Four-Stranded Coordination Helices Containing Silver−Adenine (Purine) Metallaquartets

This Communication describes structures of a family of silver−adenine (purine) metallaquartets that occur in a four-stranded coor-dination motif, bearing a close resemblance to nucleic acid quadru-plexes. Using modified purine frameworks, it is further demonstrated
that subtle variations in nucleobase heterocycle are tolerable and
a metallaquartet is obtained irrespective of the substitution, thus
suggesting a high-propensity silver−adenine interaction to achieve
quartet structures. All of the solid-state structures studied were
orthorhombic, belonging to the Fdd2 space group.