Learning from B12 enzymes: biomimetic and bioinspired catalysts for eco-friendly organic synthesis

Cobalamins (B12) play various important roles in vivo. Most B12-dependent enzymes are divided into three main subfamilies: adenosylcobalamin-dependent isomerases, methylcobalamin-dependent methyltransferases, and dehalogenases. Mimicking these B12 enzyme functions under non-enzymatic conditions offers good understanding of their elaborate reaction mechanisms. Furthermore, bio-inspiration offers a new approach to catalytic design for green and eco-friendly molecular transformations. As part of a study based on vitamin B12 derivatives including heptamethyl cobyrinate perchlorate, we describe biomimetic and bioinspired catalytic reactions with B12 enzyme functions. The reactions are classified according to the corresponding three B12 enzyme subfamilies, with a focus on our recent development on electrochemical and photochemical catalytic systems. Other important reactions are also described, with a focus on radical-involved reactions in terms of organic synthesis

Evaluation of the impact of a flowchart-type leaflet for cancer inpatients

Objectives: This study aimed to evaluate the benefits of an interactive and visual flowchart-type leaflet for head and neck cancer inpatients who received induction chemotherapy, docetaxel, cisplatin, and 5-fluorourasil (DCF), or docetaxel, cisplatin, and S-1 (DCS) from September 2009 to April 2012. The flowchart-type leaflet group used a flowchart-type leaflet during chemotherapy, while the non-flowchart-type leaflet group did not. Methods: A retrospective cohort study was performed using patient records. The endpoints of this study were to determine the following: the number of emergency hospital admissions/visits, incidence of Grade 2 or higher non-haematological adverse drug reactions, nonadherence to treatment, and the number of telephone calls from subjects. Results: A total of 109 subjects were identified as follows: 49 in the flowchart-type leaflet group (139 chemotherapy sessions) and 60 in the non-flowchart-type leaflet group (163 chemotherapy sessions). No significant differences were observed in age, performance status, or chemotherapy regimen. The incidence of emergency hospital admissions was significantly lower in the flowchart-type leaflet than in the non-flowchart-type leaflet group (1% vs 10%, p < 0.01). No difference was seen between groups (12% vs 19%, p = 0.1) in the nonadherence rate of supportive medication for adverse drug reactions. Telephone call rates were significantly higher in the flowchart-type leaflet (16%, 30 calls) than in the non-flowchart-type leaflet group (7%, 11 calls) in each chemotherapy regimen. Of the 30 calls from patients in the FCL group, 24 (80%) were made to the hospital, compared with only 5 (45%) of the 11 calls from patients in the non-flowchart-type leaflet group. Conclusions: Our results suggest that the flowchart-type leaflet can reduce nonadherence and improve patient judgment during chemotherapy, leading to a decrease in emergency hospital admissions

Dihedral-Angle Dependence of Intermolecular Transfer Integrals in BEDT-BDT-Based Radical-Cation Salts with θ-Type Molecular Arrangements

We report the structural and physical properties of a new organic Mott insulator (BEDT-BDT)AsF6 (BEDT-BDT: benzo[1,2-g:4,5-g′]bis(thieno[2,3-b][1,4dithiin). This AsF6 salt has the same structure as the PF6 salt. Although the anions are disordered, the donor molecules form a θ-type arrangement. The temperature dependence of the resistivity exhibits semiconducting behavior. The static magnetic susceptibility follows Curie–Weiss law over a wide temperature range; however, below 25 K, the magnetic susceptibility is in agreement with a one-dimensional chain model with the exchange coupling J = 7.4 K. No structural phase transition was observed down to 93 K. At 270 K, the Fermi surface calculated by the tight-binding approximation is a two-dimensional cylinder; however, it is significantly distorted at 93 K. This is because the dihedral angles between the BEDT-BDT molecules become larger due to lattice shrinkage at low temperatures, which results in a smaller transfer integral (t1) along the stack direction. This slight change in the dihedral angle gives rise to a significant change in the electronic structure of the AsF6 salt. Radical-cation salts using BEDT-BDT, in which the highest occupied molecular orbital does not have a dominant sign throughout the molecule, are sensitive to slight differences in the overlap between the molecules, and their electronic structures are more variable than those of conventional θ-type conductors

Electrochemistry, Charge Transfer Properties, and Theoretical Investigation of a Macrocyclic Boronate Dimer of 1′,1‴-Biferrocenediboronic Acid and Related Ferrocenyl Boronate Complexes

