Picosecond Kerr-gated time-resolved resonance Raman spectroscopy of the [Ru(phen)(2)dppz](2+) interaction with DNA.
To investigate the basis of the 'light-switch' effect, the solvent dependence of the Kerr-gated picosecond-time resolved resonance Raman (TR(3)) spectra of [Ru(bpy)(2)dppz](2+), [Ru(phen)(2)dppz](2+), and the modified complex [Ru(phen)(2)cpdppzOMe](2+) and a dimer [mu-C4(cpdppz)(2)-(phen)(4)Ru(2)](4+) were studied. The investigation focussed on comparing the behaviour of [Ru(phen)(2)dppz](2+) in acetonitrile, ethanol, H(2)O, D(2)O, and DNA. The data are consistent with a model wherein excitation induces metal-to-ligand charge transfer (MLCT) to any of the ligands (termed the 'precursor' state) which, by interligand electron transfer (ILET), produces an excited state localised on the dppz ligand, MLCT(1). In water this state relaxes with a characteristic time of approximately 6 ps to a non-emissive state (MLCT(2)). The TR(3) spectra in water, acetonitrile and DNA are all distinctly different. However, the early (4 ps) water spectrum resembles the spectrum in DNA. This interesting observation suggests that the DNA-bound excited state of the complex can be thought of as a model for the initial, poorly solvated state in water.
Olofsson
Johan
J
Department of Physical Chemistry, Chalmers University of Technology, SE-412 96, Göteborg, Sweden
Onfelt
Björn
B
Lincoln
Per
P
Nordén
Bengt
B
Matousek
Pavel
P
Parker
Anthony W
AW
Tuite
Eimer
E
D000097:Acetonitriles / Q000737:chemistry; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D000431:Ethanol / Q000737:chemistry; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D010618:Phenanthrolines / Q000737:chemistry*; D010619:Phenazines / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D013059:Spectrum Analysis, Raman; D013997:Time Factors; D014867:Water / Q000737:chemistry
D000097:Acetonitriles; D009942:Organometallic Compounds; D010618:Phenanthrolines; D010619:Phenazines; C466600:Ru(phen)(2)dipyrido(3,2-a-2',3'-c)phenazine; D012997:Solvents; C443808:dipyrido(3,2-a-2',3'-c)phenazine; D014867:Water; D000431:Ethanol; D012428:Ruthenium; D004247:DNA; C032159:acetonitrile