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This work presents eight coordination assemblies based on divalent metal ions (M = CoII, CuII, ZnII, and CdII), dicyanamide anion (N(CN)2−, dca), and two isomeric bent dipyridyl coligands (L), namely, 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (3-bpo) and 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (4-bpo). In the resulting crystalline materials, both bpo and dca tectons generally display the bidentate bridging fashion (except in the mononuclear species 5), extending the metal centers to afford diverse one-, two-, and three-dimensional (1-D, 2-D, and 3-D) coordination networks that are not commonly observed in M−dca−L systems. Notably, the inclined polycatenated 2-D → 3-D framework and 3-D polyknotting network with the unique 6-connected (44.611) topology are formed for the CuIIand CdIIspecies with dca and 4-bpo. For the polymeric CoIIand CuIIcomplexes, very weak antiferromagnetic or ferromagnetic interactions are observed between the metal centers due to the μ1,5-bridging mode of dca, and their magneto-structural correlations have been discussed in detail. The ZnIIand CdIIcomplexes show solid-state fluorescent emissions at room temperature. [ABSTRACT FROM AUTHOR]

Two new flexible dipyridyl building blocks, N,N‘-bis(4-picolinoyl)hydrazine (4-bph) and its N-orientation isomer N,N‘-bis(3-picolinoyl)hydrazine (3-bph), have been synthesized as versatile cocrystallizing agents and introduced into the reactions with pyromellitic acid (H4BTA) and fumaric acid (H2Fa). Hydrogen-bonded directed assemblies of two hydrates of bphs and four binary cocrystals were validated by single-crystal X-ray diffraction analysis. With the presence of the reliable hydrogen-bonding donor/acceptor(s) of bph, the crystalline lattices of 4-bph·2H2O (1) and 3-bph·2H2O (4) are managed by N−H···Owaterand O−H···Ocarbonylto afford one-dimensional (1D) arrays, which are further extended to distinct three-dimensional (3D) (for 1) and two-dimensional (2D) (for 4) networks via O−H···Npyridylinteractions. While for the concomitant polymorphs (H2BTA)·(H2-4-bph) (2and 3), charge-assistant bifurcated N−H···O bonds do favor 1D acid−base hydrogen-bonding tapes, which are interlinked to result in a 2D layer in 2and a 3D network in 3through the competition of O−H···Ocarboxyland O−H···Ocarbonylforces. (H3BTA)2·(H2-3-bph)·4H2O (5) is also a charge-transfer organic salt with a 2D bilayered array. Proton transfer from weak H2Fa to 3-bph is not observed, and this leads to the formation of a binary neutral cocrystal (H2Fa)·(3-bph) (6), in which the 2D undulating herringbone pattern is constructed via the expected carboxylpyridyl heterosynthon and amide−amide homosynthon. [ABSTRACT FROM AUTHOR]

A bent dipyridyl compound, 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (4-bpo), was employed to crystallize with 1,4-cyclohexanedicarboxylic acid (H2chdc), hydroquinone, citric acid (H4ca·H2O), barbituric acid, and ferrocene dicarboxylic acid (H2Fc) under general conditions, affording binary cocrystals [(H2chdc)·(4-bpo)] (1), [(hydroquinone)·(4-bpo)2] (2), [(H4ca)·(4-bpo)] (3), [(barbituric acid)·(4-bpo)] (4), and [(HFc)·(H-4-bpo)] (5) in high yield. X-ray single-crystal structures of these compounds reveal that a supramolecular synthon [%@mt;sys@%R%@sx@%2%@be@%2%@sxx@%%@mx@%(7)] containing classical O−H···N and weak C−H···O interactions, usually observed in organic cocrystals of carboxylic acid and heterocyclic base, is again involved in constructing the hydrogen-bonding networks of 1, 3, and 5. Its ionic analogous synthon [consisting of strong N−H···O and weak C−H···O/C%@mt;sys@%R%@sx@%2%@be@%2%@sxx@%%@mx@%(7)] also appears in the partly charge-transfer salt 5. For 2, only hydroxyl of the hydroquinone component can act as the hydrogen-bonding contributor, giving a strong O−H···N bond with 4-bpo. Multiple hydrogen-bonded donating/accepting sites in compound 3 saline 86.3 +/- 34.3 nmol/L per milligram of tissue per hour;4, another heterosynthon ring [containing strong N−H···N and weak C−H···O/C%@mt;sys@%R%@sx@%2%@be@%2%@sxx@%%@mx@%(7)] is formed due to the presence of the imide functional group. As a consequence, robust hydrogen-bonding interactions in these compounds afford diverse 2-D waved or planar layers (1 or 4), 1-D extended tape (2), 3-D net (3), and 1-D molecular-box type (5) supramolecular architectures. Thermal stability of these compounds has been investigated by thermogravimetric analysis (TGA) of mass loss. [ABSTRACT FROM AUTHOR]

