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Describes the synthesis and structural characterization of di- and tetranuclear zinc complexes with phenolate and carboxylate bridges. Corrections between [sup 13]C NMR chemical shifts and carboxylate binding modes; Elemental analyses; IR; X-ray single-crystal diffraction. [ABSTRACT FROM AUTHOR]

Presents information on a set of binuclear metal complexes with the formula M2 (Im)4(OAc)4(H2O), where M=Mn, Co or N1, which were subjected to EPR and magnetic susceptibility studies. Results of the reactivity of each complex; Factor highlighted by the weak coupling.

The title compound, [Zn(C15H13N2O)Cl(C15H14N2O)], has a mononuclear structure, in which the central zinc ion is coordinated by two benz­imidazole N atoms, one phenolate O atom and a chloride ion in a distorted tetrahedral arrangement. In the crystal structure, there are intramolecular π–π stacking interactions between the phenol and benz­imidazole ring systems; intermolecular π–π stacking interactions between the benz­imidazole ring systems of adjacent mol­ecules are also present. A strong intermolecular O—H⋯O hydrogen bond is also observed. [ABSTRACT FROM AUTHOR]

Cyclic water hexamers containing 1-D metal-water chains have been observed in the complexes of [M(H2biim)2(OH2)2](ina)2·4H2O [M = Zn (1) and Co (2), H2biim = 2,2'-biimidazole, ina = isoniconate]. The water clusters are trapped by the cooperative association of coordination interactions as well as hydrogen bonds. [ABSTRACT FROM AUTHOR]

The article presents the structure and composition of Triaqua(2,2'-bipyridine)(thiophene-2,5-dicarboxylato)manganese(II) 4,4'-bipyridine hemisolvate trihydrate Mn(tdc)(bpy)(H2O)3].3H2O.0.5(bpyn). Here tdc denotes thiophene-2,5-dicarboxylate, bpy stands for 2,2'-bipyridine and bpyn is 4,4'-bipyridine. Its structure includes double stranded chains having centrosymmetric bpyn uncoordinated molecules which are linked through hydrogen bonds. A significant role is played by metal-ion-directed coordination bonds in the case of coordination polymers.

In the crystal structure of the title compound, [Ag2(N3)2(C2H8N2)], the Ag atoms of adjacent polymeric AgN3 chains are bridged by the 1,2-di­amino­ethane ligand to furnish a ribbon structure. The Ag atom shows trigonal planar coordination. The 1,2-di­amino­ethane ligand lies on an inversion center. [ABSTRACT FROM AUTHOR]

Five imidazole-based anion receptors A–E are designed for cyanide anion recognition via hydrogen bonding interaction in water. Only receptors A [Ru(bpy)2(mpipH)](ClO4)2 (bpy is bipyridine and mpipH is 2-(4-methylphenyl)-imidazo[4,5-f]-1,10-phenanthroline) and E [Ru2(bpy)4(mbpibH2)](ClO4)4 (mbpibH2 is 1,3-bis([1,10]-phenanthroline-[5,6-d]imidazol-2-yl)-benzene) selectively recognize CN– from OAc–, F–, Cl–, Br–, I–,NO3–, HSO4–, CIO4–, H2PO4–, HCO3–, N3–, and SCN– anions in water (without organic solvent) at physiological conditions via formation of multiple hydrogen bonding interaction with binding constants of KA(H2O) = 345 ± 21 and KE(H2O) = 878 ± 41, respectively. The detection limits of A and E toward CN– in water are 100 and 5 μM, respectively. Receptor E has an appropriate pKa2* value (8.75) of N–H proton and a C-shape cavity structure with three-point hydrogen bonding, consisting of two NH and one cooperative phenyl CH hydrogen bonds. Appropriate acidity of N–H proton and multipoint hydrogen bonding are both important in enhancing the selectivity and sensitivity toward CN– in water. The phenyl CH···CN– hydrogen bonding interaction is observed by the HMBC NMR technique for the first time, which provides an efficient approach to directly probe the binding site of the receptor toward CN–. Moreover, CN– induced emission lifetime change of the receptor has been exploited in water for the first time. The energy-optimized structure of E–CN adduct is also proposed on the basis of theoretical calculations. [ABSTRACT FROM AUTHOR]

