Small Molecules Based On Divinylanthracene: Design And Synthesis, Crystal Structure, Self-assembly And Piezochromic Properties

Organic photoelectric functional materials increasingly highlight its position inmaterial science and have attracted extensive attention since the1950s. Because of theirunique properties and prospective applications in nanoscale biological and optoelectronicdevices, such as organic electroluminescent, organic solid laser, photoelectric sensors,biological imaging and many other high-tech areas, they have become a newinterdisciplinary cutting edge. This paper based on the vinyl anthracene conjugatestructure, discussed the relationship between their molecular structure and photophysicalproperties. The main research contents are as follows:1A series of9,10-distyrylanthracene(DSA) derivatives,9,10-bis(3,5-dimethylstyryl)anthracene(TMDSA),9,10-bis(3,5-difluorostyryl)anthracene(TFDSA), and9,10-bis(3,5-bis(trifluoromethyl)styryl)anthracene(TFMDSA), were synthesized and characterized.Photophysical investigations and crystal structure analysis indicate that inhibition ofvibrational relaxation in aggregate state should be the origin for the aggregation-inducedenhanced emission and blueshift in crystals of our material system. Crystal structureanalysis demonstrates that substitution of various groups in DSA is effective for modifyingintermolecular interactions and forming different molecular packing feature. Bycontrolling the experiment conditions, TFDSA could easily achieve its perfect regular1Dnanowires, in which the weak intermolecular C-H···F hydrogen bond together witheffective π-π interaction play a significant role. High quantum efficiency (75%forTFDSA) and regular1D nanowires suggest that these kind of materials may have potentialapplications in optoelectronic device applications.2.9,10-bis((E)-2-(pyridin-2-yl)vinyl)anthracene(BP2VA),9,10-bis((E)-2-(pyridin-3–yl)vinyl)anthracene(BP3VA), and9,10-bis((E)-2-(pyridin-4-yl)vinyl)anthracene (BP4VA) were synthesized and characterized. These three compounds all possess multiplecrystalline phases, with high fluorescence quantum efficiencies (up to54%). Crystalstructure analysis shows that different linkage positions in the pyridine lead to differentcrystalline stacking modes effectively. Photophysical investigation under differentexternal pressure indicates that three compounds have the piezochromic effect. Throughthe analysis of crystal structure and its corresponding fluorescence spectrum, we proposethat piezochromic effects of these pyridine-vinyl-anthracene molecules should originatefrom the external force induced changes of molecular aggregation state.