Assembly of pamoic acid (H2PA) with piperazine (PIPO) or 4,4′-bipyridyl (BIPY) results in two distinct supramolecular complexes [(PA)·(H2PIPO)]·3H2O (1) and [(H2PA)·(BIPY)] (2). The former displays triple-helix host arrays via charge-assisted N+−H···O−interactions with the inclusion of helical water chains, whereas the latter represents the first cocrystal of pamoic acid sustaining by the familiar carboxyl-pyridyl H-bonding synthons. Notably, the structure of 1can be dehydrated/rehydrated with retention of crystallinity. [ABSTRACT FROM AUTHOR]

Three kinds of three-dimensional (3D) cadmium(II) pyridine-2,4,6-tricarboxylate ( L) coordination polymers, L-[Cd( L)](NH 2Me 2) ( 1a), R-[Cd( L)](NH 2Me 2) ( 1b), [Cd 3( L) 2(H 2O) 4] ( 2), and [Cd 4( L) 2(OH) 2(H 2O) 3](H 2O) ( 3), have been hydro/solvothermally synthesized and structurally characterized by single-crystal X-ray diffraction. The variations of reaction medium and temperature not only led to an occurrence of spontaneous chiral resolution but also afforded two achrial molecular building block structures. Complexes 1aand 1bcrystallize in trigonal P3 121 and P3 221 space groups with homochiral left- and right-handed double-helical strand arrays, while 2and 3self-assemble into two kinds of achiral coordination polymers with molecular building block structures. Complexes 2and 3remain intact after removal of the coordinated water molecules, which indicates that their dehydrated frameworks possess guest-free metal coordination sites. Complexes 1– 3also display strong fluorescent emissions at 638, 594, and 604 nm in the solid state. [ABSTRACT FROM AUTHOR]

A series of AgI coordination polymers, {[Ag2L][Ag1/2(ONO)2(NO2)1/2](H2O)} n (1), {[AgL](BF4)} n (2), and {[Ag2L2](ClO4)2} n (3), have been prepared by assembly of AgX (X- = NO2 -, BF4 -, and ClO4 -) with 3,4-bis(2-pyridyl)-5-(4-pyridyl)-1,2,4-triazole (L). Single-crystal X-ray diffraction analyses indicate that 1-3 show distinct two-dimensional networks and lattice stacking, with the counteranions [Ag1/2(ONO)2(NO2)1/2]2-, BF4 -, and ClO4 - located in the interlayered voids. Interestingly, when the crystals of 1 were immersed in a water solution of BF4 - or ClO4 - anion, 2 or 3 can be irreversibly formed via anion-driven structural transformation. This process has also been investigated by means of PXRD, elemental analysis, FT-IR, and SEM-EDS, revealing a solvent-mediated mechanism. Moreover, the dynamic anion-exchange behavior is highly anion-selective but cation-independent. [ABSTRACT FROM AUTHOR]

Two chiral d10metallosupramolecular systems based on an achiral fluorinated Schiff-base ligand have been prepared and characterized. The ZnIIcomplex 1reveals 21helical coordination chains with the inclusion of rare water chains of opposite helix in the perpendicular channels, whereas the CdIIcomplex 2displays the homochiral 1D coordination motifs with 31symmetry and a 3D supramolecular architecture built by C–H···F interactions. [ABSTRACT FROM AUTHOR]

