Specific Binding of Primary Ammoniums in Aqueous Media by Homooxacalixarenes Incorporated into Micelles

Abstract

The development of artificial receptors for efficient recognition of analytes in water is a challenging task. Homooxacalix[3]­arene-based receptor 1, which is selective toward primary ammoniums in organic solvents, was transferred into water following two different strategies: direct solubilization and micellar incorporation. Extensive 1H NMR studies showed that recognition of ammoniums is only observed in the case of micellar incorporation, highlighting the beneficial effect of the microenvironment of the micellar core. The selectivity of the system for primary ammoniums over secondary and tertiary ones was also maintained. The hydrophobic effect plays an important role in the recognition properties, which are counterion-dependent due to the energy penalty for the dissociation of certain ammonium salts in the apolar micellar core. This study shows that the straightforward self-assembly process used for the encapsulation of artificial receptors in micelles is an efficient strategy for developing water-soluble nanosized supramolecular recognition systems.

Vanadium Catalyst in Micelles: Toward a Greener Aerobic Oxidative Cleavage of Vicinal Diols in Water

“…Full conversion is nevertheless achieved as the micelles are “reloaded” when the substrate is consumed. The local concentration of the substrate in the core of a micelle could be derived quantitatively by DOSY NMR: when a species partitions between two environments (the aqueous and the micellar phases in this case), the measured diffusion coefficient is a weighted average of its diffusion coefficient in the two environments . The diffusion coefficient of 1a was determined in water and in the DPC solution at 60 °C, and the fraction of 1a incorporated in the micelles was determined to be 66 ± 6%, which corresponds to a local concentration of 475 ± 43 mM (SI-10).…”

“…The local concentration of the substrate in the core of a micelle could be derived quantitatively by DOSY NMR: when a species partitions between two environments (the aqueous and the micellar phases in this case), the measured diffusion coefficient is a weighted average of its diffusion coefficient in the two environments. 78 The diffusion coefficient of 1a was determined in water and in the DPC solution at 60 °C, and the fraction of 1a incorporated in the micelles was determined to be 66 ± 6%, which corresponds to a local concentration of 475 ± 43 mM (SI-10). DPC forms small homogeneous micelles, and using the Stokes−Einstein equation, 79 the hydrodynamic radius of the loaded micelles was derived and observed not to be significantly different from the hydrodynamic radius of the empty micelles (SI-10).…”

Supramolecular protection with a recyclable molecular container: an efficient strategy for the one-pot selective functionalization of polyfunctional substrates

“…17 Very recently, we described the unique binding properties of a hexahomotrioxacalix [3]arene 18 -based molecular container (Ox3). 19,20 We showed that this host is able to accommodate primary ammonium ions (RNH 3 + ) in its polyaromatic cavity with high binding constants (log K a > 4 even in a protic environment) (Fig. 2).…”

Development of a Cone Homooxacalix[3]arene-Based Fluorescent Chemosensor for the Selective Detection of Biogenic Ammonium Ions in Protic Solvents

“…Following our recent investigations on homooxacalix [3]arenes, 19,35 we sought to design a homooxacalix [3]arene-based fluorescent chemosensor with the specific goal of achieving cavity-based selectivity for detecting biogenic amines. To achieve this, we targeted the synthesis of compound Ox3F with a pyrene unit on the wide rim (Figure 1, inset).…”