A nanocage complex [Co(H2O)6⊂Co8L12](NO3)6·12H2O (1) (HL = 2-amino-4,6-bis(2-pyridyl)-1,3,5-triazin) has been synthesized under solvothermal conditions and characterized by single-crystal X-ray diffraction. A [Co(H2O)6]2+ion as a guest is included in the central cavity of the cubelike nanocage [Co(H2O)6⊂Co8L12]6+cation, assembled by 8 cobalt ions at the corners and 12 bis-bidentate ligands L at the edges, via the formation of 12-fold strong hydrogen bonds between the six coordinated water molecules and the nitrogen atoms of 12 L ligands. When compound 1cocrystalizes with KHCO3and trimesic acid (H3TMA), complexes [Co(H2O)6⊂Co8L12](HCO3)6·24H2O (2) and [Co(H2O)6⊂Co8L12](H2TMA)6·6EtOH·3H2O (3) are obtained, respectively. In 2, a planar [(HCO3)2]2−dimer motif R22(8) synthon plus six lattice water molecules constitute a planar supramolecular synthon R88(20), which acts as a 4-connector, generating a three-dimensional (3D) hydrogen-bonded NbO net with an approximately 20 Å diameter cavity. In 3, the R44(24) synthon, regarded as a 4-connector, connects each other via the phenyl ring of H3TMA as a spacer into a NbO net with a cavity of ∼20 Å diameter. The hydrophobic, cubic, nanosize cations [Co(H2O)6⊂Co8L12]6+embed in the cavities of NbO nets as templates and play an indispensable role in the formation of 3D hydrogen-bonded networks. The work presented here seems to suggest that the nanosize complex as a template plays a crucial role in the formation and stabilization of supramolecular architecture and crystal engineering. [ABSTRACT FROM AUTHOR]

The facile and effective one-pot solvothermal syntheses of 3,5-disubstituted 1,2,4-triazole and its derivatives (substituted group = alkyl, aryl, and pyridyl) through cyclocondensations of organonitriles and hydrazine hydrate in the absence/presence of metal salts have been established. By control of the solvothermal conditions and/or the addition of counteranions, different intermediates and final products were derived from various organonitriles, in which an intermediate N,N′-bis(picolinamide)azine (H4bpa) has been successfully trapped in its neutral manganese(II) complexes. A systematical study shows that, after the initial formation of 2-pyridylamidrazone from 2-cyanopyridine and hydrazine, two reaction paths are involved in the formation of 1,2,4-triazoles: via the formation of 3,6-bis(2-pyridyl)-l,2-dihydro-l,2,4,5-tetrazine and H4bpa as intermediates. The tetrazine and H4bpa paths are preferred in the absence and presence of metal ions, respectively. In the presence of metal ions, metal ion binding can stabilize the tautomers, enhance the nucleophilic reactivity of the imino C atom, and inhibit the tautomerization of H4bpa, hence leading to the formation of 1,2,4-triazolates or H4bpa in complexed forms. The in situ cyclocondensation reactions of 2-pyridylamidrazone and carboxylate into asymmetric 3,5-disubstituted 1,2,4-triazolates under solvothermal conditions have also been observed for the first time. Crystal structures of the crystalline metal complexes have been obtained, including dinuclear [Mn2(bpt)2Cl2(H2O)2] (1) and [Mn2(bpt)2(SCN)2(H2O)2] (3; Hbpt = 3,5-bis(2-pyridyl)-4H-1,2,4-triazole), tetranuclear [Mn4(H3bpa)2(mpt)4(N3)2]·2H2O (5; Hmpt = 3-methyl-5-(2-pyridyl)-1H-1,2,4-triazole), [Mn4(H3bpa)2(pt)4(N3)2]·2C2H5OH (6; Hpt = 5-(2-pyridyl)-1H-1,2,4-triazole), and [Mn4(H3bpa)4(SCN)4]. 2C2H5OH (7), as well as helical [Cu(bpt)] (2). Among them, 7 is the first example of a neutral tetranuclear [2 × 2] grid manganese(II) complex. Both 5 and 7 exhibit antiferromagnetic interactions. [ABSTRACT FROM AUTHOR]

