Abstract:
Supramolecular systems hold great potential as ferroelectric materials because they are easy to prepare and do not require toxic and environmentally damaging elements. However, directing the self‐assembly process of a supramolecular array to yield polarizable solids is still challenging. Here, we describe induced ferroelectricity in a supramolecular framework of metal‐organic cages that are supported by a flexible tripodal ligand (NHCH2‐(3‐Py))3PO (TPPA). Ferroelectric responses on the discrete cage [Cu6(H2O)12(TPPA)8](NO3)12 ⋅ 45H2O (1) and its 2D‐connected framework [{Cu6Cl4(H2O)6(TPPA)8}(NO3)8 ⋅ 60H2O]n (2) yielded well‐resolved rectangular hysteresis loops at room temperature with remnant polarization values of 27.27 and 29.09 μC/cm2, respectively. Thermal hysteresis measurements (THM) and capacitance‐voltage (C−V) plots further corroborate the ferroelectric behavior in these compounds. The polarization in them is due to the displacements of solvated molecules and nitrate ions in the pockets of these frameworks.