Aggregation-Induced Emission in Tetraphenylethene Derivatives

Aggregation-Induced Emission in Tetraphenylethene Derivatives

Author: Asian Journal of Organic Chemistry

The development of new luminescent materials based on π-conjugated organic molecules is important because of their applications in electronics, optics, storage media, and biological sciences. Such compounds are usually used in the aggregated state for practical applications. However, a common problem associated with the emission of most luminescent materials is aggregation-caused quenching (ACQ): although fluorescent materials are highly emissive in the solution state, they become weakly emissive or even non-emissive when aggregated in the condensed phase. This effect has significantly limited the high-tech application of conventional fluorophores.

In 2001, Ben Zhong Tang, Hong Kong University of Science & Technology, China, and co-workers observed the phenomenon of aggregation-induced emission (AIE) [1]. It is the exact opposite of ACQ.
Tang and colleagues now report a yellow AIE luminogen (TPE-DCV), which was synthesized by treating tetraphenylethene with two dicyanovinyl units. The solid-state emission of TPE-DCV can be reversibly switched between green and yellow by grinding then fuming with acetone vapor or heating because of a morphological change between the thermodynamically stable crystalline phase and the metastable amorphous state.
This demonstrates that TPE-DCV can serve as a recyclable optical storage medium. In addition, crystalline microrods and microslices of TPE-DCV are excellent optical waveguides with very low optical loss.

[1] J. Luo, Z. Xie, J. W. Y. Lam, L. Cheng, H. Chen, C. Qiu, H. S. Kwok, X. Zhan, Y. Liu, D. Zhu, B. Z. Tang, Aggregation-induced emission of 1-methyl-1,2,3,4,5-pentaphenylsilole, Chem. Commun. 2001, 1740–1741. DOI: 10.1039/B105159H

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