6APZ:
reference: Anion-pi Interactions in Computer-Aided Drug Design: Modeling the Inhibition of Malate Synthase by Phenyl-Diketo Acids., Ellenbarger J, Krieger I, Huang HL, Gomez-Coca S, Ioerger TR, Sacchettini JC, Wheeler SE, Dunbar KR, J Chem Inf Model. 2018 Aug 23. doi: 10.1021/acs.jcim.8b00417. PMID: 30137983

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