Anion Complexation by Triazolium “Ligands”: Mono- and Bis-tridentate Complexes of Sulfate

Schulze, Benjamin; Friebe, Christian; Hager, Martin D.; Günther, Wolfgang; Köhn, Uwe; Jahn, Burkhard O.; Görls, Helmar; Schubert, Ulrich S.

doi:10.1021/ol100776x

Cited by 97 publications

(70 citation statements)

References 23 publications

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“…Several seminal studies have demonstrated the ability of acyclic and macrocyclic bis- and poly(triazole) containing systems to bind anions in organic solvents through triazole C–H···anion interactions [4–7]. More recently, we [8], and others [9–10], have shown that alkylating the triazole group to give the triazolium group increases the strength of anion binding significantly by further polarising the C–H bond of the heterocycle.…”

Section: Introductionmentioning

confidence: 99%

A ferrocene redox-active triazolium macrocycle that binds and senses chloride

White

Beer

2012

Beilstein J. Org. Chem.

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SummaryA ferrocene bis(triazole) macrocycle was synthesised in good yield by the Eglinton coupling of an acyclic bis(alkyne) precursor and characterised in the solid state by X-ray crystallography. Alkylation gives the corresponding triazolium macrocycle, which binds chloride and benzoate strongly in CD3CN solution through favourable charge-assisted C–H···anion interactions, as evidenced by 1H NMR titration experiments. Preliminary electrochemical studies reveal that the redox-active macrocycle is capable of sensing chloride in CH3CN solution.

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Section: Introductionmentioning

confidence: 99%

A ferrocene redox-active triazolium macrocycle that binds and senses chloride

White

Beer

2012

Beilstein J. Org. Chem.

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“…While there are several classes of anion receptors containing neutral NH groups including ureas, thioureas, amides, pyrroles, imidazoles and indoles, 6–11 exclusive fluoride receptors that selectively recognize fluorides over other halides are indeed rare. 6 In most cases, such receptors bind other anions also, thereby hampering the selectivity for fluoride.…”

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confidence: 99%

An exclusive fluoride receptor: fluoride-induced proton transfer to a quinoline-based thiourea

Başaran

Khansari

Pramanik

et al. 2014

Tetrahedron Letters

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A new quinoline-based tripodal thiourea has been synthesized, which exclusively binds fluoride anion in DMSO, showing no affinity for other anions including, chloride, bromide, iodide, perchlorate, nitrate and hydrogen sulfate. As investigated by 1H NMR, the receptor forms both 1:1 and 1:2 complex yielding the binding constants of 2.32(3) (in log β1) and 4.39(4) (in log β2), respectively; where quinoline groups are protonated by the fluoride-induced proton transfer from the solution to the host molecule. The 1:2 binding is due to the interactions of one fluoride with NH binding sites of urea sites and another fluoride with secondary +NH binding sites within the tripodal pocket. The formation of both 1:1 and 1:2 complexes has been confirmed by the theoretical calculations based on density functional theory (DFT).

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“…3 Therefore, an increasing attention has recently been devoted to sulfate binding with synthetic receptors which include polyamines, 4 polyamides, 5 ureas, 6 indoles, 7 self-assembled metal–organic hosts, 8 and triazolium hosts. 9 The oxygen atoms in oxoanions are generally coordinated with two hydrogen bonds, thus sulfate with four oxygens is often found to be octacoordinated with synthetic receptors. 5a,10 Custelcean et al have shown that a tren-based urea linked with Ag 2 SO 4 is capable of binding a sulfate by twelve hydrogen bonds ( d N ··· O = 2.8516 to 3.1741 Å), 8a which is consistent with Hay’s prediction that each oxygen could be involved in a maximum of three hydrogen bonds.…”

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confidence: 99%