Cyclen is widely used as a chelating agent in the field of medical imaging, particularly in magnetic resonance imaging (MRI). It forms stable complexes with gadolinium ions, which are employed as contrast agents to enhance the visibility of internal structures in MRI scans. This application is crucial for diagnosing various medical conditions, including tumors, inflammation, and vascular diseases. Additionally, cyclen derivatives are utilized in the development of radiopharmaceuticals for targeted cancer therapy, where they help deliver radioactive isotopes directly to cancer cells. In research, cyclen is also employed in supramolecular chemistry for creating complex molecular structures and studying host-guest interactions. Its ability to bind metal ions makes it valuable in catalysis and environmental applications, such as metal ion separation and recovery from industrial waste streams.