Ellagic　acid　(EA),　a　biologically　active　polyphenol　abundant　in　various　natural　plants,　has　been　widely　applied　in　diverse　pharmacological　systems.　This　study　investigates　cocrystals　formed　by　EA　with　common　pharmaceutical　intermediates,　yielding　crucial　insights　into　their　atomic-level　biological　performance.　Three　novel　cocrystals　of　EA·Phenazine　were　synthesized　in　different　solvents　(cocrystal　1:　EA·Phenazine;　cocrystal　2:　EA·Phenazine·2MeOH;　cocrystal　3:　EA·Phenazine·2H2O).　In　addition,　their　structures　are　characterized　using　single-crystal　X-ray　diffraction.　Co-crystal　1　without　lattice　solvent　and　cocrystal　3　containing　lattice　H2O,　exhibited　intriguing　EA-EA　and　phenazine-phenazine　π-π　stacking　interactions.　Conversely,　cocrystal　2　bearing　methanol　can　illustrate　robust　interligand　EA/phenazine　π-π　stacking　interactions.　Thus,　cocrystal　2　displayed　a　wider　absorption　range　and　a　more　negative　oxidation　potential,　indicative　of　enhanced　functional　performance.　The　superior　properties　of　cocrystal　2　were　attributed　to　the　lower　energy　level　of　the　lowest　unoccupied　molecular　orbital,　particularly　the　p−π*　antibonding　orbitals　of　phenazine,　owing　to　the　potent　π-π　interactions,　as　unveiled　by　theoretical　calculations.　In　summary,　the　presence　of　interligand　interactions　emerges　as　a　pivotal　factor　in　augmenting　the　biological　activities　of　cocrystals,　with　the　extent　of　enhancement　contingent　on　specific　packing　modes.　This　structure-property　relationship　allows　a　profound　understanding　of　the　polymorphism　observed　in　drug　molecules.　©　2024　American　Chemical　Society.