Ion-Specific Self-Assembly of a Lipophilic Guanosine Derivative in Thin Surface Films

We investigated the effect of various ions on the surface assembly of a guanosine derivative with one hexadecanoyl chain at the air-water interface. The ions were added to the water subphase prior to spreading of the surface film. Like in bulk water, also at the air water interface, K+ ions exhibit the strongest influence on the assembly features as they induce structural transformation from lamellar to mosaic-like assembly. In contrast, Li+ and Na+ ions only slightly modify the properties of the assembled film with respect to those observed on pure water. The nature of anions plays an important role in the surface self-assembly as well. We found that (Pic(-)) is 2 orders of magnitude more effective for assembly regulation than Cl-. All surface assemblies observed in our study are very stable and robust, and consequently they remain practically unperturbed after Langmuir-Blodgett transfer onto a solid support.