Noncovalent Catch and Release of Carboxylates in Water

Abstract

Association constants of a bis-(acetylguanidinium)ferrocene dication to various (di)carboxylates were determined through UV-vis titrations. Association constant values greater than 10 4 M -1 were determined for both phthalate and maleate carboxylates to the bis-(acetylguanidinium)ferrocene salt in pure water. Density functional theory computations of the binding enthalpy of the rigid carboxylates for these complexes agree well with the experimentally determined association constants. Catch and release competitive binding experiments were done by NMR for the cation-carboxylate ion-pair complexes with cucurbit [7]uril, and they show dissociation of the ion-pair complex upon addition of cucurbit [7] ABSTRACT: Association constants of a bis-(acetylguanidinium)ferrocene dication to various (di)carboxylates were determined through UV−vis titrations. Association constant values greater than 10 4 M −1 were determined for both phthalate and maleate carboxylates to the bis-(acetylguanidinium)ferrocene salt in pure water. Density functional theory computations of the binding enthalpy of the rigid carboxylates for these complexes agree well with the experimentally determined association constants. Catch and release competitive binding experiments were done by NMR for the cation−carboxylate ion-pair complexes with cucurbit [7]uril, and they show dissociation of the ion-pair complex upon addition of cucurbit [7]uril and release of the free (di)carboxylate.

Binding Interactions between a Ferrocenylguanidinium Guest and Cucurbit[n]uril Hosts

“…Beck and Winter have shown that CB7 forms a stable complex with a guest related to FcG + , bis(acetyl-guanidinium)ferrocene, leading to a disruption of the binding interactions of this dicationic ferrocene derivative with dicarboxylates in aqueous media. 3 Our experimental results clearly show that the monocationic ferrocenyl guanidinium (FcG + ) guest forms stable complexes with both hosts, CB7 and CB8. The CB7•FcG + complex exhibits higher thermodynamic stability than its CB8 counterpart.…”

“…Guanidine-based functional groups are common in biomolecules and may find applications in areas of chemistry as diverse as coordination compounds, organocatalysis, and anion recognition. , Bis­(cyclopentadienyl)­iron­(II), better known as ferrocene, is an important organometallic compound that can be easily functionalized to yield a large number of derivatives. Very recently, some of us have reported the catalytic generation of ferrocene-containing guanidines and their use as precursors for the preparation of platinum­(II) complexes with anticancer activity .…”

Electropolymerization of N,N'-Diphenylguanidine in Non-Aqueous Aprotic Solvents and Alcohols

“…Functionalization with guanidinium moiety can make possible sensing of carboxylates [19,20], and any other oxoanions [21][22][23]. Metal-free redox active guanidines were also synthesized and used as reducing agents [24].…”

AAAA–DDDD Quadruple H-Bond-Assisted Ionic Interactions: Robust Bis(guanidinium)/Dicarboxylate Heteroduplexes in Water

“…Two of the more distinctive approaches pursued to date in an effort to modulate guanidinium/carboxylate dimers are Hamilton’s design of V- or claw-shaped/size complementary hosts and guests − and Schmuck’s elegant use of auxiliary pyrrolyl NH hydrogen bond donors to reinforce the bonding of a guanidinium cation to a carboxylate anion, respectively (Figure ). Nevertheless, these system still fall short of being ideal.…”