A new family of porous lanthanide-based coordination polymers with tunable luminescent properties based on reversible ion-dependent exchange was reported.

Using a temperature-dependent synthetic approach, four distinct new silver(I) coordination polymers resulting from the different conformations adopted by the flexible ligand at different temperatures were obtained.

Coordination-driven self-assembly of discrete nanosized molecular cages has become one of the most active areas of supramolecular chemistry. 1 Over the past decade, extensive studies have been made on discrete molecular assemblies M x L y with various values of x and y. 2 Among these metal-ligand clusters, the assembly of M 2 L 4 tetragonal cage remains quite rare, although a few such d-block metal supramolecular complexes have appeared in the literature recently. 3 Canonical symmetric Ln 2 L 4 lanthanide cages have, to the best of our knowledge, never been described. This is clearly due to inherent difficulties in harmonizing the subtle relationship between the versatile coordination modes of the lanthanide metals (coordination numbers usually g8) and the ligand conformations in the synthetic cage systems. Lanthanide discrete cage-like assemblies, however, are of considerable interest in broad scientific areas, especially as the luminescent materials.We have recently reported a series of coordination polymers and supramolecular complexes based on bent five-membered heteroatom-ring-bridged ligands. 4 By taking into account the bent geometry of such spacers, we wondered if the five-membered heteroatom ring-bridged 3,3′-biphenylcarboxylate type ligands could be used as an "organic clip" 5 to bind lanthanide ions into discrete molecular cages, especially the Ln 2 L 4 tetragonal cages.Depending on this ligand-directed approach, 3 a series of lanthanide nanosized tetragonal cages Ln 2 L1 4 (Ln(III) ) La (1), Ce (2), Sm (3), Eu (4), and Tb (5) 6 The X-ray crystal structure analysis (Supporting Information) revealed that 1-5 are isostructural. They crystallize in the high-symmetry tetragonal space group, I4/m. For example 3, each Sm(2) node lies in a distorted singlecapped square antiprism coordination sphere (Figure 1), which is defined by eight carboxylic oxygen and one aquo oxygen donors and with Sm-O distances range from 2.457 to 2.576 Å. 7 For 1-5, the ligand donor to Ln(III) bond lengths simply reflect the ionic radius variation. 7 The most important structural feature of 1-5 is their cationic cage-like structure. As shown in Figure 1, four equivalent L1 ligands act as the desired organic clip to bridge two Ln(2) ions to form a tetragonal prismatic cage. It is interesting that the two phenyl rings on the same L1 ligand are basically coplanar, while the central triazole ring rotates by about 40°with respect to the phenyl plane and orients to the tangential direction of the cage. Such organized manner leaves an opening of ∼6.8 Å in the side of the cage. One (Figure 1). Top view of 3 shows that the four ligands crosswise arrange around the Ln(2)‚‚‚Ln(1)‚‚‚Ln(2) axis and the two Ln 2 L1 2 planes are perpendicular to each other, which results in the tetragonal cage canonical. There is a crystallographically imposed C 4 axis passing through these three Ln(III) ions and σ h mirror across the center of the molecule, leading to S 4 symmetry of the cage. The Ln‚‚‚Ln distance is ca. 11 Å, and the distance between the two ...

Three new rigid conjugated fulvene ligands L1-L3 were synthesized. L1 and L3 have been prepared by an aroylation reaction of cyclohexyl-substituted cyclopentadienyl anions. L2 was prepared by the reaction of L1 with PhNHNH2 in hot enthanol. Six new coordination polymers, namely [Ag(C25H20N2O2)(ClO4)] x 3.5C6H6 (1), [Ag2(mu-C31H24N4)(eta2-C6H6)(H2O)](ClO4)2 x (C6H6) x (H2O)0.5 (3), [Ag(C31H24N4)]SbF6 x solvate (4), [Ag(C31H24N4)](SbF6)2 x 2C6H6 x CH2Cl2 (5), [Ag(C25H20N2O2)2]SbF6 (6), and [Ag(C25H20N2O2)2]SbF6 (7), and one seven-membered cobaltacycle-containing complex, namely Co(C25H20N2O2)2(C2H5OH)2 (2), were obtained through self-assembly based on these three new fulvene lignads. L2-L3 and compounds 1-7 have been fully characterized by infrared spectroscopy, elemental analysis, and single-crystal X-ray diffraction. The results indicate that the coordination chemistry of new fulvene ligands is versatile. They can bind metal ions not only through the terminal N-donors and fulvene carbon atoms into organometallic coordination polymers but also through the two chelating carbonyl groups into unusual seven-membered metallo-ring supramolecular complexes. In the solid state, ligands L1-L3 are luminescent. A blue-shift in the emission was observed between the free ligand L1 and the one incorporated into Co(II)-containing complex 2, and a red-shift in the emission was observed between the free ligand L3 and the one incorporated into Ag(I)-containing polymeric compounds 6 and 7.

