Cyclen

Cyclen is a macrocyclic tetraamine chelating agent. Cyclen is the aza analogue of crown ether, used as a precursor for MRI contrast agents, and is an intermediate for the preparation of effective macrocyclic chelates. Cyclen is employed as a structural regulator through interfacial polymerization of polyethleneimine (PEI) and trimesoyl chloride (TMC) to develop polyamide NF membrane with efficient Li⁺/Mg²⁺ separation performance. Cyclen has specific cavity structure and exhibits selective coordination properties for Li⁺ ions. In Vitro: Cyclen binds dehydrated Li⁺ with an adsorption energy of -75.0 kJ/mol, forming a stable complex due to a well-matched molecular cavity size^[2].
Cyclen in PEI/Cyclen-TMC composite membrane reduces the Mg²⁺/Li⁺ mass ratio of simulated salt lake brine from 40 to 0.3 over three nanofiltration stages, achieving a 45.5% Li⁺ recovery rate and producing Li₂CO₃ with 93% purity after precipitation and filtration^[2].