Diastereoselective synthesis of bis-cyclometalated Ir(III) stereoisomers δ/Λ-[Ir(C∧N)2(d-pro)] and δ/Λ-[Ir(C∧N)2(l-pro)] (where C∧N is 2-phenylpyridine (Hppy), (4,6-difluorophenyl)pyridine (Hdfppy), and 2-phenylquinoline (Hpq) and pro is proline) with dual stereogenic centers at the metal and auxiliary ligand has been developed. The diastereomers Λ-l and Λ-d, and δ-l and δ-d exhibit distinguishable photophysical properties in both solution and the solid state. The thermodynamically stable diastereomers Λ-[Ir(ppy)2(l-pro)], Λ-[Ir(dfppy)2(l-pro)], and Λ-[Ir(pq)2(l-pro)] emit a green emission at 524 nm (Φ = 3.5% and τ = 35 ns), a blue-green emission at 480 nm (Φ = 4.5% and τ = 59 ns), and a red emission at 588 nm (Φ = 6.5% and τ = 200 ns) in DCM solution, respectively, which are blue-shifted accompanied by a large quantum yield and long lifetime relative to the corresponding unstable diastereomers δ-[Ir(ppy)2(l-pro)] at 537 nm (Φ = 2.3% and τ = 29 ns), δ-[Ir(dfppy)2(l-pro)] at 489 nm (Φ = 2.8% and τ = 43 ns), and δ-[Ir(pq)2(l-pro)] at 591 nm (Φ = 5.4% and τ = 192 ns). Similar cases were also observed in crystals, but the signals were significantly red-shifted with respect to those in solution. Single-crystal structural analyses show that the δ-l and Λ-d diastereomers exhibit larger interligand repulsion and loose molecular packing with respect to the δ-d and Λ-l diastereomers, resulting in energy and photophysical property differences. In addition, the isomers with δ and Λ configurations at the metal center exhibit positive and negative circularly polarized luminescence (CPL) signals, respectively, indicating that the effects of the chiral carbon atoms in pro ligands on CPL signals are negligible. [ABSTRACT FROM AUTHOR]

In the crystal structure of the title complex, C10H8N2·C6H4O4S or bpy·tdc (bpy is 4,4′-bi­pyridine and tdc is thio­phene-2,5-di­carboxyl­ic acid), bpy and tdc form one-dimensional zigzag chains as a result of O—H⋯N hydrogen bonds. These chains are further assembled into layers by van der Waals attractions, which are extended into a three-dimensional network by van der Waals and aromatic π–π stacking interactions. [ABSTRACT FROM AUTHOR]

