Recent Advancements in Ion‐Pair Receptors

Abstract

Over the past two decades, non‐covalent chemistry has introduced various promising artificial receptors and revolutionized the host‐guest chemistry. These versatile receptors have particularly been entertained in sensing and recognizing of diverse neutral molecules and/or ionic entities (e. g. anions, cations and ion‐pair) of particular interest. Notably, supramolecular chemistry had given birth to a plethora of important molecules, explored in the chemical, biological, environmental, and pharmacological world to resolve the critical issues related to the human health while keeping environmental concerns in mind. Amongst the various types of supramolecular monotopic receptors (anions, cations, and neutral molecules), heteroditopic receptors (ion‐pair receptors) consisting of distinct binding sites in one system for both cation and anion, have gained much interest from the scientific community in recent past because of their unique binding abilities. Interestingly, these promising artificial receptors have shown potential applications in sensing, recognition, transport and extraction processes besides their uses in salt/waste purification. Bearing the importance of these systems in mind, we intended to report the recent developments in ion‐pair chemistry. Herein, we divided the whole document into three main sections; first one describes the introduction and history of the ion‐pairs receptors. The second portion highlights the synthesis and applications of ion‐pair receptors in sensing, recognition, molecular machines, photoswitching behaviour, extraction and transport properties, whereas the last part of this manuscript provides concluding remarks as well as future prospects of ion‐pair receptors. We hope that this manuscript will be helpful to stimulating researchers around the globe to find out the hidden opportunities in this and related areas.

Supramolecular chemistry of liquid–liquid extraction

“…Several reviews have summarized this early progress on ion-pair binding. 12,13,107–109 Ion pair binding with different receptors can be categorized into three modes: (a) contact, (b) solvent-bridged and (c) host–guest separated ion pair (Fig. 22).…”

Unraveling the Potential Role of Deep Eutectic Solvents (DESs): Synthesis of Ketazines & Pyrazolines

“…In recent years, azines have received a considerable interest of the scientific community because of their noteworthy physiochemical properties for example, electron delocalization, unique reactivity pattern, charge distribution, E/Zisomerization, conformational isomerism tautomerism, and polymorphisim addition to their materialistic signatures. [2][3][4][5] Moreover, azines are considered as the constructive frameworks for the synthesis of various valued N-heterocycles such as pyrazoles, diazepines, triazoles, isoquinolines, pyrroles, dihydropyridines, imidazopyridines, triazines, and oxadiazoles etc. [6][7][8][9][10][11][12][13][14][15][16] Besides these, azines are also measured as the promising candiates for the design and construction of the molecular organic frameworks (MOFs), covalent organic frameworks (COFs), liquid crystals, nonlinear optical (NLO), electro-or photo-switchable devices and conducting, sensing & energetic materials etc.…”

Facile synthesis and anion binding studies of fluorescein/benzo-12-crown-4 ether based bis-dipyrromethane (DPM) receptors

“…Generally, a combination of noncovalent/supramolecular interactions participates in the anion recognition chemistry, including coulombic interactions, halogen bonding, hydrogen bonding, CH-anion, anion-p interactions, p-p stacking, and other important non-covalent forces, as well. [33][34][35][36][37][38][39][40][41][42][43][44][45][46] However, most frequent moieties consisting of the active hydrogen bonding sites for instance urea, thiourea, phenol, amide, pyrrole etc., have prominently been used for the design and synthesis of the anion receptors. [47][48][49][50][51][52] Remarkably, as can be inspected from the Fig.…”