Providing evidence for the requirements to achieve supramolecular materials based on metal–nucleobase entities

Abstract

Nucleobases are known as suitable builders of porous materials not only due to their high number of heteroatoms leading to different coordination modes, but also because they establish strong and predictable supramolecular interactions. In this contribution, nucleobases (adenine and guanine), functionalized nucleobases (9-methyladenine) and nucleobase derivatives (6-chloropurine) have been evaluated as ligands for the construction of metal–nucleobase building blocks which can afford supramolecular porous materials, analyzing in detail the requirements that these entities must fulfill and pointing out the relevance of accomplishing the suggested requisites. More concisely, we have evaluated a paddle-wheel shaped dimeric entity, [Cu₂(μ-Hade)₄Cl₂]Cl₂·8H₂O (1) (where Hade: adenine), a trimeric unit, [Co₃(μ-Hade)₂(μ-Cl)₄Cl₂(H₂O)₄]·2H₂O (2), a dimeric entity, [Cu₂(Hgua)₂(H₂gua)₂(μ-Cl)₂Cl₂(H₂O)][CuCl₄] (3) (where Hgua: guanine, H₂gua: guaninium), a monomeric unit with 9-methyladenine as the pendant ligand, [Co(9-Meade)₂(H₂O)₄]Cl₂·2H₂O (4), zigzag chains, [Cu₂(μ-CH₃COO)₄(μ-9-Meade)]_n·nCH₃OH (5), and a monomeric unit with 6-chloropurinato ligands, [Co(6-Clpur)₂(H₂O)₄]·4H₂O (6).