Time-resolved surface-enhanced Raman scattering studies of iron-bleomycin and 3-hydroxyflavone on a Ag electrode.
Item
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Title
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Time-resolved surface-enhanced Raman scattering studies of iron-bleomycin and 3-hydroxyflavone on a Ag electrode.
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Identifier
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AAI9720150
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identifier
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9720150
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Creator
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Wang, Minfa.
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Contributor
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Advisers: Ronald L. Birke | John R. Lombardi
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Date
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1997
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Analytical | Chemistry, Physical
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Abstract
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Drug mechanism and kinetics of oxygen activation of Fe-Bleomycin (BLM) and O{dollar}\sb2{dollar}-Fe-BLM systems were studied by time resolved surface enhanced Raman spectroscopy (TRSERS) combined with electrochemical methods. By applying an electrode potential step from 0.02 V to {dollar}-{dollar}0.65 V, reduction reactions of O{dollar}\sb2{dollar}-Fe-BLM system can be initiated which are similar to that of in the drug system. Three intermediates were observed during the potential initiated reduction of O{dollar}\sb2{dollar}-Fe-BLM system by monitoring the changes of SERS band at 1574 cm{dollar}\sp{lcub}-1{rcub}{dollar}, which is sensitive to the redox state of central iron and assigned to the carbonyl stretching vibration of the {dollar}\beta{dollar}-hydroxyhistidinyl amide. One of the intermediates may correspond to the so called "activated BLM". Our experiments also confirmed two of ligands in the iron-drug complex which were controversial assigned by previous researches. The TRSERS, SERS and cyclic voltammetry experimental results revealed more information of the oxygenate activated mechanism.;Normal Raman and surface enhanced Raman scattering of 3-hydroxyflavone (3-HF) have been obtained and used to interpret the low frequency of the carbonyl stretching in 3-HF. Photo initiated intramolecular ground state reverse proton transfer of 3-HF was also studied by TRSERS. By measuring vibrational spectra of the ground state tautomer of 3-HF, two dynamic processes were observed during the ground state tautomer decay. One process may simply correspond to the reverse proton transfer with life time about 1.4 {dollar}\mu{dollar}s. The second may correspond to a peroxide intermediate formed in the proton transfer cycle. In spite of the ultrafast rate of the proton transfer in the excited state, the measurements by TRSERS technique demonstrate that a long-lived ground-state tautomer at room temperature is involved in the ground state proton transfer. The mechanism of the photooxygenation of 3-HF in the tautomer ground state has been proposed.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
