Purely Covalent Molecular Cages and Containers for Guest Encapsulation

Abstract

Cage compounds offer unique binding pockets similar to enzyme-binding sites, which can be customized in terms of size, shape, and functional groups to point toward the cavity and many other parameters. Different synthetic strategies have been developed to create a toolkit of methods that allow preparing tailor-made organic cages for a number of distinct applications, such as gas separation, molecular recognition, molecular encapsulation, hosts for catalysis, etc. These examples show the versatility and high selectivity that can be achieved using cages, which is impossible by employing other molecular systems. This review explores the progress made in the field of fully organic molecular cages and containers by focusing on the properties of the cavity and their application to encapsulate guests.

Influence of the solvent in the self-assembly and binding properties of [1 + 1] tetra-imine bis-calix[4]pyrrole cages

“…1,2 The portals connecting the two phases and their sizes control the in and out exchange of the guests. These singular features make cage containers attractive molecular designs for different applications such as molecular recognition, [3][4][5] stabilization of reactive species 6 and mediation of chemical reactivity, 7,8 among others. [9][10][11][12] The rst examples of molecular cages date back to the middle 80s'.…”

“…17,18 The resulting poly-imine POCs displayed a well-dened interior cavity that did not collapse into more dense or twisted structures owing to the conformational restrictions imposed by the imine bonds. 19 The rst Schiff base molecular container was described in 1991 by Quan and Cram, via the condensation reaction between two molecules of a tetraaldehyde resorcin [4]arene cavitand and four molecules of 1,3diaminobenzene. 20 The derived octa-imine cage was able to include a series of guests forming kinetically stable hemicarceplexes owing to constrictive binding.…”

“…The cage systems acted as shape-persistent POCs for the selective adsorption of CO 2 . [28][29][30] Our group introduced the use of a,a,a,a-aryl-extended calix [4]pyrrole scaffolds for the construction of hydrogen-bonded 31 and mechanically-bonded 32 molecular capsules with polar interiors. We also described the template-directed self-assembly of octa-imine cages having polar interiors via the [2 + 4] Schiff base condensation reaction of a tetra-formyl aryl-extended calix [4]pyrrole and 1,2-diamines (Fig.…”

A triple-diazonium reagent for virus crosslinking and the synthesis of an azo-linked molecular cage

“…On the other hand, CMCs have been the focus of considerable interest because of their potential to encapsulate guest species, deliver drugs, catalyze reactions within their cavities, etc. 8–10 Moreover, exploring new linkage chemistry has always been one of the research focuses, 8 d since the emergence of a new-type linkage not only enriches the structural diversity but also may result in distinctive properties and applications of CMCs. To this end, various CMCs with linkages including –B–O–, 9 a ,11 –CN–, 12 –C–N–, 13 –C–O–, 14 –Si–O–, 15 and –C–C– 16 bonds have been developed in the past decade.…”

A tetraphenylethene-based hexacationic molecular cage with an open cavity

“…, cyclophane, cyclodextrin, calixarene, and cucurbituril) with selective recognition function for specific guests. 2 Inspired from three-dimensional (3D) hydrophobic pockets of some functional proteins, furthermore, many molecular cages with 3D cavities of different sizes and shapes were designed and synthesized to achieve some specific functions, such as catalysis, separation, and drug delivery. 3–5…”