Influence of cyano groups on the properties of piezofluorochromic aggregation-induced emission enhancement compounds derived from tetraphenylvinyl-capped ethane

Three tetraphenylvinyl-capped ethane derivatives with 0, 1, and 2 cyano groups at the ethane moiety, namely, biTPE, biTPE-CN, and TPE-CN, respectively, were synthesized and characterized via photoluminescence, ultraviolet-visible absorption, wide-angle X-ray diffraction, fluorescence lifetime, and other techniques. The results indicate that the compounds possess piezofluorochromic properties and exhibit aggregation-induced emission enhancement. The distinct piezofluorochromic properties of all three compounds were reversible upon grinding and fuming. The introduction of cyano groups to the molecular structures of the derivatives significantly enhanced their piezofluorochromic activity. The relationship between structure and property was studied in detail. The results obtained will be of great help in understanding the piezofluorochromic mechanism and designing new piezofluorochromic materials.