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Issue 33, 2010
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On-off QD switch that memorizes past recovery from quenching by diazonium salts

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Abstract

The understanding of the interaction of CdSe/ZnS semiconductor quantum dots (QD) with their chemical environment is fundamental, yet far from being fully understood. p-Methylphenyldiazonium tetrafluoroborate has been used to get some insight into the effect of diazonium salts on the spectroscopy of QD. Our study reveals that the surface of CdSe/ZnS quantum dots can be modified by diazonium salts (although not functionalized), showing and on-off fluorescence behaviour that memorizes past quenching recoveries. Facile modification of the surface confers protection against quenching by new molecules of diazonium salt and other known quenchers such as 4-amino-TEMPO. The reaction mechanism has been explored in detail by using different spectroscopic techniques. At the first time after addition of diazonium salt over QD the fluorescent is turned off with Stern–Volmer behaviour; the fluorescence recovers following irradiation. Subsequent additions of diazonium salts do not cause the same degree of quenching. We have noted that the third addition (following two cycles of addition and irradiation) is unable to quench the fluorescence. Monitoring the process using NMR techniques reveals the formation of p-difluoroborane toluene as a result of the irradiation of diazonium-treated QD; the treatment leads to the fluorination of the QD surface.

Graphical abstract: On-off QD switch that memorizes past recovery from quenching by diazonium salts

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Supplementary files

Article information


Submitted
23 Feb 2010
Accepted
14 May 2010
First published
08 Jun 2010

Phys. Chem. Chem. Phys., 2010,12, 9757-9762
Article type
Paper

On-off QD switch that memorizes past recovery from quenching by diazonium salts

M. Liras, M. González-Béjar and J. C. Scaiano, Phys. Chem. Chem. Phys., 2010, 12, 9757
DOI: 10.1039/C003490H

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