Ion Pair-Driven Heterodimeric Capsule Based on Boronate Esterification:  Construction and the Dynamic Behavior

Abstract

We describe the ion pair-driven heterodimeric capsule formation of a cyclotricatechylene 1 and a boronic acid-appended hexahomotrioxacalix[3]arene 2. Although 1 does not interact with 2 in a protic solution, in the presence of Et4NAcO quantitative formation of a heterodimeric capsule via boronate esterification was observed in the NMR, a direct result of anion-induced boronate ester formation and the Et4N+ template. Reversible boronate esterification allowed us to selectively control capsule assembly using pH switching.

An Iminoboronate Construction Set for Subcomponent Self‐Assembly

“…The dynamic covalent [20] nature of both B À O and C=N bonds [21] allows both diol and amine subcomponents to be independently displaced within these structures in well-defined ways, allowing one structure to be transformed into another. This work thus applies the concepts of subcomponent self-assembly to the rich field of boron-based self-assembly, which includes such recent examples as chemosensors, [22] multicomponent architectures, [18] reversibly formed cages, [23] boroxoaromatics, [21] anionic borate assemblies, [24] borylferrocene structures, [25] macrocycles, [26] as well as self-repairing polymers [27] and porous networks. [28] …”

“…[23,34] The reaction of cyclotricatechylene E (1 equiv) with 2-formylphenylboronic acid and amine 11 (3 equiv each) led to the formation of trinuclear 11 3 E (Scheme 3). Again, the prior observation of 11A allowed us to predict that the structurally similar 11 3 E would be stable.…”

“…In contrast with aliphatic tetrol D, aromatic subcomponent E might be expected to produce better-defined cagetype [23] architectures due to the possibility of N!B coordinative interactions. This prediction was borne out by the preparation of trigonal cage 17 3 E 2 (Scheme 5) upon mixing cyclotricatechylene E with m-xylylenediamine 17 and 2-formylphenylboronic acid in deuterated DMF under argon.…”

Shape‐Persistent Organic Cage Compounds by Dynamic Covalent Bond Formation

“…[50] They found that the condensation does not occur at room temperature in a protic solution; the addition of Et 4 N +…”

“…[50] Scheme 11. Solvent effect of different regioisomers of xylene on the formation of cage compounds from a racemic tetraol precursor and 1,3,5-benzenetrisboronic acid.…”