Self-assembled cation transporters made from lipophilic 8-phenyl-2′-deoxyguanosine derivatives

Abstract

We have previously reported that 8-phenyl-2′-deoxyguanosine derivatives (8PhGs) are able to extract metal cations from an aqueous phase into an organic phase. Herein, we report on the ability of 8PhGs to transport metal cations across a bulk lipophilic liquid membrane. The experiments were performed using lithium, sodium, potassium and strontium picrate salts with the parent lipophilic Gi, two isomeric 8PhG derivatives, cis-dicyclohexano-18-crown-6 (DC18C6) and [2 · 2 · 2] cryptand as reference compounds. The relative amounts of the picrate salts were measured by UV spectroscopy in both the source phase and the receiving phase over a period of 24 h. The results show that the transport efficiency of the self-assembled ionophores formed by 8PhGs is either similar or superior to that of DC18C6, and in all but one case higher than the parent compound Gi. The varying efficiencies between the derivatives can be attributed to the stability (kinetic and thermodynamic) and the different molecularities of the supramolecules formed by these 8PhGs. The ease of the synthesis of 8PhGs, their anion-independent assembly and the fact that the transport efficiency can be modulated as a function of the structure of the 8PhGs bode well for the use of such compounds in the development of novel antimicrobial agents and cation-sensing devices.

Keywords:

• self-assembly
• ion transport
• cation recognition

Acknowledgements

We thank Doriann de Jesús and Rosa Haddock for technical support during the initial stages of this work and Marilyn García-Arriaga for the preparation of molecular models. MMH thanks NIH-RISE (2 R25 GM61151), Alfred P. Sloan Foundation and PRIDCO, and KCS thanks NIH-MARC (5 T38 GM07821) for financial support.