Chiral Bambusurils for Enantioselective Recognition of Carboxylate Anion Guests

Abstract

Synthesis of the first enantiomerically pure chiral bambusurils is reported. The bambusurils were prepared on the gram scale without using any chromatography techniques. The bambusurils formed supramolecular complexes with all tested chiral carboxylates including amino acids and drug molecules with the enantioselectivity ranging from 1.1 to 3.2.

Formation and trapping of the thermodynamically unfavoured inverted-hemicucurbit[6]uril

“…Following the protons that point inside and outside of the cavity of macrocycle (see SI, Figure S18), confirms that external complexes with fast exchange on the NMR time scale are formed. Previously, 1:1 and 1:2 binding of carboxylic acids and carboxylates have also been studied for other single-bridged cucurbiturils, the bambus[6]urils 40,54,55 .…”

Bambusuril Macrocycles as Mediators of Supramolecular Interactions: Application to the Europium Cage Helicate

“…The bambusuril molecules used in this study ( BU C , Figure 1 b) have been synthetized recently [12a] . The chirality of BU C was obtained by introducing chiral glycoluril building blocks together with the attachment of ( S )‐1‐phenylethylamine substituents on the macrocycle, which gave rise to a good enantioselectivity for chiral carboxylates.…”

“…The europium nitrate salt was prepared from the corresponding oxide (Aldrich, 99.99 %) and dried according to published procedures. The anion‐free chiral BU C was prepared according to previously described procedures [12a] . Its CD spectrum was recorded with a JASCO 810 spectropolarimeter at 293 K by using a quartz cuvette of 0.1 cm pathway and is given in Figure S10 (in the Supporting Information).…”

“…[10] Recently,n ew derivativeso fb ambusurils bearing fluorinated substituents have been prepared and applied for transmembrane transport [11] and for enantioselective recognition of chiral carboxylate guests (chiral BU C ,F igure 1b). [12] In supramolecular systems, especially in metal-mediated selfassemblies, different anionsare systematicallyp resentand may play the following roles: [13] (i)a templating agent in anion-assisted synthesis, (ii) coordinating species, (iii)non-coordinating and non-competing counterions (weakly coordinating, spectator) compensating positive charges in the system,a nd (iv) ionpairing agentsfor tuning solubility and crystallization. It can be of interest to carry out an anion metathesis or removal, which can be realized by selective complexation, precipitation of salts, or alternatively by using oxidation/reductiono f anions.…”

Size-Control by Anion Templating in Mechanochemical Synthesis of Hemicucurbiturils in the Solid State

“…The quantitative conversion to cycHC[6] was reproducibly obtained by aging of products from either 30 or 60 minutes LAG (Table 1 lines 4 and 5, also Table S4). In contrast, milling for only 5 minutes produced waxy, transparent solids ( Figure S4) which, upon aging, gave low and inconsistent conversions to cycHC[6] (Table S4, lines [14][15]. The mechanochemical step was also explored by manual kneading with aqueous HCl, which revealed that the waxy material results from solidification of an initially formed liquid phase.…”