The smallest cucurbituril analogue with high affinity for Ag+

Abstract

A new host, Me₈TD[4], was prepared for the first time from propanediurea–formaldehyde condensation in the presence of CaCl₂ as the template and it is the smallest cucurbituril analogue reported so far. Measurements of the thermodynamic quantities (log K, ΔH, and ΔS values) of the interactions of Me₈TD[4] with a series of cations by isothermal titration calorimetry indicated that Me₈TD[4] binds selectively towards Ag⁺ with a high binding constant, K ∼ 1.3 × 10⁶ M⁻¹.