Self-Assembled Organometallic [12]Metallacrown-3 Complexes

Piotrowski, Holger; Hilt, Gerhard; Schulz, Axel; Mayer, Péter; Polborn, Kurt; Severin, Kay

doi:10.1002/1521-3765(20010803)7:15<3196::aid-chem3196>3.0.co;2-m

Cited by 115 publications

(90 citation statements)

References 105 publications

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“…For 1, three irreversible oxidations are observed at 683, 963, and 1,150 mV (against Ag͞AgCl). These values are higher than those found for the [(arene)Ru(C 5 H 3 NO 2 )] 3 complexes previously described (15), indicating an increased stability of 1 toward oxidation. In the presence of LiCl, the first peak potential is shifted by more than 350 mV toward anodic potential.…”

Section: Resultssupporting

confidence: 91%

“…17-21 (Cp* represents pentamethylcyclopentadienyl)]. The bond length and angles are within the expected range (15). The complex cocrystallizes with two molecules of water, one of which is found inside the cavity.…”

Section: Resultssupporting

confidence: 50%

“…In elaboration of a synthetic scheme which we have reported recently (14,15), the trinuclear metallamacrocycle 1 was obtained by reaction of commercially available 3-hydroxy-2-pyridone with [(C 6 H 5 CO 2 Et)RuCl 2 ] 2 in the presence of base (Scheme 1). The chloro-bridged ruthenium complex used in this reaction is a common starting material in organometallic chemistry and can easily be obtained from RuCl 3 ⅐(H 2 O) n and ethyl-1,4-cyclohexadiene-3-carboxylate (16).…”

Section: Resultsmentioning

confidence: 99%

“…It is interesting to compare our receptor with the metallamacrocyclic ionophores that we have reported recently (15). Competitive extraction experiments described above were performed by using the structurally related trinuclear complex [(cymene)Ru(C 5 H 3 NO 2 )] 3 (cymene ϭ p-i Pr-C 6 H 4 -CH 3 ) (2).…”

Section: Resultsmentioning

confidence: 99%

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A self-assembled, redox-responsive receptor for the selective extraction of LiCl from water

Piotrowski

Severin

2002

Proc. Natl. Acad. Sci. U.S.A.

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There is considerable interest in synthetic ionophores with high affinity and selectivity for Li ؉ . But so far, compounds that selectively bind Li ؉ in the presence of other alkali and alkaline earth metal ions are rare and current approaches toward this goal are often accompanied with substantial synthetic efforts. Here we describe a trinuclear ruthenium metallamacrocyclic complex (1) that was obtained by self-assembly of ruthenium halfsandwich complexes and 3-hydroxy-2-pyridone ligands. This complex was shown to be an extremely potent receptor for LiCl with an affinity high enough to extract LiCl from water. The selectivity of this receptor is exceptional: even in the presence of a large excess of Na ؉ , K ؉ , Cs ؉ , Ca 2؉ , and Mg 2؉ , Li ؉ was extracted exclusively. The Li ؉ ͞Na ؉ selectivity ratio was determined to be higher than 1,000:1. Compared with other synthetic ionophores, the receptor 1 offers two additional advantages: (i) the synthesis can be accomplished in one step by using simple starting materials; and (ii) the presence of lithium ions can be detected electrochemically. Complex 1 is therefore a very attractive candidate for the construction of a Li ؉ -specific chemosensor.L ithium salts have found various applications in technology and medicine. Methods to selectively sequester and detect Li ϩ are therefore of importance. Li 2 CO 3 , for example, is one of the most important drugs for the treatment of manic depression (1, 2). Because of its narrow therapeutic range, the Li ϩ concentration in the blood of the patients needs to be controlled during the treatment. Thus, a small amount Li ϩ has to be detected in the presence of other metal ions such as Na ϩ , K ϩ , Ca 2ϩ , and Mg 2ϩ (3).To selectively sequester Li ϩ , ionophores have been considered early on. But the design and the synthesis of molecules that display a high affinity and selectivity for Li ϩ is a challenging task (4-9). Although considerable progress has been made in this field, the synthesis of such ionophores often requires substantial synthetic efforts. This difficulty is nicely illustrated by probably the best Li ϩ receptor known so far, a spherand developed by Cram and his colleagues (10). Because of the perfect preorganization of six oxygen donor atoms, a very high affinity combined with an excellent selectivity for Li ϩ is observed. The synthesis, however, requires several steps and gives less than 7% overall yield.Here we describe a redox-responsive metallamacrocycle (1; see Scheme 1) that was obtained by self-assembly (for selfassembled metallacrowns see ref. 11). With this receptor we were able to selectively extract LiCl from an aqueous solution containing an excess of NaCl, KCl, CsCl, CaCl 2 , and MgCl 2 . The presence of LiCl can subsequently be detected by electrochemical means. Materials and MethodsGeneral. The synthesis of all complexes was performed under an atmosphere of dry dinitrogen, by using standard Schlenk techniques. The 1 H, 13 C, and 7 Li spectra were recorded on a JEOL EX 400 or a GSX 270 spectrometer u...

