Bambusuril analogs based on alternating glycoluril and xylylene units

• Tomáš Lízal and
• Vladimír Šindelář

Beilstein J. Org. Chem. 2019, 15, 1268–1274, doi:10.3762/bjoc.15.124

• product. Two disastereomers of the macrocycle were separated and characterized by means of NMR spectroscopy and X-ray crystallography. Conformational changes of these diastereomers were investigated using DFT models and variable-temperature NMR. Keywords: bambusurils; conformers; glycolurils; macrocycles

• urea groups can participate in intermolecular hydrogen bonding resulting in the formation of tubular [5][6][7] or gel-like [8] structures. Ureas lacking of N–H hydrogen atoms such as ethyleneureas, glycolurils, and biotin are also important building blocks of macrocyclic receptors such as cucurbiturils

• induced any change in the NMR spectra of the macrocycles. This indicates that these macrocycles do not bind the studied anions. We assume that the cavity of the macrocycles is too small to be able to include any anions. Indeed the conformer 1b-1 with two facing glycolurils resembles the bambus[4]uril

Control of stilbene conformation and fluorescence in self-assembled capsules

• Mark R. Ams,
• Dariush Ajami,
• Stephen L. Craig,
• Jye-Shane Yang and
• Julius Rebek Jr

Beilstein J. Org. Chem. 2009, 5, No. 79, doi:10.3762/bjoc.5.79

• λexc = 318 nm. For comparison, the emission of the permanently twisted, o-substituted stilbene 5 (λexc = 300 nm) is also shown [9]. Can the fluorescence of the encapsulated stilbene be restored? When suitable guests are present, addition of glycolurils such as 7 to solutions of 1.1 generates extended

• capsule 1.74.1 (Figure 3) [10]. The glycolurils are arranged in a chiral manner, in either cycloenantiomer of the extended capsule. The glycolurils force the two square prisms of 1.74.1 into registry (Figure 3A). That is, the square prisms are now aligned and stilbene as well as related guests may be