What is it about?

Supramolecular organization is a key factor to obtain materials with technologically relevant properties. For example, electronic excitation energy transfer, which is the working mechanism of photosyntetic antenna systems, is based on a perfectly tuned organization of molecules able to absorb and transfer solar energy. Here, we investigated whether the confinement of very simple guest molecules inside the channels of zeolite molecular sieves could give molecular assemblies with new interesting electronic properties.

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Why is it important?

How energy captured from the sun can travel from a molecule to another one is one of the most important and fascinating questions in science. How this process occurs at the microscopic scale, is still an open question. In this work, for the first time, we provided a molecular-level view of how electronic excitation is transferred in a confined, one-dimensional aggregate of molecules. We achieved this goal by simulating a row of chlorine molecules in a zeolite nanochannel in the electronic excited state. We've seen that an excited molecule can transfer its excitation to a neighbouring unexcited molecule simply by collisions. This mechanism is short-range, and may become particularly important when the molecules are very close to each other - hence, at high concentration.


Modeling the excitation and the excitation energy transfer in a confined molecular wire was indeed a challenge, some years ago. I think that our results are still significant today, because it is still difficult to get from experiments detailed information on such subtle processes. Useful insight on the excitation transfer mechanism has been gleaned: confinement in a nanochannel compels the excited molecule to collide with neighbouring molecules, to whom excitation is transferred. The time-scale of the excitation transfer is of the order of picoseconds, like that of molecular collisions. I think that future studies on these important and ubiquitous processes could still benefit from our atomic-level picture of a short-range excitation transfer.

Gloria Tabacchi
university of insubria

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This page is a summary of: Intermolecular Electronic Excitation Transfer in a Confined Space: A First-Principles Study, ChemPhysChem, September 2005, Wiley, DOI: 10.1002/cphc.200400561.
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