title: Hydration of a Binding Site with Restricted Solvent Access: Solvatochromic Shift of the Electronic Spectrum of a Ruthenium Polypyridine Complex, One Molecule at a Time.
abstract: We report the electronic spectra of mass selected [(bpy)(tpy)Ru-OH2]2+·(H2O)nclusters (bpy = 2,2'-bipyridine, tpy =2,2':6'2″-terpyridine, n = 0-4) in the spectral region of their metal-to-ligand charge transfer bands. The spectra of the mono- and dihydrate clusters exhibit partially resolved individual electronic transitions. The water network forming at the aqua ligand leads to a rapid solvatochromic shift of the peak of the band envelope: addition of only four solvent water molecules can recover 78% of the solvatochromic shift in bulk solution. The sequential shift of the band shows a clear change in behavior with the closing of the first hydration shell. We compare our experimental data to density function theory (DFT) calculations for the ground and excited states.
authors.affiliation: JILA and Department of Physics, University of Colorado , 440 UCB, Boulder, Colorado 80309-0440, United States.
authors.forename: Shuang
authors.initials: S
authors.lastname: Xu
authors.affiliation: JILA and Department of Chemistry and Biochemistry, University of Colorado , 440 UCB, Boulder, Colorado 80309-0440, United States.
authors.forename: James E T
authors.initials: JE
authors.lastname: Smith
authors.affiliation: JILA and Department of Chemistry and Biochemistry, University of Colorado , 440 UCB, Boulder, Colorado 80309-0440, United States.
authors.forename: J Mathias
authors.initials: JM
authors.lastname: Weber