Ionothermal synthesis, crystal structure, and properties of an anionic two-dimensional cadmium metal organic framework based on paddle wheel-like cluster

We report on the ionothermal synthesis of a novel two-dimensional (2D) cadmium metal organic framework, namely, [Emim][CdBr(1,4-NDC)] (1) (Emim = 1-ethyl-3-methylimidazolium, 1,4-NDCH2 = 1,4-naphthalenedicarboxylic acid) using an ionic liquid (IL) [Emim]BF4 or mixed ILs of [Emim]BF4 and [Emim]Br both as solvent and template. Single-crystal X-ray diffraction reveals that the structure features an anionic two-dimensional network based on the paddle wheel-like cluster. The imidazolium cations acting as charge compensating agent intercalate into the interlayer spaces. The current result is the first example of ionothermal synthesis of 1,4-NDC based metal organic framework. The thermal and photoluminescent properties have also been investigated.