Direct Synthesis of 1,4‐Diols from Alkenes by Iron‐Catalyzed Aerobic Hydration and CH Hydroxylation

Various 1,4‐diols are easily accessible from alkenes through iron‐catalyzed aerobic hydration. The reaction system consists of a user‐friendly iron phthalocyanine complex, sodium borohydride, and molecular oxygen. Furthermore, the effect of additional ligands on the iron complex was examined for a model reaction. The second hydroxy group is installed by direct C(sp³)? H oxygenation, which is based on a [1,5] hydrogen shift process of a transient alkoxy radical that is formed by formal hydration of the olefin.     

Nonequilibrium acoustic phonons in Y3Al5O12-based nanocrystalline ceramics

The phonon transport processes in high-transparency nanocrystalline laser ceramics based on cubic Y₃Al₅O₁₂ garnet oxide were investigated by the heat-pulse technique. The propagation kinetics of nonequilibrium acoustic phonons was studied in the range of helium temperatures (1.7–3.8 K). The structural model is suggested for the intergrain layers, and their thickness is estimated.     

A mean-absolute deviation-skewness portfolio optimization model

It is assumed in the standard portfolio analysis that an investor is risk averse and that his utility is a function of the mean and variance of the rate of the return of the portfolio or can be approximated as such. It turns out, however, that the third moment (skewness) plays an important role if the distribution of the rate of return of assets is asymmetric around the mean. In particular, an investor would prefer a portfolio with larger third moment if the mean and variance are the same. In this paper, we propose a practical scheme to obtain a portfolio with a large third moment under the constraints on the first and second moment. The problem we need to solve is a linear programming problem, so that a large scale model can be optimized without difficulty. It is demonstrated that this model generates a portfolio with a large third moment very quickly.Presently at Mitsubishi Trust Bank Co., Ltd.     

Cyclotrimerization of acetylene by the tris(acetylacetonato)titanium(III)–diethylaluminum chloride system

Reaction of acetylene with tris(acetylacetonato)titanium(III) and diethylaluminum chloride system leads to formation of benzene, a trace of ethylbenzene, and a small amount of polyacetylene. The isotopic composition of products obtained from cyclotrimerization of acetylene-d₂ and an equimolar mixture of acetylene and acetylene-d₂ is investigated to elucidate the mechanism of the cyclotrimerization. The results suggest a mechanism in which an acetylene inserts into the metal—ethyl bond formed by reaction of Ti(acac)₃ and Al(C₂H₅)₂Cl, followed by insertion of two acetylene molecules and elimination of a hydrogen atom from the first inserted acetylene to yield an ethylbenzene and a metal hydride intermediate. The metal hydride intermediate catalyzes acetylene cyclotrimerization to give benzene. During the reaction, the hydrogen atom in the metal hydride intermediate does not exchange with the hydrogen atom in the inserted acetylene molecules.     

Sum frequency generation from Langmuir-Blodgett multilayer films on metal and dielectric substrates

Sum frequency generation (SFG) vibrational spectra of cadmium arachidate multilayer films adsorbed on a substrate with high nonresonant susceptibility, i.e., gold, and on a low nonresonant susceptibility substrate, i.e., fused quartz, have been investigated in the C-H stretching region in air. The films were formed by Langmuir-Blodgett (LB) deposition and their spectra recorded using SFG spectrometers employing both 532-nm nanosecond and 800-nm femtosecond lasers, with counter-propagating and co-propagating beam geometries, respectively. Both kinds of substrate were rendered hydrophobic by coating them with per-deuterated octadecanethiol (gold) or per-deuterated cadmium arachidate (fused quartz) monolayers. Single per-protonated arachidate layers in otherwise per-deuterated 10-layer films were used to show that the SFG resonances arise only from the topmost and lowermost layers in a LB film comprised of an even number of per-protonated layers, although the SFG spectra from the two hydrophobic substrates are different from each other. The differences in the spectra from the same ten-layer per-protonated films deposited on the two types of hydrophobic substrate have been explained in terms of a simple model that accounts for resonant and nonresonant contributions.     

Solvent-dependent fac/mer-isomerization and self-assembly of triply helical complexes bearing a pivot part

Tris–chelate metal complexes of unsymmetrical bidentate ligands can form two geometric stereoisomers, facial (fac) and meridional (mer) isomers. Due to the small difference in their properties, the highly-selective synthesis of one of the isomers is challenging. We now designed a series of tripodal ligands with a tris(3-(2-(methyleneoxy)ethoxy)phenyl)methane pivot. Surprisingly, the ratio of the fac/mer isomers of the triply helical Fe^II complexes significantly changed depending on the solvents. To the best of our knowledge, this is the first example of fac/mer isomerism of a labile tris(2,2′-bipyridine) Fe^II complex governed by the solvent. Furthermore, well-defined self-assemblies were quantitatively produced by imine bond formation with a suitable diamine. The supramolecular assemblies contained only the fac isomer even though a mixture of the two isomers existed in solution before the condensation reaction. Namely, the self-assembly formation effectively adjusted the geometries of the building unit that results in the suitable supramolecular structure.

The novel tripodal complexes isomerize in response to environmental change, and well-defined self-assemblies were quantitatively produced by imine bond formation.     

13C high-resolution NMR study of undoped polyacetylene

¹³C NMR spectra of undoped polyacetylene,(CH)_x, have been measured. The existence of 3.4 mol% methylene moieties as defects in the (CH)_x chains has been observed in trans-(CH)_x. Measurements of partially cis-to-trans isomerized (CH)_x suggest the existence of isolated cis regions.     

Aliphatic polyimides from phenylene bis(succinic anhydride) and bis(glutaric anhydride)

Meta and para derivatives of phenylene bis(succinic anhydride) and bis(glutaric anhydride) were obtained from 1,3- and 1,4-bis(β-cyano-β-carbethoxyvinyl)benzene with potassium cyanide or Meldrum acid followed by hydrolysis with concentrated hydrochloric acid and dehydration with acetic anhydride. Aliphatic polyimides were prepared from these anhydrides with six aromatic diamines through thermal ring closure of polyamic acids obtained by solution polymerization in dimethylacetamide, and thermal stability of these polyimides was examined by thermogravimetric analysis.     

Time resolved fluorescent analysis for sealed heating of dimethyl-β-cyclodextrin and naphthalene system

The inclusion process of naphthalene into heptakis-(2,6-di-O-methyl)--cyclodextrin (DMCD) during the sealed heating was investigated by using solid state time,resolved fluorescent analysis. Fluorescence lifetimes of naphthalene in naphthalene crystals and in inclusion complex with DMCD prepared by coprecipitation were determined 59 ns and 88 ns, respectively. Fluorescence lifetime of naphthalene monomer becomes longer after inclusion complex formation. Fluorescence lifetimes of naphthalene monomer and excimer in the sealed heating complex were determined about 80 ns and 100 ns, respectively. By setting the observing wavelength of time resolved fluorescent analysis at 355 nm, the formation and the decay of the excimer state of naphthalene during the sealed heating process were successfully confirmed.