A series of tris(2-aminoethyl)amine (TREN) derivatives functionalized on th
e arms with pyridine or methylimidazole ligands bind very strongly to a tri
sporphyrin derivative via apical coordination, with formation of molecular
cages; the strength of the binding (K-b up to 10(8.8) mol(-1) dm(3)) depend
s on the structure of the TREN derivative as well as on its coordination to
Zn(II).