Lanthanide (III) Metal-Organic Frameworks: Syntheses, Structures and Supercapacitor Application

Three new lanthanide-MOFs, [(TATMB)(2)Ce-2 center dot 3DMSO-H2O] center dot 7H(2)O (MOF-Ce), [(TATMB)(2)Pr-2 center dot 4DMSO] center dot 7H(2)O center dot DMF (MOF-Pr) and [(TATMB)(2)Nd-2 center dot 3DMSO center dot H2O] center dot 6H(2)O (MOF-Nd) were synthesized by the reaction of hydrated lanthanide salts and 3,3 ',3 ''-((1,3,5-triazine-2,4,6-triyl)tris(azanediyl))tribenzoic acid (H(3)TATMB) under solvothermal reaction condition. All MOFs were characterized by standard instrumentation techniques, for example, FT-IR spectroscopy, elemental analysis, etc. The solid-state structures were determined by single-crystal X-ray diffraction analyses. It revealed that all MOFs formed two-dimensional frameworks by the coordination assisted pathway of ligand molecules and lanthanide(III) ions. All MOFs were investigated as supercapacitor electrode material by using the conventional three-electrode method by using TEABF(4) in acetonitrile as electrolyte. It was observed that MOF-Ce exhibited a maximum specific capacitance of 572 Fg(-1) at a current density of 1 A g(-1) among all three MOFs. The specific capacitance retention of the material was found to be 81% after successful completion of 5000 charging-discharging cycles. To the best of our knowledge, the specific capacitance of MOF-Ce is highest reported for lanthanide MOFs without any redox-active additive until now. Moreover, for the first time, MOF-Ce has been used to fabricate a device, which exhibited significant responses for various LED lights and showed a maximum specific capacitance of 88 Fg(-1) at a current density of 2 A g(-1).