The preparation of chiral 2-(alkylsulfinyl)phenol compounds by enantioselective coordination-oxidation of the thioether ruthenium complexes with a chiral-at-metal strategy has been developed. The enantiomerically pure sulfoxide complexes δ-[Ru(bpy)2{(R)-LO-R}](PF6) (bpy is 2,2'-bipyridine, HLO-R is 2-(alkylsulfinyl)phenol, R = Me (δ-1a), Et (δ-2a), iPr (δ-3a), Bn (δ-4a), and Nap (δ-5a)) and Λ-[Ru(bpy)2{(S)-LO-R}](PF6) (R = Me (Λ-1a), Et (Λ-2a), iPr (Λ-3a), Bn (Λ-4a), and Nap (Λ-5a)) have been synthesized by the reaction of δ-[Ru(bpy)2(py)2]2+ or Λ-[Ru(bpy)2(py)2]2+ with the prochiral thioether ligands 2-(alkylthio)phenol (HL-R), followed by enantioselective oxidation with m-CPBA as oxidant. The X-ray crystallography was used to verify the stereochemistry of ruthenium complexes and sulfur atoms. The configurations of the ruthenium complexes are stable during the coordination and oxidation reactions. Moreover, the chiral sulfoxide ligands are enantioselectively generated by controlling of the configuration of ruthenium centers in the course of oxidation reaction. That is, the Λ configuration at the ruthenium center generates the S sulfoxide ligand; on the contrary, the δ configuration of the ruthenium complex originates the R sulfoxide ligand. Acidolysis of Λ-[Ru(bpy)2{(R)-LO-R}](PF6) and δ-[Ru(bpy)2{(S)-LO-R}](PF6) complexes in the presence of TFA-MeCN afforded the chiral ligands (R)-HLO-R and (S)-HLO-R in 96-99% ee values, respectively. Importantly, the chiral ruthenium complexes can be recycled as δ/Λ-[Ru(bpy)2(MeCN)2](PF6)2 and reused in a next reaction cycle with complete retention of the configurations at ruthenium centers. [ABSTRACT FROM AUTHOR]

Four new ruthenium(II) complexes [Ru(bpy)2(TMBiimH2)](ClO4)2 (Ru-5; bpy is 2,2'-bipyridine and TMBiimH2 is 4,5,4',5'-tetramethyl-2,2'-biimidazole), [Ru(bpy)2(LIH2)](ClO4)2·H2O (Ru-6; LIH2 is 4,5-dimethyl-2-(N,N-diacetyl)carboximidamide-1H-imidazole), [Ru(bpy)2(L2H2)](ClO4)2 (Ru-7; L2H2 is N¹,N¹,N²,N²-tetrakis(acetyl)ethanediimidamide), and [Ru(phen)2(TMBiimH2)](ClO4)2 (Ru-8; phen is 1,10'-phenanthroline) have been synthesized and characterized. Their photophysical and electrochemical properties have been studied and compared to the previously reported [Ru(bpy)2(BiimH2)](PF6)2 (Ru-1), [Ru(bpy)2(BbimH2)](PF6)2 (Ru-2), [Ru(bpy)2(DMBbimH2)](PF6)2 (Ru-3), and [Ru(bpy)2(TMBbimH2)](PF6)2 (Ru-4). Under irradiation with either sunlight or household light in atmosphere, Ru-5 reacts with molecular oxygen to produce Ru-6 in an acetonitrile solution with a relatively high concentration and Ru-7 in a methanol or dilute acetonitrile solution, respectively. The mechanism studies show that singlet oxygen is the reactive oxygen species in the ring-opening reaction and the photooxidation reaction is solvent- and concentration-dependent. The photoreaction product Ru-6 is an intermediate, which has been isolated and structurally characterized by single-crystal X-ray diffraction. Ru-6 is stable in the solid state and an acetonitrile solution with a high concentration, but can be further oxidized to Ru-7 in a methanol or dilute acetonitrile solution. [ABSTRACT FROM AUTHOR]

