Coordination site discrimination in substituted bioessential purine ligands

1041-1046The synthesis and crystallographic investigations of N6 and/or N9 substituted adenine analogues with coinage metal ions are described. While N6 disubstitution in an N9-unsubstituted adenine unit results in N3,N9-bidentate coordination mode resulting in a dinuclear motif, further substitution at N9 position directs the incoming metal to get coordinated at N3 position. However, N6,N9-monosubstituted adenine derivative, which relieves some steric hindrance at N6, allows for N7 coordination of copper ions