Pillar[n]MaxQ: A New High Affinity Host Family for Sequestration in Water

We report the synthesis, X‐ray crystal structure, and molecular recognition properties of pillar[n]arene derivative P[6]AS, which we refer to as Pillar[6]MaxQ along with analogues P[5]AS and P[7]AS toward guests 1–18. The ultratight binding affinity of P[5]AS and P[6]AS toward quaternary (di)ammonium ions renders them prime candidates for in vitro and in vivo non‐covalent bioconjugation, for imaging and delivery applications, and as in vivo sequestration agents. Ultratight binding: The synthesis, crystal structure, and molecular recognition properties of a new series of ultratight binding hosts dubbed Pillar[n]MaxQ is reported.