Novel ionophores with 2n-crown-n topology: anion sensing via pure aliphatic C-H···anion hydrogen bonding.

A series of novel coronands having a 2n-crown-n topology based on trioxane (6-crown-3) derivatives are designed and characterized. These neutral hosts can sense anions through pure aliphatic C-H hydrogen bonding (HB) in condensed phases due to the unusual topology of 2n-crown-n. C-H bonds are strongly polarized by two adjacent oxygen atoms in this scaffold. These hosts provide a rare opportunity to modulate anion binding strength by changing the electronic nature of aliphatic C-H bonds and offer ease of synthesis.