Yun-Sheng Ma

Tetranuclear clusters containing a CrIII-doped MnIII4O2 core: syntheses, structures, and magnetic properties.

The oxidation of MnII carboxylates by (NBu4)Cr2O7 in the presence of different phosphonic acids and chelating ligands results in six CrIII-doped tetranuclear manganese clusters formulated [Mn3CrO2(O2CCH3)4(O3PC5H4N)2(bpy)2] (1), [Mn3CrO2(O2CCH3)4(O3PC5H4N)2(phen)2] (2), [Mn3CrO2(O2CPh)4(O3PC5H4NO)2(phen)2] (3), [Mn3CrO2(O2CPh)4(O3PC6H11)2(bpy)2] (4), [Mn 3CrO2(O2CPh)4(O3PC6H11)2(phen) 2] (5), and [Mn3CrO2(O2CCH3)4(O3PC6H11)2(bpy)2] (6). Single-crystal X-ray analyses reveal that all the compounds contain similar [M4O2]8+ cores with the four metal sites arranged in planar topologies. The metal ions within the core are bridged by both carboxylate and phosphonate ligands. Temperature-dependent magnetic measurements show that in all cases dominant antiferromagnetic interactions are propagated between the metal centers. The ac magnetic measurements on compounds 5 and 6 reveal that both the in-phase and the out-of-phase signals are frequency dependent, characteristic of single-molecule magnet behaviors.

Synthesis and structural and magnetic characterization of a hexadecanuclear cobalt phosphonate compound

A wheel-like hexadecanuclear cobalt phosphonate [Co(16)(OH)(6)(chp)(22)(O(3)PC(6)H(9))(2)(H(2)O)(4)] has been synthesized by reactions of cobalt perchlorate with cyclohexenephosphonic acid (H(2)O(3)PC(6)H(9)) and 6-chloro-2-hydroxypyridine (Hchp) in the presence of Et(3)N. Magnetic studies on the compound show a general decline of chi(M)T with decreasing T. The appeared maximum of chi(M)T at low temperature suggests the presence of a non-diamagnetic ground state. The alternating current susceptibilities show frequency-dependent signals.

Structural diversification and photocatalytic properties of zinc(II) polymers modified by auxiliary N-containing ligands

Four new coordination polymers, {[Zn(bismip)]·2H2O}n (1), {[Zn2(bismip)2(4,4′-bipy)]·2H2O}n (2), {Zn2(bismip)2(phen)}n (3) and {[Zn(bismip)(bimb)]2·2H2O·DMF}n (4) (H2bismip = 5-(1H-benzoimidazol-2-ylsulfanylmethyl)-isophthalic acid, 4,4′-bipy = 4,4′-bipyridine, phen = 1,10-phenanthroline, bimb = 4,4-bis(1-imidazolyl)bibenzene) were synthesized under solvothermal conditions. All these compounds were characterized by elemental analysis, IR spectroscopy, thermal analysis, powder X-ray diffraction and single-crystal X-ray diffraction. Compound 1 features a two-dimensional (2D) binodal (3,6)-connected kgd network with (43)2(46·66·83) topology. 2 exhibits two-fold interpenetrating 3D architecture with a (4·82)(42·84) Schlafli symbol in which 2D layers are interlinked by 4,4-bipy ligands. In 3, the [Zn4(bismip)4] and [ZnO4N2] units are interconnected, affording a binodal 3D (3,4)-connected network with the Schlafli symbol (83)(86). 4 is a 2D (3,4)-connected coordination network with (42·6)(42·63·8) topology. The photoluminescence properties and photocatalytic properties of these compounds were also investigated.

Two yttrium(III) coordination compounds containing a3-ptz or atza [a3-ptz = 5-[N-acetato(3-pyridyl)]tetrazole; atza = 5-aminotetrazole-1-acetato]

Two yttrium(III) coordination compounds, [Y(a3-ptz)2(H2O)5]Cl · 4H2O (1) and [Y(atza)2(H2O)2(CH3OH)]Cl (2) [a3-ptz = 5-[N-acetato(3-pyridyl)]tetrazole; atza = 5-aminotetrazole-1-acetato], have been synthesized. Single-crystal X-ray diffraction analysis reveals that 1 has a distorted monocapped square-antiprism coordination geometry around YIII. Complex 2 is a distorted pentagonal bipyramid with coordination from four atza ligands, two waters, and one methanol; the coordination of atza in 2 leads to its 1-D polymeric chain structure. 1 and 2 are self-assembled to form 3-D supramolecular structures through hydrogen bonds. The luminescence properties of 1 and Ka3-ptz were investigated at room temperature in the solid state.

