Enhancing the enantioselective recognition and sensing of chiral anions by halogen bonding

Lim, Jason Y. C.; Marques, Igor; Ferreira, Liliana; Félix, Vítor; Beer, Paul D.

doi:10.1039/c6cc01701k

Cited by 77 publications

(72 citation statements)

References 31 publications

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“…Indeed, formation and detection of XBs in solution are more complicated as compared to the solid state because the interactions can be influenced by conformational freedom of the molecules, a less ordered medium, and solvent effects on both donor and acceptor [5]. Another open issue concerns the application of XB in chiral systems, and few chiral molecules having σ-holes on halogens as recognition sites were described recently [5][6][7][8][9][10][11]. Perfluorinated and cationic N-heterocyclic substructures ( Figure 1B) are able to activate potential σ-hole sites and generate strong XBs, which are detectable by means of a variety of spectroscopic techniques, of which NMR spectroscopy is the most widely used [12].…”

Section: Introductionmentioning

confidence: 99%

Polysaccharide‐based chiral stationary phases as halogen bond acceptors: A novel strategy for detection of stereoselective σ‐hole bonds in solution

Peluso

Mamane

Dallocchio

et al. 2018

J of Separation Science

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In the last few years, halogen bonds have been exploited in a variety of research areas both in the solid state and in solution. Nevertheless, several factors make formation and detection of halogen bonds in solution challenging. Moreover, to date, few chiral molecules containing electrophilic halogens as recognition sites have been reported. Recently, we described the first series of halogen-bond-driven enantioseparations performed on cellulose tris(3,5-dimethylphenylcarbamate) by high-performance liquid chromatography. Herein the performances of amylose tris(3,5-dimethylphenylcarbamate) as halogen bond acceptor were also investigated and compared with respect to cellulose tris(3,5-dimethylphenylcarbamate). With the aim to explore the effect of polysaccharide backbone on the enantioseparations, the thermodynamic parameters governing the halogen-dependent enantioseparations on both cellulose and amylose polymers were determined by a study at variable temperature and compared. Molecular dynamics were performed to model the halogen bond in polysaccharide-analyte complexes. Chiral halogenated 4,4'-bipyridines were used as test compounds (halogen bond donors). On this basis, a practical method for detection of stereoselective halogen bonds in solution was developed, which is based on the unprecedented use of high-performance liquid chromatography as technical tool with polysaccharide polymers as molecular probes (halogen bond acceptors). The analytical strategy showed higher sensitivity for the detection of weak halogen bonds.

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Section: Introductionmentioning

confidence: 99%

Polysaccharide‐based chiral stationary phases as halogen bond acceptors: A novel strategy for detection of stereoselective σ‐hole bonds in solution

Peluso

Mamane

Dallocchio

et al. 2018

J of Separation Science

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“…Polyhalides continue being an attractive research field which, although discovered almost 200 years ago, keeps providing the community of inorganic chemists with novel fascinating results . These studies, both theoretical and experimental, are important from the point of view of main group chemistry; besides, they are of interest in terms of halogen bonding concept which is intensively developed within the last years …”

Section: Introductionmentioning

confidence: 99%

1D and 2D Polybromotellurates(IV): Structural Studies and Thermal Stability

et al. 2018

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“…15,16 System 4 also includes a chiral (S)-binaphthol core in order to investigate XB chiral recognition, which has only previously been observed in a bidentate receptor. 17 Importantly, the XB foldamers exhibited overall stronger anion affinity than their HB analogs with the chiral XB host 4b displaying chiral discrimination with bulky amino acid anions. XB and HB foldamers 1-4 were synthesized via Cu(I)-catalysed azide-(iodo)alkyne cycloaddition (CuAAC) reactions (Scheme 1) using Cu(MeCN) 4 PF 6 in the presence of tris(benzyltriazolylmethyl) amine (TBTA) ligand.…”

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confidence: 99%

Neutral iodotriazole foldamers as tetradentate halogen bonding anion receptors

et al. 2017

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Neutral tetradentate halogen bond donor foldamers were synthesised and exhibit enhanced anion affinities over their hydrogen bonding analogues, displaying iodide selectivity over lighter halide, carboxylate and dihydrogen phosphate anions. A foldamer with a chiral (S)-binaphthol motif was demonstrated to distinguish between enantiomers of chiral anions.Halogen bonding (XB) is the attractive non-covalent interaction between a terminal s-hole on an electron deficient halogen atom and a Lewis base.1 Its strength and directionality have led to several applications in materials science and, more recently, in supramolecular chemistry 2,3 and organocatalysis. 4 In particular, XB donors have been successfully used in anion receptors for molecular recognition and sensing applications. 5 Many of these have shown enhanced binding properties over their hydrogen bonding (HB) analogues.6,7The electron-deficient 8 1,2,3-triazole motif has been exploited for anion recognition as an effective C-H hydrogen bond donor when integrated into multidentate macrocycles 9 and acyclic foldamers. [10][11][12] While the related 5-iodotriazole unit has been used as XB donor for anion binding, such XB anion hosts are rare in the literature. 13 No tetradentate XB donor foldamers have been described to date; the closest examples are a tridentate halopyridinium 14 and the use of triazole foldamers as XB acceptor hosts for organohalogens. 15Herein we sought to apply the potency of XB to enhance the anion affinity of the known triazole-based HB foldamer framework. Thus, XB foldamers with four 5-iodo-1,2,3-triazole XB donors were synthesized (Fig. 1) and their anion binding properties probed in comparison with HB analogues. A few variants were prepared: 1 and 2 contain triethylene glycol (TEG) chains for improved solubility, while in 3 and 4 9-anthrylmethyl termini have been introduced to provide a fluorescent response. 15,16 System 4 also includes a chiral (S)-binaphthol core in order to investigate XB chiral recognition, which has only previously been observed in a bidentate receptor. 17 Importantly, the XB foldamers exhibited overall stronger anion affinity than their HB analogs with the chiral XB host 4b displaying chiral discrimination with bulky amino acid anions. XB and HB foldamers 1-4 were synthesized via Cu(I)-catalysed azide-(iodo)alkyne cycloaddition (CuAAC) reactions (Scheme 1) using Cu(MeCN) 4 PF 6 in the presence of tris(benzyltriazolylmethyl) amine (TBTA) ligand. For the preparation of 1a and 2a an alternative benzyltriazolylmethylamine (BTA) ligand 18 was used as these compounds co-eluted with TBTA during chromatographic purification. As seen in Scheme 1, a terminal azide synthon 5-7 was reacted statistically with an excess of bis-alkyne 8a or 8b to afford an arm fragment 9-11. Two equivalents of 9-11 were then coupled under CuAAC conditions with a bis-azide core synthon 12 or 13 to give the anion receptors 1-4. The cycloadditions proceeded in moderate to high yields of 64-88% for 5H-triazole and 46-85% for 5I-triazole formation (s...

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Enhancing the enantioselective recognition and sensing of chiral anions by halogen bonding

Cited by 77 publications

References 31 publications

Polysaccharide‐based chiral stationary phases as halogen bond acceptors: A novel strategy for detection of stereoselective σ‐hole bonds in solution

Polysaccharide‐based chiral stationary phases as halogen bond acceptors: A novel strategy for detection of stereoselective σ‐hole bonds in solution

1D and 2D Polybromotellurates(IV): Structural Studies and Thermal Stability

Neutral iodotriazole foldamers as tetradentate halogen bonding anion receptors

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