Anion recognition properties of pyridine-2,6-dicarboxamide and isophthalamide derivatives containing l-tryptophan moieties

Recognition of Chiral Carboxylates by Synthetic Receptors

Recognition of anionic species plays a fundamental role in many essential chemical, biological, and environmental processes. Numerous monographs and review papers on molecular recognition of anions by synthetic receptors reflect the continuing and growing interest in this area of supramolecular chemistry. However, despite the enormous progress made over the last 20 years in the design of these molecules, the design of receptors for chiral anions is much less developed. Chiral recognition is one of the most subtle types of selectivity, and it requires very precise spatial organization of the receptor framework. At the same time, this phenomenon commonly occurs in many processes present in nature, often being their fundamental step. For these reasons, research directed toward understanding the chiral anion recognition phenomenon may lead to the identification of structural patterns that enable increasingly efficient receptor design. In this review, we present the recent progress made in the area of synthetic receptors for biologically relevant chiral carboxylates.

Fluoride binding by an anionic receptor: tuning the acidity of amide NH groups for basic anion hydrogen bonding and recognition

Here we report the first family of bis-amide receptors able to bind fluoride in their anionic form.

A new class of silica-supported chromo-fluorogenic chemosensors for anion recognition based on a selenourea scaffold

The first example of a chemosensor (L) containing a selenourea moiety is described here. L is able to colorimetrically sense the presence of CN^- and S^2- in H₂O : MeCN (75 : 25, v/v). Moreover, when L is loaded into functionalised mesoporous silica nanoparticles an increase in the selectivity towards S^2- occurs via a selective fluorescence response.

Anion and sugar recognition by 2,6-pyridinedicarboxamide bis-boronic acid derivatives

Two 2,6-pyridinedicarboxamide derivatives containing arylboronic acid fragments were prepared and fully characterized including X-ray crystal diffraction analysis of a pinacol ester. These compounds are potential bifunctional receptors for sugars and anions. Acid dissociation and stability constants for complexation of both receptors with glucose and fructose were determined by potentiometric titrations in aqueous DMSO. Also, binding of alizarin red S indicator was studied spectrophotometrically and a highly sensitive detection of fructose by an indicator displacement assay was proposed. Complexation with anions was studied by 1H NMR titrations in DMSO-d6. Binding of acetate anion occurs only via hydrogen bonding to OH groups of boronic acid fragments and does not affect signals of NH protons but chloride anion induces large shift of the signals of NH protons and small shifts of the signals of OH groups. This behavior makes possible anion discrimination based on preference in the type of binding site rather than simply on anion basicity as is typical for majority of neutral hydrogen bonding anion receptors.

Beryllium-based fluorenes as efficient anion sponges

The F⁻, Cl⁻, CN⁻, NO₂⁻, NO₃⁻, and SO₄²⁻ anion affinities of 4,5-bis(BeX)-fluorene (X = H, F, Cl, CN, NC, and OCH₃) derivatives have been calculated at the B3LYP/6-311+G(3df,2p)//B3LYP/6-31+G(d,p) level of theory.

An ion pair receptor facilitating the extraction of chloride salt from the aqueous to the organic phase

A squaramide supported molecular receptor with the ability to extract chloride salt from the aqueous to the organic phase was synthesized and characterized.

Reply to the ‘Comment on “Non-symmetric substituted ureas locked in an (E,Z) conformation: an unusual anion binding via supramolecular assembly” by B. Ośmiałowski and E. Kolehmainen, New J. Chem., 2014, , DOI: 10.1039/c3nj01282d

The interaction between ureidic receptors and acetate is described via NMR experiments.