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Molecular energy transfer in the systems based on layered silicates
and organic dyes
J. Bujdák, A. Czímerová, A. Čeklovský
The formation of supramolecular assemblies of cationic dyes was observed in colloids and
films of layered silicates. The distribution of dye molecules influenced the phenomenon of
energy transfer upon the excitation with visible light. Fluorescence spectroscopy indicated the
intermolecular interactions based on a non-radiant energy transfer taking place between
isolated dye cations and the supramolecules. For example, the energy transfer in a few
nanometers’ scale was directly proven for more complex systems composed of two different
dyes: oxazine and rhodamine. Molecules of rhodamine took a role of molecular antennas
absorbing green light (λ=500-520 nm). Light absorption was accompanied with a non-radiant
energy transfer to the molecules of the second dye, oxazine. The transfer was detected as a
quenching of the light emission from the rhodamine (580 nm) in favour of the red light
luminescence from oxazine (near 635 nm). Oxazine had not been directly excited by green
light, and did not emit in rhodamine absence. The phenomenon shows how inorganic layered
materials can be used to mediate the transfer of electromagnetic energy between adsorbed dye
cations. The energy transfer yields were influenced by the distances between interacting
molecules, which depended on the layer charge density of the silicate. These results could
contribute to the development of novel types of hybrid materials potentially useful for laser or
optical technologies.
Scheme showing RET processes in the hybrids based on fluorescent dyes adsorbed on the
surface of layered silicate particles. Using a suitable silicate and an optimal composition of
the hybrids, quenching by molecular aggregates (left) can be minimized in favour of the
energy transfer leading to the emission from the energy acceptor (right).
Further information: J. Bujdák: juraj.bujdak@savba.sk
1. Bujdák J., Iyi N.: Chem. Mater. 18, 2618-2624, 2006
2. Czímerová A., Bujdák J., Iyi N.: J. Photoch. Photob. A 187, 160-166, 2007
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