1229653-82-0Relevant articles and documents
Photocontrolled molecular assembler based on cucurbit[8]uril: [2+2]autophotocycloaddition of styryl dyes in the solid state and in water
Gromov, Sergey P.,Vedernikov, Artem I.,Kuz'Mina, Lyudmila G.,Kondratuk, Dmitry V.,Sazonov, Sergey K.,Strelenko, Yuri A.,Alfimov, Michael V.,Howard, Judith A. K.
, p. 2587 - 2599 (2010)
Three styryl dyes of the 4-pyridine series that form syn-headto-tail dimeric pairs in polycrystalline films were synthesised. NMR and UV/Vis spectroscopic studies showed that this promotes stereospecific [2+2]-autophotocycloaddition (PCA) in the dimeric pairs to give rctt-isomers of cyclobutane derivatives. For the dye with an N-ammoniopropyl substituent, this transformation was accomplished according to the singlecrystal-to-single-crystal pattern. In aqueous solutions, the dyes and cucurbit[n]urils (CB[n], n = 7, 8) form complexes with a pseudorotaxane structure. CB[7] tends to form 1:1 complexes, and CB[8] forms 1:1 and 2:1 complexes. The structure of the termolecular complex formed by the betaine of the N-sulfonatopropyl styryl dye and CB[8] was determined by X-ray diffraction. The stability of the complexes was measured by 1H NMR titration in a D2O/[D3]MeCN (10:1) mixture (logK1:1 ≥ 3.2, logK2:1 ≥ 2.6). Free dyes and their complexes with CB[7] in water undergo only (E)/(Z) photoisomerisation. Termolecular complexes of all dyes with CB[8] were found to undergo effective stereospecific PCA reactions to give rctt isomers of cyclobutane derivatives. The 1:1 complexes of the obtained cyclobutanes with CB[8] (logKcb = 3.2-4.8) are less stable than those of the starting dyes with the same stoichiometry. Thus, CB[8] can play the role of a photocontrolled molecular assembler, i.e., even in the presence of 5 mol-% of CB[8], complete conversion of styryl dyes into the corresponding cyclobutane derivatives takes place upon irradiation in solution.
