The most successful antimalarial drug to date is the 7-chloro-4-amino-quinoline, chloroquine, which targets the Hb digestion pathway. The mechanism is not completely understood [1-6] but a critical facet is the inhibition of ferriprotoporphyrin IX (FPIX) heme crystallization to Hz [5-10]. As early as 1964 [11] the likelihood of important CQ-FPIX interactions was realized, and the idea gained momentum via the work of Fitch [12] . The Hz crystal unit is a curious 'head to tail' FPIX dimer, wherein oxygens, coordinating adjacent irons in the two tetrapyrrole rings, are donated by FPIX propionic acid side chains [13] . Formation of this dimer within the DV competes with the formation of the better studied µ -oxo dimer. In simple aqueous solutions the µ-oxo dimer is favored over the head to tail dimer. Overall, equilibria between multiple chemical forms of FPIX within the DV is poorly understood. However, it is known that both FPIX dimerization and Hz crystallization are highly pH dependent, and that Hz formation is accelerated by lipids and is obligatory for parasite survival.