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Section: Resultssupporting

confidence: 91%

Section: Resultssupporting

confidence: 50%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

A self-assembled, redox-responsive receptor for the selective extraction of LiCl from water

Piotrowski

Severin

2002

Proc. Natl. Acad. Sci. U.S.A.

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“…Indeed, except for the porphyrin derivative reported by Tabata et al, 9 no host compound has been shown to be so selective that it can be applied to the analysis of Li + in seawater. In the early 2000s, a new class of host molecules, macrocyclic trinuclear complexes [{M(arene)(pyO2)}3] (M = transition metal, pyO2 = 2,3-pyridinediolate), were found by Severin et al [14][15][16] These "metallacrowns" can be easily prepared through self-assembly reactions, and most of them are highly selective for Li + . In addition, a few derivatives for the fluorometric detection of Li + in water were designed.…”

Section: Introductionmentioning

confidence: 98%

Application of a Lithium-ion Selective Metallacrown to Extraction-Spectrophotometric Determination of Lithium in Saline Water

2018

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The solvent-extraction behavior of Li + and Na + with a Li + selective metallacrown, [{Ru(η 6 -3,5-dimethylanisole) (2,3-pyridinediolate)}3], was investigated in the presence of organic dye anions, 3′,3″,5′,5″-tetrabromophenolphthalein ethyl ester ([TBPE] -), 2,6-dichloroindophenolate, and picrate ([pic] -). Each alkali metal ion was extracted as a 1:1:1 ternary complex of the metal ion, metallacrown, and anion. The Li + /Na + extraction selectivity is anion dependent and highest with [pic] -. Therefore, we devised an extraction-spectrophotometric determination method for Li + in saline water based on the extraction of Li + using the metallacrown and [pic] -for high selectivity and subsequent replacement of [pic] -in the extracted species with [TBPE] -for high sensitivity. When applying this to artificial seawater samples containing known concentrations of Li + , a linear relationship was observed between the absorbance at 571 nm of the organic phase and the Li + concentration in the samples. By this method, the determination of Li + at the sub-ppm level in natural seawater is possible.

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Selective Recognition of Fluoride Anion Using a Li+–Metallacrown Complex

et al. 2002

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With the final goal of constructing specific chemosensors for fluoride anions, considerable efforts have been put into the synthesis of compounds that are able to bind fluoride ions with high affinity and selectivity. The receptors described include organic macrocycles with convergent H-bond donor groups and compounds containing Lewis acidic boron, silicon, or tin atoms. [1,2] Here we report a conceptually new fluoride receptor, the basic principle of which is shown in Figure 1. A lithium ion, which serves as a binding site, is coordinated Figure 1. Schematic representation of a selective fluoride receptor with a Li ion binding site.inside a three-dimensional host compound. The accessibility of the Li center is controlled by the steric requirements of the host: the small fluoride anion is able to enter the cavity whereas larger anions are efficiently blocked. Since the radius of the fluoride ion is significantly shorter than that of most other anions, [1b] a highly specific receptor is obtained.The utilization of the hard acid Li ion for the binding of the hard base F À appears to be very attractive, but so far Libased fluoride receptors have not been described. In fact, there is not even structural data available on complexes containing molecular LiF, [3, 4] although numerous examples of other alkali metal halide complexes are known. The difficulty of stabilizing molecular LiF arises from its very high lattice energy which makes crystalline LiF a thermodynamic trap. [4b] Recently, we have described the synthesis of trimeric organometallic complexes of the general formula [L n M(C 5 H 3 NO 2 )] 3 (L n M arene-Ru or Cp*Rh; Cp* C 5 Me 5 ). [5] These analogues of [12]crown-3 [6] were shown to bind alkali metal halides with remarkable affinity and selectivity. In an extension of this work we have investigated the reaction of [{Cp*IrCl 2 } 2 ] with 3-hydroxy-2-pyridone in the presence of base. As in the cases with the analogous ruthenium and rhodium complexes, a trimeric complex [Cp*Ir(C 5 H 3 NO 2 )] 3 (1) was obtained. The metallamacrocycle was characterized by NMR spectroscopy ( 1 H, 13 C), elemental analysis, and single-crystal X-ray analysis (Figure 2). [7] A pseudo-C 3 -symmetric geometry is observed in the solid state, with dianionic pyridonate ligands bridging the Cp*Ir III frag- Figure 2. a) The molecular structure of 1 in the crystal; b) view along the pseudo-C 3 axis of 1 highlighting the sterically shielded binding site (space filling representation); c) the molecular structure of 1 ¥ LiF in the crystal; d) view along the pseudo-C 3 axis of 1 ¥ LiF. Four very short CH ¥¥¥ F contacts are observed (the water molecule is omitted in the space filling representation).

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Self-Assembled Organometallic [12]Metallacrown-3 Complexes

Cited by 115 publications

References 105 publications

A self-assembled, redox-responsive receptor for the selective extraction of LiCl from water

A self-assembled, redox-responsive receptor for the selective extraction of LiCl from water

Application of a Lithium-ion Selective Metallacrown to Extraction-Spectrophotometric Determination of Lithium in Saline Water

Selective Recognition of Fluoride Anion Using a Li+–Metallacrown Complex

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