We have selectively synthesized and characterized several aliphatic internal imine isomers, which show selectivity towards various transition metal ions with large shifts in the UV–Vis and OFF-ON switching of fluorescence in solution. The stoichiometry with different transition metals has been determined to be 1:1, with the 1,2-ethylenediamine dimer showing the best selectivity towards Hg(II). Selectivity in different solvent media and the varying kinetics of transition metal binding with the macrocycle has been presented, along with the crystallography of the ligands and their metal complexes.