Fox, Lucius Seiberling (1989) Intramolecular electron transfer in an iridium d [supercript 8]-d [superscript 8] donor-acceptor system. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-06072007-081509
NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. A series of donor-acceptor complexes, [...] 2,4,6-trimethylpyridinium, 4-methylpyridinium, pyridinium, and 4-phenylpyridinium; [...], have been synthesized for studying the rate of photoinduced electron transfer from the metal localized [...] excited states of [...] chromophores. The pyridinium electron acceptors are covalently attached to the iridium metal centers (donor) via a three atom hydrocarbon linker bound to the terminal phosphine ligands. The x-ray crystallographic structure of [...] reveals a metal-metal distance of 3.219(1) [...] and a solid state donor-acceptor separation of 5.34(1) [...]. Additional donor-acceptor separations and orientations are available to the compounds in fluid solution through rotations about the Ir-P and linker group C-O, C- N, and C-C bonds. Steady state emission spectra show that the fluoresence and phosphoresence quantum yields in these compounds are substantially reduced relative to a appropriate model complex. To date the excited state reactivity of [...] metal dimers has been exclusively attributed to their [...] states. These findings represent the first evidence for reactivity from a shorter lived [...] state. Picosecond and nanosecond laser flash-photolysis techniques were employed to measure the rates of photoinduced electron transfer and charge recombination in these systems. Values of [...], obtained from these studies, vary between [...] and [...] as a function of reaction exoergicity [...]. Clear evidence for the inverted behavior predicted by classical and semiclassical electron transfer models is seen at high driving force. Rate constants for reactions involving the [...] and [...] excited states, as well as the rates of charge recombination are characterized by very similar values of [...] and [...]. Our data are adequately modeled by the classical theory of electron transfer proposed by Marcus [...] or by a semiclassical model for [...] where nuclear tunneling involves a low frequency metal-ligand mode [...]. These findings are explored with regard to utilizing the donor-acceptor complexes as molecular photochemical energy storage systems.
|Item Type:||Thesis (Dissertation (Ph.D.))|
|Degree Grantor:||California Institute of Technology|
|Division:||Chemistry and Chemical Engineering|
|Awards:||The Herbert Newby McCoy Award, 1989|
|Thesis Availability:||Restricted to Caltech community only|
|Defense Date:||31 January 1989|
|Default Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Imported from ETD-db|
|Deposited On:||14 Jun 2007|
|Last Modified:||26 Dec 2012 02:52|
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