Spectroelectrochemistry spectrometry

Although the instrumental techniques described here give detailed mechanistic information, they do not provide an insight into the structure of intermediates. If we, however, combine electrochemical and spectroscopic methods, this is advantageously accomplished (spectroelectrochemistry) [73]. Various spectroscopies have been coupled with electrochemical experiments, among them ESR [74], optical [75], and NMR spectroscopy [76, 77], as well as mass spectrometry [78, 79]. 

The two reviews, Spectroelectrochemistry Applications and Spectroelectro-chemistry Methods and instrumentation , both by Mortimer, R. J., appear in The Encyclopedia of Spectroscopy and Spectrometry, Lindon, J. C., Trantor, G. E. and Holmes J. L. (Eds), Academic Press, London, 2000, pp. 2161-2174 and 2174-2181, respectively, and give excellent coverage of this combined spectroscopic and electrochemical technique. 

Surface-Enhanced Raman Spectroscopy (SERS) Raman Spectroelectrochemistry Time-Resolved Raman (TR-) Spectroscopy Matrix-Isolation Raman Spectroscopy 2D Correlation Raman Spectroscopy Raman Imaging Spectrometry Nonlinear Raman Spectroscopy References... 

Refs. [i] Hamberg I, Granqvist CG (1986) / AppI Phys 60-.R123 [ii] Granqvist CG, Hultaker A (2002) Thin Solid Films 411 1 [iii] Mortimer R) (1999) Electronic spectroscopy Spectroelectrochemistry, methods and instrumentation. In Lindon JC, Tranter GE, Holmes ]L (eds), Encyclopedia of spectroscopy and spectrometry. Academic Press, London, pp 2174-2181 jivj Bard AJ, Faulkner LR (2001) Electrochemical methods, 2nd edn. Wiley, New York, Chap. 17... 

A variety of spectroscopic techniques including Raman, luminescence, NMR, EPR, mass spectrometry, and circular dichroism, have been used to monitor the nature and redox behavior of electrogenerated or adsorbed spedes. The simphdty and richness of the structural information obtained from infrared spectroelectrochemistry have contributed to its widespread use. Because the pz bridged dimers have relatively stable 1 mixed valence states and contain a good spectroscopic chromophore, i.e., CO, the nature and rate of charge transfer have been investigated further by infrared spectroelectrochemistry. 

The information power of electrochemistry can be expanded by coupling it with methods which can determine the chemical identity of intermediates and products of electrode reactions. In-situ information can be obtained by on-line spectroscopic methods such as ultraviolet/visible (UV/vis) thin-layer spectroelectrochemistrys. Recently, effective on-line coupling of an electrochemical cell with a mass spectrometer has been demonstrated and its application to the study of biological redox reactions has been described . Electrochemistry/mass spectrometry as well as off-line methods were used in determining redox and related chemical reactivity of purine drugs. 

Oxidation pathways of the purine antimetabolite 2,6-diaminopurine and its metabolite 2,6-diamino-8-purinol have recently been reported ,i4, Electrochemistry was used to determine the number of electrons and protons involved in the oxidation as well as the sequence, rate of formation, and stability of the reaction intermediates and products. Stability and rate of formation of intermediates and products were confirmed by UV/vis thin-layer spectroelectrochemistry. The products and stable intermediates were isolated at different stages in the oxidation and were identified by gas chromatography/mass spectrometry and by FAB MS. 

On-line thin-layer spectroelectrochemistry can provide chemical information but by itself it is not sufficient to confirm chemical identity. Typically the supporting evidence has been obtained by off-line methods such as mass spectrometry, FTIR and NMR. 

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