Anion Sensing by Fluorescent Expanded Calixpyrroles

Abstract

Expanded calixpyrrole-type macrocycles, calix[2]benzo[4]pyrroles, bearing fluorescent moieties attached via conjugated vinyl spacers, have been synthesized from the corresponding formyl derivatives through Knoevenagel condensation. The anion-binding properties of the resulting fluorescent macrocycles have been studied by means of NMR, UV/Vis, and fluorescence spectroscopies. Our main focus has been on dicarboxylates matching the size of the binding cavity of the calix[2]benzo[4]pyrrole skeleton. The observed anion-binding properties were compared with those of the regular calix[4]pyrroles bearing identical fluorophores. Surprisingly, the parent calix[4]pyrroles appear to be equally efficient, if not more so, for sensing anions such as dicarboxylates. Affinity constants determined for various anions and dianions show the sensors S1-S5 to be highly cross-reactive. The cross-reactivity of the sensors was utilized in a microchip-based array, which showed perfect (100 %) classification of 18 analytes utilizing only five sensors. Finally, the same array was used to quantitatively analyze dicarboxylates such as oxalate and malonate. The data from the array were subjected to linear regression, allowing the determination of various concentrations of dianions with low error (<2 %).

Advances in fluorescent and colorimetric sensors for anionic species

“…Anzenbacher and co-workers have expanded on their previous research by synthesising a series of dyeappended calixpyrroles (66)(67)(68)(69)(70) for sensing dicarboxylates (Fig 58) [130]. Probes 68 and 69 contain expanded calixpyrrole cores to promote the inclusion of larger carboxylate ions.…”

Photochromism and Colorimetric Ion Sensing of a Spiropyran Derivative—Spiropyran‐Rhodamine Dyad

“…The development of chemosensors for the recognition and sensing of various metal cations, proton, and some anions has drawn intense attention due to their crucial effects in many environmental, clinical, and biological processes.…”

“…Molecules that change color or fluorescence properties by changing the structure when metal cations and anions are added can be applied as good chemosensors. The structural interconversions could occur in response to a variety of the stimuli such as light, heat, mechanical forces, or pH as well as metal cations and anions …”

“…

The development of chemosensors for the recognition and sensing of various metal cations, 1-6 proton, 6-9 and some anions 10-13 has drawn intense attention due to their crucial effects in many environmental, clinical, and biological processes.

Molecules that change color or fluorescence properties by changing the structure when metal cations and anions are added can be applied as good chemosensors. [10][11][12][13] Fe 3+ is the physiologically most abundant and the most essential metal ion in biological systems. [10][11][12][13] Fe 3+ is the physiologically most abundant and the most essential metal ion in biological systems.

…”

Conformationally adaptable macrocyclic receptors for ditopic anions: analysis of chelate cooperativity in aqueous containing media

“…Nonetheless, there are many excellent examples in the literature of receptors that utilise hydrogen, [11][12][13][14] halogen 15 and chalcogen bonds, 16 ionpairing interactions 17,18 and metal-ligand interactions 19,20 to discriminate di-(and multi)topic carboxylate species in competitive (and non-competitive) solvents with both macrocycles [21][22][23] and cages 24 used to achieve some levels of dicarboxylate discrimination. More recently, arrays have been utilised to selectively detect ditopic anionic species, [25][26][27] although these oen require complex calibration.…”