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As the Cr2O72– anion is highly toxic, new sensors have been developing for its effective detection from water, among which metal–organic frameworks (MOFs) show distinct superiority over many other materials. Herein, a new fluorescent Zr(IV)-based MOF, [Zr6O4(OH)8(H2O)4(sbtc)2] (referred to as BUT-28), based on the di-isophthalate ligand with a central CH═CH moiety, trans-stilbene-3,3′,5,5′-tetracarboxylate (sbtc4–), has been prepared and structurally determined. The MOF shows excellent stability in neutral, highly acidic, and weakly basic aqueous solutions. Moreover, no essential uptake loss in three cycles of water vapor adsorption–desorption measurements was observed for BUT-28, suggesting the robustness of the porous framework and its great potential for long-term use. Fluorescent measurements were carried out for BUT-28 and an isostructural MOF, Zr-abtc, which is constructed from the di-isophthalate ligand with a central N═N moiety, azobenzene-3,3′,5,5′-tetracarboxylate (abtc4–). Interestingly, Zr-abt...

Three new water-stable In(III)-based metal–organic frameworks, namely, [In3(TTTA)2(OH)3(H2O)]·(DMA)3 (BUT-70, DMA = N,N-dimethylacetamide), [In3(TTTA)2(CH3O)3] (BUT-70A), and [In3(TTTA)2(OH)3] (BUT-70B), with rod-shaped secondary building units (SBUs) and an new acrylate-based ligand, (2E,2′E,2″E)-3,3′,3″-(2,4,6-trimethylbenzene-1,3,5-triyl)-triacrylate (TTTA3–) were obtained and structurally characterized. BUT-70A and -70B were generated in a single-crystal to single-crystal transformation fashion from BUT-70 through guest exchange followed by their removal. The solvents used for guest exchange were methanol and dichloromethane, respectively. Single-crystal structure analyses show that the guest exchange and removal process is accompanied by the substitution of coordinated water molecules of In(III) centers with uncoordinated carboxylate O atoms of TTTA3– ligands. Moreover, hydroxyl groups bridging two In(III) centers are also replaced by methoxyl groups in the transformation from BUT-70 to -70A. Overall...

As the Cr

A series of yttrium oxide-carbonyls are prepared via a laser vaporization supersonic cluster source in the gas phase and identified by mass-selected infrared photodissociation (IRPD) spectroscopy in the C-O stretching region and by comparing the observed IR spectra with those from quantum chemical calculations. For YO(CO)4(+), all four CO ligands prefer to occupy the equatorial site of the YO(+) unit, leading to a quadrangular pyramid with C4v symmetry. Two energetically nearly degenerate isomers are responsible for YO(CO)5(+), in which the fifth CO ligand is either inserted into the equatorial plane of YO(CO)4(+) or coordinated opposite the oxygen on the C4 axis. YO(CO)6(+) has a pentagonal bipyramidal structure with C5v symmetry, which includes five equatorial CO ligands and one axial CO ligand. The present IRPD spectroscopic and theoretical study of YO(CO)n(+) extends the first shell coordination number of CO ligands in metal monoxide carbonyls to six. The transition from equatorial to axial CO chemisorption in these yttrium oxide-carbonyls is fortunately observed at n = 5, providing new insight into ligand interactions and coordination for the transition metal oxides.

The homoleptic heterodinuclear copper-nickel carbonyl anions CuNi(CO)n(-) (n = 2-4) were generated in a pulsed-laser vaporization source and investigated using photoelectron velocity-map imaging spectroscopy. The electron affinities of CuNi(CO)2 (2.15 ± 0.03 eV), CuNi(CO)3 (2.30 ± 0.03 eV), and CuNi(CO)4 (1.90 ± 0.04 eV) were deduced from the photoelectron spectra. Theoretical calculations at the B3LYP level were carried out to elucidate the structures and the electronic properties of CuNi(CO)n(0/1-) (n = 1-4) and to support the experimental observations. Comprehensive comparisons between experiments and calculations suggest that there is a turnover point of the absorption site during the progressive carbonylation process. The carbonyl groups are determined to be preferentially bonded to the nickel atom. When the nickel center satisfies the 18-electron configuration, the copper atom starts to adsorb additional CO molecules. These results will shed light on the bonding mechanisms of the heterometallic carbonyl clusters.

