Halide selective anion recognition by an amide-triazolium axle containing [2]rotaxane

Abstract

A new rotaxane containing the 3-amido-phenyl-triazolium group incorporated into the interlocked structure's axle component has been prepared by a chloride anion templated clipping strategy. Proton NMR titration experiments reveal that the interlocked host displays a high degree of halide anion recognition in competitive 1 : 1 CDCl3-CD3OD solvent mixture. Chloride and bromide anions are bound strongly and selectively, with negligible complexation of the larger, more basic oxoanions, acetate and dihydrogen phosphate being observed. Density functional theory calculations on the related axle motifs 3-amido-phenyl-triazolium, pyridinium bis-triazole and pyridinium bis-amide were performed, and indicate that the new rotaxane axle motif displays much weaker oxoanion binding than the pyridinium based systems.

Sensitive water-soluble fluorescent chemosensor for chloride based on a bisquinolinium pyridine-dicarboxamide compound

“…Artificial biomimetic receptors containing amide and urea groups as anion recognition sites constitute one of the largest sub-groups in this field (Asthana et al, 2013;Chang et al, 2015;Ge et al, 2014;Kubik et al, 2005;Lin et al, 2015;Pinter et al, 2013;Warwick et al, 2013;White and Beer, 2013;White et al, 2014, Warwick et al, 2013. Chloride recognition with these systems is mostly achieved by hydrogen bonding interactions, which in many cases are not strong enough to overcome the high energy of hydration (ΔG = -340 kJ/mol) besides the fact that water molecules efficiently compete for the binding sites (Butler and Parker, 2013;Kubik, 2010).…”

“…In principle, a chemosensor with sensibility for chloride could be achieved using synthetic receptors containing a binding site with a high affinity for Cl -and a signaling unit that can transduce the phenomenon of association to an optical change. Recent works in Page 3 of 20 A c c e p t e d M a n u s c r i p t 3 this line in aqueous media include synthetic receptors such as rotaxanes and cryptands with amide groups (Ambrosi et al, 2011;Hancock et al, 2010;White et al, 2014), colorimetric sensors with phenol groups (Zhang et al, 2009), calix[4]arenes (McConnell et al, 2010), pseudopeptidic host (Martí et al, 2014) and metal-based receptors (Dorazco-González, 2014). However, the creation of a selective sensor for chloride in pure water is an ongoing challenge.…”

Nitrate Anion Recognition in Organic–Aqueous Solvent Mixtures by a Bis(triazolium)acridine‐Containing [2]Rotaxane

“…[37] Interestingly,t he halide anions are bound with comparable affinity to nitrate in the order Br À > Cl À > I À .S ignificantly,t his bromide halide preference is also observed in an umber of relatedt riazolium-axle- containing rotaxane host systems. [23][24][25] It is noteworthy that the associationc onstant for nitrate with rotaxane 11·2 PF 6 (1010 m À1 )i sl arger than the association constants determined for nitrate binding by our previously reported interlocked hosts (430 m À1 and 250 m À1 for the rotaxane [21] and catenane receptors, [22] respectively) in the same competitive organicaqueous solvent mixture. This may in part reflect the increased positive charge of the bis(triazolium)acridine axle component of 11·2 PF 6 compared with the previous mono-cationic pyridinium-containing interlocked hosts.…”

“…Herein, we report the synthesis of a novel [2]rotaxane host containing a bis(triazolium)acridine axle, which exhibits enhanced nitrate recognition in a competitive organic–aqueous solvent mixture, with excellent selectivity over a range of more basic oxoanions (AcO − , HCO 3 − and H 2 PO 4 − ). The nitrate anion is bound within a complementary three‐dimensional, trigonal cavity through convergent charge‐assisted triazolium CH hydrogen bonds23–25 donated from the acridine axle component and amide NH hydrogen bonds from the macrocycle (Figure 1).…”

The Synthesis and Anion Recognition Property of Symmetrical Chemosensors Involving Thiourea Groups: Theory and Experiments

“…So far, the focus has been mainly on the design a chemosensor which has the ability to bind the biologically important anions. The binding sites in artificial chemosensors are significant and often include amide [ 17 ], urea [ 18 ], hydroxyl [ 19 , 20 ] and pyrrole [ 21 ] moieties due to the strong binding ability to act as hydrogen-bond donors. Among the possible hydrogen-bond donors, thiourea derivatives are particularly good [ 22 , 23 , 24 ].…”