Direct evidence to support the restriction of intramolecular rotation hypothesis for the mechanism of aggregation-induced emission: temperature resolved terahertz spectra of tetraphenylethene

In contrast to the traditional fluorescent dyes that exhibit a decrease in fluorescence upon aggregation, Aggregation-Induced Emission (AIE) molecules are a family of fluorophors which exhibit increased fluorescence upon aggregation. Consequently, AIE molecules represent an interesting new material...

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Bibliographic Details
Published in:Materials horizons 2014-03, Vol.1 (2), p.251-258
Main Authors: Parrott, Edward P. J., Tan, Nicholas Y., Hu, Rongrong, Zeitler, J. Axel, Tang, Ben Zhong, Pickwell-MacPherson, Emma
Format: Article
Language:English
Subjects:
Agglomeration
Biosensors
Constrictions
Devices
Emission
Fluorescence
Medical
Medical devices
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Summary:In contrast to the traditional fluorescent dyes that exhibit a decrease in fluorescence upon aggregation, Aggregation-Induced Emission (AIE) molecules are a family of fluorophors which exhibit increased fluorescence upon aggregation. Consequently, AIE molecules represent an interesting new material with potential applications in fluorescent chemo/biosensors, light emitting devices and medical diagnostics. Numerous mechanisms have been proposed to explain this phenomenon, including E-Z isomerization, and restriction of intramolecular rotations (RIR). However, there has not been any direct experimental evidence to support either one of these hypotheses. Here we use terahertz time-domain-spectroscopy (THz-TDS) and solid-state computational simulations of an AIE molecule to link the increase in intensity of intramolecular rotation and rocking modes to the measured fluorescence and reveal direct evidence supporting the RIR hypothesis. This is the first time that terahertz spectroscopy has been used to directly probe such molecular motions in AIE materials and in doing so we have found conclusive evidence to fully explain the AIE mechanism.
ISSN:2051-6347
2051-6355
DOI:10.1039/C3MH00078H