Resorcin[4]arenes: A Convenient Scaffold To Study Supramolecular Self-Assembly and Host:Guest Interactions for the Undergraduate Curriculum

Abstract

In response to the call for an increased emphasis from the American Chemical Society on including macromolecular studies in the undergraduate curriculum, a supramolecular-themed experiment was designed for undergraduatelevel organic laboratory courses that provides a convenient platform to study physical behaviors of supramolecular assemblies. Students synthesize an easily purified resorcin[4]arene and characterize the product of its self-assembly via 1 H NMR spectroscopy. These bowl-shaped molecules are noteworthy because of their propensity to self-assemble in organic solution in the presence of trace water or alcohol solvents. Upon self-assembly, the resulting hexamer adopts a well-defined molecular cage structure with a large internal cavity that can be used to explore host:guest chemistry. After completing the experiment, students are expected to gain a better understanding of electrophilic aromatic substitution, 1 H NMR spectroscopy, supramolecular chemistry and self-assembly, and molecular recognition.

Combining iminium and supramolecular catalysis for the [4 + 2] cycloaddition of E-cinnamaldehydes

“…20 The resorin[4]arene is readily prepared by an acid-catalysed condensation of resorcinol and dodecanal, and can be easily prepared by undergraduate students in a standard 3- or 4-hour lab period. 21 For ease of analysis, we began our study using CDCl 3 as solvent (for which the behavior of the hexamer is well-understood). 22 While some supramolecular catalysts require stoichiometric or superstoichiometric loadings, we were delighted to find that we could achieve the DA reaction between E -cinnamaldehyde and 2,3-dimethylbutadiene using 20 mol% of hexamer as well as 20 mol% of l -proline, though with catalytic loading of capsule the reaction required a 5 d reaction time at 40 °C to reach completion (Table 1, entry 1).…”

Combining Iminium and Supramolecular Catalysis for the [4 + 2] Cycloaddition of E-Cinnamaldehydes

“…19 The hexamer is readily prepared by an acid-catalyzed condensation of resorcinol and dodecanal, and can be easily prepared by undergraduate students in a standard 3-or 4-hour lab period. 20 For ease of analysis, we began our study using CDCl3 as solvent (for which the behavior of the hexamer is well-understood). 21 While some supramolecular catalysts require stoichiometric or superstoichiometric loadings, we were delighted to find that we could achieve the DA reaction between cinnamaldehyde and 2,3-dimethylbutadiene using 20 mol% of hexamer A as well as 20 mol% of L-proline, though with catalytic loading of cage the reaction required a 5 d reaction time at 40 °C to reach completion (Table 1, Entry 1).…”

Decamethyl-pillar[5]arene: Synthesis and Recognition Properties

“…Even though some well devised experiments on the synthesis and study of macrocyclic compounds were already available in the literature (e.g., on calix[4]­pyrrole , and cyclodextrins, among others), in response to the ACS call some laboratory experiments on the supramolecular properties of macrocyclic compounds have lately been designed. These experiments approach the subject from different perspectives, often employing commercially available macrocycles to highlight their recognition or self-assembly properties − or to use them as components of mechanically interlocked molecules . Within this frame, with the aim of providing the students with a complete supramolecular chemistry experience, we have designed a two-part laboratory exercise consisting of two four-hour sessions, the first targeted to the synthesis of a pillar[5]­arene and the second focused on the evaluation of its recognition properties.…”