Deciphering the Conformational Choreography of Zinc Coordination Complexes with Standard and Novel Proton NMR Techniques Combined with DFT Methods

Abstract

The presence of water has been shown to deeply impact the stability and geometry of Zn complexes in solution. Evidence for tetra- and penta-coordinated species in a pyridylmethylamine-Zn(II) model complex is presented. Novel (1) H NMR tools such as T1 -filtered selective exchange spectroscopy and pure shifted gradient-encoded selective refocusing as well as classical 2D ((1) H-(1) H) exchange spectroscopy, diffusion-ordered spectroscopy and T1 ((1) H) measurements, in combination with density functional theory methods allow the full conformational dynamics of a pyridylmethylamine-Zn(II) complex to be revealed. Four conformers and two families of complexes depending on the hydration states are elucidated.

Keywords: DFT methods; NMR spectroscopy; chemical exchange; conformational exchange; zinc.