Interaction between PAMAM-NH2 G0 dendrimer and dissociated sodium chloride in aqueous solution

The protonation constants of poly(amidoamine) dendrimer (PAMAM-NH2 GO) in an aqueous solution of sodium chloride with an ionic strength of 0.05 M were determined by the potentiometric method. The interaction between PAMAM-NH2 and sodium chloride dissociated in water at room temperature was assessed by means of calorimetric and conductometric measurements. Using isothermal calorimetric titration, the number of the moles of dissociated electrolyte combined by a dendrimer mole was estimated. The conductometric measurements indicate a decrease in electrolyte conductivity in the dendrimer solution in relation to the electrolyte solution and confirm that the dendrimer investigated combines electrolyte ions. The results of DFT calculations performed for the protonated structure of PAMAM-NH3+ suggest that the chlorine atom considered is combined with terminal amino groups, which confirms the results of calorimetric and conductometric measurements. (C) 2012 Elsevier B.V. All rights reserved.