Titration characteristics of fluorous 1,2,3-triazol-4-ylmethyl ethers, bis(1,2,3-triazol-4-ylmethyl) ethers and bis(1,2,3-triazol-4-ylmethyl) amines

Abstract

The titration of a series of fluorous bis(1,2,3-triazol-4-ylmethyl) molecules with camphorsulfonic acid has been examined by 1H NMR spectroscopy to investigate any conformational changes that might occur on protonation; it is envisaged that this information will assist in predicting their potential as ligands. Structure activity relationships based on the equilibrium constants of protonation and changes in chemical shift of the H5 triazolyl signals provide consistent information that support weak but evident cooperativity between the triazolyl rings in bis-triazolylmethyl ethers. This is overridden by replacement of the ether oxygen with a secondary amino group, but similar principles apply in subsequent protonation. An attempt is made to interpret the cooperative behavior.