Three new water-stable In(III)-based metal-organic frameworks, namely, [In

Solvothermal reactions with different solvents produced two iron trimesates [Fe2(H2O)2(BTC)4/3]Cl x 4.5(DMF) (1) and [Fe4Cl(BTC)8/3]Cl2 x H2O x 2.5(DEF) (2) (BTC = 1,3,5-benzenetricarboxylate, DMF = N,N'-dimethylformamide, DEF = N,N'-diethylformamide). The framework of 1 is a (3,4)-connected net constructed from mixed-valence paddlewheel Fe2(II, III) units and BTC linkers, while the framework of 2 is a (3,8)-connected net built from mixed-valence square-planar Fe4(III, III, III, II) units and BTC linkers. The large volume inside the framework of 1 (or 2) is occupied by disordered Cl- anions and guest DMF (or DEF) molecules. The mixed-valence character of the frameworks of 1 and 2 was confirmed by Mössbauer spectroscopy studies. The active electronic property of iron cations may be the origin of the variability of the iron-organic frameworks, which are readily affected by some synthetic factors, such as solvents. Magnetic studies reveal that there are antiferromagnetic exchange interactions among the Fe atoms in 1 and 2. Ion-exchange studies for 1 show that the Cl- anions inside the framework of 1 can be exchanged by CNS- anions.

Two novel organic-inorganic hybrid compounds based on Anderson-type polyoxoanions, [Cu2(bpy)2(mu-ox)][Al(OH)7Mo6O17] (1) and [Cu2(bpy)2(mu-ox)][Cr(OH)7Mo6O17] (2), have been synthesized and characterized by elemental analyses, IR, and X-ray powder diffraction. The crystal structures of 1 and 2 have been established by single-crystal X-ray diffraction, which reveals the presence of 1D chains constructed of alternating Anderson-type polyoxoanions and oxalato-bridged dinuclear copper complexes for both compounds and extensive hydrogen bonding that plays an important role in the formation of the 3D supramolecular network structures of 1 and 2. To elucidate the electronic properties and magnetic properties of the metal ions (Cu2+ or Cu2+ and Cr3+), EPR studies and magnetic susceptibility studies have been performed, respectively. The results are consistent with the structural feature of these compounds.

Four porous metalloporphyrinic framework materials, [(CH3)2NH2][Zn2(HCOO)2(Mn(III)-TCPP)]·5DMF·2H2O (1; H6TCPP = tetrakis(4-carboxyphenyl)porphyrin), [(CH3)2NH2][Cd2(HCOO)2(Mn(III)-TCPP)]·5DMF·3H2O (2), [Zn2(HCOO)(Fe(III)(H2O)-TCPP)]·3DMF·H2O (3), and [Cd3(H2O)6(μ2-O)(Fe(III)-HTCPP)2]·5DMF (4) were synthesized by heating a mixture of M(III)Cl-H4TCPP (M = Mn and Fe) and M' (M' = Zn or Cd) nitrate in a mixed solvent of DMF and acetic acid. Compounds 1-3 are built up from M'2(COO)4 paddle-wheel subunits bridged by M(III)-TCPP and formate ligands to form their 3D connections. The formate pillar heterogeneously connects with M and M' cations in 1 and 2 and homogeneously joins M' cations in 3. The μ2-O bridged Fe(III)-HTCPP dimer performs as a decadentate ligand to link 10 cadmium cations for the formation of an interesting 3D coordination network of 4. The four porphyrinic frameworks present interesting catalytic properties in the selective epoxidation of olefins, oxidation of cyclohexane, and intermolecular aldol reaction of aldehydes and ketones.

Two new [12]metallacrown-6 compounds, [M(II)(6)(SMe)(12)] [M = Ru (1), Zn (2)], were constructed from a dimethyl sulfoxide decomposed methylthiol product to doubly bridged metal centers. The Ru(II) compound can prompt alkenylation reactions of phenylpyridines with alkynes to generate monoalkenylated arylpyridines in moderate yields with high regioselectivity and stereoselectivity.

Reactions of 1:13 heteropoly anions [MV13O38](7-) (M = Mn, Ni) and lanthanide cations Ln3+ (Ln = La, Ce, or Pr) produce five isomorphic compounds, which are crystallized in the triclinic crystal system, space group P1, and formulated as [Ln6(H2O)25(MV12O38)(HMV13O38)].nH2O ((1) Ln = La, M = Mn, and n approximately 31; (2) Ln = Ce, M = Mn, and n approximately 29; (3) Ln = Pr, M = Mn, and n approximately 31; (4) Ln = La, M = Ni, and n approximately 28; (5) Ln = Pr, M = Ni, and n approximately 33). These compounds are two-dimensional polymeric structures constructed by hydrated lanthanide cations and two types of heteropoly anions, [MV13O38](7-) and [MV12O38](12-). In contrast to the previous reported 1:13 heteropoly anions, all with disordered structures, [MV13O38](7-) clusters in 1-5 are non-disordered with a distinct mode. The second kind of anionic cluster [MV12O38](12-) with O(h) symmetry, which consists of 13 entire edge-sharing MO(6) (M = V, Mn or Ni) octahedra, has not been reported hitherto. The emergence of the new cluster may be correlated to the six capping lanthanide cations surrounding it with a stabilization effect. In this paper, the syntheses and structures of the five polymeric lanthanide heteropolyvanadates of manganese(IV) and nickel(IV) have been presented.