Straightforward Synthesis of Single-Crystalline and Redox-Active Cr(II)-carboxylate MOFs.

We report on a facile and environmentally friendly synthetic approach for single-crystalline chromium(II) carboxylate metal-organic frameworks (i.e., Cr3(BTC)2·3H2O (1) and Cr(hfipbb)·H2O (2) at room temperature in water. Both MOFs can be easily dehydrated, affording single-crystalline materials with open Cr(II) sites. In addition, the redox activity and porosity of the resulting Cr(II) MOFs were examined.