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The coordination-directed self-assembly approach is an extremely powerful strategy for the synthesis of various 2-and 3D metallasupramolecules and can provide a structural and functional basis for its potential application toward molecular sensing and catalysis by using supramolecular chemistry.[1] In particular, discrete 3D self-assemblies derived from the multiple noncovalent interactions between monomeric metallo-subunits, such as chains, squares, and/or cages, are very intriguing because they are structurally complex but symmetrically simple and synthetically convenient to make. [2] Whereas various functional groups have been utilized for such purposes, little attention has been paid to metal-halide bonds, although they are well known as hydrogen-bond acceptors in molecular recognition and crystal engineering.[3] The halides are usually destined to be eliminated, presumably as a result of limited coordination sites on the metal center for incoming ligands.[1] These facts prompted us to explore the way to get the metal-halide groups to participate in both the coordination-directed and noncovalent self-assembly processes without their abstraction. Considering the molecular library model, [1g] we envisioned that the octahedral geometry of a transition metal might provide a novel approach for the use of metal-halide bonds as a self-assembly motif. For example, octahedral transition-metal centers with axial halide and cisprotecting ligands could serve as a 908 building block. The axial halide, then, may participate in hydrogen bonding with suitably functionalized bridging ligands.Herein, we demonstrate the unprecedented self-complementary dimer of Ru II metallamacrocycles which uses the intact metal-halide bonds in the coordination-directed selfassembly process and its reversible dissociation/association behavior, which is controlled by halide anions in solution.The ligand N,N'-bis(pyridin-4-yl)pyridine-2,6-dicarboxamide (1) was quite suitable for our purpose because it has central amide protons as hydrogen-bonding donors and is well known for bridging two metal centers, thus giving metallamacrocycles.[4] In addition, its bisamide configuration has proven to be very useful in hydrogen-bonding-mediated rotaxane formation [5] and anion recognition [6] with metallasupramolecules. As a precursor for the metal center, [RuCl 2 (PPh 3 ) 3 ] (2) was chosen for its ability to give a transCl 2 -cis-N 2 -cis-P 2 coordination environment around the Ru II center by reaction with a chelating phosphine and N-donor ligands. [7] Stirring equimolar amounts of 1, 2, and 1,3-bis(diphenylphosphino)propane (DPPP) in acetone at room temperature yielded the orange solid of 3 2 in good yield (87 %; Scheme 1).A single-crystal X-ray structure determination of 3 2 unambiguously revealed an interesting supramolecular association between two severely folded molecules of Ru II metallamacrocycle 3 (Figure 1). [8] The folded metallacycles 3, self-complementary monomers of 3 2 , are oriented orthogonally to each other. This orthogonal assembly s...
The coordination-directed self-assembly approach is an extremely powerful strategy for the synthesis of various 2-and 3D metallasupramolecules and can provide a structural and functional basis for its potential application toward molecular sensing and catalysis by using supramolecular chemistry.[1] In particular, discrete 3D self-assemblies derived from the multiple noncovalent interactions between monomeric metallo-subunits, such as chains, squares, and/or cages, are very intriguing because they are structurally complex but symmetrically simple and synthetically convenient to make. [2] Whereas various functional groups have been utilized for such purposes, little attention has been paid to metal-halide bonds, although they are well known as hydrogen-bond acceptors in molecular recognition and crystal engineering.[3] The halides are usually destined to be eliminated, presumably as a result of limited coordination sites on the metal center for incoming ligands.[1] These facts prompted us to explore the way to get the metal-halide groups to participate in both the coordination-directed and noncovalent self-assembly processes without their abstraction. Considering the molecular library model, [1g] we envisioned that the octahedral geometry of a transition metal might provide a novel approach for the use of metal-halide bonds as a self-assembly motif. For example, octahedral transition-metal centers with axial halide and cisprotecting ligands could serve as a 908 building block. The axial halide, then, may participate in hydrogen bonding with suitably functionalized bridging ligands.Herein, we demonstrate the unprecedented self-complementary dimer of Ru II metallamacrocycles which uses the intact metal-halide bonds in the coordination-directed selfassembly process and its reversible dissociation/association behavior, which is controlled by halide anions in solution.The ligand N,N'-bis(pyridin-4-yl)pyridine-2,6-dicarboxamide (1) was quite suitable for our purpose because it has central amide protons as hydrogen-bonding donors and is well known for bridging two metal centers, thus giving metallamacrocycles.[4] In addition, its bisamide configuration has proven to be very useful in hydrogen-bonding-mediated rotaxane formation [5] and anion recognition [6] with metallasupramolecules. As a precursor for the metal center, [RuCl 2 (PPh 3 ) 3 ] (2) was chosen for its ability to give a transCl 2 -cis-N 2 -cis-P 2 coordination environment around the Ru II center by reaction with a chelating phosphine and N-donor ligands. [7] Stirring equimolar amounts of 1, 2, and 1,3-bis(diphenylphosphino)propane (DPPP) in acetone at room temperature yielded the orange solid of 3 2 in good yield (87 %; Scheme 1).A single-crystal X-ray structure determination of 3 2 unambiguously revealed an interesting supramolecular association between two severely folded molecules of Ru II metallamacrocycle 3 (Figure 1). [8] The folded metallacycles 3, self-complementary monomers of 3 2 , are oriented orthogonally to each other. This orthogonal assembly s...
