Synthesis and rotational dynamics of diazamacrocycles having bridged 1,4-naphthylene as framed molecular rotors

• Published in: Organic & biomolecular chemistry Vol. 2; no. 43; pp. 8465 - 847
• Main Authors: Kurimoto, Taichi, Inagaki, Yusuke, Ohara, Kazuaki, Yamaguchi, Kentaro, Setaka, Wataru
• Format: Journal Article
• Language: English
• Published: CAMBRIDGE Royal Soc Chemistry 09.11.2022; Royal Society of Chemistry
• Subjects: Chains; Chemistry; Chemistry, Organic; Coalescence; Magnetic Resonance Spectroscopy; NMR; Nuclear magnetic resonance; Physical Sciences; Rotation; Rotors; Science & Technology; Sodium carbonate; Temperature; Temperature dependence; GYROTOPS; CAGE
• DOI: 10.1039/d2ob01613c
• ISSN: 1477-0520

The rotation of a part of a molecule has attracted attention because of its possible role in the development of an artificial molecular rotor. In this study, 1,4-naphthylene bridged diazamacrocycles, in which the 1,4-diaminonaphthalene moiety is bridged by two long alkyl chains, were designed as novel framed molecular rotors, and the dependence of the rotation on the frame size were investigated. Framed rotors C n Np ( n = 12, 14, 16, 18), where the number in the compound name indicates the length of a side chain, were synthesized by direct cyclization of 1,4-naphthalenediamine with α,ω-dihaloalkane in the presence of Na 2 CO 3 as the base. The rotation of the naphthylene rotor in C12Np , C14Np , and C16Np was nearly suppressed in solution, whereas the rotor in C18Np showed rotation, as confirmed by the temperature-dependent coalescence of the NMR signals of the α-CH 2 . 1,4-Naphthylene bridged diazamacrocycles were synthesized and characterized as novel framed molecular rotors, and dependence of the rotation on the frame size was investigated.