Unravelling binding effects in cyclodextrin inclusion complexes with diamondoid ammonium salt guests

Abstract

With an ever-growing application of inclusion complexes of cyclodextrins (CDs) and other hydrophobic guests in pharmaceutical industry and other scientific and industrial fields, the demand for deeper understanding of effects...

Hosting of diamantane alcohols in water and hydrogen-bonded organic solvents: the (non-)classical hydrophobic effect

“…As far as cyclodextrins are concerned, β-CD is more compatible with adamantane-based guests, whereas γ-CD prefers the larger diamantane derivatives. 38,40,48,49 Somewhat surprisingly, both β- and γ-CD did not bind the permethylated 4,9-diammonium diamantane derivative 40 for which the octameric, and particularly, the heptameric cucurbiturils exhibited especially high affinity. 33,47…”

“…Strong hydration of the directly attached charged functionality usually reduces the inclusion depth of hydrophobic subunits within these receptors, thus lowering the guest binding affinity. 21,39–43…”

“…Strong hydration of the directly attached charged functionality usually reduces the inclusion depth of hydrophobic subunits within these receptors, thus lowering the guest binding affinity. 21,[39][40][41][42][43] Rigid diamantanes 44,45 seem to be almost custom-tailored for constrained, barrel-shaped cavities of CB[n]s. This fact, combined with peculiar hydration of the host cavities and the guest, leads to remarkable complex stability in water. For example, log K Z 7 for hosting of neutral diamantane-based guests with both CB [7] and CB [8] has been reported.…”

Overcoming barriers with non-covalent interactions: supramolecular recognition of adamantyl cucurbit[n]uril assemblies for medical applications

“…26 Going from our own experience, adamantane and similar cage compounds have demonstrated an amazing versatility and can serve as a backbone in various cation [27][28][29][30][31][32][33][34] and anion receptors [35][36][37][38][39][40][41][42][43][44] as well as being desirable guest molecules in inclusion complexes. [45][46][47][48][49][50][51] While in macrocyclic receptors the adamantane cage usually serves as a rigid backbone that reduces the conformational mobility of a macrocycle and thus pre-organizes the receptor molecule for binding, in the inclusion complexes the role of adamantane is primarily limited to enabling preferential binding of the polycyclic subunit into a host molecules. Exactly this host-guest behavior of adamantane derivatives will be the focus of our continued discussion, as it provides a useful tool for recognition in biological systems.…”

“…It is known that adamantane derivatives excellently bind to a β-cyclodextrin host and afford stable 1 : 1 inclusion complexes, with association constants typically between 10 3 -10 5 M −1 . 24,50,[52][53][54][55][56][57] Cyclodextrins (CDs) are macrocycles consisting of glucose monomers and are widely used in drug delivery since they are water-soluble, naturally occurring, cheap, and able to bind a wide range of substrates. 58 Important to note is that cyclodextrins have a well-defined central hydrophobic cavity that is crucial for successful adamantane incorporation and formation of a strong inclusion complex.…”