Simultaneous catalytic removal of NOϰ and diesel soot particulates

The simultaneous removal of NO_? and soot particulates in an oxidizing atmosphere is desirable for the aftertreatment of diesel exhausts. After briefly reviewing the development of catalysts for reactions involving carbons, our recent studies on the simultaneous NO_?–soot removal using perovskite-related and spinel-type oxides are described.     

Photochemical study of [3(3)](1,3,5)cyclophane and emission spectral properties of [3n]cyclophanes (n = 2-6)

Thephotochemical reaction of [3(3)](1,3,5)cyclophane 2, which is a photoprecursor for the formation of propella[3(3)]prismane 18, was studied using a sterilizing lamp (254 nm). Upon photolysis in dry and wet CH2Cl2 or MeOH in the presence of 2 mol/L aqueous HCl solution, the cyclophane 2 afforded novel cage compounds comprised of new skeletons, tetracyclo[6.3.1.0.(2,7)0(4,11)]dodeca-5,9-diene 43, hexacyclo[6.4.0.0.(2,6)0.(4,11)0.(5,10)0(9,12)]dodecane 44, and pentacyclo[6.4.0.0.(2,6)0.(4,11)0(5,10)]dodecane 45. All of these products were confirmed by the X-ray structural analyses. A possible mechanism for the formation of these photoproducts via the hexaprismane derivative 18 is proposed. The photophysical properties in the excited state of the [3n]cyclophanes ([3n]CP, n = 2-6) were investigated by measuring the emission spectra and determining the quantum yields and lifetimes of the fluorescence. All [3n]CPs show excimeric fluorescence without a monomeric one. The lifetime of the excimer fluorescence becomes gradually longer with the increasing number of the trimethylene bridges. The [3n]CPs also shows excimeric phosphorescence spectra without vibrational structures for n = 2, 4, and 5, while phosphorescence is absent for n = 3 and 6. With an increase in symmetry of the benzene skeleton in the [3(3)]- and [3(6)]CPs, the probability of the radiation (phosphorescence) process from the lowest triplet state may drastically decrease.     

Enantioselective ester synthesis in the presence of optically active polymers

Enantiomer-differentiating ester syntheses from acid salts, chlorides, and an anhydride were studied in the presence of optically active polyamines. Enantiomer selection occurred in reactions of a racemic salt with an achiral alkyl bromide and vice versa, which is good evidence of the importance of activation of the carboxylate group by complexation of the counterion and activation of alkyl bromide by the formation of a quaternary salt with polyamine under solid–liquid, phase-transfer reaction conditions. Only small optical activity was observed in the products of acid anhydride or chloride with alcohol.     

Convenient synthetic routes to α-oligosiloxanylacrylonitriles

Novel 1,4-elimination reaction of C,N-bis(trimethylsilyl)-C- trimethylsiloxymethylketenimine and retro Diels-Alder reaction of 2-oligosiloxanyl-5-norbornene-2-carbonitrile cleanly gave α-oligosiloxanylacrylonitriles in excellent yield.     

Power dependence of Brillouin linewidths in a silica fiber

We report the dependence of Brillouin linewidths on the pump power below the threshold of Brillouin lasing in a silica fiber. The Stokes Brillouin shift in a silica fiber is nearly unchanged, and its linewidth decreases with increasing pump power. However, the anti-Stokes Brillouin shift becomes smaller and its linewidth larger with increasing pump power. We explain these experimental results by the distributed fluctuating source model.     

Synthesis of macrocyclic cage compounds by diamine-dihalide one-step coupling reaction

Macropolycyclic cage compounds were synthesized by a direct reaction between diamines and bis(bromomethyl) compounds. The procedure for constructing the polycyclic cage structure is simple and straightforward. The macropolycyclic compounds obtainable from this cyclization procedure are three-dimensional cage compounds, and any other isomers were not obtained except for two examples. Benzene, pyridine, and aliphatic units could be introduced into the cage structure. The macrocycles that have strong cation affinity were obtained as their potassium complexes.     

Formation of a Novel Cage Compound with a Pentacyclo

Abnormally long C-C single bonds are found in the polycyclic caged diol with a pentacyclo[6.3.0.1(4,11).0(2,6).0(5,10)]dodecane skeleton formed by photolysis (see scheme). This skeleton resembles the structure of diamantane, but instead of having six cyclohexane rings in a chair conformation it contains only two cyclohexane rings in a distorted chair conformation and four cyclopentane rings, which makes it more highly strained than diamantane.     

22 dB all-fiber green amplifier using Er-doped fluoride fiber

We demonstrate a 22 dB all-fiber amplifier at 546 nm using Er³⁺-doped fluoride fiber by forward upconversion pumping of a 974 nm laser diode. The gain saturation effects and the power conversion efficiency of this amplifier are investigated in detail based on gain characteristics and numerical simulations.     

Desulfonyloxyiodination of arenesulfonic acids with mCPBA and molecular iodine

Treatment of p-alkylbenzenesulfonic acids with mCPBA and molecular iodine gave p-alkyliodobenzenes in good to moderate yields via electrophilic ipso-substitution by the iodonium species (I⁺) formed. This desulfonyloxyiodination was promoted by the addition of a catalytic amount of iodoarenes, such as o-iodobenzoic acid. The same treatment of dimethylbenzenesulfonic acids and trimethylbenzenesulfonic acids with mCPBA and molecular iodine proceeded smoothly both in the absence and in the presence of o-iodobenzoic acid to provide the corresponding monoiodo-dimethylbenzene and diiodo-dimethylbenzene, and diiodo-trimethylbenzene and triiodo-trimethylbenzene, in good to moderate yields, respectively. On the other hand, the same desulfonyloxyiodination of benzenesulfonic acid and p-chlorobenzenesulfonic acid with mCPBA and molecular iodine proceeded only in the presence of o-iodobenzoic acid to generate iodobenzene and p-chloroiodobenzene, respectively, in moderate yields.     

Synthetic studies on jadomycins: synthesis of dimethyljadomycin A

Dimethyljadomycin A was synthesized as the first example for the construction of 8H-benzo[b]oxazolo[3,2-f]phenanthridine skeleton.