Structure, dynamics, and hydration of POPC/POPS bilayers suspended in NaCl, KCl, and CsCl solutions

► Fluorescence experiments and MD simulations report on specific ion-lipid interactions. ► Alkali metal chlorides dehydrate and compress the POPC/POPS (4:1, mol:mol) bilayer. ► No binding of the studied cations to the carboxylate group of POPS was observed. ► Cations penetrate toward the carbonyls and bridge neighboring lipid molecules. ► The observed changes follow the Hofmeister ordering: Na > K > Cs.