N-Donor Functionalized Acetylacetones for Heterobimetallic MOFs, the Next Episode: Trimethylpyrazoles

While metal-organic frameworks (MOFs) have been investigated intensively throughout the last decades, only a fraction of the published articles on MOFs feature heterobimetallic structures. Combining two metallic centers in a rigid framework could lead to interesting effects, such as magnetic coupling, collaborating fluorescence or catalytic properties; however, its synthesis is more sophisticated than for monometallic MOFs. We utilize ditopic ligands which coordination sites differ in their Pearson hardness (HSAB). This enables a stepwise selective formation of heterobimetallic MOFs: first, a monometallic building block is synthesized. In a second step the framework can be achieved by crosslinking with a second metal ion. In this work we present our newest ligand as a candidate for this purpose: 3-(1,3,5-trimethyl-1H-pyrazol-4-yl)acetylacetone. Its synthesis is straightforward and inexpensive. The O,O’ coordination was accomplished with a variety of hard cations like Fe(III) or Ga(III). First crosslinking attempts with N coordination of the Fe(III) building block to Ag(I) lead to a one-dimensional coordination polymer with high porosity.