Mechanofluorochromic and thermochromic properties of simple tetraphenylethylene derivatives with fused fluorine containing 1,4-dioxocane rings

A series of tetraphenylethylenes (TPE) derivatives in which one or more of the phenyl rings have been replaced by a fused fluorine containing 2,3,4,5-tetrahydrobenzo[b][1,4]dioxocane unit have been synthesized. The analysis of the photoluminescence emission under application of mechanical grinding and thermal treatment show that in addition to the expected aggregation induced emission behavior observed in solution, these simple modifications of the TPE system confer mechanofluorochromic properties to the corresponding materials. The results of X-ray diffraction and theoretical calculations suggest that the introduction of tetrafluorobutylenedioxy “loops” control the balance between weak intermolecular interactions and thus the interconversion between “macro” and “micro-aggregates” which is proposed as the basic mechanism for the observed MFC properties.