Dandan Gao

Heterometallic SrII-MII (M=Co, Ni, Zn and Cu) Coordination Polymers: Synthesis, Temperature-Dependent Structural Transformation, and Luminescent and Magnetic Properties

The use of pyridine-2,4-dicarboxylic acid (H2 pydc) in the construction of Sr(II) and Sr(II) -M(II) (M=Co, Ni, Zn and Cu) coordination polymers is reported. Eight complexes, that is, [Sr(pydc)H2 O]n (1), [MSr(pydc)2 (H2 O)2 ]n (M=Co (2), Ni (3), Zn (4)), [ZnSr(pydc)2 (H2 O)7 ]n ⋅4 nH2 O (5), [SrCu(pydc)2 ]n (6), [SrCu(pydc)2 (H2 O)3 ]n ⋅2 nH2 O (7), and [Cu3 Sr2 (pydc)4 (Hpydc)2 (H2 O)2 ]n (8), have been synthesized via dexterously choosing the appropriate strontium sources and transition metal salts, and rationally controlling the temperature of the reaction systems. Complexes 1, 2 (3, 4), 6, and 8 display four types of 3-D framework structures. Complexes 5 and 7 exhibit a 2-D network and a 1-D chain structure, respectively. The 2-D complex 7 can be reversibly transformed into 3-D compound 6 through temperature-induced solvent-mediated structural transformation. The luminescent property studies indicated that complex 1 shows a strong purple luminescent emission and 4 exhibits a strong violet luminescence emission. The magnetic properties of 2, 3, and 8 were also studied. Antiferromagnetic M(II) ⋅⋅⋅M(II) interactions were determined for these complexes.

Synthesis, structures and properties of the first series of SrII–MII (M = Cu, Co, Ni and Zn) coordination polymers based on pyridine-2,5-dicarboxylic acid

The first series of heterometallic SrII–MII (M = Cu, Co, Ni and Zn) coordination polymers based on pyridine-2,5-dicarboxylic acid (H2pydc) are reported. Eight complexes of compositions, [Sr(pydc)(H2O)]n (1), [CuSr(pydc)2(H2O)4]n (2), [CoSr(pydc)2(H2O)6]2n·H2O (3), [NiSr(pydc)2(H2O)4]n·3nH2O (4), [Sr(H2O)6]n·n[Ni(pydc)2(H2O)2]·2nH2O (5), [NiSr2(pydc)3(H2O)8]n·2nH2O (6), [ZnSr(pydc)2(H2O)5]n (7) and [ZnSr2(pydc)3(H2O)10]n·2nH2O (8), have been prepared and characterized. The structures of the complexes could be controlled via rationally choosing the appropriate metal salts, adding the starting materials in different orders, and tuning the ratio of the starting materials. Eight varieties of structures, ranging from 1-D chains to 3-D networks, were obtained. The magnetic properties of 2, 3 and 6 were investigated from 2 K to 300 K. Antiferromagnetic MII⋯MII interactions were found for 2 and 6, and ferromagnetic interactions were determined for 3. The solid state luminescent properties of 1, 7 and 8 were also studied.

Syntheses, structures and luminescent properties of a series of ladder-shaped [Ln2Sr3] heterometal-organic frameworks

A series of LnIII–SrII heterometallic coordination polymers formulated as [Ln2Sr3(pda)6(H2O)18]·nH2O (Ln = Pr-1, n = 14; Nd-2, n = 12; Sm-3, n = 11; Eu-4, n = 11; Gd-5, n = 16; Tb-6, n = 13; Dy-7, n = 13) were synthesized via assembly of Ln(NO3)3·6H2O, SrCl2·6H2O, pyridine-2,6-dicarboxylic acid (H2pda) and imidazole (im) in H2O/C2H5OH solution. Single crystal X-ray diffraction revealed that they are isostructural. All of these complexes possess ladder-shaped 1-D chain structures. The luminescent properties of Sm-3, Eu-4, Gd-5, Tb-6 and Dy-7 have been investigated. The solid-state quantum yields and the lifetimes of Eu-4 and Tb-6 are also studied.

A series of tetranuclear [Ln4] clusters with defect-dicubane cores including a Dy4 single-molecule magnet

A series of tetranuclear lanthanide compounds, [Ln4(μ3-OH)2L4(NO3)2(DMF)2] (H2L = 2-(2-hydroxy-3-methoxybenzylideneamino)phenol; Ln = Dy (1); Tb (2); Er (3); and Gd (4)), have been prepared under hydrothermal conditions. X-ray crystal structure analysis reveals that 1–4 are polymorphs. The cores of the structures can be described as co-planar defect-dicubane. The solid-state luminescent properties indicate that the LnIII ions have very deep influence on the luminescence of H2L. The magnetic properties for 1–4 were studied. The Dy4 complex exhibits single-molecule magnet behavior. Graphical abstract A series of tetranuclear lanthanide compounds have been prepared. The Dy4 complex exhibits single-molecule magnet behavior.