Two isostructural 1D coordination polymers {[Ln(OAc)2(H2O)(OBPT)]·3H2O}n (HOBPT = 4,6-bis(2-pyridyl)-1,3,5-triazin-2-ol, Ln = Eu3+, 1; Tb3+, 3) and two discrete complexes [Ln(OAc)2(DMF)2(OBPT)] (Ln = Eu3+, 2; Tb3+, 4) have been synthesized in H2O-MeOH or DMF solvents, respectively. Their structures were identified by powder X-ray diffraction. Single-crystal X-ray studies for complexes 1 and 2 revealed that the coordination geometries of the Eu3+ ions are similar and can be described as a distorted tricapped trigonal prism with six oxygen atoms and three nitrogen atoms. The difference between them is that one aqua ligand and one oxygen atom from the OBPT ligand complete the coordination sphere in complex 1, whereas two DMF molecules complete the coordination sphere in complex 2. Interestingly, the solvent-mediated, reversible crystal-to-crystal transformation between them was achieved by immersing the crystalline samples in the corresponding solvent (H2O or DMF) or by exposing them to solvent vapor. Complex 1 shows a highly selective luminescence enhancement in response to DMF in comparison to that observed in response to other examined solvents such as acetone, ethyl acetate, ethanol, acetonitrile, methanol, and THF. [ABSTRACT FROM AUTHOR]

Two new complexes [Cu4(2-OBPT)2(μ-OAc)4(μ-OH)2]·H2O (1) and [Cu2(2-OBPT)(μ-OAc)2(μ-OH)]·1.75H2O (2) (2-HOBPT = 4,6-bis(2-pyridyl)-1,3,5-triazin-2-ol) have been synthesized and characterized by single-crystal X-ray diffraction. Complex 1is a tetranuclear macrocycle with a centrosymmetric space group P1, while complex 2is a zigzag chain coordination polymer with a P21/cspace group. They are supramolecular isomers based on the dicopper [Cu2(μ-OAc)2(μ-OH)] core and 2-OBPT ligand. Interestingly, each isomer can be afforded by control of the crystallization temperature. A mixture of complexes 1and 2were obtained in the range of 60–100 °C, while the unique 2crystallized at 20 °C in a high yield of 82% and the sole 1was afforded at 120 °C. Moreover, both the complexes are antiferromagnetic and the theoretical fit of the magnetic susceptibility data in the temperature range of 2–300 K gives J1/kB= −33.6(5) K, g= 2.26(1) for 1and J1= −29.1(6) K, g= 2.30(1) for 2. [ABSTRACT FROM AUTHOR]

Two new isomorphous complexes [M(OBPT)2]·0.6H2O (M = Co, (1), M = Ni, (2), HOBPT = 4,6-bis(4-pyridyl)-1,3,5-triazin-2-ol) have been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction. Each ligand bridges two metal ions and each metal ion links to four ligands, resulting in a (4,4) 2D framework with rhombic cavities. Furthermore, the uncoordinated pyridine rings are further linked to each other viaforming hydrogen bonding with the lattice water molecules into 3D three-fold interpenetrated, hydrogen-bonded networks. Interestingly, they are high stable up to 450 °C and exhibit reversible single crystal to single crystal transformation triggered by thermal treatment involving dehydration and rehydration processes. Moreover, they selectively adsorb/desorb water molecules over organic solvents much depending on the strength of hydrogen bonding between water molecule and solvent. [ABSTRACT FROM AUTHOR]

Five different cobalt complexes were synthesized by the combination of the multidentate ligand 2,2′-bibenzimidazole (H2bbim) and the coordination plasticity of cobalt ion in the presence of 4-cyanopyridine under hydrothermal conditions using temperature as the only independent variable. The structural features of theses complexes, which ranged from zero-dimensional (0D) in [Co(Hbbim)3]·3H2O (1) and [Co(ina)2(H2O)4] (5) to two-dimensional (2D) layer in {[Co4(Hbbim)4(bbim)2]·2H2O}n(2) or three-dimensional (3D) networks in [Co2(Hbbim)(bbim)2(H2O)]n(3) and [Co5(Hbbim)(bbim)3(ina)2(μ3-OH)]n(4), were extremely dependent on the reaction temperature. At 130 °C, discrete 1was the unique product. However, 4was the main product when the reaction temperatures were set in the range of 160−200 °C. 2and 3yielded at 140 °C as main products. In spite of the structural diversity of this system, crystallographic studies reveal that the H2bbim ligand typically displays tridentate (Hbbim−) and/or tetradentate (bbim2−) coordination modes at high temperature, however, a chelating mode at low temperature. The ligands Hbbim−and bbim2−offering donor atoms and charge balance may have both advantages of bipyrimidine and oxalate in the assembly of high-dimensional structures. Indeed, 2is the first instance of 2D honeycomb (6,3), neutral coordination polymer constructed by only one type of ligand and one type of metal ion. Magnetic properties of 3and 4have been studied in the temperature range of 2−300 K. Both compounds exhibit antiferromagnetic interactions between metal ions through the bridging ligand. [ABSTRACT FROM AUTHOR]

