Two carbazole disulfonamide-diamide macrocycles with semi-flexible meta-xylyl linkages for anion recognition?

New Journal of Chemistry Pub Date: 2022-12-13 DOI: 10.1039/D2NJ04412A

Abstract

Two novel carbazole disulfonamide-diamide macrocycles 1 and 2 with semi-flexible meta-xylyl linkages were designed, synthesized, and assessed for their anion binding properties, via1H NMR and UV-vis titration studies. The single-crystal X-ray diffraction analysis indicated that all five of the NH groups in macrocycle 1 pointed into its inner cavity, with a favorable geometrical conformation for the complexation of anionic guests. The 1H NMR titration results demonstrated that both macrocycles bound strongly and selectively to fluoride ions in DMSO-d6 solution with the affinities in the order of magnitude of 103 M?1 through the formation of 1?:?1 complexes, which was higher than other ten anions tested (including its competitors acetate and dihydrogen phosphate ions). The binding affinities of the two macrocycles were found to follow the order F? ? AcO? > PhCOO? > H2PO4? > Cl? > NO2?/N3?/Br?/HSO4?/NO3?/ClO4? (no measurable binding), which was not in accordance with the basicity order of these anions. In particular, macrocycle 1 containing the pyridine-2,6-diamide moiety displayed a preference for F? over AcO? and H2PO4? (having the selectivity factors of 30 and 182, respectively), which was improved by nearly 3-fold after comparison with those for macrocycle 2 bearing the isophthalamide moiety.

Graphical abstract: Two carbazole disulfonamide-diamide macrocycles with semi-flexible meta-xylyl linkages for anion recognition
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