of FT-IR absorption spectroscopy of HF, DF, and their clusters in solid parahydrogen (pH(2)). The observed spectra contain many absorption lines which were assigned to HF monomers, HF polymers, and clusters with other species, such as N(2), O(2), orthohydrogen (oH(2)), etc. The rotational constants of HF and DF monomers were determined from the cooperative transitions of the vibration of solid pH(2) and the rotation of HF and DF. Small reduction of the rotational constants indicates that HF and DF are nearly free rotors in solid pH(2). Time dependence of the spectra suggests that HF and DF monomers migrate in solid pH(2) and form larger polymers, probably via tunneling reactions through high energy barriers on inserting another monomer to the polymers. The line width of HF monomers in solid pH(2) was found to be 4 cm(-1), which is larger than that of other hydrogen halides in solid pH(2). This broad line width is explained by rapid rotational relaxation due to the accidental coincidence between the rotational energy of HF and the phonon energy with maximum density of states of solid pH(2) and the rotational-translational coupling in a trapping site.     

Photo-driven anti-Markovnikov alkyne hydration in self-assembled hollow complexes

Under UV-light irradiation, the anti-Markovnikov hydration of internal arylalkynes proceeds in the cavity of an electron-deficient coordination cage to give benzyl ketones; the reaction is triggered by cage-mediated, photo-induced electron transfer from the alkynes to the cage.     

Improvement of hydrogen desorption kinetics in the LiH-NH3 system by addition of KH

It was found that, when a little amount of KH (5 mol%) was added in the LiH-NH(3) hydrogen storage system, the hydrogen desorption kinetics of this system at 100 °C was drastically improved by the KH "pseudo-catalytic" effect.     

Metal-intercalated aromatic hydrocarbons: a new class of carbon-based superconductors

New carbon-based superconductors are synthesized by intercalating metal atoms into the solid-phase hydrocarbons picene and coronene. The highest reported superconducting transition temperature, T(c), of a hydrocarbon superconductor is 18 K for K(3)picene. The physics and chemistry of the hydrocarbon superconductors are extensively described for A(x)picene (A: alkali and alkali earth-metal atoms) for x = 0-5. The theoretical picture of their electronic structure is also reviewed. Future prospects for hydrocarbon superconductors are discussed from the viewpoint of combining electronics with condensed-matter physics: modification of the physical properties of hydrocarbon solids is explored by building them into a field-effect transistor. The features of other carbon-based superconductors are compared to clarify the nature of hydrocarbon superconductors.