Fig. (2) Structure of the azithromycin-Zn⁺⁺ complex. (A) Balls and sticks 3D-structure featuring azithromycin and Zn⁺⁺ in a cluster of four hetero-atoms (three oxygens in red and a nitrogen in blue).(B) 3-D total charge density contour envelope. Green volumes represent positively charged zones while red volumes show negatively charged zones. Zinc (center) is completely surrounded by a large negatively charged continuum.