Exploiting Miraculous Atmospheric CO2 Fixation in the Design of Dysprosium Single-Molecule Magnets

A system of CO3 2–-bridged polynuclear dysprosium complexes has been complemented with the emergence of a key component, namely, [Dy6(μ4-CO3)3­(μ3-OH2)­(spch)6­(MeOH)6­(H2O)3]­·4MeOH­·3H2O (3), and thus four dysprosium­(III) clusters (1–4) spontaneously fixing one, two, three, and four atmospheric CO2 molecules, respectively, have been successfully assembled. Compound 1 is a Dy6 single-molecular magnet (SMM) (1) based on Dy3 triangles, with one CO3 2– group being derived from atmospheric CO2. The incorporation of an ortho-methoxy substituent into the ligand enables access to a double-CO3 2– bridged Dy6 SMM (2), where two CO3 2– groups occupy the two bases of the triangular prism. The trapping of three CO2 molecules of the atmosphere results in the formation of compound 3, where the three CO3 2– groups reside on the lateral faces of a triangular prismoid. Finally, a Dy8 SMM (4) with four CO3 2– bridges on the four lateral faces of the square prismoid can be isolated by converting four CO2 molecules. The magnetic investigations reveal that all four complexes exhibit SMM behavior with a gradual transition from the multiple to single relaxation process observed in their relaxation of the magnetization. This synthetic approach represents an efficient method to develop novel CO3 2–-bridged lanthanide clusters through spontaneous fixation of atmospheric CO2 for magnetic dynamic studies.