Anion Recognition through Multivalent C–H Hydrogen Bonds: Anion-Induced Foldamer Formation and Transport across Phospholipid Membranes

Abstract

A series of triazole–cyanostilbene receptors were designed and synthesized. The receptor binds with the anions through various CH···anion hydrogen bonding interactions, where strong binding was observed for SO4 2– anions followed by Cl–, Br–, NO3 –, and I–, calculated from the 1H NMR titration experiment. The NOESY NMR experiment of the receptor confirmed the formation of anion-induced folded conformation. The CH···anion hydrogen bonding interaction-mediated anion recognition and foldamer formation were further confirmed from geometry optimization studies of the anion-bound complex. The receptor transports Cl– anions efficiently compared to SO4 2– anions across the lipid bilayer membrane via a mobile carrier mechanism.

Multistate Redox-Switchable Ion Transport Using Chalcogen-Bonding Anionophores

“…The precise regulation of charged species in biological systems underpins many of the processes required for life, and as a consequence, ionic imbalances can severely compromise physiological function. Supramolecular ionophores that function as mobile carriers for ions have garnered significant interest as potential therapeutics for diseases associated with ion misregulation, − such as cystic fibrosis and Bartter syndrome, or as novel cancer treatment strategies to trigger tumor cell apoptosis. − Indeed, in the context of anion transport, there now exists a vast library of predominantly hydrogen bonding (HB) − synthetic anion receptors, possessing a wide range of donor motifs and topologies, and capable of facilitating membrane transport for a range of biologically relevant anions. Many of the fundamental factors that govern anionophore transport behavior including activity, − anion selectivity, , and membrane deliverability, including in chalcogen bonding systems, − have now been established.…”

Chloride Transport across Liposomes and Cells by Nontoxic 3-(1H-1,2,3-Triazol-1-yl)benzamides

“…The magnificent transport activity of triazole 1d served as an inspiration to evaluate the ion transport mechanism along with ion selectivity of 1d . To assess the preferred transport among cations and anions, the transmembrane ion transport of 1d was checked using EYPC-LUVs⊃HPTS by varying the extravesicular ionic buffers. , The insignificant differences in the transport rate of 1d in the presence of different external cations (Figure S16) exclude the involvement of any cation, that is, neither H + /M + antiport nor M + /OH – symport is preferred during the transport process.…”

“…To assess the preferred transport among cations and anions, the transmembrane ion transport of 1d was checked using EYPC-LUVs⊃HPTS by varying the extravesicular ionic buffers. 34,35 The insignificant differences in the transport rate of 1d in the presence of different external cations (Figure S16) exclude the involvement of any cation, that is, neither H + /M + antiport nor M + /OH − symport is preferred during the transport process. This was followed by an evaluation of anion selectivity by varying the anions in the intravesicular and extravesicular buffers, 36 − > ClO 4 − (Figure 3C).…”

Fluorinated leaning pillar[6]arene: synthesis, structure and selective iodide anion binding by anion–π interactions

“…Among a plethora of these synthetic macrocycle receptors using different association forces, the majority of the effective macrocycle-based anion receptors documented in the literature were designed by means of aligning multiple binding sites based on the directionality of noncovalent hydrogen bonds. [36][37][38][39][40][41][42][43] Anion-π interactions, which were defined as attractive interactions between negatively charged species and electrondeficient aromatic rings, were recognized as nascent and important non-covalent interactions since the generality, binding models and binding strength were unveiled experimentally and computationally recently. [44][45][46][47][48][49][50] For example, Stoddart and his colleagues investigated the selective recognition of linear I 3 − anions via anion-π interactions by NDI units in electron-deficient molecular prisms, providing us with a rare emergent example of anion-induced self-assembly with potential application as ion-channels.…”

“…Among a plethora of these synthetic macrocycle receptors using different association forces, the majority of the effective macrocycle-based anion receptors documented in the literature were designed by means of aligning multiple binding sites based on the directionality of noncovalent hydrogen bonds. 36–43…”