SUPRAMOLECULAR CHEMISTRY .68. NUCLEOTIDE COMPLEXES WITH AZONIACYCLOPHANES CONTAINING PHENYL-UNIT, BIPHENYL-UNIT OR BIPYRIDYL-UNIT

Three cyclophanes (1-3) with p-phenyl, p-biphenyl- and m-bipyridyl spa cers between diethylenetriamine units are studied by NMR titrations in water (D2O) with naturally occurring mononucleotides in the form of m onophosphates. The biphenyl host 1 shows association constants K (in m ol dm(-3) units) of 2200 with AMP5', 1270 with the isomeric AMP3', and smaller constants with G, C and U derivatives. An exception is GMP5' with 3, which in contrast to most host compounds shows a four-fold str onger binding than AMP5'. Thymidine (TMP5') is complexed with K = 2050 dm(3) mol(-1); the intracavity immersion of the T methyl substituent is visible also in the observed upheld NMR shifts. With the smaller ho sts 2 and 3, constants of approximately 100-200 dm(3) mol(-1) are obse rved, indicating essentially salt bridge contributions. Structural con clusions are supported by the observed NMR shieldings and by selected molecular mechanics calculations.