Synthesis and Dynamic Behavior of Ce(IV) Double-Decker Complexes of Sterically Hindered Phthalocyanines

Jeevithra Dewi Subramaniam (1) , Toshio Nishino (1) , Kazuma Yasuhara (1) , Gwénaël Rapenne (2, 3)

1 Nara Institute of Science and Technology
2 NAIST - Nara Institute of Science and Technology - Graduate School of Information Science
3 CEMES-GNS - Groupe NanoSciences

Phthalocyanines and their double-decker complexes are interesting in designing rotative molecular machines, which are crucial for the development of molecular motors and gears. This study explores the design and synthesis of three bulky phthalocyanine ligands functionalized at the α-positions with phenothiazine or carbazole fragments, aiming to investigate dynamic rotational motions in these sterically hindered molecular complexes. Homoleptic and heteroleptic double-decker complexes were synthesized through the complexation of these ligands with Ce(IV). Notably, Ce$^{IV}$(Pc2)$_2$ and Ce$^{IV}$(Pc3)$_2$, both homoleptic complexes, exhibited blocked rotational motions even at high temperatures. The heteroleptic Ce$^{IV}$(Pc)(Pc3) complex, designed to lower symmetry, demonstrated switchable rotation along the pseudo-C4 symmetry axis upon heating the solution. Variable-temperature 1H-NMR studies revealed distinct dynamic behaviors in these complexes. This study provides insights into the rotational dynamics of sterically hindered double-decker complexes, paving the way for their use in the field of rotative molecular machines.

Mots clés: double-decker complex; homoleptic; heteroleptic; cerium ion; ligand rotation; phthalocyanine; carbazole; phenothiazine

Domaines: Chimie de coordination

Jeevithra Dewi Subramaniam, Toshio Nishino, Kazuma Yasuhara, Gwénaël Rapenne. Synthesis and Dynamic Behavior of Ce(IV) Double-Decker Complexes of Sterically Hindered Phthalocyanines. Molecules, 2024, 29 (4), pp.888. ⟨10.3390/molecules29040888⟩. ⟨hal-04636062⟩