Liming Fan

Two cadmium coordination polymers based on tris(p-carboxyphenyl) phosphane oxide with highly selective sensing of nitrobenzene derivatives and Hg2+ cations

Two coordination polymers (CPs), namely, [Cd1/2(L)1/3(bib)1/2(H2O)]n (1) and {[Cd2(HL)2(bibp)2]·3H2O}n (2), have been assembled from the tripodal ligand tris(p-carboxyphenyl)phosphane oxide (H3L) with the help of 1,4-bis(imidazol-1-yl)benzene (bib) or 4,4′-bis(imidazol-1-yl)biphenyl (bibp). Structural analyses revealed that complex 1 is an unprecedented (3,4)-connected {103}2{106}3 net with 2D [Cd3(L)2]n sheets arranged in an ABCA′B′C′A′′B′′C′′ fashion. Complex 2 exhibits 3-fold interpenetrated sheets with a 4-connected {44·62}-sql sheet. Structural comparison reveals that the length of bis(imidazole) ancillary linkers plays a critical role in determining the structures and topologies. To our delight, fluorescence measurements show that the two Cd(II) CPs can selectively and sensitively detect Hg2+ cations and nitrobenzene derivatives (nitrobenzene, p-nitrotoluene, p-nitroaniline, and p-nitrophenol), which suggests that the two Cd(II) CPs are promising bifunctional luminescence sensor materials that could sense metal ions and small organic molecules.

Magnetic properties and luminescence sensing of five coordination polymers based on a rigid terphenyl-tetracarboxylic acid

Herein, five coordination polymers, namely {[Ni2(tptc)(4,4′-bibp)2]·2H2O·2cyclohexanol}n (1), {[Co2(tptc)(4,4′-bibp)2]·2H2O·2cyclohexanol}n (2), {[Zn2(tptc)(1,2-bimb)2]}n (3), {[Co(tptc)0.5(1,4-bib)]·H2O·DMF}n (4), and {[Co2(tptc)(1,2-bimb)(H2O)]·H2O}n (5) (H4tptc = terphenyl-3,3′′,5,5′′-tetracarboxylic, 4,4′-bibp = 4,4′-bis(imidazolyl)biphenyl, 1,4-bib = 1,4-bis(imidazol-1-yl)benzene, and 1,2-bimb = 1,2-bis(imidazol-1-ylmethyl)benzene) were successfully constructed based on a rigid terphenyl-tetracarboxylic acid ligand and N-containing auxiliary ligands under solvothermal conditions. Their structures were determined by single-crystal X-ray diffraction and further characterized by elemental analyses, IR spectroscopy, powder X-ray diffraction (PXRD), and thermogravimetric (TG) analyses. Complexes 1 and 2 involved a new 4,6-c 3D network structure. Complex 3 displayed an open 3D structure with the bbf topological type. Complex 4 involved an extended 3D (4,6)-c network with the point symbol of {44·610·8}{44·62}. Complex 5 had a 2D framework with the dinuclear [Co2(COO)2] SBUs. The variable-temperature magnetic susceptibilities of complexes 1, 2, 4, and 5 were also investigated, and the results indicated that the isophthalic acid bridge exhibited weak ferromagnetic coupling. Moreover, the fluorescence experiments showed that complex 3 had a potential application in the sensing of small organic molecules.

Two lanthanide metal–organic frameworks constructed from tris(4-carboxyphenyl)phosphane oxide with gas adsorption and magnetic properties

