Pigment–Acceptor–Catalyst Triads for Photochemical Hydrogen Evolution

In order to solve the problems of global warming and shortage of fossil fuels, researchers have been endeavoring to achieve artificial photosynthesis: splitting water into H₂ and O₂ under solar light illumination. Our group has recently invented a unique system that drives photoinduced water reduction through “Z‐scheme” photosynthetic pathways. Nevertheless, that system still suffered from a low turnover number (TON) of the photocatalytic cycle (TON=4.1). We have now found and describe herein a new methodology to make significant improvements in the TON, up to around TON=14–27. For the new model systems reported herein, the quantum efficiency of the second photoinduced step in the Z‐scheme photosynthesis is dramatically improved by introducing multiviologen tethers to temporarily collect the high‐energy electron generated in the first photoinduced step. These are unique examples of “pigment–acceptor–catalyst triads”, which demonstrate a new effective type of artificial photosynthesis.     

Simple process for fabricating a monolithic polymer optical waveguide

A simple and economical fabrication process for a monolithic polymer optical waveguide in which different materials are serially grafted is proposed and demonstrated. A cladding layer with a waveguide core groove is fabricated by microtransfer molding. An epoxy resin solution is spin coated onto the cladding before selective photoexposure to form a transparent waveguide core. An optical functional polymer solution is then spin coated to form a serially grafted waveguide structure. Thus two types of polymer fill the groove to realize a monolithically integrated waveguide. Controlling the groove shape results in a flat surface. A low connection loss between the two polymers, less than 0.01 dB/point, is obtained.     

Dianion of 1,2-bis(4′,4′-dimethyl-2′-oxazolin-2′-yl)ethane versatile synthetic reagent for annulation

Treatment of 1,2-bis(4′, 4′-dimethyl-2′-oxazolin-2′-yl)ethane with butyllithium produced the corresponding dianion, which on exposure with 1, ω -dihalides gives cyclic derivatives. The same dianion reacts with the β-bromoesters to yield substituted cyclopentanones.     

A synthesis of 5-amino- and 5-hydroxy-l-ethyl-1,4-dihydrio-4-oxo-3-quinolinecarboxylic acids and their derivatives

The synthesis and antimicrobial activity of 5-Hydroxy-l-ethyl-1,4-dihydrio-4-oxo-3-quinolinecarboxylic acids and their derivatives have been investigated. The 5-hydroxy-3-quinolinecarboxylic acids were prepared by thermal cyclization of 3-oxocyclohexenylaminomethylenemalonates followed by aromatiza-tion with iodine-ethanol, ethylation and hydrolysis of products. The 5-amino derivatives were prepared by several steps involving novel aromatization of isoxazole intermediates.     

Extraction—spectrophotometric determination of boric acid with 1,8-dihydroxynaphthalene-4-sulfonic acid and zephiramine

l,8-Dihydroxynaphthalene-4-sulfonic acid (DHNS) is described as a new reagent for the extraction—spectrophotometric determination of boric acid. The reagent and its boron complex are extracted into 1,2-dichloroethane as ion-associates with tetradecyldimethyl-benzylammonium chloride (zephiramine). The extracted complex of boron—DHNS—zephiramine has the composition 1:2:3 and is stable to back-washing with 1 M sodium chloride solution (pH 9.2), whereas the excess of reagent co-extracted is removed to the aqueous phase. The apparent molar absorptivity of the complex in the organic phase is 2.45 × 10⁴ l mol^-1 cm^-1 at 341 nm, which is 1.7 times larger than that with chromotropic acid. Addition of EDTA prevents most interferences. The improved method with DHNS is successfully applied to the determination of boron as boric acid in waters. The exchange equilibrium constants,

, for the reagent and complex were also determined for four monovalent anions (X^- = Cl^-, Br^-, NO₃^-and I^-). Some of these constants are compared with those pertaining to chromotropic acid and 1,8-dihydroxynaphthalene.     

The solvent extraction of the ternary complexes of iron(II)-rhodamine b with various nitrosophenols: Determination of iron in waters

Twenty nitrosophenols and nitrosonaphthols were examined as reagents for ternary complex formation with iron(II) and rhodamine B. Only reagents containing electron-attracting substituents were satisfactory, and of these, 2-nitroso-4-chlorophenol was best. The ternary complex contains 2-nitroso-4-chlorophenol, iron(II) and rhodamine B in the ratio 3:1:1, and can be readily extracted into benzene. The red extracted complex shows maximal absorbance at 558 nm with a molar absorptivity of9.0·10⁴. Beer's law is obeyed over the range 0-1· 10^?5M iron (II); the pH range for extraction is 4.3–5.3, and the color is stable for at least 1 week. The application of'the method to the determination of iron in potable and river waters is described.     

Synthesis of both epimeric triacid ananlogs of kainic acid

A practical and cheap method for synthesis of C-4 carboxylic acid substituted kainic acid analogue 5 and its epimer 6 from trans-4-hydroxyproline is described. Using this method, more interesting intermediates and analogues could be obtained easily.