Pressocucurbit[5]uril

Abstract

A novel macrocycle, decamethylpressocucurbit[5]uril (Me10prCB[5]), was synthesized by acid-catalyzed condensation of propanediurea and paraformaldehyde. This macrocycle binds methane with higher affinity than cucurbit[5]uril and its permethylated derivative.

Templating Effects in the Dynamic Chemistry of Cucurbiturils and Hemicucurbiturils

“…[64][65][66][67] The isolation of first prCB, the Me-prCB [5] was reported simultaneously by Sindelar [64] and Wang. [64][65][66][67] The isolation of first prCB, the Me-prCB [5] was reported simultaneously by Sindelar [64] and Wang.…”

“…[66] The templated synthesis of prCB [4] and prCB [5] was demonstrated in the presence of Ca 2 + in 23 % yield and Ba 2 + in 20 % yield, respectively (Table 2, lines 7 and 8). [64] The presence of Ca 2 + and Ba 2 + salts induced the precipitation of 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 macrocycles from the reaction mixture in a 1 : 2 complex, with metals bound to prCBs at the portals ( Figure 6). [64] The presence of Ca 2 + and Ba 2 + salts induced the precipitation of 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 macrocycles from the r...…”

“…Pressocucurbiturils (prCB) are CB derivatives, where instead of glycoluril, the propanediurea is used as the monomer (Scheme 6). [64][65][66][67] The isolation of first prCB, the Me-prCB [5] was reported simultaneously by Sindelar [64] and Wang. [65] Very recently it was demonstrated that presence of CaCl 2 induces the formation of the first 4-membered double bridged CB, the Me-prCB [4] ( Table 2, line 6).…”

“…[67] Without the BaCl 2 additive and in presence of NaCl, 5-membered prCB [5] was also formed, but could not be isolated in pure form. [64] The presence of Ca 2 + and Ba 2 + salts induced the precipitation of 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 macrocycles from the reaction mixture in a 1 : 2 complex, with metals bound to prCBs at the portals ( Figure 6). This reflects the importance of the solubility equilibrium of the macrocycle complexes, and determines that the template effect by route C on Scheme 5 is most likely effective in this case.…”

Propanediurea-Based Molecular Clips Bind Halide Anions: An Insight into the Mechanism of Cucurbituril Formation

“…In contrast, cucurbiturils are known as the artificial hosts with the highest binding affinities toward neutral and cationic organic guests in water. − Acyclic cucurbituril derivatives have been studied by our group and that of Isaacs in order to further explore the mechanism of cucurbituril formation and also to design host molecules with more flexible structures in comparison with cucurbiturils. − This paper focuses on molecular clips formed by glycoluril dimers and framed by aromatic sidewalls. Recently, it was shown that the glycoluril units in the cucurbituril structure can be replaced by propanediurea. − This inspired us to investigate whether the substitution of propanediurea for glycoluril was also possible in glycoluril dimers and how the substitution would affect the supramolecular properties of the resulting host molecules. Here, we present our results.…”