A series of novel three-dimensional (3-D) lanthanide−organic frameworks (LnOFs), with the general formula [Ln2(H-L)3(H2O)4]∞(Ln = DyIIIfor 1, GdIIIfor 2, TbIIIfor 3, EuIIIfor 4, and HoIIIfor 5; H-L= N-protonated 2,6-dihydroxypyridine-4-carboxylate), have been synthesized under hydrothermal conditions. X-ray structural analysis reveals that complexes 1−5are isostructural and show the unique 3-D coordination framework with a trinodal (3,4,5)-connected (4.62)(42.6)(42.84)(43.6.86)(42.65.83) net topology, in which the H-Lligands adopt different μ4- and μ3-bridging forms. Variable-temperature magnetic susceptibility studies reveal that complexes 1−3and 5show ferromagnetic behaviors. Notably, complex 1(DyIII) is the first instance leading to ferromagnetic coupling for a lanthanide ion through a spin-polarization mechanism. The alternating current (ac) signal observed for 1and 5should originate from the long-range ferromagnetic ordering, or it could reflect the splitting of the Jmultiplet for DyIIIor HoIIIunder a low symmetry crystal field, which would give rise to slow relaxation of the magnetization. Additionally, thermal stability of these crystalline materials has also been investigated by thermogravimetric analysis of mass loss. [ABSTRACT FROM AUTHOR]

Seven Zn(II) and Cd(II) coordination polymers, formulated as {[Zn2(5-Br-ip)2(bpy)(H2O)]·2H2O}n(1), {[Zn(5-Br-ip)(bpa)(H2O)]}n(2), {[Cd(5-Br-ip)(bpp)(H2O)]}n(3), {[Zn(5-Br-ip)(bpe)]}n(4), {[Zn2(4-Br-ip)2(bpy)]·H2O}n(5), {[Zn(4-Br-ip)(bpa)(H2O)]}n(6), and {[Cd(4-Br-ip)(bpp)]}n(7), were prepared by hydrothermal reactions based on 4-bromo- or 5-bromoisophthalic acid (4-Br-H2ip or 5-Br-H2ip) and different dipyridyl-type coligands 4,4′-bipyridyl (bpy), 1,2-bi(4-pyridyl)ethane (bpa), 1,3-di(4-pyridyl)propane (bpp), and 1,2-di(4-pyridyl)ethene (bpe). All complexes 1−7were characterized by elemental analysis, IR spectra, and X-ray single-crystal diffraction. Complex 1is a 2D (6,3) coordination network and further assembled into a 3D framework via π−π stacking interactions. Complex 2shows a 1D coordination array and further forms a 2D supramolecular network via H-bonding interactions. Complex 3has a 2-fold interpenetrating 3D diamond framework. Complex 4is a 3-fold interpenetrating 3D network with CdSO4topology, constructed from alternately left- and right-handed helical arrays. Complex 5has a 3D (3,4)-connected network with (4·82)(4·82·103) topology. Complex 6features a 1D coordination chain and further forms a 2D helical supramolecular pattern by H-bonding. Complex 7exhibits a (3,5)-connected 2D layer with the Schläfli symbol of (42·6) (42·67·8). The results reveal that the diverse coordination networks of 1−7can be adjusted by the different dispositions of the -Br substituent of isophthalate building blocks, as well as the metal ions and the dipyridyl coligands. Moreover, the luminescent properties of the complexes have been investigated. [ABSTRACT FROM AUTHOR]

