New Triazole-Containing Branched Bis(dipeptidomimetic) – Switching from Self-Dimerization to Anion-Binding Properties

Abstract

A triazole-containing branched bis(dipeptidomimetic) 2 using l-lysine as a flexible branching unit was synthesized and characterized. The compound was found to form weak dimers (K dim = 19 M–1) in chloroform as shown by vapor pressure osmometry (VPO) and concentration-dependent 1H NMR studies. On the other hand, the compound was capable of binding chloride and monobasic diethyl phosphate (DEP) in chloroform. Job plot analysis, MALDI-TOF mass spectrometry, and NMR titration studies revealed a 1:1 binding stoichiometry with good binding affinities (K a ≈ 640–780 M–1). Structural studies using ­ROESY NMR spectroscopy and molecular modelling on the 2–DEP complex indicated the adoption of a helix-like conformation by the host with the guest situated near the branching juncture.