Pillar[n]arenes at the Chemistry‐Biology Interface

Abstract

Macrocyclic chemistry has provided chemists with a wealth of molecular 'hosts'. Ever since resurgence in the field during the 1970s and 1980s these hosts' similarities to natural structures, such the active sites of enzymes, have been noted. Latterly there has been great interest in the recently reported pillar[n]arenes. As if to underline the importance of these compounds, exciting applications are starting to emerge, from electrochemical sensors to antimicrobial agents. Novel uses appear destined to have an impact on clinical conditions from Alzheimer's disease to cancer treatment. In order to demonstrate the impact of pillar[n]arenes across the chemistry-biology interface this review will cover the current state of the art from biomimicry and analyte-specific detection to emerging clinical applications. Examples include pillar[n]arene-based ion channels, enzyme-responsive compounds, imaging agents, biofilm inhibiting derivatives, drug complexing and drug releasing systems.

Probing Reversible Guest Binding with Hyperpolarized 129Xe-NMR: Characteristics and Applications for Cucurbit[n]urils

“…Pillar[n]arenes are an example of hosts that have been recently demonstrated to form box-shaped structures [147] with matching "lids". They have also been under investigation for drug complexation and release [148]. As their portals without such lids are rather open, a fast exchange of Xe occurs.…”

Antimicrobial Activity of Calixarenes and Related Macrocycles

“…Functionalization, though upper and lower rims, offers up the possibility of their use as inhibitors of biochemical processes or as prodrugs with the active substituents released in response to external stimuli. Some useful summaries of the broader biological and biochemical effects of water-soluble calixarenes [2,3] and pillararenes [4] have been published.…”

“…Once a calixarene or its complex has been shown to be 'druggable', it needs to reach its target. A water-soluble calix [4]arene with quaternary ammonium groups on the upper rim and a fluorophore on the lower rim, shown in Figure 2, was used by Matthews, Mueller, and colleagues to probe calixarene transport into cells [11]. Using fluorescence confocal microscopy, it was possible to show that the molecules were not transported across the membrane by endocytosis, nor did they appear to traverse the membrane between lipid raft domains.…”

Nanoparticles based on the zwitterionic pillar[5]arene and Ag+: synthesis, self-assembly and cytotoxicity in the human lung cancer cell line A549

“…The ability of macrocyclic systems to form supramolecular associates, due to noncovalent interactions with Ag + , can reduce toxicity and preserve the biomedical properties of the resulting nanoscale particles that do not contain Ag-Ag bonds [14]. However, the main problem is the fact that macrocyclic hosts have low solubility in water, which significantly narrows their application [15][16][17][18][19][20]. Therefore, we propose to use water-soluble derivatives of decasubstituted pillar [5]arenes containing sulfobetaine fragments in their structure as target structures.…”