J. Org. Chem. 1995,60, 4167-4176
4167
Self-AssembledIonophores from Isoguanosine Jeffery T. DavisTt Sampath Tirumala,' James R. Jenssen,t Eric Radler,' and Dan Fabris' Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742 and Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, 5401 Wilkens Avenue, Baltimore, Maryland 21228 Received December 12,1994 (Reuised Manuscript Received April 18, 199.P)
The isoguanosine h o G , mononucleoside 3 forms a CI-symmetrictrtramer in organic solvents. Thr isoC tetramer 6 has been characterized by 2D NMR spectroxopy. lJV spectroscopy, and FAR mass spectrometry. Specilic NOEs hetwem the exocyclic C6N11, amino protons and the ribose H I ' and H2' protons confirmed the isoC self-association and was the basis for thr trtramrr model. Molecular models of isoC dimers, trimers, and tetramers show that only the C,-symmrtric tetramer 6 id consistent with the observed NH6-Hl', H2' NOEs. In the isoG tetramer, hydrogen bonds between CGNH, and a purine N3 bring both exocyclic amino prutons within :
