Hydrogen-transfer catalysis with Cp*Ir^III complexes:The influence of the ancillary ligands

Fourteen Cp*IrIII complexes, bearing various combinations of N- and C-spectator ligands, are assayed in hydrogen-transfer catalysis from isopropyl alcohol to acetophenone under various conditions to investigate ligand effects in this widely used reaction. The new cationic complexes bearing monodentate pyridine and N-heterocyclic carbene (NHC) ligands were characterized crystallographically and by variable-temperature nuclear magnetic resonance (VT-NMR). Control experiments and mercury poisoning tests showed that iridium(0) nanoparticles, although active in the reaction, are not responsible for the high activity observed for the most active precatalyst [Cp*Ir(IMe) 2Cl]BF4 (6). For efficient catalysis, it was found necessary to have both NHCs in monodentate form; tying them together in a bis-NHC chelate ligand gave greatly reduced activity. The kinetics of the base-assisted reaction showed induction periods as well as deactivation processes, and H/D scrambling experiments cast some doubt on the classical monohydride mechanism. © 2013 American Chemical Society

Clients’ expectations from and satisfaction with medicine retail outlets in Gondar town, northwestern Ethiopia: a cross-sectional study

Mulualem Workye,1 Sewunet Admasu,2 Tamrat Abura,1 Yared Belete,1 Yonas Getaye,2 Fitsum Sebsibe Teni,1 Abdrrahman Shemsu Surur31Pharmaceutics and Social Pharmacy Unit, 2Clinical Pharmacy Unit, 3Pharmaceutical Chemistry Unit, School of Pharmacy, College of Medicine and Health Sciences, University of Gondar, Gondar, Amhara Regional State, EthiopiaPurpose: The aim of this study was to assess clients' level of expectation from and satisfaction with medicine retail outlets (MROs) in Gondar town, northwestern Ethiopia.Patients and methods: An institutions-based cross-sectional study was conducted from April 20 to May 5, 2014, by sampling five pharmacies and eight drug stores through simple random sampling. Clients, 424, who came to the MROs during the study period were included in the study. Data were collected using structured questionnaires measuring expectations and satisfaction of clients using a Likert scale of 1–5 through face-to-face interviews.Results: Out of the total 424 interview encounters, 422 (99.5% response rate) questionnaires were included in the analysis, of which 61.1% were of males. The overall mean expectation of respondents toward MRO setting and services was 3.82 and that of satisfaction of the respondents was 3.02. More than three-quarters (76.8%) of the respondents expected medicines in affordable prices from MROs, but nearly half (44.8%) were not satisfied with it. Much more than half (58.5%) of the respondents were dissatisfied with the comfort and convenience of private counseling area. Also, nearly half (47.6%) of the respondents claimed that pharmacy professionals did not provide information regarding the storage condition of medications. There was statistically significant difference in overall expectation (t=2.707, P=0.007) and satisfaction (t=2.260, P=0.024) with the setting and services of MROs between respondents who claimed to know the difference between a pharmacy and a drug store and those who claimed they did not.Conclusion: Clients’ expectation from MRO services was high, with average satisfaction. The overall expectation and satisfaction of the respondents toward MROs were lower in those who reported they did not know the difference between a pharmacy and a drug store than in those who claimed to know the difference. Supportive supervision by the town’s health bureau on the MROs is recommended to help improve clients' satisfaction.Keywords: community, drug store, pharmacy, pharmacy professional, service

Potassium formate as a small molecule switch: controlling oxidation-reduction behaviour in a two-step sequence

Contains fulltext : 111394.pdf (preprint version ) (Open Access

Artificial metalloenzymes based on biotin-avidin technology for the enantioselective reduction of ketones by transfer hydrogenation

Most physiological and biotechnological processes rely on molecular recognition between chiral (handed) molecules. Manmade homogeneous catalysts and enzymes offer complementary means for producing enantiopure (single-handed) compounds. As the subtle details that govern chiral discrimination are difficult to predict, improving the performance of such catalysts often relies on trial-and-error procedures. Homogeneous catalysts are optimized by chemical modification of the chiral environment around the metal center. Enzymes can be improved by modification of gene encoding the protein. Incorporation of a biotinylated organometallic catalyst into a host protein (avidin or streptavidin) affords versatile artificial metalloenzymes for the reduction of ketones by transfer hydrogenation. The boric acid·formate mixture was identified as a hydrogen source compatible with these artificial metalloenzymes. A combined chemo-genetic procedure allows us to optimize the activity and selectivity of these hybrid catalysts: up to 94% (R) enantiomeric excess for the reduction of p-methylacetophenone. These artificial metalloenzymes display features reminiscent of both homogeneous catalysts and enzymes