This paper presents synthesis and crystallographic investigations of certain cobalt complexes of N9-functionalized mono-and bis-adenine analogues, containing a carboxylic group pendant. These observations were meant to expand the coordination space provided by an unmodified adenine moiety, based on known interactions between cobalt and carboxylate functional group, and to examine the structural consequences. A bisadenine analogue, when compared to the mono-functionalized adenine nucleobase, invokes N7 coordination, in addition to the carboxylate groups, thus supporting formation of complex three-dimensional structures. This study permits entry into novel cobaltbased metallacyclic complexes containing adenine nucleobase as the coordinating N-ligand. © 2011 American Chemical Society.