Two new complexes [Co(H2O)6⊂Co8(L1)12]X6·nH2O (X = NO3-, n = 12(1); X = HCO3-, n = 24, (2); HL1 = 4,6-bis(2-pyridyl)-1,3,5-triazin-2-ol) have been synthesized and characterized by single-crystal X-ray diffraction. A [Co(H2O)6]2+ ion is encapsuled in the central cavity of the cubelike nanocage [Co(H2O)6⊂Co8(L1)12]6+ cation, assembled by eight cobalt ions at the corners and twelve bis-bidentate ligands Li as the edges, via the formation of 12-fold strong hydrogen bonds between the six coordinated water molecules and the oxygen atoms of twelve Li as a guest. Complex 1 crystallizes in a centrosymmetric space group P1, while 2 is in a very high symmetric space group Im3. In 2, a planar [(HCO3)2]2- dimer motif R²2(8) synthon plus six lattice water molecules constitute a planar supramolecular synthon R88(20), which acts as a four connector, generating a 3D hydrogen-bonded NbO net with cubelike host cavities of ~20 Å diameter. Interestingly, the cubelike nanocage [Co(H2O)6⊂Co8(L1)12]6+ cations fill in the cavities as templates. The magnetic properties of 1 have also been studied in the temperature range of 2-300 K, and its magnetic susceptibility obeys the Curie-Weiss law, showing antiferromagnetic coupling. [ABSTRACT FROM AUTHOR]

A ruthenium(II) complex [Ru(bpy)2(H2bbim)](PF6)2 (1) as anions receptor has been exploited, where Ru(II)-bpy moiety acts as a chromophore and the H2bbim ligand as an anion binding site. A systematic study suggests that 1 interacts with the Cl-, Br-, I-, NO3-, HSO4-, and H2PO4- anions via the formation of hydrogen bonds. Whereas 1 undergoes a stepwise process with the addition of F- and OAc- anions: formation of the monodeprotonated complex [Ru(bpy)2(Hbbim)] with a low anion concentration, followed by the double-deprotonated complex [Ru(bpy)2(bbim)], in the presence of a high anion concentration. These stepwise processes concomitant with the changes of vivid colors from yellow to orange brown and then to violet can be used for probing the F- and OAc- anions by naked eye. The deprotonation processes are not only determined by the basicity of the anion but also related to the strength of hydrogen bonding, as well as the stability of the formed compounds. Moreover, a double-deprotonated complex [Ru(bpy)2(bbim)]·CH3OH·H2O (3) has been synthesized, and the structural changes induced by the deprotonation has also been investigated. In addition, complexes [Ru(bpy)2(Hbbim)]2(HOAc)3Cl2·12H2O (2), [Ru(bpy)2(Hbbim)](HCCl3CO2)(CCl3CO2)·2H2O (4), and [Ru(bpy)2(H2bbim)](CF3CO2)2·4H2O (5) have been synthesized to observe the second sphere coordination between the Ru(II)-H2bbim moiety and carboxylate groups via hydrogen bonds in the solid state. [ABSTRACT FROM AUTHOR]

