Molecular and electronic structure of the electron-transfer probe analogue [trans-(NH[sub 3])[sub 4]Ru(imidazole)(isonicotinamide)](CF[sub 3]CO[sub 2])[sub 3][center dot]2-propanol

Journal Article · Wed Jul 08 04:00:00 EDT 1992 · Inorganic Chemistry; (United States)

DOI:https://doi.org/10.1021/ic00040a037· OSTI ID:6997916

Wishart, J F; Zhang, Xiaohua; Isied, S S; Potenza, J A; Schugar, H J ^[1]

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1. Rutgers, The State Univ. of New Jersey, New Brunswick (United States)

Kinetic and thermodynamic studies of long-range electron transfer in cytochrome c, azurin, and myoglobin have exploited the modification of these metalloprotein surfaces with ruthenium ammine probes attached to surface histidine imidazole groups. The authors combined structural, polarized electronic spectrosocopic, and calculational study of the (L-histidinato)(NH[sub 3])[sub 5]Ru[sup III] chromophore characterized the strong d[pi]/p[pi] overlap between the Ru(III) d-vacancy and the histidine imidazole [pi]-system. One implication of this study for the use of (NH[sub 3])[sub 5]Ru[sup III](his) probes as surface electron acceptors is that the effective electron-transfer pathway from the protein active site should be that calculated to the edge of the probe imidazole unit rather than to the metal center. Use of the modified surface probe trans-(NH[sub 3])[sub 4](isonicotinamide)Ru[sup III/II](his) in the cytochrome c system results in an approximate reversal of the driving force for electron transfer. No information has been obtained on the angular relationship between the histidine imidazole and the isonicotinamide groups in Ru[sup III](NH[sub 3])[sub 4](his)(isonicotinamide)-modified cythochrome c and its effects on the electronic spectrum of this chromophore. Depending upon the mutual orientations and electronic properties of the isonicotinamide and imidazole rings in the modified probe, coupling of the Ru(III) d-vacancy to the imidazole could be substantially different from that of the parent (NH[sub 3])[sub 5]Ru[sup III](his) probe and thus might constitute an additional barrier in the electron-transfer pathway. These questions prompted the authors to examine in detail the structure and electronic spectroscopic properties of trans-(NH[sub 3])[sub 4]Ru[sup III](isonicotinamide)(imidazole).

• DOE Contract Number: FG05-90ER14120
• OSTI ID: 6997916
• Journal Information: Inorganic Chemistry; (United States), Journal Name: Inorganic Chemistry; (United States) Vol. 31:14; ISSN 0020-1669; ISSN INOCAJ
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400400* -- Electrochemistry
550200 -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
ABSORPTION SPECTRA
AMIDES
AZINES
AZOLES
BINDING ENERGY
BOND ANGLE
BOND LENGTHS
COHERENT SCATTERING
COMPLEXES
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CYTOCHROMES
DIFFRACTION
DIMENSIONS
ELECTRON TRANSFER
ELECTRONIC STRUCTURE
ELECTRONS
ELEMENTARY PARTICLES
ENERGY
FERMIONS
HETEROCYCLIC COMPOUNDS
IMIDAZOLES
LENGTH
LEPTONS
MOLECULAR STRUCTURE
NICOTINAMIDE
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANOMETALLIC COMPOUNDS
PH VALUE
PIGMENTS
PROTEINS
PYRIDINES
RUTHENIUM COMPLEXES
SCATTERING
SPECTRA
TRANSITION ELEMENT COMPLEXES
TRICLINIC LATTICES
VALENCE
VITAMIN B GROUP
VITAMINS
X-RAY DIFFRACTION