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.

Deciphering preferred geometries of pyridylmethylamines-based complexes: A robust strategy combining NMR, DFT and X-ray

“…Alternatively, complex 3 could be crystallized and X-ray derived structures of complex 3 (in light blue to the calculation detailed in the Supporting Information. 46 4.1.3. X-Ray X-ray crystallography data were collected at 150 K on a Bruker Kappa APEX II diffractometer using a Mo-κ (λ=0.71069Å) X-ray source and a graphite monochromator.…”

“…[43][44][45] While the preparation of pma-ZnCl2 complexes and the description of their properties accompanied by solid state data were disclosed in a few reports, 28,37 the pma-ZnBr2 complexes are more scarcely described. 46,47 In this communication we focused on the preparation of pma-ZnBr2 complexes based on N,N-bidentate ligands. In order to gain accurate structural information in both solution and solid state, we describe herein the first issue of an approach combining DFT calculations and advanced NMR such as pure shift gradient-encoded selective refocusing (PS-GSERF) and standard NOESY experiments towards well-defined neutral Zn II complexes.…”

Monitoring Conformational Changes in an Enzyme Conversion Inhibitor Using Pure Shift Exchange NMR Spectroscopy

“…The arrow indicates the main chemical bond involved in the conformational equilibrium as described elsewhere. [2] Articles For Trandolapril, in the temperature range corresponding to physiological conditions (20-40°C), the regime of the conformational exchange is slow, leading to the observation of doubled 1 H and 13 C resonances, on spectrometers operating at proton resonance frequencies in the range 400-600 MHz. [2] When the exchange rate is on the same time scale as the longitudinal relaxation of the probed nucleus, exchange spectroscopy (EXSY) provides a convenient way of identifying and analyzing doubled resonances, while taking benefit of the dispersion of correlation peaks across multi-dimensional spectra.…”

“…[7] They allow for probing physical processes in the 10-2000 ms time window. [8][9][10][11][12][13] These processes include slow conformational changes such as domain movement, [14,15] ligand binding [16,17] and release, [18] topological interconversion of secondary structure [19,20] and cis-trans isomerization, [21] all of which may affect catalytic turnover rates in enzymes. [12,22,23] A problem that is however often encountered in such approach is the spectral resolution that can be achieved.…”

“…EXSY experiments are among the earlier multi‐dimensional experiments . They allow for probing physical processes in the 10–2000 ms time window . These processes include slow conformational changes such as domain movement, ligand binding and release, topological interconversion of secondary structure and cis‐trans isomerization, all of which may affect catalytic turnover rates in enzymes .…”