Dynamic Covalent Self‐Assembly of Chloride‐ and Ion‐Pair‐Templated Cryptates

Abstract

While supramolecular hosts capable of binding and transporting anions and ion pairs are now widely available, self-assembled architectures are still rare, even though they offer an inherent mechanism for the release of the guest ion(s). In this work, we report the dynamic covalent self-assembly of tripodal, urea-based anion cryptates that are held together by two orthoester bridgeheads. These hosts exhibit affinity for anions such as Cl À , Br À or I À in the moderate range that is typically advantageous for applications in membrane transport.In unprecedented experiments, we were able to dissociate the Cs•Cl ion pair by simultaneously assembling suitably sized orthoester hosts around the Cs + and the Cl À ion.

A Charge-Neutral Self-Assembled L2Zn2 Helicate as Bench-Stable Receptor for Anion Recognition at Nanomolar Concentration

“…In the worst case, the counteranion itself can be bound by the receptor and is in competition with the target analytes . In contrast, organic macrocycles and cages are often uncharged because of this reason, which makes it hard to compare receptors from these two dominant approaches with each other. − ,− …”

Trialkoxysilane Exchange: Scope, Mechanism, Cryptates and pH‐Response

“…To this end, we subjected a selection of trimethoxysilanes studied in the kinetic experiments to conditions that represented a compromise between fast trialkoxysilane exchange and an optimal template effect (the latter requirement precludes the use of high polarity solvents such as DMSO). [78,81] Specifically, we used chloroform as solvent and diethylene glycol (DEG) as a ligand for metal binding and as diol to exchange with the trialkoxysilane. TFA or TfOH were used as acid catalysts (Figure 6), while NaBArF acted as alkali metal template and agent to enhance the rate of the exchange reaction (see above).…”

“…Herein, we report a comprehensive experimental and computational study on the DCvC of trialkoxysilanes with stoichiometric amounts of alcohols in aprotic solvents. By combining our two groups' experience on silicon esters, silicate anions and macrocycles [66,[75][76][77] and orthoester cryptates, [78][79][80][81][82] we gain insights into the exchange mechanism and leverage these insights for identifying mild reaction conditions that ultimately allow the synthesis of a new class of supramolecular hosts. Valuable trends on solvent and salt additives are identified and manifest the ubiquitous SiÀ O bond as a tool for all fields making use of DCvC.…”

Steric Control over the Threading of Pyrophosphonates with One or Two Cyanostar Macrocycles during Pseudorotaxane Formation

“…Since the first reports half a century ago, [1–4] the field of supramolecular anion recognition [5,6] and anion receptor chemistry [7–13] has made significant advances. Notable applications [14] of anion recognition include sensing, [15–17] membrane transport, [18,19] catalysis [20–24] and increasingly the self‐assembly of supramolecular architectures [25–34] . Anion recognition has also been used to synthesize mechanically interlocked molecules [35–38] .…”

“…Notable applications [14] of anion recognition include sensing, [15][16][17] membrane transport, [18,19] catalysis [20][21][22][23][24] and increasingly the selfassembly of supramolecular architectures. [25][26][27][28][29][30][31][32][33][34] Anion recognition has also been used to synthesize mechanically interlocked molecules. [35][36][37][38] In most of these interlocked examples, anions play the role of a template, such that the anion is not part of either the thread or the macrocycle and can be removed after synthesis.…”