Under different solvothermal reaction conditions I(60 °C for 48 h) and II(140 °C for 72 h), the dipyrazinyl compounds bearing oxadiazole and triazole spacers, that is, 2,5-bis(2-pyrazinyl)-1,3,4-oxadiazole (L1) and 4-amino-3,5-bis(2-pyrazinyl)-1,2,4-triazole (L2), may suffer reversible conversions in the presence of certain metal salts. Other related derivatives such as 3,5-bis(2-pyrazinyl)-1,2,4-triazole-4-yl-N-pyrazinamide (HL4) and pyrazine-2-carboxylic acid (HL0) can also be (in situ) obtained from L1and L2, respectively, under conditions Iand II. Beyond this, N,N′-bis(2-pyrazineamide) (H2L3) can be in situ afforded from both precursors L1and L2, and thus, may be considered as the potential intermediate during the interconversions. The possible mechanisms and influence factors of these reactions have also been established based on the experimental results. As a result, a variety of crystalline materials (co-crystals and coordination complexes) with attractive supramolecular architectures have been isolated by regulating the reaction conditions well (reaction temperature, metal ion, and even inorganic counteranion). [ABSTRACT FROM AUTHOR]

Eight ZnIIand CdIIcoordination complexes, {[Zn3(nbta)2(bpy)2(H2O)2](H2O)2}n(1), [Zn4(nbta)2(bpe)2(OH)2]n(2), {[Cd3(nbta)2(bpy)5(H2O)2](H2O)6}n(3), {[Cd3(nbta)2(bpe)2(H2O)2](H2O)2}n(4), [Zn2(Hbta)2(bpy)2(H2O)2](H2O) (5), [Zn(bta)(Hbpe)]n(6), [Cd5(bta)2(Hbta)2(bpy)3(H2O)2]n(7), and {[Cd4(bta)2(bpe)2(H2O)4(OH)2](H2O)2}n(8), were prepared via hydrothermal reactions based on H3nbta or H3bta (H3nbta = 5-nitro-1,2,3-benzenetricarboxylic acid and H3bta = 1,2,3-benzenetricarboxylic acid) and the dipyridyl-type coligand 4,4′-bipyridyl (bpy) or 1,2-di(4-pyridyl)ethene (bpe). All complexes were characterized by elemental analysis, IR spectra, and X-ray powder diffraction techniques. Complexes 1−4all display unusual three-dimensional (3-D) self-penetrating coordination networks. From the topology point of view, complexes 1and 2display the 4-connected frameworks with the Schläfli symbols of (4.104.12)2(43.62.8)2(44.62) and (4.62.72.8)2(42.62.7.8), respectively. Complex 3features an unprecedented 3-nodal network with (3,5,6)-connectivity and the Schläfli symbol of (52.64.72.86.10)(52.65.72.8)2(52.6)2, also exhibiting an intriguing polyrotaxane entangled motif. Complex 4shows a new 4-connected (42.63.8)4(64.8.10) topology. Different from 1−4, complexes 5−8based on H3bta all present the non-self-penetrating structural type. Complex 5possesses binuclear units which are further extended to a two-dimensional (2-D) supramolecular network via extensive H-bonding interactions, showing alternate left- and right-handed helical chains. Complex 6has a 2-D layered motif generated via H-bonding interactions between the one-dimensional (1-D) coordination chains. Complex 7shows a 3-D coordination framework, which is constructed from the 2-D metal-carboxylate layers pillared by the rod-like bipy spacers. Complex 8presents a 2-D net with the [Cd4(μ3-OH)2]6+clusters as the linking nodes. These results reveal that the existence of the electron-withdrawing -NO2group in such a tricarboxyl building block plays a critical role in structural direction of the self-penetrating coordination frameworks. [ABSTRACT FROM AUTHOR]

