Distance dependence of intramolecular electron transfer across oligoprolines in [(bpy)[sub 2]Ru[sup II]L[sup [sm bullet]]-(Pro)[sub n]-Co[sup III](NH[sub 3])[sub 5]][sup 3+], n = 1-6: Different effects for helical and nonhelical polyproline II structures

Journal Article · Thu Nov 04 04:00:00 EST 1993 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100146a019· OSTI ID:5651714

Ogawa, M Y; Young, Z; Isied, S S ^[1]; Wishart, J F ^[2]; Miller, J R ^[3]

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1. Rutgers, The State Univ. of New Jersey, Piscataway, NJ (United States)
2. Brookhaven National Lab., Upton, NY (United States)
3. Argonne National Lab., IL (United States)

A series of complexes of the type [(bpy)[sub 2]Ru[sup II]L-(Pro)[sub n]-Co[sup III](NH[sub 3])[sub 5]][sup 4+], n = 1-6, where L = 4-carboxy-4[prime]-4-methyl-2,2[prime]-bipyridine, bpy = 4,4[prime]-bipyridine, and Pro = l-proline, have been synthesized from the corresponding [(bpy)[sup 2]Ru[sup II]L] and [(NH[sub 3])[sub 5]Co[sup III](Pro)[sub n]] components. The compounds were characterized by metal analyses, electrochemical measurements, and absorption spectroscopy. For n = 4-6 prolines, the CD spectra of the complexes show a proproline II helical structure. Intramolecular electron transfer within these complexes was studied by generating the [(bpy)[sub 2]Ru[sup II]L[sup [sm bullet]]-(Pro)[sub n]-Co[sup III](NH[sub 3])[sub 5]] intermediate by the reaction of e[sub aq] (generated by pulse radiolysis) with the [(bpy)[sub 2]Ru[sup II]L-(Pro)[sub n]-Co[sup III](NH[sub 3])[sub 5]] molecules. The driving force for this reaction is estimated to be [vert bar][Delta]G[sup [circ]][vert bar] [approximately] [minus]1.1 V. The rates of intramolecular electron transfer decrease rapidly with distance for n = 1-3 prolines but show a surprisingly weak decrease with distance for the n = 4, 5, and 6 prolines, which exhibit the polyproline II helical structure. 42 refs., 6 figs., 3 tabs.

• DOE Contract Number: AC02-76CH00016; W-31109-ENG-38
• OSTI ID: 5651714
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 97:44; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400102 -- Chemical & Spectral Procedures
400201* -- Chemical & Physicochemical Properties
400400 -- Electrochemistry
ABSORPTION SPECTROSCOPY
COBALT COMPLEXES
COMPILED DATA
COMPLEXES
DATA
DICHROISM
ELECTRON TRANSFER
INFORMATION
MOLECULAR STRUCTURE
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANOMETALLIC COMPOUNDS
POLAROGRAPHY
RUTHENIUM COMPLEXES
SPECTROSCOPY
SYNTHESIS
TRANSITION ELEMENT COMPLEXES