Accessing New Microporous Polyspirobifluorenes Via a C/Si Switch

Microporous spirosilabifluorene networks were synthesized via Yamamoto coupling of tetrabromospirosilabifluorene precursors. Both materials exhibit fluorescence, with the 2,2’,7,7’-coupled framework emitting around 454 nm, and the 3,3’,6,6’-coupled framework emitting at 389 nm. The fluoresecence of both materials are quenched in the presence of nitroaromatics, with increasing Stern-Volmer constants for the series nitrobenzene < 2,6-dinitrotoluene (DNT) < 2,4,6-trinitrotoluene (TNT). The C/Si switch has subtle effects on the optical properties of the spirobifluorene network and provides a convenient route to 3,3’6,6’-coupled and other new polybifluorene frameworks.