Assembly of a non-centrosymmetric molecular ferroelectric Cu(II) complex from a chiral pybox ligand: applications in energy harvesting.

Molecular ferroelectric materials have garnered profound interest in the last two decades owing to their structural flexibility, tunability, and homochirality, enabling a variety of technological applications. Achieving polar point groups through rational molecular design is crucial for discovering new molecular ferroelectrics. Herein, we report a mononuclear Cu(II) complex, [Cu((S,S)-L)(NO3)(CH3OH)]·NO3 (1), where (S,S)-L = 2,6-bis((S)-4-isopropyl-5,5-diphenyl-4,5-dihydrooxazol-2-yl)pyridine, synthesised using a chiral (S,S)-L ligand bearing two chiral carbon centers. 1 crystallises in the polar monoclinic P21 space group and shows ferroelectric behaviour, characterized by a P-E hysteresis loop with a remanent polarization of 0.92 μC cm-2. Piezoelectric energy harvesting using its thermoplastic polyurethane (TPU) composites gives a maximum output voltage of 13.4 V, which was further used to charge a 10 μF capacitor within 90 seconds.