Nor-Seco-Cucurbit[10]uril Exhibits Homotropic Allosterism

Abstract

The condensation of glycoluril and formaldehyde in concentrated HCl at 50 degrees C delivers nor-seco-cucurbit[10]uril (ns-CB [10]). 1H NMR and X-ray crystallographic evidence indicates that the two cavities of ns-CB[10] accommodate guests that are typically bound within CB[6] or CB[7]. Several interesting types of selectivity are possible within these ternary complexes-top/center isomerism, diastereoselective complexation of chiral (but racemic) guest pairs, and guest size controlled homotropic allosterism.

Sequence-Specific, Nanomolar Peptide Binding via Cucurbit[8]uril-Induced Folding and Inclusion of Neighboring Side Chains

“…[11][12][13] Numerous Qn homologues, 14,15 derivatives, [16][17][18][19][20] and acyclic congeners 21 have extended the family to myriad structures and applications. 22 Q8 and its homologue cucurbit [7]uril (Q7) have been shown to bind amino acids, peptides, and proteins, with preference for the aromatic residues tryptophan (Trp), phenylalanine (Phe), and tyrosine (Tyr), especially when located at the N-terminal position in the polypeptide chain.…”

Multivalent Recognition of Peptides by Modular Self-Assembled Receptors

“…While Q5, Q6, and Q7 typically bind one equivalent of organic guest, multiple guests can be accommodated simultaneously by Q8, 6b, 8 Q10, 9 and nor-seco-Q10. 10 Q8 binds to one equivalent of methyl viologen (MV) with an equilibrium association constant (Ka) value of 10 5 -10 6 M -1 , 8a, 11 and the resulting Q8•MV complex can then bind efficiently to electron-rich aromatic guests such as dopamine or tryptophan (Trp). 12 We have previously reported the binding of Q8•MV to Trpcontaining peptides with Ka values in the range 10 3 -10 5 M -1 , depending on the peptide sequence.…”

Self‐Healable Supramolecular Hydrogel Formed by Nor‐Seco‐Cucurbit[10]uril as a Supramolecular Crosslinker

“…[5] However, the recovery of the physical properties of the hydrogel was suppressed over time due to rapid passivation of the exposed ionic surfaces of the hydrogel with otherc ounter ions in an onspecific manner.M aterials crosslinked with specific high-affinity interactions would possess greatlyi mproved self-healing andd urability properties. [6] Cucurbit[n]urils (CB[n], n = 6-8, 10,14), af amily of pumpkinshaped macrocycle hostm olecules, have specific and strong bindinga ffinities to various guest molecules. [7,8] CB [8] accommodates two aromatic moieties (such as methylviologen (MV) and naphthyl( Np) units) in its cavity to form at ernary complex, which hasb een utilized as as upramolecular crosslinker to link MV-a nd Np-conjugated hydrophilic polymers together to form ah ydrogel.…”

“…Thes ynthesis wasc arried out by ao ne-step reactionw ith glycoluril and paraformaldehyde in ac oncentrated HCl solution at 50 8C, and the product wasi solated by recrystallization in acidic aqueous solutions. [14] Interestingly, NS-CB [10] accommodates two guest molecules such as adamantylamine (AdA) or MV in the cavity to form at ernary complex. [15] The binding capacity of NS-CB [10] was utilized to form supramolecular polymers [16] and polymer nanoparticles, [17] demonstratingt he potential use of NS-CB [10] as an oncovalent crosslinker to prepare useful supramolecular materials.…”

“…NS-CB [10] was synthesized following ap revious report. [14] We first examined the formation of ah ydrogel with NS-CB [10] and AdA-4-arm-PEG.Asimple addition of as olution of NS-CB [10] into as olution of AdA-4-arm-PEG (2 equiv.o fA dA moieties on the polymer to the cavityi nN S-CB [10]) provided spontaneous formation of ah ydrogel, then vigorous vortexing allowed it to become am ore rigid hydrogel within am inute (Figure 2). It should be noted that as olutiono fN S-CB [10] was prepared by dissolving it in ah ighly acidic solution (> 2 m HCl) due to its limited solubility in water.A fter forming the hydrogel, HCli n the hydrogel was removedb ye vaporation under reduced pressure until it became af ilm.…”