QSPR prediction of the stability constants of gadolinium(III) complexes for magnetic resonance imaging.

Gadolinium(III) complexes constitute the largest class of compounds used as contrast agents for Magnetic Resonance Imaging (MRI). A quantitative structure-property relationship (QSPR) machine-learning based method is applied to predict the thermodynamic stability constants of these complexes (log KGdL), a property commonly associated with the toxicity of such organometallic pharmaceuticals. In this approach, the log KGdL value of each complex is predicted by a graph machine, a combination of parametrized functions that encodes the 2D structure of the ligand.

Calix[6]arene-based cuprous "funnel complexes": a mimic for the substrate access channel to metalloenzyme active sites.

Two calixarene-based model systems (a and b) for monocopper enzymes are compared. Both present a tris(pyridine) coordination site for Cu that mimics the imidazole-rich neutral binding site in enzymes. Upon reaction with 1 equiv of copper(I), the tridentate ligands gave rise to ill-defined unsymmetrical complexes.

Calixarene-Based Copper(I) Complexes as Models for Monocopper Sites in Enzymes.

A cavity that acts as a molecular funnel is formed from calix[6]arene 1 and [Cu (NCCH ) ]PF [Eq. (a)]. An exchange of the well-protected acetonitrile ligand for other nitriles RCN is only possible with small R groups.