Synthesis And Properties Of Photochromic Diarylethene Materials Based On Aggregation-induced Emission Enhancement

Diarylethene photochromic compounds have many excellent properties, which suggest their important application in the high-tech fields of molecular switches, ultrahigh-density optical memories, logic gates, biological imaging, actuators and so on. Organic fluorescent photochromic material is one of the most active research fields because the fluorescence signal is easy to identify with high sensitivity, switchable, can realize the nondestructive readout and has many other advantages, which is the important output signal of fluorescent molecular probes, fluorescence molecular switch, biological imaging and its device applications. But when conventional fluorescent molecules aggregate, their fluorescence quantum yield will be decreased, which hinders their practical application. A good solution is to design molecules with aggregation-induced enhanced emission（AIEE）. In this paper,several new aggregation-induced enhanced emission diarylethene photochromic compounds were designed and synthesized, and their photochromic and AIEE properties were studied.Meanwhile, their applications in fluorescent molecular switch and rewritable information storage were investigated. The main contents and conclusions are as follows:1. By introducing pyrrole-indoles fluorophore to both ends of bisthienylethene（BTE）structure, a special class of molecule with high-contrast on/off fluorescence switching properties was successfully synthesized, but it exhibited aggregation-caused quenching phenomenon. Then, by continuing to introduce cyanostilbene group to both ends of this molecule, the product showed AIEE properties, but it lost the photochromic properties.2. A novel multifunctional molecule was designed and synthesized. Its photochromic,AIEE and fluorescence switching properties were investigated. A simple optical storage device was successfully developed using its 1 wt% loaded PMMA film. Moreover, it could self-assembly to form regular nanowires in V（H₂O）: V（THF） = 6:4 mixture, which would melt under the UV irradiation.3. Two novel π-conjugated cyanostilbene derivatives were designed and synthesized.Their photochromic and AIEE properties were studied and both of them showed AIE active.Their HOMO and LUMO were calculated to investigate the relationship between the structure and properties.4. Two kinds of terpolymer based on PNIPAM containing BTE photochromic unit and AIEE dye unit were synthesized via free radical polymerization. Their photochromic, AIEE and heat-sensitive properties were studied respectively, and a new multiple response fluorescence polymer switch was successfully developed.