Tripodal Tris-tacn and Tris-dpa Platforms for Assembling Phosphate-Templated Trimetallic Centers

Cao, Rui; Müller, Péter; Lippard, Stephen J.

doi:10.1021/ja108212v

Cited by 51 publications

(63 citation statements)

References 42 publications

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“…25 Because technetium is radioactive with a long half-life (~10 6 years), we decided to use perrhenate as a model of pertechnetate for these studies. Table 2 reveals that the geometric features of perrhenate and pertechnetate, including the radii of the metal center, 30 metal-oxo bond lengths, 31 and effective ionic radii of the two tetraoxoanions, 1,32 are very similar.…”

Section: Synthesis and Structural Characterization Of Complexmentioning

confidence: 99%

“…The binding constants of anions in these systems are small, and this problem is especially troubling for the binding of pertechnetate, which is relatively large, of low charge density, and has a small enthalpy of complexation. 2 As a consequence, it has proved difficult to prepare receptors for 25 As a result, the tridentate bridging tetraoxoanion is immobilized by the trinuclear metal complex via strong covalent bonds.…”

Section: Introductionmentioning

confidence: 99%

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Immobilization, Trapping, and Anion Exchange of Perrhenate Ion Using Copper-Based Tripodal Complexes

2011

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Abstract:We describe a multidentate tripodal ligand in which three pendant arms carrying di(2-picolyl)amine units are linked to the ortho-positions of a tris (o-xylyl) scaffold, providing N(CH 2 -o-C 6 H 4 -CH 2 N(CH 2 py) 2 ) 3 (L). Reaction of L with CuCl 2 in the presence of hexafluorophosphate anion afforded blue cubes of [(CuCl) 3 L](PF 6 ) 3 ⋅5H 2 O (1). Crystallographic studies of 1 revealed that the three symmetry-related arms each coordinate a {Cu II Cl} unit, and two molecules of 1 are connected to one another through a Cu(µ-Cl) 2 Cu bridge, extending the molecular structure to form a two-dimensional layer.These 2-D layers pack in an ABCABC… fashion with PF 6 -anions located in between.Reaction of 1 with a stoichiometric amount of perrhenate ion afforded blue plates ofCompound 2 has the same lattice structure of 1, but the tricopper unit backbone now traps one ReO 4 -anion through Coulombic interactions.In addition, three molecules of 2 are bridged by a perrhenate ion forming a Cu 3 (µ 3 -ReO 4 )cluster to give a different 2-D structure, displaying a rare tridentate bridging ReO 4 -mode.Thus in addition to classic perrhenate trapping through weak Coulombic interactions, 2 represents an exceptional example in which the ReO 4 -anion is immobilized in an extended framework through tight covalent interactions. The interlamellar PF 6 -anions in 1 can be exchanged with other anions including perrhenate, perchlorate, or periodate. The structural similarity between perrhenate and pertechnetate makes these materials of potential interest for pertechnetate trapping.3

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Section: Synthesis and Structural Characterization Of Complexmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Immobilization, Trapping, and Anion Exchange of Perrhenate Ion Using Copper-Based Tripodal Complexes

2011

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“…Our interest in studying zinc coordination and catalysis led us to generate trinuclear zinc complexes that are able to bind m 3 -oxoanions of biological significance (for example, phosphate and carbonate) 4,8,9,13 . Tris-DPA ligand L, which contains a tris(xylyl)amine scaffold and three DPA coordination moieties 42,43 , was chosen. The tris(xylyl)amine scaffold provides Trinucleating ligand L has three DPA units attached to the ortho positions of a tris(xylyl)amine scaffold.…”

Section: Resultsmentioning

confidence: 99%

“…1). Complex 2 is the first example of a synthetic {Zn 3 (m 3 -PO 4 )} core stabilized in a single ligand framework that mimics the natural zinc core of enzymes 42 such as P1 nuclease 44,45 and phospholipase C 46,47 . The stability in solution of the m 3 -oxoanions is evaluated via multinuclear nuclear magnetic resonance (NMR) and high-resolution mass spectrometry (HRMS).…”

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confidence: 99%

Trinuclear zinc complexes for biologically relevant μ3-oxoanion binding and carbon dioxide fixation