A Convenient Strategy for Designing a Soft Nanospace: An Atomic Exchange in a Ligand with Isostructural Frameworks

Direct observation of gas molecules confined in the nanospace of porous materials by single-crystal X-ray diffraction (SXRD) technique is significant because it leads to deep insight into the adsorption mechanism and the actual state of the adsorbents in molecular level. A recent study revealed that flexibility is one of the important factors to achieve periodic guest accommodation in the nanospace enabling direct observation of gas molecules. Here, we report a convenient strategy to tune the framework flexibility by just an atomic exchange in a ligand, which enables us to easily construct a soft nanospace as the best platform to study gas adsorption. Indeed, we succeeded to observe C2H2 and CO2 molecules confined in the pores of a flexible porous coordination polymer (PCP-N) in different configurations using SXRD measurement, whereas gas molecules in a rigid framework (PCP-C) isostructural to PCP-N were not seen crystallographically. The result of the coincident in situ powder X-ray diffraction and adsorption measurement for PCP-N unambiguously showed that the framework could flexibly transform to trap gas molecules with a commensurate fashion. In addition, for PCP-N, we found that the adsorbed gas molecules induced significant structural change involving dimensional change of the pore from one-dimensional to three-dimensional, and subsequently, additional gas molecules formed periodic molecular clusters in the nanospace.

U(VI) and Zn(II) coordination complexes with 5-(N-acetato(4-pyridyl))tetrazolate anions

A U(VI) mononuclear coordination complex [UO2(a4-ptz)2·(H2O)3] (1) and a Zn(II) 1-D coordination polymer [Zn(a4-ptz)2·(H2O)2]·2H2O (2) have been synthesized with 5-[N-acetato(4-pyridyl)]tetrazolate (a4-ptz) as ligand. Complex 1 has a slightly distorted pentagonal bipyramid around each U center. Complex 2 is octahedral with four a4-ptz and two water ligands. Each Zn center is linked by carboxylate-O(1) and tetrazolate-N(2) of a4-ptz forming a 1-D polymeric chain. Complexes 1 and 2 are self-assembled to form 3-D supramolecular structures through hydrogen bonds. The luminescence properties of 1 and 2 were investigated at room temperature in the solid state. The results suggest that 1 and 2 may be useful as photoactive materials.

Four coordination clusters using fluorenyl and carbazyl phosphonates as ligands

Four polynuclear complexes, [Co4(FluPO3)2(FluPO3H)2(CH3CO2)2(py)6(H2O)2] (1), [Mn5O3(FluPO3)2(PhCO2)5(CH3OH)(phen)2] (2), [Mn5O3(CarbPO3)2(PhCO2)5(CH3OH)(phen)2] (3) and [MnII4MnIII6O2(OH)2(CarbPO3)8(PhCO2)4(py)6] (4) (FluPO3H2 = (9-methyl-9H-fluoren-9-yl)phosphonic acid, CarbPO3H2 = N-carbazolylmethylphosphonic acid), were synthesized and characterized. In compound 1, the cobalt centers are bridged by phosphonate ligands into a circle. Both the cores of complexes 2 and 3 feature three μ3-O and two capping FluPO32− or CarbPO32− groups bridging five MnIII atoms to form a basket-like cage structure. Complex 4 contains divalent and trivalent ions and has a butterfly-like [MnII4MnIII6O2(OH)2(CarbPO3)4]12+ core with four phosphonate ligands in the body position and five Mn atoms on each wing side. Magnetic susceptibility measurements reveal the existence of antiferromagnetic interactions in 1, 2·4CH3CN·2H2O, 3·PhCO2H·6CH3CN·2H2O and 4·py·8H2O. Fitting the experimental data led to the following parameters: J1 = −10.1 cm−1, J2 = −18.0 cm−1, J3 = −8.0 cm−1, J4 = −5.9 cm−1, J5 = −2.8 cm−1, g = 2.0 for 2·4CH3CN·2H2O, and J1 = −7.4 cm−1, J2 = −22.8 cm−1, J3 = −6.9 cm−1, J4 = −4.8 cm−1, J5 = −0.3 cm−1, g = 2.0 for 3·PhCO2H·6CH3CN·2H2O.

