Spirofluorene-Cored Difluoroboron -Diketonate Complexes with Terminal Carbazole: Synthesis, Self-Assembling, and Fluorescent Sensory Properties

Spirofluorene-cored bis(difluoroboron -diketonate) complexes bearing terminal carbazoles (CbzBSF) and tert-butylcarbazoles (TCbzBSF) have been synthesized. It was found that only TCbzBSF could form organogels in cyclohexane and methylcyclohexane, suggesting that tert-butylcarbazole was essential for its organogelation directed by weak - interactions. It is worth noting that TCbzBSF could entrap ca. 5800 molecules of methylcyclohexane per gelator molecule, so this fully conjugated complex without traditional gelation group could be considered as a supergelator. The gained organogel showed reversible thixotropic and temperature-dependent sol-gel transitions. In particular, the orange red fluorescence of the xerogel-based film of TCbzBSF could be quenched when exposed to gaseous aromatic amines of aniline, N-methylaniline, and N,N-dimethylaniline. The detection limit for aniline vapor of the xerogel-based film was as low as 0.56 ppb.