Crystal Engineering and Self-Assembled Nanoring Formation with Purine-Cd II /Hg II Supramolecular Frameworks.

We report three complexes of Cd II and Hg II with two purine rare tautomers, N9-(pyridin-2-ylmethyl)-N 6 -methoxyadenine, L1 and N7-(pyridin-2-ylmethyl)-N 6 -methoxyadenine, L2, highlighting diverse crystallographic signatures exhibited by them. Influence of substituents, binding sites, steric effects and metal salts on the different modes of binding enabled an insight into metal-nucleobase interactions. L1 interacted with two and three equivalents of Cd(NO 3 ) 2 .4H 2 O and HgCl 2 , respectively, while L2 interacted with two equivalents of HgCl 2 , altogether leading to three different complexes (1 [C 48 H 48 Cd 6 N 34 O 50 ], 2 [C 12 H 12 Cl 4 Hg 2 N 6 O] and 3 [C 12 H 12 Cl 2 HgN 6 O]) possessing varied dimensionality and stabilising interactions. The photoluminescent properties of these coordination frameworks have also been probed. Notably, nanoring-like structures were obtained, as a result of self-assembly of 3 when investigated by transmission electron microscopy, additionally supported by molecular dynamics simulations.