Spatiotemporally-controlled aggregation of tetraphenylethene derivative by optical manipulation

Shun-Fa Wang^1*, Jhao-Rong Lin¹, Fumitaka Ishiwari², Takanori Fukushima², Hiroshi Masuhara^1,3, Teruki Sugiyama^1,3,4

¹Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan
²Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
³Center for Emergent Functional Matter Science, National Chiao Tung University, Hsinchu, Taiwan
⁴Division of Materials Science, Nara Institute of Science and Technology, Ikoma, Japan

* Presenter:Shun-Fa Wang, email:wangshunfa@nctu.edu.tw

Spatiotemporal control of a single aggregate of a protonated dye molecule, tetraphenylethene derivative showing aggregation-induced emission enhancement (AIEE), was successfully demonstrated by optical manipulation. A single sub-micrometer-sized aggregate was initially confined by optical trapping when its fluorescence was hardly detectable. The continuous irradiation into the formed aggregate led to sudden and rapid growth when the fluorescence intensity at a peak wavelength of 540 nm was tremendously enhanced. Thus, we succeeded in inducing AIEE by optical manipulation. Furthermore, we also found that the switching on/off of the AIEE was controlled arbitrarily by alternating laser power. This is due to the change in aggregate structure by optical manipulation, indicating that optical manipulation overcomes the electrostatic repulsion between the protonated molecules in the aggregate. The dynamics and mechanism of optical manipulation-controlled AIEE will be discussed from the viewpoint of change in molecular association and conformation depending on laser power.

Keywords: optical manipulation, fluorescence microspectroscopy, molecular aggregation, tetraphenylethene derivative