Phenanthridine is a nitrogen-containing heterocyclic compound. Phenanthridine serves as the structural backbone of fluorescent dyes that bind to DNA, enabling visualization of nucleic acid positions post-electrophoresis, as seen with dyes like ethidium bromide and propidium iodide. Acridine is an isomer of Phenanthridine. Used in ecotoxicological studies. Employed in rotational spectroscopy and radio astronomy research. Functions as a dye in biological and chemical sensors.