The target compound of this study is the macrocyclic tetraferrocenyl boronate complex <b>CP</b>_<b>2</b><b>C</b>, which has two types of metal connections (i.e., Fe^II–CpCp–Fe^II and Fe^II–CpBO₂C₅H₈O₂BCp–Fe^II (Cp = cyclopentadienyl)) in the finite structure (<b>C</b> = 1′,1‴-biferrocenediboronic acid, <b>P</b> = pentaerythritol). The electrochemical behavior of <b>CP</b>_<b>2</b><b>C</b> in dichloromethane was compared with that of the related boronate complexes <b>APA</b> and <b>BP</b>_<b>2</b><b>B</b>, having Fe^II–CpBO₂C₅H₈O₂BCp–Fe^II, and <b>Cester</b>, having Fe^II–CpCp–Fe^II. The effects of the counteranion of the supporting electrolyte on potential splitting revealed that <b>CP</b>_<b>2</b><b>C</b> exhibits an intrabiferrocenyl through-bond interaction through the CpCp ligand, as well as an interbiferrocenyl through-space interaction across the CpBO₂C₅H₈O₂BCp ligand. Chemical oxidation of <b>CP</b>_<b>2</b><b>C</b> with AgSbF₆ produced the one- and two-electron-oxidized species <b>CP</b>_<b>2</b><b>C</b>^<b>+</b> and <b>CP</b>_<b>2</b><b>C</b>^<b>2+</b>, which exhibit intervalence charge transfer transition bands through the CpCp ligand in the near-infrared region, giving one and two valence isomers, respectively. DFT calculations revealed the charge distribution of <b>CP</b>_<b>2</b><b>C</b>^<b>2+</b>; the positive charges are localized on each biferrocenium unit, especially on the longer diagonal, to minimize the electrostatic repulsion over the CpBO₂C₅H₈O₂BCp ligand

Electrochemistry, Charge Transfer Properties, and Theoretical Investigation of a Macrocyclic Boronate Dimer of 1′,1‴-Biferrocenediboronic Acid and Related Ferrocenyl Boronate Complexes

The target compound of this study is the macrocyclic tetraferrocenyl boronate complex <b>CP</b>_<b>2</b><b>C</b>, which has two types of metal connections (i.e., Fe^II–CpCp–Fe^II and Fe^II–CpBO₂C₅H₈O₂BCp–Fe^II (Cp = cyclopentadienyl)) in the finite structure (<b>C</b> = 1′,1‴-biferrocenediboronic acid, <b>P</b> = pentaerythritol). The electrochemical behavior of <b>CP</b>_<b>2</b><b>C</b> in dichloromethane was compared with that of the related boronate complexes <b>APA</b> and <b>BP</b>_<b>2</b><b>B</b>, having Fe^II–CpBO₂C₅H₈O₂BCp–Fe^II, and <b>Cester</b>, having Fe^II–CpCp–Fe^II. The effects of the counteranion of the supporting electrolyte on potential splitting revealed that <b>CP</b>_<b>2</b><b>C</b> exhibits an intrabiferrocenyl through-bond interaction through the CpCp ligand, as well as an interbiferrocenyl through-space interaction across the CpBO₂C₅H₈O₂BCp ligand. Chemical oxidation of <b>CP</b>_<b>2</b><b>C</b> with AgSbF₆ produced the one- and two-electron-oxidized species <b>CP</b>_<b>2</b><b>C</b>^<b>+</b> and <b>CP</b>_<b>2</b><b>C</b>^<b>2+</b>, which exhibit intervalence charge transfer transition bands through the CpCp ligand in the near-infrared region, giving one and two valence isomers, respectively. DFT calculations revealed the charge distribution of <b>CP</b>_<b>2</b><b>C</b>^<b>2+</b>; the positive charges are localized on each biferrocenium unit, especially on the longer diagonal, to minimize the electrostatic repulsion over the CpBO₂C₅H₈O₂BCp ligand

Electrochemistry, Charge Transfer Properties, and Theoretical Investigation of a Macrocyclic Boronate Dimer of 1′,1‴-Biferrocenediboronic Acid and Related Ferrocenyl Boronate Complexes

The target compound of this study is the macrocyclic tetraferrocenyl boronate complex <b>CP</b>_<b>2</b><b>C</b>, which has two types of metal connections (i.e., Fe^II–CpCp–Fe^II and Fe^II–CpBO₂C₅H₈O₂BCp–Fe^II (Cp = cyclopentadienyl)) in the finite structure (<b>C</b> = 1′,1‴-biferrocenediboronic acid, <b>P</b> = pentaerythritol). The electrochemical behavior of <b>CP</b>_<b>2</b><b>C</b> in dichloromethane was compared with that of the related boronate complexes <b>APA</b> and <b>BP</b>_<b>2</b><b>B</b>, having Fe^II–CpBO₂C₅H₈O₂BCp–Fe^II, and <b>Cester</b>, having Fe^II–CpCp–Fe^II. The effects of the counteranion of the supporting electrolyte on potential splitting revealed that <b>CP</b>_<b>2</b><b>C</b> exhibits an intrabiferrocenyl through-bond interaction through the CpCp ligand, as well as an interbiferrocenyl through-space interaction across the CpBO₂C₅H₈O₂BCp ligand. Chemical oxidation of <b>CP</b>_<b>2</b><b>C</b> with AgSbF₆ produced the one- and two-electron-oxidized species <b>CP</b>_<b>2</b><b>C</b>^<b>+</b> and <b>CP</b>_<b>2</b><b>C</b>^<b>2+</b>, which exhibit intervalence charge transfer transition bands through the CpCp ligand in the near-infrared region, giving one and two valence isomers, respectively. DFT calculations revealed the charge distribution of <b>CP</b>_<b>2</b><b>C</b>^<b>2+</b>; the positive charges are localized on each biferrocenium unit, especially on the longer diagonal, to minimize the electrostatic repulsion over the CpBO₂C₅H₈O₂BCp ligand