Spectral differences between enantiomeric and racemic Ru(bpy)[sub 3][sup 2+] on layered clays: Probable causes

Journal Article · Wed Nov 27 23:00:00 EST 1991 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100177a074· OSTI ID:7072575

Kamat, P V; Gopidas, K R ^[1]; Mukherjee, T ^[2]; Joshi, V; Kotkar, D; Pathak, V S; Ghosh, P K ^[3]

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1. Univ. of Notre Dame, IN (United States)
2. Bhabha Atomic Research Centre, Bombay (India)
3. Alchemie Research Centre, Thane (India)

The preferential self-annihilation (static and dynamic) of [Delta],[Lambda]-Ru(bpy)[sub 3][sup 2+]* over [Delta]- or [Lambda]-Ru(bpy)[sub 3][sup 2+]* is reported for aqueous dispersions of sodium hectorite lightly loaded with the Ru(II) chelate and subjected to pulsed laser excitation. By varying the loading level over a factor of ca. 60, it is also shown that racemate emission falls off sharply with increased loading whereas emission from the enantiomeric adsorbate remains more nearly constant. The decrease in luminescence yield of racemate with increased loading is mainly associated with an attenuation in the peak emission intensity, I(0), as found from time-resolved measurements. It is proposed, based on these studies, that clays offer both quenching and nonquenching sites for sorption and that [Delta],[Lambda]-Ru(bpy)[sub 3][sup 2+] prefers the latter at low loadings, the ions being clustered within such regions. Enantiomeric Ru(bpy)[sub 3][sup 2+], on the other hand, is more randomly distributed over the sites. The above model also permits rationalization of (i) observed changes in emission intensity with time, (ii) anomalies in the relative emission yields of Ru(bpy)[sub 3][sup 2+]* and Ru(phen)[sub 3][sup 2+]*, and (iii) the effect of Zn(phen)[sub 3][sup 2+] on emission. Finally, differences in binding modes of enantiomeric and racemic chelate forms also induce differences in the flocculation trends of dispersed clays, the effects being most prominent for freshly prepared ruthenium(II) montmorillonite.

• OSTI ID: 7072575
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 95:24; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
AZINES
BIPYRIDINES
CATIONS
CHARGED PARTICLES
CLAYS
COMPLEXES
DATA
ELECTROMAGNETIC RADIATION
EMISSION SPECTROSCOPY
ENANTIOMORPHS
EXPERIMENTAL DATA
HETEROCYCLIC COMPOUNDS
INFORMATION
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
IONS
LASER RADIATION
MATERIALS
MONTMORILLONITE
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PYRIDINES
RACEMATES
RADIATIONS
RESOLUTION
RUTHENIUM COMPLEXES
SORPTIVE PROPERTIES
SPECTROSCOPY
SURFACE PROPERTIES
TIME RESOLUTION
TIMING PROPERTIES
TRANSITION ELEMENT COMPLEXES