DETECTION OF HYDROGEN-BONDED ADENINE-THYMINE BASE-PAIR COMPLEXES BY ELECTROSPRAY MASS-SPECTROMETRY

Bibracchial lariat ether compounds having three-carbon sidearms termin ated in either adenine or thymine have the potential to form a molecul ar box in which the ''ends'' are crown ethers and the ''sides'' are hy drogen-bonded base pairs. Previous solution studies relying upon NMR a nd vapor pressure osmometry confirmed the formation of complexes. In t he present study, four diaza-18-crown-6 derivatives having either one or two sidearms each terminated in either adenine or thymine have been studied in a mixture of CHCl3 and CH3OH. Either acetic acid or sodium chloride was added to the solutions. For the two-armed systems, the p referred complex was the dimer involving adenines on one monomer and t hymines on the other. Homodimers and other complexes sere detected as well, The preferred single-armed complex was that occurring between th e monomer whose sidearm was terminated in thymine and either H+ or Na.