Quaternary ammonium analog of ethidium; an intercalating dye with a specific affinity to certain forms of DNA and, used as diiodide, to separate them in density gradients.

AQC (6-Aminoquinolyl-N-hydroxysccinimidyl carbamate) is a reagent for the fluorescence detection of amino acid or protein sequence by HPLC.

Cyclen is a macrocycle capable of selectively binding cations that used as a ligand in chemistry for instance with chemicals used in MRI contrast agents.