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  • 1
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    A functional [NiFe]hydrogenase mimic that catalyzes electron and hydride transfer from H2 (2013)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2013-02-09
    Description: Chemists have long sought to mimic enzymatic hydrogen activation with structurally simpler compounds. Here, we report a functional [NiFe]-based model of [NiFe]hydrogenase enzymes. This complex heterolytically activates hydrogen to form a hydride complex that is capable of reducing substrates by either hydride ion or electron transfer. Structural investigations were performed by a range of techniques, including x-ray diffraction and neutron scattering, resulting in crystal structures and the finding that the hydrido ligand is predominantly associated with the Fe center. The ligand's hydridic character is manifested in its reactivity with strong acid to liberate H(2).〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ogo, Seiji -- Ichikawa, Koji -- Kishima, Takahiro -- Matsumoto, Takahiro -- Nakai, Hidetaka -- Kusaka, Katsuhiro -- Ohhara, Takashi -- New York, N.Y. -- Science. 2013 Feb 8;339(6120):682-4. doi: 10.1126/science.1231345.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉World Premier International Research Center Initiative-International Institute for Carbon-Neutral Energy Research, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan. ogotcm@mail.cstm.kyushu-u.ac.jp〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23393260" target="_blank"〉PubMed〈/a〉
    Keywords: Catalysis ; *Electrons ; Hydrogen/*chemistry ; Hydrogenase/*chemistry/metabolism ; Iron/*chemistry ; Ligands ; Models, Chemical ; Molecular Mimicry ; Molecular Structure ; Nickel/*chemistry ; Organometallic Compounds/*chemistry ; Oxidation-Reduction
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 2
    Electronic Resource
    Electronic Resource
    Simultaneous assay of four stereoisomers of diltiazem hydrochloride. Application to in vitro chiral inversion studies (1995)
    Springer
    Chromatographia 41 (1995), S. 450-454 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Diltiazem hydrochloride stereoisomers ; Chiralcel OF ; Chiral inversion ; Epimerization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The simultaneous stereospecific assay of four stereoisomers of diltiazem hydrochloride in bulk drug and aqueous solution was developed using HPLC on a Chiralcel OF column. The four isomers were quantitated with good precision by the internal standard method. The chiral inversion of (+)-cis-diltiazem hydrochloride in vitro, stability of its (2S, 3S) configuration in the solid and aqueous states was examined by HPLC. Chiral inversion of (+)-cis-diltiazem hydrochloride was not observed in the solid state, and its (2S, 3S) configuration was stable to heat, humidity and light. Chiral inversion of (+)-cis-diltiazem hydrochloride (2S, 3S) was observed in aqueous solution under UV, but not in aqueous solution stored at 80°C for 5h nor under visible light for 10 h. The (+)-cis-diltiazem hydrochloride (2S, 3S) epimerized to (+)-trans-diltiazem hydrochloride (2R, 3S) with a half-life of 5h in aqueous solution under UV but the reverse chiral inversion of (+)-trans-diltiazem hydrochloride (2R, 3S) to (+)-cis-diltiazem hydrochloride (2S, 3S) was not observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02318621
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  • 3
    Electronic Resource
    Electronic Resource
    Assay of four stereoisomers of desacetyl diltiazem hydrochloride. Application toin vitro chiral inversion studies (1996)
    Springer
    Chromatographia 43 (1996), S. 413-418 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Desacetyl diltiazem hydrochloride stereoisomers ; Chiralcel OF ; Chiral inversion ; Epimerization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Direct resolution of four stereoisomers of the related compound of diltiazem hydrochloride, namely desacetyl diltiazem hydrochloride, was studied by both normal and reversed-phase chiral HPLC. The four stereoisomers were completely resolved on a Chiralcel OF column. The technique developed was applied to a chiral inversion study of desacetyl diltiazem hydrochloride. This inversion was observed neither in the solid state, in aqueous solution at 100°C for 3 h nor under visible light for 10h, but was observed in aqueous solution under UV irradiation. The (+)-(2S, 3S)-cis-desacetyl diltiazem hydrochloride degraded with a half-life of 1.9 h in aqueous solution under UV and epimerized to (+)-(2R, 3S)-trans-desacetyl diltiazem hydrochloride. Similarly, (+)-(2S, 3S)-cis-desacetyl diltiazem hydrochloride degraded about three times faster than diltiazem hydrochloride. Reverse epimerization of (+)-(2R, 3S)-trans-desacetyl diltiazem hydrochloride to (+)-(2S, 3S)-cis-desacetyl diltiazem hydrochloride was not observed. The overall degradation was the result of two competitive processes, the epimerization and the decomposition of the benzothiazepin ring. The degradation and epimerization rate of (+)-(2S, 3S)-cis-desacetyl diltiazem hydrochloride in solution under UV depended upon the solvent, the aqueous pH, and concentration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02271021
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