Crystal structure of the supramolecular linear polymer formed by the self-assembly of mono-6-deoxy-6-adamantylamide-β-cyclodextrin

Abstract

Mono-6-deoxy-6-adamantylamide-beta-cyclodextrin-dimethylformamide-15H2O, C53H85NO35.C3H7NO.15H2O, crystallizes in the orthorhombic space group P2(1)2(1)2(1). The adamantyl group is inserted into the cyclodextrin cavity of the adjacent molecule, entering by the side of the secondary hydroxy rim, thus forming a supramolecular linear polymer by self-assembly. Adjacent macrocycles are linked into columns by hydrogen bonds involving the nearest glucose residues, and the structure is further stabilized by their involvement in hydrogen bonding with water molecules which reside in channels surrounding the polymer columns, thus acting as bridges between the cyclodextrin units. The centroid of the adamantyl group lies below the plane formed by the seven glycosidic O atoms of the host cyclodextrin, excluding water molecules from the secondary side of beta-cyclodextrin (beta-CD). Between the adamantyl group and the primary hydroxy rim of the cyclodextrin cavity lies a dimethylformamide molecule, which shields the hydrophobic adamantyl group from the primary hydroxy rim of its carrying beta-CD and excludes water molecules from the primary side of the beta-CD cavity.

High‐Relaxivity Magnetic Resonance Imaging (MRI) Contrast Agent Based on Supramolecular Assembly between a Gadolinium Chelate, a Modified Dextran, and Poly‐β‐Cyclodextrin

“…[50,51] Crystal structures of the complexes between adamantyl derivatives and bCD have confirmed the inclusion of this moiety inside the cavity. [52,53] Moreover the bulkiness of the adamantyl groups prevents the formation of large hydrophobic microdomains (as is the case with alkyl tails) and therefore avoids the selfassociation of the contrast agent. [54] DO3A and adamantane were connected through an acetamide spacer, although it is known that in some cases this function is deleterious for the water-exchange-rate parameter.…”

A comprehensive study of the spontaneous formation of nanoassemblies in water by a “lock-and-key” interaction between two associative polymers

“…Values of K very high as 6.1 Â 10 4 M À1 were obtained for the interaction between MD 6.5 (<CAC) and pb-CD (Table 3). These constants are among the highest reported in the literature [39][40][41][42][43][44][45][46]. Examples of high K (10 3 -10 6 M À1 ) mainly concern the interaction between adamantly derivatives and b-CDs [40][41][42][43]45].…”

Bridging β‐Cyclodextrin Prevents Self‐Inclusion, Promotes Supramolecular Polymerization, and Promotes Cooperative Interaction with Nucleic Acids

“…[24] Interestingly,t he classical adamantane/CD host-guest system, [25] which has one of the highest affinity constants,has only seldomly been used in this kind of structures.T his is probably due to the lack of solubility of the resulting conjugate. [26] We have recently synthesized such amolecule,but, although the adamantane is too large to penetrate the CD cavity from the upper rim, the CD-adamantane conjugate was shown to exist in solution exclusively as aself-included species. [27] This was attributed to as o-called "tumbling" phenomenon, which consists of the turnaround of the sugar unit attached to the hydrophobic conjugate,amotion which can then place the attached group inside the cavity of the CD.This underestimated phenomenon is becoming more widely accepted.…”