Two Cu21 clusters with pseudo-D3 symmetry derived from the D-saccharate pentaanion, C6H5O8(5-)

The combination of Cu(NO₃)₂, potassium hydrogen saccharate (KC₆H₉O₈) and 1,10‐phenanthroline (phen) yields a pair of chiral cluster compounds, each with composition Cu₂₁(C₆H₅O₈)₆(phen)₁₂(NO₃)₁₂?solvate. One of the compounds forms as orthorhombic crystals, while the other forms cubic crystals. Each of the clusters has D₃ or approximate D₃ symmetry, but the arrangement of the saccharate ion in the clusters is quite different in the two cases. The clusters in the cubic form interact with neighbouring clusters through face‐to‐face π interactions involving the phen ligands, an association that leads to the generation of very large solvent‐filled spaces in the crystal structure. In contrast the clusters in the orthorhombic form are much more densely packed. At the centre of each cluster that crystallises in the orthorhombic form is a nitrate anion that binds to six Cu^II centres. ESI mass spectral studies indicate that the Cu₂₁ clusters exist in solution. Solid‐state magnetic studies of the cubic form of Cu₂₁ show that antiferromagnetic coupling occurs to leave a non‐zero‐spin ground state, and comparisons are made to the magnetic data for other large Cu^II clusters.     

Self-assembly of supramolecular architectures and polymers by orthogonal metal complexation and hydrogen-bonding motifs

A modular construction kit with two orthogonal noncovalent binding sites for self-assembly of supramolecular architectures is presented. The heteroditopic building blocks contain a terpyridine (tpy) unit for coordination of metal ions and a Hamilton receptor for multiple H-bonding of cyanuric acid derivatives. The association constants of ligand binding of M(II) complexes (M=Ru, Zn, Fe, and Pt) with a dendritic end cap were determined to be in the range of 10(2) and 10(4) L mol(-1) in chloroform. The capabilities for binding of metal ions were investigated by (1)H NMR and UV/Vis spectroscopy. The Fe complexes are most appropriate for the generation of discrete and high-ordered architectures due to their strong tendency to form FeL(2) complexes. Superstructures are readily formed in a one-pot procedure at room temperature. No mutual interactions between the orthogonal binding motifs were observed, and this demonstrates the highly specific nature of each binding process. Decomplexation experiments were carried out to examine the reversibility of Fe-tpy coordination. Substitution of the terminal end cap with a homoditopic bis-cyanurate linkage leads to formation of an iron-containing supramolecular strand. Formation of coordination polymers was confirmed by viscosity measurements. The supramolecular polymer strands can be reversibly cleaved by addition of a terminating cyanuric acid building block, and this proves the dynamic nature of this noncovalent polymerization process.     

Two three-dimensional 2p-3d-4f heterometallic frameworks featuring a Ln6Cu24Na12 cluster as a node

Two three-dimensional 2p-3d-4f heterometallic frameworks featuring a nanosized Ln(6)Cu(24)Na(12) (Ln = Gd, Dy) cluster as a node have been obtained under microwave irradiation conditions through the reaction of H(2)ANMA (H(2)ANMA = L-alanine-N-monoacetic acid), Cu(NO(3))(2), and Ln(NO(3))(3) (Ln = Gd for 1, Dy for 2) with NaOH in deionized water. Investigations on the magnetic properties show that 1 exhibits ferrimagnetic behavior. The electrical conductivity measurements reveal that 1 behaves as a proton conductor.     

Reversible Transformation between Cubane and Stairstep Cu4I4 Clusters Using Heat or Solvent Vapor

The controlled self‐assembly of CuI and an asymmetric ligand with mixed N/S donors, 2‐(tert‐butylthio)‐N‐(pyridin‐3‐yl)acetamide ( L ), afforded three Cu^I coordination polymers (CPs), [Cu₄I₄ L ₂(MeCN)₂]_n ( 1 ), [Cu₄I₄ L ₂]_n ( 2 ), and {[Cu₄I₄ L ₂] ? MeOH}_n ( 3 ). X‐ray analyses showed that CPs 1 – 3 are supramolecular isomers with 1, 2, and 3D structures, respectively. CP 1 adopts a stairstep Cu₄I₄ cluster, whereas CPs 2 and 3 are composed of cubane‐like Cu₄I₄ clusters. Crystal‐to‐crystal transformations of 1 to 2 and 3 showed reversible transformations between different Cu₄I₄ clusters using heat or solvent (acetonitrile or methanol) vapor. CP 2 was reversibly transformed to 3 by the addition of methanol and heat. Therefore, the transformations between supramolecular isomers 1 , 2 , and 3 are completely reversible.     

