A butterfly shaped Eu4(OH)2 cluster-based luminescent metal-organic framework with Lewis basic triazole sites demonstrating turn off sensing in the presence of organic amines.

The effective detection of organic amines is particularly important for environmental protection and human health. Herein, according to hard and soft acid base theory, a novel three-dimensional (3D) butterfly shaped Eu4(OH)2 cluster-based metal-organic framework with Lewis basic triazole sites, {[Eu4(taip)4(ox)(OH)2(H2O)4]·3H2O}n (1) (H2taip = 5-(1,2,4-triazol-1-yl) isophthalic acid, H2ox = oxalic acid), was successfully synthesized under solvothermal conditions, and was characterized by single crystal X-ray diffraction, powder X-ray diffraction, elemental analysis, infrared spectroscopy and thermogravimetric analysis. Structural analysis reveals that compound 1 is a 3D net constructed from butterfly shaped Eu4(OH)2 clusters and contains isosceles triangular channels with dimensions of 8.84 × 8.84 × 8.63 Å3, which shows an unprecedented 8-connected topology with a Schläfli symbol {36·418·53·6}. Fluorescence experiments of compound 1 show sensitive luminescence quenching responses to organic amines such as diethylamine (DEA), trimethylamine (TMA), triethylamine (TEA), ethylenediamine (EDA) and aniline, and the quenching constants (KSV) decrease in the following order: EDA > DEA > TMA > TEA > aniline. The fluorescence quenching responses may be attributed to the energy gap between the LUMO energy values of H2taip and organic amines, which hinders the transfer of excited state energy to the emission state of Eu3+ and results in luminescence quenching. The fluorescence lifetimes of compound 1 in ethanol and organic anilines indicate that the fluorescence recognition process of organic amines was static.

Four new Cu6S6 cluster-based coordination compounds: synthesis, crystal structures and fluorescence properties.

A hexagonal prismatic Cu6S6 cluster exhibits excellent near-infrared fluorescence properties due to its short Cu-Cu bonds, however, the construction of Cu6S6 cluster-based compounds with extended structures is still a challenge. Here, four new Cu6S6 cluster-based coordination compounds, formulated as Cu3(pymt)3 (1), {(CuCN)2[Cu3(mpymt)3]}n (2), {(CuSCN)[Cu3(mpymt)3]}n (3) and {(CuCN)2[Cu3(dmpymt)3]·CH3CN}n (4) (Hpymt = pyrimidine-2-thiolate, Hmpymt = 4-methyl-pyrimidine-2-thione and Hdmpymt = 4,6-dimethylpyrimidine-2-thione), have been synthesized through the reactions of mercaptopyrimidine derivatives and CuCN or CuSCN under solvo-thermal conditions and characterized by single-crystal X-ray diffraction, powder X-ray diffraction, IR spectroscopy, elemental analysis, and thermal gravimetric analysis. Single-crystal X-ray diffraction analysis reveals that compound 1 is a zero-dimensional Cu6(pymt)6 molecule containing a distorted pseudo-hexagonal prismatic Cu6S6 core. Compounds 2 and 4 with isomorphic frameworks but different organic linkers show a rare three-dimensional framework with nor topology constructed from Cu6(mpymt)6 units and one-dimensional chiral [Cu(CN)]n chains; compared with compound 2, a more hydrophobic one-dimensional channel in compound 4 is observed due to the increase of the methyl groups on the pyrimidine ligand, in which acetonitrile molecules are filled in the channels of compound 4. Compound 3 shows a rare two-dimensional layer constructed from Cu6(mpymt)6 units and one-dimensional puckered (CuSCN)n chains. For the first time, Cu6S6 clusters are connected to one-dimensional inorganic CuCN (or CuSCN) chains through mercaptopyrimidine derivatives to obtain extended arrays in compounds 2-4. The crystals of compounds 1-4 in the solid state all show apparent red light emission. Compound 4 shows sensitive luminescence quenching response to nitrobenzene (NB), and the corresponding quenching constant (Ksv) and detection limit are 2.06 × 103 M-1 and 9.27 ppm, respectively. This study provides a new strategy to construct Cu6S6 cluster-based coordination polymers that have great potential in various applications such as luminescence sensing.

Three novel Cu6S6 cluster-based coordination compounds: synthesis, framework modulation and the sensing of small molecules and Fe(3+) ions.

