Carbazole sulfonamide-based macrocyclic receptors capable of selective complexation of fluoride ion

Abstract

Two carbazole sulfonamide-based macrocycles 1 and 2 were facilely synthesized and carefully evaluated for their anion recognition properties.

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

“…[1][2][3] Among common anions, the fluoride ion is of particular importance due to its beneficial effects on human health at low doses and its adverse effects at high doses. [4][5][6] However, only a very limited number of anion receptors [7][8][9][10][11][12][13][14][15][16] capable of highly selective binding of fluoride over its competing anions (such as acetate and dihydrogenphosphate ions, which have a similar basicity to fluoride 17,18 ) have been reported so far, excluding some special examples of reaction-based fluoride detection. In addition, the preparation of such fluoride-selective receptors is generally time-consuming, costly, and cumbersome.…”

“…On the other hand, the skeleton of carbazole-1,8-disulfonamides has unique advantages as an ideal molecular platform for developing anion receptors, 16,[19][20][21][22][23] based on the following reasons: firstly, carbazole NH itself and its two adjacent sulfonamide NHs can easily work together to facilitate anion binding via three convergent N-H hydrogen bond donors. Secondly, compared with the most-commonly used amide group, its analogous sulfonamide group has a more acidic NH proton and is thus a better hydrogen bond donor.…”

“…24,25 Thirdly, it is easy to introduce various functional groups into the carbazole backbone for tuning its anion binding properties. 26 As part of our continuing interest in the development of carbazole 1,8-sulfonamide-based anion receptors/sensors, 16,[20][21][22] we have recently synthesized two carbazole disulfonamidediamide macrocyclic receptors with rigid meta-phenylene spacers and have studied their anion binding properties in DMSO-d 6 solution. 27 The experimental results revealed that it was difficult to leverage all the available NH groups in the macrocycles to complex the examined anions (except for spherical Cl À ), probably due to the existing structural rigidity of these macrocycles.…”

A Carbazole-1,8-Disulfonamide-Derived Cryptand Receptor for Anion Recognition

“…So far, a limited number of anion receptors employing the carbazole-1,8-disulfonamide moiety as the binding motif have been reported by others and us. − Clearly, all of these receptors can be categorized into cleft-shaped or cyclic geometries. To the best of our knowledge, the development of cryptand-like anion receptors based on the carbazole-1,8-disulfonamide moiety is still unprecedented.…”