Liu

Cao

2013

Nat Commun

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Tremendous efforts have been made to model multinuclear zinc enzymes. Despite such efforts, it remains a challenge to design single molecules that stabilize m 3 -oxoanion-bridged trinuclear zinc cores as analogues of enzymatic active sites. The conversion of carbon dioxide to carbonates is a biological process mediated by carbonic anhydrases and a natural process for large-scale carbon dioxide fixation. Here we report a trinuclear zinc scaffold for capturing biologically relevant m 3 -oxoanions, such as phosphate and carbonate, and its ability to catalytically convert carbon dioxide to carbonates. Structurally characterized {Zn 3 (m 3 -PO 4 )} and {Zn 3 (m 3 -CO 3 )} cores are observed in solution by nuclear magnetic resonance and high-resolution mass spectrometry. The activity of the m 3 -carbonate unit can be sterically controlled, which makes the carbon dioxide fixation cycle feasible. Our results suggest that this trinuclear zinc scaffold catalytically converts carbon dioxide to carbonates under mild conditions and provides a good model for studying oxoanion-bridged zinc cores in solution.

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“…This substrate was synthesised by reduction of ethyl 2-cyanobenzoate according to literature procedure. 16 When the cyclisation reaction of 8 was conducted in the presence of a strong base (2.5 eq. mol.)…”

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confidence: 99%

5-Membered N-heterocyclic compounds by dimethyl carbonate chemistry

2012

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Aliphatic and aromatic 1,4-bifunctional compounds bearing a primary alcoholic function and an amine can be efficiently cyclised with dimethyl carbonates in the presence of a base to achieve 5-membered N-heterocyclic compounds. This novel synthetic pathway is quantitative, one-pot and green as it does not involve the use of chlorine solvents or reagent.N-Based heterocycles are very abundant in nature since they are present as structural subunits in many natural products such as vitamins, hormones and alkaloids. 1 These compounds are also interesting from an industrial point of view especially for the synthesis of pharmaceuticals, herbicides, pesticides, dyes, etc. 1 Among the reaction pathways leading to nitrogen-containing heterocycles, many involve heavy metals, e.g. metal-catalyzed intramolecular cyclisation of aliphatic a,w-diamine, 2 intramolecular and intermolecular Ru-catalyzed reactions, 3 intramolecular cyclisation of diallyl amine by Grubb's catalyst, 4 or gas-phase high-temperature reaction using zeolites. 5 In recent years, more sustainable approaches for the synthesis of N-based heterocycles have been reported, 6 such as photocatalytic cyclisation of a,w-diamine carboxylic acids by aqueous semiconductor suspensions 7 and microwave-assisted synthesis from alkyl dihalides and primary amines. 8 However, most of the above-mentioned reactions still require high temperature and long reaction time, utilize chlorine-based chemistry or eventually organic chlorinated solvents.Short chain dialkyl carbonates such as dimethyl carbonate (DMC), produced nowadays by clean processes, 10 are renowned for possessing properties of low toxicity and high biodegradability, which make them true green solvents and reagents. 11 DMC has been used as efficient eco-sustainable substitute of the most common methylating and carboxymethylating agents such as phosgene, methyl halides or methylsulfate that are toxic and highly corrosive. 12 Dialkyl carbonates and in particular DMC have shown high selectivity with different monodentate and bidentate nucleophiles acting as methylating and/or carboxymethylating agent. 13 The reactivity of the two electrophilic centers of DMC can be selectively tuned, temperature being the key factor. In fact, usually at reflux temperature (T = 90 • C) DMC acts as methoxycarbonylation agent by B Ac 2 mechanism while at higher temperature (T > 150 • C) the methylation reaction occurs via the B Al 2 mechanism. Both reactions produce as by-product only methanol and eventually CO 2 . 11-13 Exploiting the DMC (B Al 2-B Ac 2) chemistry, recently we reported a novel, one-pot, environmentally benign and chlorinefree synthetic pathways for the synthesis of 5-membered cyclic ethers by intramolecular cyclisation of 1,4-diols. 9

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Tripodal Tris-tacn and Tris-dpa Platforms for Assembling Phosphate-Templated Trimetallic Centers

Cited by 51 publications

References 42 publications

Immobilization, Trapping, and Anion Exchange of Perrhenate Ion Using Copper-Based Tripodal Complexes

Immobilization, Trapping, and Anion Exchange of Perrhenate Ion Using Copper-Based Tripodal Complexes

Trinuclear zinc complexes for biologically relevant μ3-oxoanion binding and carbon dioxide fixation

5-Membered N-heterocyclic compounds by dimethyl carbonate chemistry

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