The coordination-directed self-assembly approach is an extremely powerful strategy for the synthesis of various 2-and 3D metallasupramolecules and can provide a structural and functional basis for its potential application toward molecular sensing and catalysis by using supramolecular chemistry.[1] In particular, discrete 3D self-assemblies derived from the multiple noncovalent interactions between monomeric metallo-subunits, such as chains, squares, and/or cages, are very intriguing because they are structurally complex but symmetrically simple and synthetically convenient to make. [2] Whereas various functional groups have been utilized for such purposes, little attention has been paid to metal-halide bonds, although they are well known as hydrogen-bond acceptors in molecular recognition and crystal engineering.[3] The halides are usually destined to be eliminated, presumably as a result of limited coordination sites on the metal center for incoming ligands.[1] These facts prompted us to explore the way to get the metal-halide groups to participate in both the coordination-directed and noncovalent self-assembly processes without their abstraction. Considering the molecular library model, [1g] we envisioned that the octahedral geometry of a transition metal might provide a novel approach for the use of metal-halide bonds as a self-assembly motif. For example, octahedral transition-metal centers with axial halide and cisprotecting ligands could serve as a 908 building block. The axial halide, then, may participate in hydrogen bonding with suitably functionalized bridging ligands.Herein, we demonstrate the unprecedented self-complementary dimer of Ru II metallamacrocycles which uses the intact metal-halide bonds in the coordination-directed selfassembly process and its reversible dissociation/association behavior, which is controlled by halide anions in solution.The ligand N,N'-bis(pyridin-4-yl)pyridine-2,6-dicarboxamide (1) was quite suitable for our purpose because it has central amide protons as hydrogen-bonding donors and is well known for bridging two metal centers, thus giving metallamacrocycles.[4] In addition, its bisamide configuration has proven to be very useful in hydrogen-bonding-mediated rotaxane formation [5] and anion recognition [6] with metallasupramolecules. As a precursor for the metal center, [RuCl 2 (PPh 3 ) 3 ] (2) was chosen for its ability to give a transCl 2 -cis-N 2 -cis-P 2 coordination environment around the Ru II center by reaction with a chelating phosphine and N-donor ligands. [7] Stirring equimolar amounts of 1, 2, and 1,3-bis(diphenylphosphino)propane (DPPP) in acetone at room temperature yielded the orange solid of 3 2 in good yield (87 %; Scheme 1).A single-crystal X-ray structure determination of 3 2 unambiguously revealed an interesting supramolecular association between two severely folded molecules of Ru II metallamacrocycle 3 (Figure 1). [8] The folded metallacycles 3, self-complementary monomers of 3 2 , are oriented orthogonally to each other. This orthogonal assembly s...
Inorganic tennis balls (ITBs), [[{Pt(betmp)(dach)}(2)Cu](2)(X)][X](3) (in which X=ClO(4) (-) (3), NO(3) (-) (4), Cl(-) (5) and Br(-) (6); dach=trans-1,2-diaminocyclohexane and betmp=bisethylthiomethylidenepropanedioate) and [[{Pt(dteym)(dach)}(2)Cu](2)(PF(6))][PF(6)](3) (7; dteym=1,3-dithiepane-2-ylidenemalonate), were prepared as crystals. Investigation of their X-ray crystal structures revealed that shapes of the cavities in ITBs show significant distortions that depend on the properties of the encapsulated anions. The CuCu* distance was observed to be longest in 7 and shortest in 5, the difference between them being 2.05 A. The flexibility of cavity structures of ITBs makes it possible to encapsulate various anions inside the cavity, while their distortions may be a reason for the difference in the encapsulating ability for anions, that is, anion selectivity. Especially, the distortions observed in 7 are so severe that the encapsulating ability of the cavity for PF(6) (-) is very low compared to other anions. The shapes of ITBs with ClO(4) (-) and BF(4) (-) ions inside their cavities are very similar; however, ClO(4) (-) is encapsulated by the cavity better than BF(4) (-), which is explicable by the difference of metal-anion interactions. This structural study on ITBs gives a clue to the origin of the anion selectivity of the cavity in ITBs previously investigated by (19)F NMR spectroscopy of the ITBs in methanol.
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