A Switchable Open/closed Polyaromatic Macrocycle that Shows Reversible Binding of Long Hydrophilic Molecules

Abstract

In spite of wide-ranging previous studies on synthetic macrocycles, the installation of open-close functions into the frameworks remains a challenge. We present a new polyaromatic macrocycle capable of switching between open and closed forms in response to external stimuli, namely, base and acid. The macrocycle, which is prepared in three steps, has a well-defined hydrophobic cavity with a length of around 1 nm, surrounded by four pH-responsive acridinium panels. The open and closed structures were confirmed by single-crystal X-ray analysis. The cylindrical cavity can bind long hydrophilic molecules up to 2.7 nm in length in neutral water and then release the bound guests through a reversible open-to-closed structural change upon simple addition of base.

Molecular memory with downstream logic processing exemplified by switchable and self-indicating guest capture and release

“…Having been inspired by the roles played by cyclophanes in supramolecular chemistry 37,42,45,48 , we felt that we could apply our experience of molecular switching 4,10–12 to make a contribution to this area. Excellent examples of switchable cyclophanes and related macrocycles already exist 37–44 , but binary all-or-none switching of cyclophanes in water still remains a worthwhile goal. Since cyclophanes are well-known to bind shape-complementary organic guests in water 37 , a method of switching the cavity size/shape should enable the guest’s release.…”

“…Reversible atom capture/release is well-established 33–35 . Molecules can also be imprisoned/liberated 36–44 but it is harder to achieve in a reversible all-or-none manner without complications of side-reactions 40 or incomplete conversion. On the other hand, related intramolecular studies are available as parts of molecular machines 5,6,45–49 .…”

Syntheses of Organic Semiconductors in Water. Recent Advancement in the Surfactants Enhanced Green Access to Polyconjugated Molecules

“…By combination of self-assembly in water solution and clever designing of coordinative bonding around palladium atoms, the group developed association colloids featuring remarkable applications in host guest chemistry, selective recognition, modulation of guest reactivity, water solubilization of organic dyes and nanocarbons. [64][65][66][67][68][69][70][71] Figure 4. Anthracene dimers-based aromatic nanocaspules.…”

A Pentacene‐based Nanotube Displaying Enriched Electrochemical and Photochemical Activities

“…Moreover,w eh ave proven the efficient generation of the excited triplet species of the nanotube,with prominent triplet quantum yield and elongated triplet lifetime,t hrough through-space-type,i ntramolecular singlet fission upon photoirradiation. Theo bserved, enriched electrochemical and photochemical activities of pentacene chromophores through tubular cyclization could open up an ovel field of polyacene chemistry and materials.The combination of polyacene-based nanotubes with supramolecular interactions [26] would develop advanced host-guest nanocomposites,f or example,w ith tunable and switchable redox and singlet fission functions.…”