Pillar[n]arenes—a Novel, Highly Promising Class of Macrocyclic Host Molecules

Abstract

Since 2008 a new field of supramolecular chemistry has developed rapidly: the chemistry of pillar[n]arenes. These “younger brothers and sisters” of calixarenes are conveniently accessible and extremely guest‐friendly. Guests from many different classes of organic compounds are welcome. Nevertheless, a high selectivity for the threading of guest molecules in the macrocyclic cavities can be achieved. The complex stability is characterized by association constants Ka between 10 and 1×108 M−1. The rate constants of the threading vary over several orders of magnitude. The focus of this article lies on the preparation (sections 2 and 3) and the structures (section 4) of pillar[n]arenes (n=5–10) in solution and in the solid state. A further important point concerns the complexation and its selectivity (section 5). Only some new or outstanding examples are discussed in section 6 on self‐assembly and aggregation.

Pillar[5]arenes with Morpholide and Pyrrolidide Substituents: Synthesis and Complex Formation with Alkali Metal Ions

“…[14] Therefore, this fact is in contrast to the review [7] about fast rotation of the benzene rings in compound 3.…”

“…[7] A characteristic indicator for these molecular dynamics is provided by the signals of the OCH 2 groups in the 1 H NMR spectra. In compounds 3-6 the proton signals of methylene bridge (peak A), both oxymethylene fragments (peak B) were observed as singlet and doublets of AB spin system correspondingly ( Figure 3, Table 1).…”

“…It indicates that the structure of pillar [5]arenes 3-6 is in frozen D n conformation [7] and mobility of the oxyme-thylene protons was suppressed. [14] Therefore, this fact is in contrast to the review [7] about fast rotation of the benzene rings in compound 3.…”

“…In recent years, a new class of synthetic macrocycles -pillar[n]arenesattracts the interest of researchers. [7,8] Pillar[n]arenes belong to a new generation of macrocyclic hosts for supramolecular chemistry. The macrocyclic cavity of pillar [5]arene has the size comparable to a cavity of cyclodextrines and calixarenes well known as effective complexing reagents for organic and inorganic compounds.…”

Pillararene-based fluorescent indicator displacement assay for the selective recognition of ATP

“…Although pillar [n]arenes are a relatively new class of macrocycles [13], numerous applications were discovered due to their easy synthesis, versatile functionalization and diverse host-guest chemistry [14][15][16][17][18][19][20][21][22]. In particular, water-soluble pillararenes are of significance as prosperous hosts for various guests of biological importance [23][24][25][26][27][28].…”