New dendritic gelator bearing carbazole in each branching unit: selected response to fluoride ion in gel phase

A new dendritic gelator with carbazole as the building block (HBCD) was synthesized. It was found that H-bonding between the amide groups and pi-pi interaction between the aromatic rings played predominant roles in the gel formation. Meanwhile, significant aggregation-induced emission enhancement was observed in the gel state due to the formation of J-aggregates and the restricted molecular motion. Notably, the gel state of HBCD can be destroyed upon addition of F-, accompanied by fluorescence enhancement on account of the formation of N-H center dot center dot center dot F-, which could further lead to the increased coplanarity of HBCD. The sensory capability of HBCD exhibited a high selectivity towards F- instead of the Cl-, Br-, I- and AcO- anions, which could be explained by the fact that the steric hindrance of the dendrimer would go against the interactions between the larger anions and HBCD.