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The triplet metal-to-ligand charge transfer ((3)MLCT) dynamics of two structurally characterized Re(I)(CO)(3)(phen)(HisX)-modified (phen = 1,10-phenanthroline; X = 83, 109) Pseudomonas aeruginosa azurins have been investigated by picosecond time-resolved infrared (TRIR) spectroscopy in aqueous (D(2)O) solution. The (3)MLCT relaxation dynamics exhibited by the two Re(I)-azurins are very different from those of the sensitizer [Re(I)(CO)(3)(phen)(im)](+) (im = imidazole). Whereas the Re(I)(CO)(3) intramolecular vibrational relaxation in Re(I)(CO)(3)(phen)(HisX)Az (4 ps) is similar to that of [Re(I)(CO)(3)(phen)(im)](+) (2 ps), the medium relaxation is much slower ( approximately 250 vs 9.5 ps); the 250-ps relaxation is attributable to reorientation of D(2)O molecules as well as structural reorganization of the rhenium chromophore and nearby polar amino acids in each of the modified proteins.

Original publication

DOI

10.1021/ja057451+

Type

Journal

Journal of the American Chemical Society

Publication Date

04/2006

Volume

128

Pages

4365 - 4370

Addresses

School of Biological and Chemical Sciences, Queen Mary, University of London, UK.

Keywords

Pseudomonas aeruginosa, Rhenium, Water, Phenanthrolines, Peptides, Azurin, Metalloproteins, Solutions, Spectrophotometry, Infrared, Protein Conformation, Models, Molecular