Three novel Cu6S6 cluster-based coordination compounds formulated as [Cu(mpymt)3]2 (1), {(CuBr4)[Cu(mpymt)6]}n (2), and {(CuI6)[Cu(mpymt)6]}n (3) (Hmpymt = 4-methylpyrimidine-2-thione), have been synthesized under solvothermal conditions and characterized by elemental analysis, infrared (IR) spectroscopy, thermal gravimetric analysis, powder X-ray diffraction and single-crystal X-ray diffraction. Structural analysis reveals that compound 1 shows a distorted octahedral core of six copper atoms (Cu6S6) constructed from four α and two ß type N[double bond, length as m-dash]C-SH parts from six mpymt(-) anions. Compound 2 displays an interesting 3D framework constructed from Cu6S6 and Cu4Br4 Cu(i) clusters simultaneously, interestingly, six mpymt(-) with α type N[double bond, length as m-dash]C-SH parts are involved in the formation of Cu6S6. Compound 3 displays an infinite 1D framework constructed from Cu6S6 and Cu6I6 Cu(i) clusters, notably, four α and two ß type N[double bond, length as m-dash]C-SH parts are involved in the formation of the Cu6S6 cluster, however, only mpymt(-) ligands containing α type N[double bond, length as m-dash]C-SH parts form the bridged Cu6I6 cluster. The experimental results reveal that halogen ions finely modulate the structural features of compounds 1-3. The fluorescent properties of compounds 1-3 in the solid state and in various solvent emulsions were investigated in detail, the results of which indicate that compounds 1-3 are all highly sensitive naked eye colorimetric sensors for NB, 2-NT and Fe(3+) (NB = nitrobenzene and 2-NT = 2-nitrotoluene).

A novel 3D Cu(I) coordination polymer based on Cu6Br2 and Cu2(CN)2 SBUs: in situ ligand formation and use as a naked-eye colorimetric sensor for NB and 2-NT.

A novel coordination polymer with the chemical formula [Cu4Br(CN)(mtz)2]n (mtz = 5-methyl tetrazole) (), has been synthesized under solvothermal conditions and characterized by elemental analysis, infrared (IR) spectroscopy, thermal gravimetric analysis, powder X-ray diffraction and single-crystal X-ray diffraction. Interestingly, the Cu(i), CN(-) and mtz(-) in compound are all generated from an in situ translation of the original precursors: Cu(2+), acetonitrile and 1-methyl-5-mercapto-1,2,3,4-tetrazole (Hmnt). The in situ ring-to-ring conversion of Hmnt into mtz(-) was found for the first time. Structural analysis reveals that compound is a novel 3D tetrazole-based Cu(i) coordination polymer, containing both metal halide cluster Cu6Br2 and metal pseudohalide cluster Cu2(CN)2 secondary building units (SBUs), which shows an unprecedented (3,6,10)-connected topology. Notably, a pseudo-porphyrin structure with 16-membered rings constructed by four mtz(-) anions and four copper(i) ions was observed in compound . The fluorescence properties of compound were investigated in the solid state and in various solvent emulsions, the results show that compound is a highly sensitive naked-eye colorimetric sensor for NB and 2-NT (NB = nitrobenzene and 2-NT = 2-nitrotoluene).

(µ-5-Carb-oxy-1H-imidazole-4-carboxyl-ato-κN,O:N,O)bis-[amminesilver(I)].

In the title compound, [Ag(2)(C(5)H(2)N(2)O(4))(NH(3))(2)], each of the two Ag(I) atoms is coordinated by two N atoms from an ammonia mol-ecule and a 5-carb-oxy-1H-imidazole-4-carboxyl-ate ligand in an almost linear geometry, and by one carboxyl-ate O atom with a weak inter-action. The Ag atoms are assembled into a linear tetra-mer through Ag⋯Ag inter-actions. Each Ag tetra-mer is linked by four 5-carb-oxy-1H-imidazole-4-carboxyl-ate ligands, forming a puckered chain. The complex involves a strong intra-molecular O-H⋯O hydrogen bond.

4-Hydr-oxy-6-[(4-hydr-oxy-1-oxo-1,2-dihydro-phthalazin-6-yl)carbon-yl]phthalazin-1(2H)-one.

In the crystal structure of the title compound, C(17)H(10)N(4)O(5), the mol-ecules lie on twofold axes (through the ketone bridge C and O atoms). The dihedral angle between the two phthalazine rings is 52.25 (1)°. In the crystal, inter-molecular N-H⋯O and O-H⋯O inter-actions link the mol-ecules.

5,5'-Di-4-pyridyl-2,2'-(p-phenyl-ene)di-1,3,4-oxadiazole.

In the crystal structure of the title compound, C(20)H(12)N(6)O(2), the mol-ecules are located on centres of inversion. The complete mol-ecule is almost planar, with a maximum deviation from the mean plane of 0.0657 (1) Šfor the O atom. In the crystal, mol-ecules are stacked into columns elongated in the a axis direction. The centroid-centroid distances between the aromatic rings of the mol-ecules within the columns are 3.6406 (1) and 3.6287 (2) Å. Mol-ecules are additionally connected via weak inter-molecular C-H⋯N hydrogen bonding.