Development and Functions of Dynamic Supramolecular Systems Coupled with Electronic Systems for Energy Conversion

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In this project, we aim at the developments of novel molecular systems based on molecular conductors and magnets with supramolecular cations having dynamic feature. As for the building blocks for molecular conductors and magnets, we are using [Ni (dmit) 2] and other metal complexes. Suplamoleclar structures based on crown ethers are combined with the complexes to form novel molecular systems. In this study, we mainly examined molecular rotator structures of organic ammonium and [18]crown-6 derivatives in [Ni (dmit) 2] salts.We introduced -NH2 at o-position of the anilinium and synthesized (HOPD)+([18]crown-6) [Ni (dmit) 2] crystals. Strong dipole-dipole interaction induced the tight packing of cation layers, which prevented flip-flop motion of aryl rings. On the other hand, [18]crown-6 was rotating in the crystal as in the case of (PhNH3) ([18] crown-6) (Ni (dmit) 2).We introduced -F and -NH2 at m-position of the anilinium and synthesized (HMFA)+(dibenzo[18]crown-6) [Ni (dmit) 2] and (HMPD)+(dibenzo [18] crown-6) [Ni (dmi1) 2] crystals. HMFA and HMPD salts gave the same composition and crystal structures.Since HMFA and HMPD have dipole moments, it was possible to control the flip-flop motion of these molecular rotators by applying external electric field. It was proved that the crystal was the ferroelectrics with the Curie temperature of at around 350 K. Adamantylammonium was introduced in the supuramolecular structure instead of arylammonium derivatives. In the crystals, the rotation of adamantly group was maintained below 120 K, which was confirmed by 1H-NMR measurements.In conclusion, we introduced supramolecular rotator structures in electronic active crystals, which is one of the key steps to realize highly efficient energy conversion systems. In addition, we could develop novel ferroelectrics based on molecular rotator structures.