Inclusion excluded: Chiroptical sensing of the external surface of sulfated cyclodextrins

Abstract

It is shown that the heparin antagonist bis-aminoquinoline derivative surfen interacts with sulfated cyclodextrins in a unique fashion. Analysis of the UV spectroscopic data revealed exceptionally strong association (K a ~ 10 7 M -1 ) of several surfen molecules to the external surface of the cyclodextrin hosts. H-bonded to the sulfate groups in 1:1 stoichiometry, the drug molecules form a chiral layer around the macrocycles. Due to the steric proximity, dipole-dipole coupling occurs between the adjacent aminoquinoline rings that accounts for the large UV hypochromism and the induced exciton couplet in the circular dichroism spectra.

Glycosaminoglycans are potential pharmacological targets for classic DNA minor groove binder drugs berenil and pentamidine

“…These CD and absorption spectroscopic features are characteristic to the intermolecular exciton coupling between the long axis polarized π-π * transition moments of berenil molecules accommodated close to each other along the heparin chain. 14,15 Chiral disposition of the drug molecules are dictated by the helically arranged sulphate/carboxylate groups to which they are attached via ionic and/or H-bonds.…”

“…These CD and absorption spectroscopic features are characteristic for intermolecular exciton coupling between the long axis polarized p-p* transition moments of berenil molecules accommodated close to each other along the heparin chain. 14,15 The chiral disposition of the drug molecules is dictated by the helically arranged sulphate/ carboxylate groups to which they are attached via ionic and/or H-bonds. Employing the exciton coupling theory, 16,17 the positivenegative CD signature predicts right-handed (P-helical) intermolecular orientation of the long axes of the adjacent drug molecules bound consecutively to the anionic sites of the asymmetric heparin template (Fig.…”

“…19 In comparison to berenil, the heparin affinity of surfen is ten times higher (B10 7 M À1 ) that may be related to its ability to adopt a crescent-shaped conformation, where the two amino groups can form multiple H-bonds with sulfate substituents of the heparin template. 14…”

Enabling Stereochemical Communication and Stimuli‐Responsive Chiroptical Properties in Biphenyl‐Capped Cyclodextrins

“…[6] Despite the presence of numerous stereogenic centers, their conformational rigidity combined with a high degree of symmetry makes the stereodifferentiation of prochiral entities challenging. [5] Nevertheless, in recent years, some CD-based chiral functional materials have been successfully developed, and they can be classified as follows: 1) CD host-guest complexes with encapsulated organic chromophores, [7][8][9][10][11][12][13][14] 2) spatial confinement of two or more pyrene units covalently installed on a CD scaffold resulting in the formation of chiral excimers, [15][16][17][18] 3) hexaphyrin-CD hybrids with rich and dynamic behavior. [19][20][21][22] While some of these strategies have yielded promising results with well-rationalized spectroscopic properties, others involve complex syntheses, and the mechanisms of chirality transfer to the chromophore are unclear and difficult to explain.…”