4G0F:
reference: Optimized End-Stacking Provides Specificity of N-Methyl Mesoporphyrin IX for Human Telomeric G-Quadruplex DNA., Nicoludis JM, Miller ST, Jeffrey PD, Barrett SP, Rablen PR, Lawton TJ, Yatsunyk LA, J Am Chem Soc. 2012 Dec 19;134(50):20446-56. doi: 10.1021/ja3088746. Epub 2012, Dec 11. PMID: 23181361

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).