Stereochemical tuning of Cr(III) photophysics with N,N prime ,N double prime -tris(alkylamine)-1,4,7-triazacyclononane complexes
- Wayne State Univ., Detroit, MI (USA)
The stereochemistry of coordinated ligands can dramatically affect the thermally activated relaxation of ({sup 2}E)Cr(III). This effect is most clearly exemplified in the much shorter (by a factor of 4.4 {times} 10{sup 5}) ambient lifetime of the hexammine complex Cr(TAE(9)aneN{sub 3}){sup 3+} (where TAE = N,N{prime},N{double prime}-tris(aminoethyl) and (9)eneN{sub 3} = 1,4,7-triazacyclononane) than to the very closely related Cr(TAP(9)aneN{sub 3}){sup 3+} (where TAP = N,N{prime},N{double prime}-tris(aminopropyl)). The large contrast in excited-state lifetimes may be due largely to ligand-promoted low-frequency vibrational modes which induce a trigonal distortion of the excited-state Cr(III) microenvironment. The tendency of these ligands to promote or inhibit such motion results in one of the shortest and one of the longest ambient lifetimes, respectively, observed for chromium(III) hexaam(m)ines. Models suggest that a trigonal distortion would mix the d-orbital character and facilitate the rapid, nonradiative return to the ground electronic state.
- OSTI ID:
- 6665151
- Journal Information:
- Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 94:4; ISSN 0022-3654; ISSN JPCHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400200* -- Inorganic
Organic
& Physical Chemistry
CALCULATION METHODS
CHEMICAL REACTIONS
CHROMIUM COMPLEXES
COMPLEXES
DATA
DATA ANALYSIS
ENERGY LEVELS
EXCITED STATES
EXPERIMENTAL DATA
INFORMATION
LIFETIME
LIGANDS
MEASURING INSTRUMENTS
MEASURING METHODS
NUMERICAL DATA
PHOTOCHEMICAL REACTIONS
STEREOCHEMISTRY
TRANSITION ELEMENT COMPLEXES