Syntheses, structures, and properties of high-nuclear 3d-4f clusters with amino acid as ligand: {Gd6Cu24}, {Tb6Cu26}, and {(Ln6Cu24)2Cu} (Ln = Sm, Gd)

Four novel high-nuclear 3d-4f heterometallic clusters were obtained through the self-assembly of Ln(III), Cu(II), and amino acid ligands (2-methylalanine (mAla), glycine (Gly), and L-proline (Pro), respectively). The metal skeleton of cluster 1, [Gd6Cu24(mu3-OH)30(mAla)16(ClO4)(H2O)22].(ClO4)17.(OH)2.(H2O)2(0), may be described as a huge {Gd6Cu12} octahedron connected with 12 additional Cu(II) ions. The structure of cluster 2, Na4[Tb6Cu26(mu3-OH)30(Gly)18(ClO4)(H2O)22].(ClO4)25.(H2O)42, may be described as a {Tb6Cu24} main structure connected with two [Cu(Gly)(H2O)2]+ groups. Compounds {[Ln6Cu24(mu3-OH)30(Pro)12(Ac)6(ClO4)(H2O)13]2Cu(Pro)2}.(ClO4)18.(OH)16.(H2O)55 (Ln= Sm (3), Gd (4)) are 61-nuclear clusters, which represent the largest known 3d-4f clusters so far, the structure can be described as two {Ln6Cu24} octahedral units connected by a trans-Cu(proline)2 bridge. The electrical conductivity measurements reveal that they are temperature-sensitive semiconductors. The magnetic susceptibility measurements display that compound 4 is ferromagnetic.     

Investigation on the supramolecular recognition behaviour of sulfonatocalix[6]arene with amino benzoic acid isomers

The formation of the complexation behaviour of host molecules water-soluble p-sulfonatocalix[6]arene (C6AS) with amino benzoic acid (ABA) isomers including o-amino benzoic acid (OABA), m-amino benzoic acid (MABA), and p-amino benzoic acid (PABA) – three guest molecules – has been studied by fluorescence spectrophotometric and nuclear magnetic resonance (NMR) spectroscopy. Experimental conditions including the concentration of C6AS and medium acidity were investigated in detail. The results showed that C6AS forms 1:1 complexes with amino benzoic isomers in water. Their stability constants determined by steady-state fluorescence measurement showed that C6AS has stronger recognition with PABA than with OABA or MABA. Moreover, their stability constants of C6AS complexing with three kinds of guest molecules were the largest at pH = 4.0, indicating C6AS has the strongest recognition ability with the dipolar ion of amino benzoic isomers. In addition, to obtain information about the binding model of the interaction, ¹HNMR studies were carried out. The related mechanism is proposed to explain the complexation processes.     

Synthesis,structure and characterization of two copper(II) supramolecular coordination polymers based on a multifunctional ligand 2‐amino‐4‐sulfobenzoic acid

Copper(II) coordination polymers have attracted considerable interest due to their catalytic, adsorption, luminescence and magnetic properties. The reactions of copper(II) with 2‐amino‐4‐sulfobenzoic acid (H₂asba) in the presence/absence of the auxiliary chelating ligand 1,10‐phenanthroline (phen) under ambient conditions yielded two supramolecular coordination polymers, namely (3‐amino‐4‐carboxybenzene‐1‐sulfonato‐κO¹)bis(1,10‐phenanthroline‐κ²N,N′)copper(II) 3‐amino‐4‐carboxybenzene‐1‐sulfonate monohydrate, [Cu(C₇H₆N₂O₅S)(C₁₂H₈N₂)₂](C₇H₆N₂O₅S)·H₂O, (1), and catena‐poly[[diaquacopper(II)]‐μ‐3‐amino‐4‐carboxylatobenzene‐1‐sulfonato‐κ²O⁴:O^4′], [Cu(C₇H₆N₂O₅S)(H₂O)₂]_n, (2). The products were characterized by FT–IR spectroscopy, thermogravimetric analysis (TGA), solid‐state UV–Vis spectroscopy and single‐crystal X‐ray diffraction analysis, as well as by variable‐temperature powder X‐ray diffraction analysis (VT‐PXRD). Intermolecular π–π stacking interactions in (1) link the mononuclear copper(II) cation units into a supramolecular polymeric chain, which is further extended into a supramolecular double chain through interchain hydrogen bonds. Supramolecular double chains are then extended into a two‐dimensional supramolecular double layer through hydrogen bonds between the lattice Hasba⁻ anions, H₂O molecules and double chains. Left‐ and right‐handed 2₁ helices formed by the Hasba⁻ anions are arranged alternately within the two‐dimensional supramolecular double layers. Complex (2) exhibits a polymeric chain which is further extended into a three‐dimensional supramolecular network through interchain hydrogen bonds. Complex (1) shows a reversible dehydration–rehydration behaviour, while complex (2) shows an irreversible dehydration–rehydration behaviour.     

