New fluorenonocrownophanes containing azobenzene: synthesis, properties and interaction with paraquat

• Published in: Journal of inclusion phenomena and macrocyclic chemistry 2015-04, Vol.81 (3-4), p.499-508
• Main Authors: Lyapunov, Alexander, Kirichenko, Tatiana, Kulygina, Catherine, Zubatyuk, Roman, Fonari, Marina, Kyrychenko, Alexander, Doroshenko, Andrey
• Format: Article
• Language: English
• Subjects: Chemistry; Chemistry and Materials Science; Crystallography and Scattering Methods; Food Science; Organic Chemistry; Original Article
• ISSN: 1388-3127; 1573-1111
• DOI: 10.1007/s10847-015-0484-0

New crownophanes containing 2,7-dioxyfluorenone and 4,4′-azobiphenoxy moieties linked by di-, tri-, tetra-, and pentaethylene glycol residues were synthesized. Just in case of obtaining largest crownophane with pentaethyleneglycol linkers, the dimeric cyclization product was also isolated in low yield. Obtained crownophanes, according to 1 H NMR spectral data exist in conformations with closed intramolecular cavity in solution. Photoinduced E – Z isomerization of crownophane containing triethylene glycol linkers were investigated. The azobenzene fragment inclusion into crownophane reduces the photoisomerization rate compared to model 4,4′-dimethoxyazobenzene. In all the obtained crownophanes according to NMR, UV–Vis and X-ray data 4,4′-azobiphenoxy fragment is in E -configuration in solution as well as in the solid state. Crystal packing of all crownophanes has distinct feature—stacking arrangement of fluorenone moieties probably due to electrostatic dipole–dipole interactions. The formation of pseudorotaxane-type host–guest complexes of these crownophanes with paraquat dication was detected by FABMS and 1 H NMR spectroscopy. UV–Vis spectra show no significant changes upon complex formation.