Cavity Effect on Perrhenate Recognition by Polyammonium Cages

Abstract

The affinity of azacryptands towards perrhenate has been investigated by potentiometric, 1 H NMR spectroscopic and ITC studies in aqueous solutions. The association constants could only be determined for the p-xylyl and m-xylyl azacryptands in the hexaprotonated form. The experimental results showed the outstanding affinity of the p-xylyl cryptand for perrhenate, attributable to the geometric complementarity between the anion and the cavity of the receptor. Single crystals of the inclusion complex could also be obtained. The Xray diffraction studies indicate that the perrhenate anion is included in the cavity of the receptor and interacts with the [a]

Bistren cryptands and cryptates: versatile receptors for anion inclusion and recognition in water

“…19 shows the distribution diagram of the species present at the equilibrium over the 2-12 pH interval, (0.1 M NaCF 3 SO 3 , T = 25°C), in the case of bistren cryptand 7. 34 The diagram in Fig. 19 shows that at pH 2 100% LH 6 6+ is present .…”

99TcO4−: Selective Recognition and Trapping in Aqueous Solution

“…Steps forward on 99 TcO 4 − recognition were made by Sessler, Katayev, and coworkers, although again not in aqueous solution 9–11. Recently, our group investigated the binding propensities of poly‐protonated azacryptands towards ReO 4 − in water 12. These studies revealed the receptor LH 6 6+ to have the most suitable cavity for incorporation of the anion.…”

“…These studies revealed the receptor LH 6 6+ to have the most suitable cavity for incorporation of the anion. The selectivity of LH 6 6+ for ReO 4 − was demonstrated by comparing the affinity constant with those obtained with several other anions (such as chloride and nitrate) 12…”

“…ITC titrations14 were performed by addition of L to NH 4 99 TcO 4 at pH 2.0±0.1 (0.1 M CF 3 SO 3 Na, T =30 °C). Under these conditions, the receptor is in the hexaprotonated form, LH 6 6+ , which is the most suitable for anion binding 12…”

An Ultrafast Molecular‐Rotor‐Based Fluorescent Turn‐On Sensor for the Perrhenate Anion in Aqueous Solution

“…Of these, some supramolecular hosts have been designed to bind perrhenate in a very selective manner, however, their operations are limited to organic media or organic/aqueous mixtures . To overcome this limitation, recently, some supramolecular receptors have been synthesized that utilize a combination of electrostatic interactions and multiple hydrogen‐bonding interactions and, more recently, halogen bonding to achieve the selective binding of the perrhenate anion in aqueous media . To exploit the selective binding of the designed supramolecular host with the perrhenate/pertechnetate anion for its analytical detection, one such receptor molecule was functionalized with a fluorophore, anthracene, which signaled the binding of the perrhenate/pertechnetate to the receptor molecule through a decrease in its fluorescence intensity .…”