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Synthesis, Structure, and Properties of Supramolecular Charge-Transfer Complexes between Bis(18-crown-6)stilbene and Ammonioalkyl Derivatives of 4,4′-Bipyridine and 2,7-Diazapyrene

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posted on 19.08.2011, 00:00 by Artem I. Vedernikov, Evgeny N. Ushakov, Asya A. Efremova, Lyudmila G. Kuz’mina, Anna A. Moiseeva, Natalia A. Lobova, Andrei V. Churakov, Yuri A. Strelenko, Michael V. Alfimov, Judith A. K. Howard, Sergey P. Gromov
4,4′-Bipyridine and 2,7-diazapyrene derivatives (A) having two ammonioalkyl N-substituents were synthesized. The complex formation of these compounds with bis(18-crown-6)stilbene (D) was studied by spectrophotometry, cyclic voltammetry, 1H NMR spectroscopy, and X-ray diffraction analysis. In MeCN, π-donor D and π-acceptors A form supramolecular 1:1 (D·A) and 2:1 (D·A·D) charge-transfer complexes. The D·A complexes have a pseudocyclic structure as a result of ditopic binding of the ammonium groups to the crown-ether fragments. The better the geometric matching between the components, the higher the stability of the D·A complexes (log K up to 9.39). A key driving force of the D·A·D complex formation is the excessive steric strain in the precursor D·A complexes. The pseudocyclic D·A complexes involving the ammoniopropyl derivative of 4,4′-bipyridine were obtained as single crystals. Crystallization of the related ammonioethyl derivative was accompanied by transition of the D·A complexes to a structure of the (D·A)m coordination polymer type.