A series of ZnII and CoII complexes based on 2-(imidazo[1,5-a]pyridin-3-yl)phenol: syntheses, structures, and luminescent and magnetic properties

The employment of 2-(imidazo[1,5-a]pyridin-3-yl)phenol (HIPP) in ZnII and CoII coordination chemistry is reported. A series of complexes of compositions, [Zn(HIPP)2Cl2] (1), [Zn2(IPP)4] (2), [Co2(HIPP)4(SO4)2] (3), [Co3(IPP)6] (4), and [Co2(IPP)2(CH3COO)2]n (5), have been synthesized via choosing appropriate metal salts and different solvents. Complexes of various nuclearities are obtained from mono-, di-, trinuclear complexes to 1-D chain polymer. UV–vis absorption properties have been investigated and rationalized by density functional theory and time-dependent DFT calculations. In addition, luminescence studies suggested strong emissions for 1, 2, and 3 in the solid state at room temperature. Variable temperature (2.0–300 K) magnetic studies for 3, 4, and 5 indicate weak antiferromagnetic coupling between the metal centers in 3 and 5, and weak ferromagnetic CoII⋯CoII exchange interactions in 4. Graphical Abstract Five coordination complexes based on 2-(imidazo[1,5-a]pyridin-3-yl)phenol were synthesized and characterized; their luminescent and magnetic properties were studied.

Seven novel SrII–SmIII and SrII–DyIII coordination polymers: construction of five classes of structural topologies using different amounts of imidazole

The employment of pyridine-2,6-dicarboxylic acid (H2pda) and imidazole (im) in the synthesis of Sr(II)-Sm(III) and Sr(II)-Dy(III) coordination polymers has been reported. Seven novel heterometallic coordination polymers of compositions, [Dy3Sr3(pda)7(Hpda)(H2O)9]·6H2O (1), [LnSr(pda)3(H2O)5]·Him·H2O (Ln = Sm(2), Dy(3)), [Ln2Sr(pda)6(H2O)5]·4Him·C2H5OH·nH2O (Ln = Sm(4), n = 4; Dy(5), n = 5), [Sm2Sr2(pda)5(H2O)9]·2H2O (6) and [DySr(pda)3(H2O)4]·Him·3H2O (7), have been prepared and characterized. Complexes 1, 2-3, and 6 display three varieties of 2-D structures. 4-5 and 7 exhibit two types of 1-D chain structures. The structures of the complexes could be controlled via choosing appropriate starting materials and tuning the amount of imidazole. The photo-luminescent properties of these complexes have been investigated. The results show the exclusive luminescence emission bands being characteristic of Sm(III) and Dy(III).

Synthesis, crystal structures and luminescent properties of CdII and ZnII complexes assembled by 4-aminophenylhydroxamic acid

Four complexes of composition [Cd(4-Apha)2]n (1), [Zn2(4-Apha)4(H2O)2]·2H2O (2), [Zn(4-Apha)(CH3COO)]n (3), and [Zn4(4-Apha)4(CH3COO)4(H2O)]n·2nCH3OH (4) (4-AphaH = 4-aminophenylhydroxamic acid) have been synthesized in different solvents and characterized by X-ray diffraction, IR spectroscopy, thermal analysis and elemental analysis. X-ray crystal analysis reveals that these complexes exhibit four varieties of structures. Complex 1 displays a 1-D chain structure, and complex 2 is binuclear. Complexes 3 and 4 possess different 3-D structures. Fluorescence emissions are observed for complexes 1, 2 and 4 in solid state.

Experimental design in the analysis of interferential effects for the determination of Sr in high Ca/Sr ratio brine by inductively coupled plasma atomic emission spectroscopy technique

The ICP-AES technique and experimental design were employed to precisely determine the content of strontium in high Ca/Sr ratio oil field brine of Qaidam basin (Qinghai province, western China). From the statistical analysis using six factor factorial, it was found that Ca2+ is the significant interfering element for the recovery of strontium. Accurate strontium content was derived by eliminating the interference contribution according to the influencing model. The experimental results indicate that, under optimal conditions, the ICP-AES method for strontium determination has low LOD and LOQ, and the precision and accuracy are good with the relatively standard deviation below 1% and recovery between 98.0% ∼ 105.0%.