A survey of the Cambridge Structural Database (CSD) indicates that 79% of complexes that contain both imidazole and carboxyl groups generate imidazolium-carboxylate supramolecular heterosynthons rather than carboxyl or imidazole supramolecular homosynthons. In the absence of other competing factors, the occurrence of such heterosynthons is increased to 100%. This observation is further supported by the crystal structures of seven new complexes that contain tris(2-benzimidazylmethyl)amine (TBMA) and a variety of carboxylic acids, including benzoic acid (HBA), p-methoxybenzoic acid (HPMBA), phthalic acid (H2PA), terephthalic acid (H2TPA), isophthalic acid (H2PIA), trimesic acid (H3TMA), and pyromellitic acid (H4PMA). In all seven complexes, (H2TBMA)·(BA)2·DMF (1), (HTBMA)·(PMBA)·(TBMA)·(HPMBA)2·2DMF·H2O (2), (HTBMA)·(H2TBMA)·(HPA)·(PA)·3DMF·H2O (3), (HTBMA)2·(TPA)·2DMF (4), (HTBMA)2·(PIA)·2DMF (5), (H2TBMA)·(HTMA)·0.5DMF·H2O (6), and (HTBMA)2·(H2PMA)·2DMF·H2O (7), proton transfer occurs from acid to aromatic nitrogen of benzimidazole (partial proton transfer for 3, 6, and 7). Analysis of the H-bonding synthons and their effect on crystal packing is also presented in the context of crystal engineering and host−guest chemistry. In the structure of 1, discrete acid/base hexamers are formed via synthons III, V, and VI, while in 2−5, self-recognition via synthons IV, V, and VIresults in one-dimensional (1-D) chains, and these structures are extended to high-dimensional architectures (two-dimensional (2-D) structures in 3and three-dimensional (3-D) structures in 2, 4, and 5) via additional C−H···O, C−H···π and π···π interactions. Interestingly, salts 6and 7display the 3-D supramolecular networks via synthons III, IV, V, and VI, which have 1-D channels that are occupied by DMF guests. [ABSTRACT FROM AUTHOR]

Five novel zinc(II) and cadmium(II) metal−organic coordination polymers with a tricarboxyl tecton and N-donor ancillary ligands, {[Zn(Hnbta)(2,2′-bipy)]·H2O}n(1), {[Cd3(nbta)2(2,2′-bipy)2(H2O)2]}n(2), {[Cd3(nbta)2(bpa)2]}n(3), {[Zn2(nbta)(OH)(bpa)1.5]·2H2O}n(4), and {[Zn3(nbta)2(bpp)2(H2O)2]}n(5) (H3nbta = 5-nitro-1,2,3-benzenetricarboxylic acid, 2,2′-bipy = 2,2′-bipyridine, bpa = 1,2-bi(4- pyridyl)ethane, and bpp = 1,3-bi(4-pyridyl)propane), have been prepared and characterized by elemental analysis, IR spectra, and X-ray diffraction. Complex 1has a two-dimensional (2D) bilayer supramolecular network constructed from one-dimensional (1D) zigzag coordination chains via π···π interactions, whereas 2exhibits a three-dimensional (3D) supramolecular network assembled from 1D coordination arrays through π···π interactions and weak C−H···O interactions. Complex 3features a (4,5)-connected self-penetrating 3D coordination net with a (43·65·82)(43·62·8)(44·64·82)(45·65) topology. The 3D framework of 4can be described as a trinodal (4,5)-connected (3·4·53·6)(3·52·62·84·9)(3·4·5·83) topology, which consists of 2D [Zn(nbta)] helical arrays and bpa pillars. Complex 5has a 3D trinodal 4-connected (4·64·8)(44·62)(43·63) topology. Moreover, thermal stabilities and luminescent properties of complexes 1−5have also been investigated. [ABSTRACT FROM AUTHOR]

A series of CdII, CoII, NiII, and PbIImixed-ligand coordination complexes 1−8based on 5-sulfoisophthalic acid (H3sip) and the bent dipyridyl ligand 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (3-bpo) or its 4-pyridyl N-donor analogue (4-bpo) have been synthesized and fully characterized by IR spectra, microanalyses, and single crystal and powder X-ray diffraction techniques. The significant pH effect on assembly of the CdIIcomplexes 1−4has been demonstrated, which leads to the formation of distinct crystalline products, whereas the CoII, NiII, and PbIIsystems 5−8are independent to pH condition of the synthetic reaction. Complexes 1−8display various coordination motifs with different existing forms, conformations, and coordination modes of the organic ligands. Further, extended supramolecular networks are constructed via secondary interactions such as hydrogen-bonding and aromatic stacking. Solid-state properties of thermal stability and fluorescence for these crystalline materials are also presented. [ABSTRACT FROM AUTHOR]

