Supramolecular assemblies and redox modulation of pyromellitic diimide-based cyclophane via noncovalent interactions with naphthol.

This paper reports the electroscopic and electrochemical properties of [2 + 2] pyromellitic diimide-based cyclophane 1 as well as acyclic N,N‘-bis(2-methoxybenzyl)pyromellitic diimide 2 and the clathrate compounds formed by 1. Compound 1 was synthesized by direct cyclocondensation. Its structure was determined by an X-ray crystallographic analysis of a single crystal obtained by recrystallization from DMF. The intramolecular charge-transfer interactions of 1 and 2 were characterized by UV/vis spectroscopy and MO calculations. The UV/vis spectra showed that the tail of a longer wavelength absorption of both 1 and 2 reached the visible region. MO calculations (B3LYP/6-31G*) showed that the HOMO and LUMO orbitals of 1 and 2 substantially localize in the xylyl and pyromellitic diimide moieties across the methylene linker, respectively. The X-ray crystallographic analyses demonstrated that single crystals grown from a mixture of 1 and α-naphthol and a mixture of 1 and β-naphthol were the clathrate compounds wi...