The Modification of the Functionality of pi-Molecules through the Structural Adjustment
Wuhan University, China
To construct p-molecules with different structures is one of the key points in the research field of opto-electronic materials. In many cases, the molecular structure not only affects the intramolecular p-conjugation, but also the intermolecular p-p stacking, to result in the different functionalities. In this talk, some typical examples will be presented to partially demonstrate the interesting different properties with minor or even ignorable structural difference.
4:30pm - 4:45pm Oral
Malonitrile-Functionalized Tetraphenylpyrazine-Based AIEgen: A Ratiometric Fluorescent Probe for detecting Hydrogen Sulfide with Unique Mechanofluorochromic Effect
Ming CHEN, Ben Zhong TANG
Department of Chemistry and the Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, the Hong Kong University of Science & Technology, Hong Kong S.A.R. (China)
Luminogens with aggregation-induced emission (AIE) characteristics have attracted great interest in organic electronics because they thoroughly solve the notorious aggregation-caused quenching (ACQ) effect confronted in conventional fluorogens. To create AIE-active luminogens (AIEgens) with mutable structures and diverse applications, suitable AIE-active cores, such as phenyl-substituted siloles and tetraphenylethene, etc. are needed. For example, by modifying the AIE-active cores with conjugated or polar groups, the emission of AIEgens can be tuned from blue to red light, which makes them suitable for fabricating organic light-emitting diodes used for full colour display. By decorating water soluble and targeting groups to AIE-active cores, the resulting AIEgens can function as biological probes. 
Based on the mechanism of restriction of intramolecular rotation as the cause for the AIE phenomenon, a new heterocycle-based AIE-active core of tetraphenylpyrazine (TPP) was developed recently by us with the advantages of easy preparation, facile modification, excellent stability and tunable emission color.  Here, a new AIEgen giving green emission is generated by modifying TPP-based AIEgen with functional malonitrile group. Due to the introduction of active functional group, the luminogen can serve as ratiometric fluorescent probe for detecting hydrogen sulphide with high sensitivity and good selectivity. Besides, unlike most reported mechanochromic dyes, which show bathochromic, turn-off or turn-on emission under the stimuli of external force, our luminogen exhibits an abnormal and reversible mechanochromic effect with hypsochromic effect. All these findings indicate a huge potential for high-tech application of TPP-containing AIE materials.
 J. Mei, N. L. C. Leung, R. T. K. Kwok, J. W. Y. Lam, B.Z. Tang, Chem. Rev., 2015, 115, 11718.
 M. Chen, L. Li, H. Nie, J. Tong, L. Yan, B. Xu, J. Z. Sun, W. Tian, Z. Zhao, A. Qin, B. Z. Tang , Chem. Sci., 2015, 6, 1932.
4:45pm - 5:00pm Oral
Synthesis, Photophysical Properties of Red- and NIR-Emissive AIEgens, and Their Applications in Biological and Optoelectronic Systems
Dong WANG1, Chun Sing LEUNG1, Dan DING2, Jacky Wing Yip LAM1, Ben Zhong TANG1
1The Hong Kong University of Science and Technology, Hong Kong S.A.R. (China); 2Nankai University, China
A series of red- and NIR-emissive luminophores with aggregation-induced emission (AIE) characteristic were prepared with facile syntheses. Their emission wavelengths can be tuned from 620 nm to 830 nm, when different electron donors (D) and electron acceptor (A) are integrated. Those dyes exhibit classic AIE property with high quantum yields (ranging from 7.6% to 38%) in both aggregation and solid states. Biological studies show that some of them can enter the cell by selectively targeting with lipid droplets, and be powerful in the application of photodynamic therapy (PDT) as photosensitizing agents; some of them having positive charge can stain bacteria and kill bacteria under room light due to the generation of reactive oxygen species (ROS); in general, those AIEgens are thermally stable, morphologically stable, electrochemically stable, highly luminescent for emitting materials, and have a suitable ionization potential and electron affinity, making them promising in the use of organic light-emitting diodes.