Functionalized Chiral Bambusurils: Synthesis and Host‐Guest Interactions with Chiral Carboxylates

Abstract

Bambusurils are a class of macrocyclic anion receptors that exhibit notable anion recognition properties, able to bind various inorganic anions as well the carboxylates or sulfonates. Recently, we reported enantioselective recognition of chiral carboxylates using non‐functionalized chiral bambusuril derivatives. Herein, we report the synthesis and host‐guest properties of two new representatives of chiral bambusuril macrocycles bearing ester functional groups, differing by the substituents attached to their portals. Their supramolecular properties in terms of carboxylate binding were studied by means of NMR in DMSO‐d6. The reported bambusurils bind selected chiral carboxylates with enantioselectivity factors up to 3.1. The results indicated that the selectivity towards different carboxylates is governed by the steric constraint of the substituents surrounding bambusuril portals. No clear trend in the binding affinities and their enantioselectivities was found.

Monofunctionalized Fluorinated Bambusurils and Their Conjugates for Anion Transport and Extraction

“…During the following years, different reaction conditions for the preparation of bambusurils were investigated, including the use of various organic solvents and applying conventional as well as microwave heating. , The majority of the bambusurils reported so far consist of six identical 2,4-disubstituted glycoluril units. Exceptions are semithio- and semiaza-bambusurils, made of 3-thio- and 3-azaglycolurils, − and chiral bambusurils, having different substituents in the 2,4-positions of the glycolurils. − Moreover, recently, we reported the synthesis of the first monofunctionalized bambusuril using a statistically driven condensation of two different glycolurils . Bambusuril properties such as solubility, lipophilicity, and binding affinity toward anions could be significantly influenced by the type of substituents on their portals.…”

Advances in Chirality Sensing with Macrocyclic Molecules

“…However, the chiral recognition by 1 H NMR spectral studies could not be easily achieved because the host-guest binding does not change the macrocycle proton signal. Later, the authors introduced ester groups into glycolurils [53] to produce the ester functionalized 37 and 38 (Figure 14), which could affect binding preference by changing the spatial constraints of substituents.…”

Cyclohexanohemicucurbit[8]uril forms inclusion complexes with heterocycles and removes sulfuric guests from water via solid-phase extraction

“…Hemicucurbiturils formed in templated single step oligomerization reactions, 18 are single-bridged cucurbituril-type macrocycles [19][20][21] that bear an electron-deficient hydrophobic cavity. The latter grants these macrocycles the ability to encapsulate anions, 19,18,[21][22][23][24][25][26][27][28][29][30][31][32] , and also the formation of complexes with acids and some neutral species has been reported. In particular, unsubstituted hemicucurbit[n]urils (n = 6, 12) bind phenol derivatives 33,34 and ferrocene, 35 and cyclohexanohemicucurbit [n]urils (cycHC[n]) (n = 6, 8, 12) 36-40 form external complexes with inorganic and organic acids.…”