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The coordination chemistry of the multidentate Schiff-base ligands 2,5-bis(3-methylpyrazinyl)-3,4-diaza-2,4-hexadiene (L5) and 2,5-bis(pyrazinyl)-3,4-diaza-2,4-hexadiene (L6) with inorganic Ag(I) salts has been investigated. Six new Ag(I)-coordination polymers were prepared by solution reactions and fully characterized by infrared spectroscopy, elemental analysis, thermogravimetric analysis, and single-crystal X-ray diffraction. [Ag(L5)]ClO(4).0.5CH(3)OH (1, orthorhombic, Fdd2; a = 20.0896(11) A, b = 48.224(3) A, c = 7.8432(4) A, Z = 16), [Ag(L5)]PF(6).0.5CH(3)OH (2, orthorhombic, Fdd2; a = 20.7255(11) A, b = 46.166(2) A, c = 8.4332(4) A, Z = 16), [Ag(L5)]SbF(6).0.5CH(3)OH (3, orthorhombic, Fdd2; a = 21.5481(11) A, b = 45.196(2) A, c = 8.7331(4) A, Z = 16), and [Ag(L5)](BF(4)).0.5CH(3)OH (4, orthorhombic, Fdd2; a = 19.8897(11) A, b = 48.358(3) A, c = 7.7491(5) A, Z = 16) were obtained by combination of L5 with AgClO(4).xH(2)O, AgPF(6), AgSbF(6), and AgBF(4), respectively, in a methylene chloride/methanol mixed solvent system. Compounds 1-4 are isostructural and feature noninterpenetrating three-dimensional zeolite-like networks. [Ag(4)(L6)(4)](PF(6))(4).CHCl(3) (5, tetragonal, Pc2; a = 16.1067(3) A, b = 16.1067(3) A, c = 14.4935(5) A, Z = 2) was generated from the reaction of L6 with AgPF(6) in a chloroform/ethanol mixed solvent system. It forms with a unique one-dimensional nanometer-tube that can be considered a new polymeric motif based on the [AgN5] coordination sphere. The tubes are square with crystallographic dimensions of 10.3 x 10.0 A. The tubes are further linked together through weak interpolymer C-H...F hydrogen bonding interactions into a novel H-bonded three-dimensional network containing square tubes, in which uncoordinated PF(6)(-) counterions and chloroform guest molecules are located. Compound 6 ([Ag(mu-C(6)H(6)N(2)O)](SO(3)CF(3)), monoclinic, P2(1)/c; a = 12.3435(6) A, b = 20.3548(10) A, c = 9.0861(5) A, Z = 8) was obtained by combination of AgSO(3)CF(3) and L6 in a methylene chloride/benzene mixed solvent system. In 6, 2-acetylpyrazine, which was generated from the hydrolysis reaction of L6 in the presence of CF(3)SO(3)(-) and a small quantity of water in solvent, chelates the Ag(I) centers through the carbonyl O-donor, and the vicinal pyrazine N-donor, furthermore, uses the para-N atoms to link other Ag(I) centers into one-dimensional zigzag chains. The triflate anions link the chains into a three-dimensional network by somewhat long Ag.O contacts.

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In the title compound, C10H7N3O4·H2O, one carboxyl group is deprotonated and the pyridyl group is protonated. The inner salt molecule has a planar structure, apart from the carboxylic acid group, which is tilted from the imidazole plane by a small dihedral angle of 7.3 (3)°.