A unique self-penetrating coordination framework with (424.64) network topology is constructed from cage-shaped [Pb6(μ4-O)2(O2C)8] clusters as eight-connected nodes and long V-shaped dicarboxylate backbones as spacers, which interestingly can be regarded as the cross-linking of two interpenetrating six-connected pcunetworks. [ABSTRACT FROM AUTHOR]

Two related CoII5-aminoisophthalate coordination frameworks [Co5(μ3−OH)2(5-NH2-bdc)4(H2O)2]·7.5H2O (1, 5-NH2-bdc = 5-aminoisophthalate) and [Co5(μ3−OH)2(5-NH2-bdc)4(bpy)0.5(H2O)]·3H2O (2, bpy = 4,4′-bipyridine) based on [Co5(μ3−OH)2] clusters have been synthesized by hydrothermal reaction, structurally described, as well as properties characterized, that have unusual 3D networks with high connectivity (3,12) and (3,13)-connected, respectively. Notably, the unique (3,13)-connected framework is constructed from the (3,12)-connected network analogue and 4,4′-bipyridyl spacer. Magnetic studies show that a dominant antiferromagnetic coupling between Co(II) ions, and the generation of relatively effective noncompensated moments at very low temperature, mainly arises from the cooperative magnetic effect of the intercluster arrangement in the Td−SP-3Ohmixed-geometry-based pentamer. [ABSTRACT FROM AUTHOR]

With solvent molecules participating in coordination systems, four new Mn IIcoordination polymers of the rigid ligand 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid (H 2BDC-Cl 4) have been obtained from different solvent media. Single-crystal X-ray analysis indicates that the coordination arrays of 1− 4vary from 1D fishbone or zigzag chain for 1or 2, 2D (4,4) layer for 3, to 3D SrAl 2coordination network for 4, respectively. In {[Mn(BDC-Cl 4)(py) 2(H 2O) 2](py) 2} n( 1) and {[Mn(BDC-Cl 4)(MeOH) 3](MeOH)} n( 2), pyridine/water (in 1) and MeOH (in 2) molecules act as the monodentate terminal ligands to fulfill the metal coordination spheres. In the case of {[Mn(BDC-Cl 4)(dioxane)(H 2O) 2](dioxane)} n( 3), the aqua ligand is monodentate and the dioxane moiety displays unusual bridging bidentate mode, whereas for [Mn 5(BDC-Cl 4) 5(DMF) 5] n( 4), three Mn IIcenters are connected by four BDC-Cl 4ligands and two DMF molecules to constitute a trimeric unit. These secondary units are extended to the final 3D network with SrAl 2( sra) topology. Significantly, the solvents play an essential role in the crystallization and construction of these coordination frameworks with distinct dimensionality and connectivity. The thermal and photoluminescence properties of complexes 1− 4in the solid state have also been discussed. [ABSTRACT FROM AUTHOR]

Two derivative ligands of nicotinic or isonicotinic acid, namely, 2-(3-pyridyl)-4-methylthiazole-5-carboxylic acid (Hpmtca) and 2-(4-pyridyl)thiazole-4-carboxylic acid (Hptca), have been employed to assemble with a variety of divalent metal ions, leading to the generation of diverse metal−organic supramolecular architectures in different dimensions. Among them, complexes 1aand 1b, Ni(pmtca)2(H2O)4n, present a pair of conformational polymorphs with different neutral layered arrays, which are obtained from similar reaction conditions with NiIIsalts of different sources. Cu(pmtca)2(H2O)n(2) and Zn(pmtca)2(H2O)n(3) are isostructural two-dimensional (2-D) corrugated coordination networks. These layered patterns adopt interdigitated three-dimensional (3-D) crystalline packing and are further consolidated by hydrogen bonding, while Co(pmtca)2(CH3CH2OH)2n(4) shows a distinct one-dimensional (1-D) double chain structure. As for the CdIIspecies, Cd(pmtca)2(H2O)2n(5) comprises a similar layered framework as that in 1a, whereas the mononuclar complex Cd(ptca)2(H2O)4(6) displays a 3-D supramolecular network via multiple intermolecular hydrogen bonds. The ligand conformation is systematically investigated to further explore its relationship with the resultant crystalline architectures. [ABSTRACT FROM AUTHOR]