Bis(oxofluorenediyl)oxacyclophanes: Synthesis, crystal structure and complexation with paraquat in the gas phase
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LUKYANENKO, Nikolay, KIRICHENKO, Tatiana, LYAPUNOV, Alexander, MAZEPA, Aleksandr, SIMONOV, Yurii A., FONARI, Marina, BOTOSHANSKY, Mark. Bis(oxofluorenediyl)oxacyclophanes: Synthesis, crystal structure and complexation with paraquat in the gas phase. In: Chemistry - A European Journal, 2005, vol. 11, pp. 262-270. ISSN 0947-6539. DOI: https://doi.org/10.1002/chem.200400870
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Chemistry - A European Journal
Volumul 11 / 2005 / ISSN 0947-6539

Bis(oxofluorenediyl)oxacyclophanes: Synthesis, crystal structure and complexation with paraquat in the gas phase

DOI:https://doi.org/10.1002/chem.200400870

Pag. 262-270

Lukyanenko Nikolay1, Kirichenko Tatiana1, Lyapunov Alexander1, Mazepa Aleksandr1, Simonov Yurii A.2, Fonari Marina2, Botoshansky Mark3
 
1 A.V. Bogatsky Physico-Chemical Institute of the NAS of Ukraine,
2 Institute of Applied Physics, Academy of Sciences of Moldova,
3 Technion-Israel Institute of Technology
 
 
Disponibil în IBN: 19 iulie 2023


Rezumat

The first three representatives of the new family of oxacyclophanes incorporating two 2,7-dioxyfluorenone fragments, connected by [-CH 2CH2O-]m spacers (m=2-4), have been synthesized. The yield of the smallest oxacyclophane (m = 2) is considerably higher with respect to the larger ones (m = 3 and m = 4), which are formed in comparable yields. Molecular modeling and NMR spectra analysis of the model compounds suggest that an essential difference in oxacyclophanes yields is caused by formation of quasi-cyclic intermediates, which are preorganized for macrocyclization owing to intramolecular π-π stacking interactions between the fluorenone units. The solid-state structures of these oxacyclophanes exhibit intra- and intermolecular π-π stacking interactions that dictate their rectangular shape in the fluorenone backbone and crystal packing of the molecules with the parallel or T-shape arrangement. The crystal packing in all cases is also sustained by weak C-H⋯O hydrogen bonds. FAB mass spectral analysis of mixtures of the larger oxacyclophanes (m = 3 and m = 4) and a paraquat moiety revealed peaks corresponding to the loss of one and two PF 6- counterions from the 1:1 complexes formed. However, no signals were observed for complexes of the paraquat moiety with the smaller oxacyclophane (m=2). Computer molecular modeling of complexes revealed a pseudorotaxane-like incorporation of the paraquat unit, sandwiched within a macrocyclic cavity between the almost parallel-aligned fluorenone rings of the larger oxacyclophanes (m = 3 and m = 4). In contrast to this, only external complexes of the smallest oxacyclophane (m = 2) with a paraquat unit have been found in the energy window of 10 kcal mol-1.

Cuvinte-cheie
Crown compounds cyclophanes, Fluorenones, Host-guest systems, Macrocycles