Madalina Ranga

The rate of exchange of the labile proton ( kex ) directly determines the magnitude of saturation transfer. Tetraalkyl-substituted 1,8-diaminonaphthalenes such as HDMAN + exhibit proton exchange rates that are five to 7 orders of magnitude slower than those of conventional ammonium ions, which typically undergo diffusion-controlled proton transfer.

1. Introduction Metal complexes have been widely employed for decades in medicine for diagnostic, therapeutic, and theranostic purposes [1,2,3]. Since most metal ions are toxic to humans, they must be strongly coordinated with a suitable chelating agent before being administered to patients. Polyaminopolycarboxylic acids (PACs) are the most popular family of chelating agents (CAs), easily forming stable complexes with a large variety of metal ions.