A fluorescent molecular capsule with a flexible polyaromatic shell for the detection of monoterpene compounds in water

Abstract

A new molecular capsule with a flexible fluorescent shell was formed by the quantitative self-complementary assembly of amphiphilic, U-shaped polyaromatic subunits in water. The capsule can fully encapsulate a variety of non-fluorescent monoterpene compounds (e.g., menthone, menthol, and p-menthane) in the hydrophobic cavity and act as a fluorescent supramolecular probe for recognizing the structural identity of the analytes by emissive signals in water at room temperature.

Cyclic monoterpenes trapped in a polyaromatic capsule: unusual selectivity, isomerization, and volatility suppression

“…Thus, these intractable features cause great difficulty in their molecularlevel recognition and microscale separation from CMT mixtures, besides the existence of plenty of derivatives with only tiny structural differences. 4 There have been many reports on molecular receptors (e.g., covalent tubular and bowl-shaped compounds, 5 hydrogenbonding and coordination capsules, 6 and p-stacking capsules 7 ), capable of binding CMTs such as camphor (CMP), menthol (MTL), and p-cymene (CMN; Figure 1a). However, the majority of the previous receptors possess open and/or flexible cavities surrounded by aliphatic and/or small aromatic frameworks 5-8 so that the selective recognition and high volatility suppression of CMTs have been hardly accomplished by the previous artificial receptors so far.…”

“… 4 There have been many reports on molecular receptors ( e.g. , covalent tubular and bowl-shaped compounds, 5 hydrogen-bonding and coordination capsules, 6 and π-stacking capsules 7 ) capable of binding CMTs such as camphor ( CMP ), menthol ( MTL ), and p -cymene ( CMN ; Fig. 1a ).…”

Maximizing Coordination Capsule–Guest Polar Interactions in Apolar Solvents Reveals Significant Binding

“…Supramolecular capsules appear at the forefront of research efforts because their propensity to partition whole molecules from the bulk phase produces interesting properties ranging from sensing [1] through catalysis [2] to the stabilization of reactive species. [3] With coordination systems,binding chargeneutral guests provides an otable challenge because of the competition with associated counter anions or cations.…”

A Polyaromatic Gemini Amphiphile That Assembles into a Well‐Defined Aromatic Micelle with Higher Stability and Host Functions

“…Herein we report new gemini‐type amphiphilic molecule 1 consisting of two V‐shaped polyaromatic amphiphiles 2 connected with a linear acetylene unit, which we chose as a simple, sterically undemanding, and freely rotatable spacer (Figure c, left) . The gemini amphiphiles assemble into a well‐defined aromatic micelle ( 3 ) in water through polyaromatic π‐stacking interactions and hydrophobic effects.…”

“…Herein we report new gemini-type amphiphilic molecule 1 consisting of two V-shaped polyaromatic amphiphiles 2 [8] connected with al inear acetylene unit, which we chose as asimple,sterically undemanding,and freely rotatable spacer (Figure 1c,l eft). [9] Theg emini amphiphiles assemble into aw ell-defined aromatic micelle (3)i nw ater through polyaromatic p-stacking interactions and hydrophobic effects. Obtained micelle 3 and amphiphile 1 emit orange and green fluorescence (F F = 9a nd 33 %), respectively,i nc ontrast to previously reported gemini amphiphiles and their particles with aliphatic chains.…”