Syntheses and properties of a series of novel surface active salts based on 1,4-dialkyl-1,4-diazoniabicyclo[2.2.2]octane and their supermolecular interactions with cucurbit[6]uril

Abstract A series of novel surface active salts, 1,4-dialkyl-1,4-diazoniabicyclo[2.2.2]octane bromides (2C x DABCOBr 2 ), have been synthesized and characterized. Their melting points show a U-shaped curve with increasing alkyl chain length, while the decomposition temperatures do not show significant differences. Critical aggregation concentration ( cac ) of 2C 6 DABCOBr 2 determined by the concentration dependence of 1 H NMR chemical shifts is about 100 mmol L −1 , which is in good agreement with the cac obtained by electrical conductivity and surface tension measurement. The aggregation number of 2C 6 DABCOBr 2 in aqueous solutions studied with a detailed analysis of 1 H NMR is 36. The interaction between 2C 6 DABCOBr 2 and cucurbit[6]uril in aqueous solution has also been investigated by 1 H NMR and spin-lattice relaxation time measurement ( T 1 ), indicating the formation of a complex with one alkyl chain of 2C 6 DABCOBr 2 inserted into the cavity of CB[6].