Multiple spectroscopic and magnetic techniques show that chloroquine induces formation of the μ-oxo dimer of ferriprotoporphyrin IX

UV-visible and MCD spectroscopy, together with magnetic susceptibility measurements have shown that chloroquine induces the formation of a μ-oxo dimer of ferriprotoporphyrin IX from its π-π dimer, producing a 1:2 chloroquine:ferriprotoporphyrin IX complex.