Cobalt-lanthanide coordination polymers constructed with metalloligands: a ferromagnetic coupled quasi-1D Dy3+ chain showing slow relaxation

Four types of cobalt-lanthanide heterometallic compounds based on metalloligand Co(2,5-pydc)(3) (3-) (2,5-H(2)pydc=pyridine-2,5-dicarboxylate acid), [Ln(2)Co(2)(2,5-pydc)(6)(H(2)O)(4)](n) 2n H(2)O (1) (Ln=Tb, Dy for 1 a, 1 b respectively), [Tb(2)Co(2)(2,5-pydc)(6)(H(2)O)(4)](n)3n H(2)O (2), [Tb(2)Co(2)(2,5-pydc)(6)(H(2)O)(9)](n)4n H(2)O (3), and [LaCo(2,5-pydc)(3)(H(2)O)(2)](n)2n H(2)O (4) have been synthesized. Compound 1 has a layer structure with well-isolated carboxylate-bridged Ln(3+) chains, compound 2 is a three-dimensional (3D) porous network with Tb(3+) chains that are also well isolated and carboxylate bridged, 3 is a layer structure based on dinuclear units, and 4 is a 3D network with boron nitride (BN) topology. DC magnetic studies reveal ferromagnetic coupling in all the carboxylate-bridged Ln(3+) chains in 1 a, 1 b, and 2. Compared to the silence of the out-of-phase ac susceptibility of 2, above 1.9 K the magnetic relaxation behavior of both 1 a and 1 b is slow like that of a single-chain magnet.     

Three new Cu(Ⅱ)-Ln(Ⅲ) heterometallic coordination polymers constructed from quinolinic acid and nicotinic acid: Synthesis, structures, and magnetic properties

Three new Cu(Ⅱ)-Ln(Ⅲ) heterometallic coordination polymers based on two N-heterocyclic carboxylic ligands, {[LnCu(L1)2(L2)(H2O)2]·mH2O}n (Ln = La(1), Nd(2), Gd(3), m = 2 (for 1), 1 (for 2, 3), H2L1 = quinolinic acid, HL2 = nicotinic acid), have been synthesized and characterized. 1 has a two-dimensional (2D) layer structure with a Schlfli symbol of (44.62), while complexes 2 and 3 are isostructural and have three-dimensional (3D) structures with a Schlfli symbol of (3.4.5)2(32.42.52.614.74.83.9)(32.63.7) of 3-nodal net. Magnetic investigations suggest that antiferromagnetic coupling exists between NdIII and CuII in 2, while weak ferromagnetic coupling between GdIII and CuII in 3. The difference of magnetic properties between 2 and 3 has been discussed.     

Neutral Penta‐ and Hexacoordinate Silicon(IV) Complexes Containing Two Bidentate Ligands Derived from the α‐Amino Acids (S)‐Alanine, (S)‐Phenylalanine,and (S)‐tert‐Leucine

The neutral hexacoordinate silicon(IV) complex 6 (SiO₂N₄ skeleton) and the neutral pentacoordinate silicon(IV) complexes 7 – 11 (SiO₂N₂C skeletons) were synthesized from Si(NCO)₄ and RSi(NCO)₃ (R=Me, Ph), respectively. The compounds were structurally characterized by solid‐state NMR spectroscopy ( 6 – 11 ), solution NMR spectroscopy ( 6 and 10 ), and single‐crystal X‐ray diffraction ( 8 and 11 were studied as the solvates 8? CH₃CN and 11? C₅H₁₂ ? 0.5 CH₃CN, respectively). The silicon(IV) complexes 6 (octahedral Si‐coordination polyhedron) and 7 – 11 (trigonal‐bipyramidal Si‐coordination polyhedra) each contain two bidentate ligands derived from an α‐amino acid: (S)‐alanine, (S)‐phenylalanine, or (S)‐tert‐leucine. The deprotonated amino acids act as monoanionic ( 6 ) or as mono‐ and dianionic ligands ( 7 – 11 ). The experimental investigations were complemented by computational studies of the stereoisomers of 6 and 7 .     

Tris(pyridylmethylamino)cyclotriguaiacylene cavitands: an investigation of the solution and solid-state behaviour of metallo-supramolecular cages and cavitand-based coordination polymers

The synthesis of the three isomeric tris(pyridylmethylamino)cyclotriguaiacylene cavitands is reported, along with the crystal structures of the 2- and 4-pyridyl derivatives. The generality of a previously described [Ag(2){tris(3-pyridylmethylamino)cyclotriguaiacylene}(2)](2+) dimeric capsule motif and the [Ag(4){tris(4-pyridylmethylamino)cyclotriguaiacylene}(4)](4+) tetrahedron with several silver salts was confirmed in the solid state and the corresponding solution species were investigated by NMR spectroscopy. Host-guest interactions in these systems have been probed and these interactions are demonstrated to alter and influence the self-assembly outcome of the reaction. Notably, introduction of larger glutaronitrile guest molecules to the [Ag(4)L(4)](4+) tetrahedron system prevents formation of the tetrahedral structure, resulting instead in the formation of a 4.8(2) coordination network in the solid state. In the absence of templating acetonitrile guests in the [Ag(2)(3)(2)](2+) capsule system, formation of a cage-based one-dimensional coordination polymer is observed.