An important feature of colloidal semiconductor nanocrystals is their ability to interact with surrounding molecular species, opening the door to applications where nanoparticles can be used as sensors of their local environment or to drive donor-acceptor transfer reactions. We have recently undertaken a systematic study of the factors controlling the donor-acceptor processes in II-VI semiconductor QDs/nitroxide mixtures, which are known prefluorophore couples. Our strategy relies in part on employing a variety of nitronyl and imino nitroxide radicals (so-called Ullman's radicals), which possess a very versatile electronic structure that can be readily be modified by simple chemical modifications, allowing for a fine tuning of the interaction between these acceptor units and semiconductor QDs. Our results show that although both energy- and electron-transfer processes can be active quenching mechanisms in these systems, electron transfer is in general much more efficient. Furthermore, we demonstrate that these processes can be manipulated by adjusting the positions of the conduction and valence band levels, which is achieved by changing the size and composition of the semiconductor nanostructures, and employing established core-shell building strategies.

Bandgap engineering of donor-acceptor processes between colloidal semiconductor nanoparticles and organic free radicals

246th National Meeting (2013)

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