An unprecedented (4,24)-connected metal–organic framework sustained by nanosized Ag12 cuboctahedral node

Abstract

A novel 3D metal–organic framework (MOF), namely [Ag₁₂(MA)₈(mal)₆·18H₂O]_n (1), (MA = melamine, H₂mal = malonic acid) has been successfully synthesized through one-pot ultrasonic reaction of AgNO₃, MA and H₂mal and characterized by elemental analysis, IR spectroscopy, and X-ray single-crystal diffraction. In 1, eight tridentate MA ligands coordinate to 12 Ag(I) ions to form a nanosized Ag₁₂ cuboctahedron with an interior diameter of 1.2 nm, which combines with the quadridentate mal anion to give 1. This is a complicated 3D MOF, which is an unprecedented (4,24)-connected net with rare twf topology when using the Ag₁₂ cage and mal as 24- and 4-connected nodes, respectively. Of particular importance, the unusual network topology and integrity of the framework of 1 after dehydration have also been validated and discussed in detail.