Syntheses and characterization of 2-D lanthanide complexes based on and isonicotinate N-oxide ligand

The lanthanide complexes [Ln2(INO)2(SO4)2(H2O)4] · H2O 1 · Ln (Ln = Ce, Pr, and Nd; INO = isonicotinate N-oxide) were synthesized under hydrothermal conditions. The compounds are isostructural and crystallized in monoclinic space group C2/c. Ln(III) is nine-coordinate in a mono-capped square antiprism coordination environment. Ln(III) ions are linked by , N-oxide groups and carboxylates from INO to give an inorganic chain. These chains are connected by INO ligands into a 2-D layer. These layers are joined through hydrogen bonding interactions into a 3-D crystal structure.

Eight novel metal diphosphonates based on 2-(4-pyridinyl)-1-hydroxyl-1,1-ethylidenediphosphonate: syntheses, structures, and magnetic properties

A systematic exploration of a series of hydrothermal reactions of 2-(4-pyridinyl)-1-hydroxyl-1,1-ethylidenediphosphonic acid (4-pyHhedpH3) with manganese, cobalt and copper salts resulted in eight new compounds, namely, Mn(4-pyHhedpH)·H2O (1), Co(4-pyHhedpH)·H2O (2), Co(4-pyHhedpH2)(C2O4)0.5(H2O)·H2O (3), Co3(4-pyHhedpH)2(C2O4)(H2O)2 (4), Cu(4-pyHhedpH2)2 (5), Cu(4-pyHhedpH) (6), CuICuII3(4-pyhedpH0.5)2 (7) and Cu3(4-pyHhedpH)2(C2O4) (8). Compounds 1 and 2 are isostructural and have ladder-like structures in which the {M2(μ-O)2} (M = Mn, Co) dimer units are connected by O–P–O bridges, whereas, compound 3 has a one-dimensional chain structure, where the Co atoms are alternatively linked by C2O42− and O–P–O bridges. Compound 4 contains one chain similar to that of compound 3, while, the chains are further connected by O–P–O bridges to generate a brick-like layer. Compound 5 has a mononuclear structure in which the central Cu ion is chelated by four O atoms from two 4-pyHhedpH ligands, giving a quadrilateral planar coordination shape. Compound 6 has chain-like structures, where {Cu2(μ-O)2} dimers are connected by edge-shared {CuO5} square pyramids to form infinite chains. In compound 7, the {Cu3(O)4} trimers are bridged by O–P–O groups to form infinite chains which are further connected by the pyridinyl groups and {O–CuI–O} units to afford layers. Compound 8 has a two-dimensional structure similar to that of compound 4. The temperature-dependent magnetic susceptibility measurements show dominant antiferromagnetic interactions in compounds 1–4 and 6–8 mediated through O–P–O and/or μ-O bridges between the metal centers. The magnetization measurements reveal that compound 2 shows field-induced magnetic transition at low temperature.

Two linear trinuclear clusters with bridging triazole: crystal structure and magnetism

Two linear trinuclear clusters, [Co3(L)6(H2O)6](ClO4)6 (1) and [Ni3(L)6(H2O)6](ClO4)6 · 3H2O (2) (L = 4-(4-hydroxyphenyl)-1,2,4-triazole), obtained by the reactions of M(ClO4)2 · 6H2O and 4-(4-hydroxyphenyl)-1,2,4-triazole have been isolated and structurally characterized. The two isostructural clusters, linear hexapositive trimers, are linked by three N1,N2-1,2,4-triazoles to the divalent central and terminal metal ions. The magnetic behaviors of the clusters were investigated from 1.8 to 300 K. Magnetic susceptibility measurements reveal antiferromagnetic exchange interactions between the metal centers in the clusters. The magnetic data were analyzed by using linear trinuclear modes with S = 3/2 and S = 1 for 1 and 2, respectively. Further studies were performed by accounting spin–orbital coupling for 1 and involving zero-field splitting within the ground state for 2.