Electron transfer in platinum(II) diimine-centered triads

Mechanistic insights From Photoinduced Transient Displacement Current Measurements

James E. McGarrah, Joseph T Hupp, Sergei N. Smirnov

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

The consequences of photoexcitation of a platinum diimine bisacetylide complex and its triads with phenothiazine species (McGarrah, J. E.; Eisenberg, R. Inorg. Chem. 2003,42,4355-4365) were investigated by the photoinduced transient displacement current (PTDC) method, with the aim of understanding the role of solvent in defining the nature and extent of intratriad electron transfer. PTDC enables reports on the distance of charge separation in photoexcited states. Photoexcition of the triad, Pt(dbbpy)(CCC 6H 4CH 2(PTZ)) 2 (where dbbpy = 4,4'-di-terr-butyl- 2,2'-bipyridine), leads to formation of the 3MLCT excited state, which in CH 2Cl 2 is intramolecularly quenched by PTZ to form a charge-separated (CS) state, Pt(dbbpy .-)(CCC 6H 4CH 2(PTZ) CCC 6H 4CH 2(PTZ .+); the CS state features a dipole moment oriented in essentially the opposite direction to that of the ground state. In toluene the last step of charge separation is shut down. In THF these two transient states are equilibrated, approximately as a 1:1 mixture of 3MLCT and CS states, causing a complex, but instructive, PTDC response. The PTDC response for Pt(dbbpy)(CCC 6H 5) 2, on the other hand, is similar in all solvents and shows a negative signal corresponding to a long-lived, and comparatively nonpolar, 3MLCT state. The ground-state dipóle moment, μ g, weakly increases with solvent polarity, from ∼11.5 D in toluene to ∼15.5 D in THF and CH 2Cl 2.

Original languageEnglish
Pages (from-to)6430-6436
Number of pages7
JournalJournal of Physical Chemistry A
Volume113
Issue number23
DOIs
Publication statusPublished - Jun 11 2009

Fingerprint

Displacement measurement
Electric current measurement
Platinum
electron transfer
platinum
Electrons
polarization (charge separation)
toluene
Toluene
Ground state
methylidyne
phenothiazines
ground state
photoexcitation
2,2'-Dipyridyl
Photoexcitation
Dipole moment
polarity
dipole moments
Excited states

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Electron transfer in platinum(II) diimine-centered triads : Mechanistic insights From Photoinduced Transient Displacement Current Measurements. / McGarrah, James E.; Hupp, Joseph T; Smirnov, Sergei N.

In: Journal of Physical Chemistry A, Vol. 113, No. 23, 11.06.2009, p. 6430-6436.

Research output: Contribution to journalArticle

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