Solvent-induced SC-SC transformation between 3D and 1D Co-MOFs: Fluorescence sensing and magnetic properties

By utilizing an aromatic π-conjugated organic ligand as a linker, we successfully synthesized two new coordination complexes, namely, a three-dimensional framework (3D) [Co(DCPA)(DMA)(H₂O)] (Co-MOF-1) and a one-dimensional chain (1D) [Co(DCPA)(H₂O)₄]·4H₂O (Co-MOF-2) (DCPA = 9, 10-di (p-carboxyphenyl) anthracene). Both complexes were determined by single crystal X-ray diffraction analysis, Thermogravimetric analysis, PXRD, XPS, UV–vis and IR spectrum, etc. Interestingly, the reversibly single-crystal-to-single-crystal (SC-SC) structural transformation between the 3D framework and 1D chain structures could be achieved successfully by controlling the stimulation of external temperature and solvent. Besides, a series of fluorescence sensing experiments were carried out for Co-MOF-1, demonstrating excellent selective and sensitive “turn-on” towards Al³⁺, Cr³⁺, Amoxicillin (AMX), and 4,5-Imidazoledicarbonitrile (DCI), especially Al³⁺ and AMX. Moreover, the detection mechanism was also further investigated. In addition, the magnetic studies indicated that Co-MOF-1 and Co-MOF-2 have weak antiferromagnetic interaction. The current research elucidates different structural variations exhibited by cobalt-containing compounds in extended framework architectures and properties.