Six complexes containing the 2,2′-biimidazole-like ligand and chloride, namely, trans-[Ni(H 2biim) 2(H 2O) 2]Cl 2( 1), trans-[Co 1.5(H 2biim) 3(H 2O) 3]Cl 3( 2), [Zn(H 2biim) 2Cl]Cl ( 3), [Ni 2(H 2bbim) 4(bbim)]Cl 2( 4), [Co(H 2bbim) 3]Cl 2·2H 2O ( 5), and [Zn 2(Hbbim) 2(bbim) 0.5Cl] ( 6) (where H 2biim = 2,2′-biimidazole, H 2bbim = 2,2′-bibenzimidazole) have been synthesized by the reactions of the H 2biim or H 2bbim ligand with the metal chloride salts. The structures of the complexes were determined by single-crystal X-ray diffraction analyses, and the results revealed that the distances of N···Cl varied from 3.10 to 3.29 Å and the angles of N−H···Cl varied from 148 to 169°, O···Cl varied from 3.09 to 3.16 Å, O−H···Cl varied from 151 to 178°, C···Cl varied from 3.49 to 3.69 Å, and C−H···Cl varied from 122 to 167°. The chloride may act as a multi hydrogen bonded acceptor varying from 3 to 6, resulting in an important collective contribution to cohesion. The data observed in this study seem to suggest that a variety of X−H···Cl (X = N, O, and C) synthons identified here play a crucial role in the formation and further stabilization of supramolecular architecture, for instance, to link the discrete (0D) or low-dimensional (1D) entities into high-dimensional frameworks. In particular, the coplanar [(H 2O) 2Cl 2] 2−guests are encapsulated in the cavities formed by four [Co(H 2bbim) 3] 2+cations and stabilized via accepting 6-fold hydrogen bonds from three H 2bbim ligands in 5. The distance between the chloride anion and the imidazolyl ring (Cl···centroid, 3.30 Å and 80°) demonstrates the possible existence of Cl···π (imidazolyl) charge-assisted interactions because the coordination of a positively charged Co(II) ion greatly enhances the electron-deficient character of the imidazolyl ring and provides sufficient polarization to produce an anion−π charge-assisted interaction. [ABSTRACT FROM AUTHOR]

A new copper(II) fluorescent sensor 5,10,15,20-tetra((p-N,N-bis(2-pyridyl)amino)phenyl)porphyrin zinc (1) has been designed and synthesized by the Ullmann-type condensation of bromoporphyrin zinc with 2,2′-dipyridylamine (dpa) under copper powder as a catalyst as well as with K2CO3 as the base in a DMF solution. It consists of two separately functional moieties: the zinc porphyrin performs as a fluorophore, and the dpa-linked-to-zinc porphyrin acts as a selected binding site for metal ions. It displays a high selectivity and antidisturbance for the Cu2+ ion among the metal ions examined (Na2+, Mg2+, Cr2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+ Ag2+, Zn2+, Cd2+, Hg2+, and Fe2+) and exhibits fluorescence quenching upon the binding of the Cu2+ ion with an "on-off"-type fluoroionophoric switching property. The detection limit is found to be 3.3 x 10-7 M (3s blank) for Cu2+ ion in methanol solution, and its fluorescence can be revived by the addition of EDTA disodium solution. The design strategy and remarkable photophysical properties of sensor 1 help to extend the development of fluorescent sensors for metal ions. [ABSTRACT FROM AUTHOR]

A new anion sensor [Ru(bpy)2(H2biim)](PF6)2 (1) (bpy = 2,2′-bipyridine and H2biim = 2,2′-biimidazole) has been developed, in which the Ru(ll)-bpy moiety acts as a chromophore and the H2biim ligand as an anion receptor via hydrogen bonding. A systematic investigation shows that 1 is an eligible sensor for various anions. It donates protons for hydrogen bonding to Cl-, Br-, l-, NO3-, HSO4-, H2PO4-, and OAc- anions and further actualizes monoproton transfer to the OAc- anion, changing color from yellow to orange brown. The fluoride ion has a high affinity toward the N-H group of the H2biim ligand for proton transfer, rather than hydrogen bonding, because of the formation of the highly stable HF2- anion, resulting in stepwise deprotonation of the two N-H fragments. These processes are signaled by vivid color changes from yellow to orange brown and then to violet because of second-sphere donor-acceptor interactions between Ru(ll)-H2biim and the anions. The significant color changes can be distinguished visually. The processes are not only determined by the basicity of anion but also by the strength of hydrogen bonding and the stability of the anion-receptor complexes. The design strategy and remarkable photophysical properties of sensor 1 help to extend the development of anion sensors. [ABSTRACT FROM AUTHOR]

