Structural Variations in Carboxylated Bispidine Ligands: Influence of Positional Isomerism and Rigidity on the Conformation, Stability, Inertness and Relaxivity of their Mn Complexes.

Mn complexes of 2,4-pyridyl-disubstituted bispidine ligands have emerged as more biocompatible alternatives to Gd -based MRI probes. They display relaxivities comparable to that of commercial contrast agents and high kinetic inertness, unprecedented for Mn complexes. The chemical structure, in particular the substituents on the two macrocyclic nitrogens N3 and N7, are decisive for the conformation of the Mn complexes, and this will in turn determine their thermodynamic, kinetic and relaxation properties.

Mn Complexes with a Bispidine-Phosphonate Ligand: High Kinetic Inertness for Imaging Applications.

Bispidine (3,7-diazabicyclo[3.3.1]nonane) provides a rigid and preorganized scaffold that is particularly interesting for the stable and inert complexation of metal ions, especially for their application in medical imaging.

Unprecedented Kinetic Inertness for a Mn -Bispidine Chelate: A Novel Structural Entry for Mn -Based Imaging Agents.

The search for more biocompatible alternatives to Gd -based MRI agents, and the interest in Mn for PET imaging call for ligands that form inert Mn chelates. Given the labile nature of Mn , high inertness is challenging to achieve. The strongly preorganized structure of the 2,4-pyridyl-disubstituted bispidol ligand L endows its Mn complex with exceptional kinetic inertness.

2,4-Substituted bispidines as rigid hosts for versatile applications: from κ-opioid receptor to metal coordination.

Bispidones (3,7-diazabicyclo[3.3.1]nonan-9-one) are bicyclic analogues of the natural antiarrhythmic agent, spartein.