Axial-ligand control of the photophysical behavior of ruthenium(II) tetraphenyl- and octaethylporphyrin. Contrasting properties of metalloporphyrin (. pi. ,. pi. *) and (d,. pi. *) excited states

Journal Article · Thu Feb 11 04:00:00 EST 1988 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100314a026· OSTI ID:5387166

Levine, L M.A.; Holten, D

The photophysical behavior of the ruthenium(II) porphyrins depends dramatically on the axial ligands coordinated to the central metal ion. The authors have measured the picosecond and slower time scale transient absorption spectra and kinetics, emission data, and ground-state absorption spectra for two classes of complexes: RuP(CO)(L) and RuP(L)/sub 2/. Results are compared for complexes in which the porphyrin macrocycle (P) is tetraphenylporphyrin (TPP) or octaethylporphyrin (OEP) and the axial ligand L is piperidine (pip), pyridine (py), dimethyl sulfoxide (Me/sub 2/SO), or ethanol (EtOH). They assign the lowest excited state of all the RuP(CO)(L) complexes, including those with L absent, as the lowest excited triplet state, /sup 3/(..pi..,..pi..*), of the porphyrin ring. /sup 3/(..pi..,..pi..*) appears to form in high yield from the ring excited singlet, /sup 1/(..pi..,..pi..*), in less than or equal to 30 ps. On the other hand, they assign the lowest excited state of the RuP(L)/sub 2/ complexes, except for RuTPP(Me/sub 2/SO)/sub 2/, as a metal-to-ring (d,..pi..*), charge-transfer (CT) state. Although /sup 3/(..pi..,..pi..*) appears to be the lowest excited state in all the RuP(CO)(L) complexes investigated, they propose that the deactivation of this state nonetheless proceeds, in part, via a shorter lived (d,..pi..*) state at higher energy. The photodissociation quantum yield is measured to be approx. 10/sup -4/ for two of the complexes.

• Research Organization: Washington Univ., St. Louis, MO (USA)
• OSTI ID: 5387166
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 92:3; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
COMPLEXES
DATA
DE-EXCITATION
ELECTRONIC STRUCTURE
ENERGY LEVELS
ENERGY TRANSFER
ENERGY-LEVEL TRANSITIONS
EXCITED STATES
EXPERIMENTAL DATA
GROUND STATES
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
INFORMATION
LIFETIME
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PORPHYRINS
RADIATIONLESS DECAY
RUTHENIUM COMPLEXES
TRANSITION ELEMENT COMPLEXES