Two new isostructural complexes [M(H2biim)3][M(btc)(Hbiim)]•2H2O (M = Co, (1); M = Ni, (2)) (btc = 1,3,5-benzenetricarboxylate; H2biim = 2,2′-biimidazole) have been synthesized and characterized by single-crystal X-ray diffraction. They present a unique structure consisting of two distinct units: the monomeric cations [M(H2biim)3]2+ and the two-dimensional (2D) anionic polymer [M(Hbiim)(btc)]2-. In the anionic moiety, the Hbiim monoanion is simultaneously coordinated to one metal atom in a bidentate mode and further to another metal atom in a monodentate mode. The imidazolate groups bridge the two adjacent metal ions into a helical chain which is further arranged in left- and right-handed manners. These chains are bridged by btc ligands into a 2D brick wall structure. The most interesting aspect is that the [M(H2biim)3]2+ cations act as pillars and link the anionic layers via robust heteromeric hydrogen-bonded synthons R²2(9) and R¹2(7) formed by the uncoordinated oxygen atoms of carboxylate groups and the H2biim ligands, resulting in a microporous metal-organic framework with one-dimensional (1D) channels (ca. 11.85 Å ⊗ 11.85 Å for 1 and 11.43 Å ⊗ 11.43 Å for 2). Magnetic properties of these two complexes have also been studied in the temperature range of 2–300 K, and their magnetic susceptibilities obey the Curie-Weiss law in the temperature range of 20–300 K (for 1) and 2–300 K (for 2), respectively, showing anti-ferromagnetic coupling through imidazolate bridging. Taking into consideration the Heisenberg infinite chain model as well as the possibility of chain-to-chain and chain-to-cation interactions, the anti-ferromagnetic exchange of 2 is analyzed via a correction for the molecular field, giving the values of gcat = 2.296, gNi = 2.564, J = -13.30 cm-1, and zJ′ = -0.017 cm-1. The microporous frameworks are stable at ca. 350 °C. They do not collapse after removal of the guest water molecules in the channels, and they adsorb methanol molecules selectively. [ABSTRACT FROM AUTHOR]

Two NbO frameworks are constructed by the reaction of Co(OAc)2·4(H2O)/Zn(OAc)2·2(H2O) with 1-(4-(1H-benzimidazol-1-yl)phenyl)butane-1,3-dione in the ratio of 1 : 2, in which they are isostructural and the NbO net exhibits a two-fold interpenetration featuring hexameric 1D channels. Theses channels are occupied by unprecedented tetrahedral tetramer water clusters. [ABSTRACT FROM AUTHOR]

A (10,3)-b framework is constructed by the reaction of [Ru(H2Biim)3](PF6)2 and trimesic acid in a ratio of 1 : 1, in which the (10,3)-b net exhibits a two-fold interpenetration featuring 1D nano-sized channels. An unprecedented water nanotube consisting of the fused (H2O)28 with a double crown fashion, anchors in the channel. [ABSTRACT FROM AUTHOR]

The article focuses on the construction of a nanoscale, global ionic cluster which is packed in a face-centered cubic (fcc) pattern. It is where the (H2O)21 clusters were caught and stabilized in the tetrahedral holes. It is stated that the structural characterization of the water cluster increases the understanding of the structural aspects and formation of the clathrate hydrates in the atmosphere and biosphere.