TiO2-Supported Re as a General and Chemoselective Heterogeneous Catalyst for Hydrogenation of Carboxylic Acids to Alcohols

TiO2-supported Re, Re/TiO2, was found to promote selective hydrogenation of carboxylic acids having aromatic and aliphatic moieties to the corresponding alcohols. Re/TiO2 showed superior results compared to other transition-metal-loaded TiO2 and supported Re catalysts for selective hydrogenation of 3-phenylpropionic acid. 3phenylpropanol was produced in 97% yield under mild conditions (5 MPa H-2 at 140 degrees C). Contrary to typical heterogeneous catalysts, Re/TiO2 does not lead to the formation of dearomatized byproducts. The catalyst is recyclable and shows a wide substrate scope in the synthesis of alcohols (22 examples; up to 97% isolated yield)

An Artificial Metallolyase with Pliable 2-His-1-Carboxylate Facial Triad for Stereoselective Michael Addition

We repurposed the metal-binding site of a cupin superfamily protein into the 2-his-1-carboxylate facial triad, which is one of the common motifs in natural non-heme enzymes, to construct artificial metalloenzymes that can catalyze new-to-nature reactions. Cu2+-H52A/H58E variant catalyzed the stereoselective Michael addition reaction and was found to bear a flexible metal-binding site in the high-resolution crystal structure. Furthermore, the H52A/H58E/F104W mutant accommodated a water molecule, which was supported by Glu58 and Trp104 residues via hydrogen bonding, presumably leading to high stereoselectivity. Thus, the 2-his-1-carboxylate facial triad was confirmed to be a versatile and promising metal-binding motif for abiological and canonical biological reactions

Transparent Protein Microtubule Motors with Controllable Velocity and Biodegradability

Slender protein microtube motors with a catalase interior surface are self-propelled in aqueous H₂O₂ by jetting O₂ microbubbles from the open-end terminus. Immobilization of a catalase biocatalyst on the internal wall is achieved using avidin–biotin complexation. It is particularly interesting that the migration of O₂ bubbles in the 1D channel and their subsequent expulsions were clearly visible because the tube walls are transparent. The microtube motor velocity reached a maximum at the optimum pH and temperature of the catalase. Furthermore, the microtubes were digested completely by proteases, showing sufficient biodegradability

Modeling the Mutual Enhancement of Regional Economy and Personal Quality of Life (QOL): A Case Study on the Mumbai–Ahmedabad High-Speed Rail Corridor in India

Among the various effects of high-speed rail (HSR), a direct benefit to users has been measured as an increase in the gross domestic product (GDP) by the conventional cost–benefit analysis (CBA), which was institutionalized in the U.K. In recent years, the importance of capturing indirect benefits to non-users has also been broadly discussed. The indirect benefits of HSR can mainly be classified into two perspectives: regional economy and personal quality of life (QOL). In this study, we modeled the mutual enhancement between those effects and analyzed the indirect benefits of the Mumbai–Ahmedabad high-speed rail (MAHSR), which is currently under construction as the first HSR in India, an emerging country with a rapidly growing economy. The indirect benefit to the regional economy along the MAHSR corridor was estimated by industry and by zone. Additionally, the indirect benefit on personal QOL by individuals’ attributes and by zone through the mutual enhancement with the regional economy was also estimated. The personal QOL tends to show greater effects in the middle cities than those in the two metropolitan areas of Mumbai and Ahmedabad. This method can evaluate interregional disparity by identifying the differences in benefits by person, according to age, income, etc., which cannot be evaluated based on a mass measure, e.g., GDP, in the conventional CBA

Rhenium-Loaded TiO2: A Highly Versatile and Chemoselective Catalyst for the Hydrogenation of Carboxylic Acid Derivatives and the N-Methylation of Amines Using H-2 and CO2

Herein, we report a heterogeneous TiO2-supported Re catalyst (Re/TiO2) that promotes various selective hydrogenation reactions, which includes the hydrogenation of esters to alcohols, the hydrogenation of amides to amines, and the N-methylation of amines, by using H-2 and CO2. Initially, Re/TiO2 was evaluated in the context of the selective hydrogenation of 3-phenylpropionic acid methyl ester to afford 3-phenylpropanol (p(H2)=5 MPa, T=180 degrees C), which revealed a superior performance over other catalysts that we tested in this study. In contrast to other typical heterogeneous catalysts, hydrogenation reactions with Re/TiO2 did not produce dearomatized byproducts. DFT studies suggested that the high selectivity for the formation of alcohols in favor of the hydrogenation of aromatic rings is ascribed to the higher affinity of Re towards the COOCH3 group than to the benzene ring. Moreover, Re/TiO2 showed a wide substrate scope for the hydrogenation reaction (19 examples). Subsequently, this Re/TiO2 catalyst was applied to the hydrogenation of amides, the N-methylation of amines, and the N-alkylation of amines with carboxylic acids or esters