Two lanthanide metal–organic frameworks (LOFs), namely, {[Eu(L3−)(H2O)]·5H2O}n (1) and {[Dy(L3−) (H2O)]·2CH3CN}n (2), have been synthesized based on tris(4-carboxyphenyl)phosphane oxide (H3L) and further characterized by powder X-ray diffraction (PXRD), IR spectroscopy, elemental analyses and thermogravimetric (TG) analyses. X-ray diffraction analyses showed that complexes 1 and 2 are isostructural, and thus the structure and gas adsorption properties of complex 1 and the magnetic properties of 2 were described as a representative in detail. Complex 1 appears to have a 3D 6-connected {412·63} net based on binuclear {Eu2(COO)2} SBUs. Furthermore, the adsorption properties of 1 have been investigated using N2, H2, CO2 and CH4 gases. 1 has high CO2 uptake and exhibits highly selective adsorption of CO2 over CH4 at room temperature, which allows 1 to have a potential application in gas separation and purification. Finally, its full magnetic properties revealed that complex 2 displays antiferromagnetic coupling between DyIII ions and single-molecule magnet (SMM) behavior. According to the Arrhenius law, the anisotropy barrier (Ueff) and pre-exponential factor (τ0) were extracted by fitting of the alternating current data, giving the values of 53.5 K and 3.1 × 10−7 s, respectively. The afforded α parameter is less than 0.10, suggesting a single relaxation process.

Gas adsorption, magnetic properties and fluorescent sensing of four coordination polymers based on 1,3,5–Tris(4-carbonylphenyloxy)benzene and bis(imidazole) linkers

Four 3D novel coordination polymers (CPs), formulated as {[Co3(TCPB)2(bibp)2(dioxane)2.5(H2O)2]·(DMF)}n (1), {[Cd6(TCPB)4(bibp)4(dioxane)(H2O)2]·(dioxane)3·DMF·(H2O)0.5}n (2), {[Co1.5(TCPB)(bimb)0.5(DMF)(dioxane)]}n (3), and {[Zn1.5(TCPB)2(bimb)(DMF)(dioxane)2]·dioxane}n (4) (H3TCPB = 1,3,5-tris(4-carbonylphenyloxy)benzene, bibp = 4,4′-bis(imidazol-1-yl)biphenyl, and bimb = 1,4-bis(imidazol-1-ylmethyl)benzene), have been synthesized under solvothermal conditions and characterized by elemental analyses (EA), single-crystal X-ray diffraction analyses, X-ray powder diffraction analyses (PXRD), IR spectra, and thermogravimetric analyses (TGA). The structural analyses reveal that complex 1 can be simplified as a new 2-nodal (3,10)-{3·42}2 {34·410·514·614·72·8}-3,10T3 net, complex 2 has a 3D 2-nodal (3,8)-c network with the point symbols of {42·5}2{44·59·68·73·83·9}, complex 3 exhibits a novel 3D framework with the point symbol of {410·632·7·82}{43}2, and the structure of 4 is a (3,8)-connected {43}2{46·618·84}-tfz-d net. Furthermore, gas sorption behaviors of complex 1 for N2, H2, CH4, and CO2 have been comprehensively studied at varying temperatures: the results reveal that the adsorption capacity of 1 to N2 is stronger than those of other gases. Meanwhile, IAST calculations reveal that 1 exhibits excellent selective separation for CO2/CH4. Magnetic measurements indicate that both 1 and 3 have antiferromagnetic interactions within the trinuclear clusters. In addition, the fluorescent measurements showed that 2 and 4 exhibit highly selective and sensitive detection of Fe3+ and Cr3+ ions.

Structural diversity, magnetic properties, and luminescence sensing of five 3D coordination polymers derived from designed 3,5-di(2′,4′-dicarboxylphenyl)benozoic acid

Based on the designed π-conjugated aromatic pentacarboxylate of 3,5-di(2′,4′-dicarboxylphenyl)benozoic acid (H5DDB) and bis(imidazole) ancillary linkers (bib = 1,4-bis(imidazol-1-yl)benzene, m-bimb = 1,3-bis(imidazol-1-ylmethyl)benzene, p-bimb = 1,4-bis(imidazol-1-ylmethyl)benzene), five 3D coordination polymers, namely, {Co2(HDDB)(bib)1.5(H2O)2]·H2O}n (1), {[Mn2.5(H2DDB)(HDDB)(bib)0.5(μ2-H2O)(H2O)1.5]·(Hbib)·0.5(H2bib)·0.5H2O}n (2), {[Cd2(HDDB)(bib)1.5(H2O)]·2.5H2O}n (3), {[Cd2(HDDB)(m-bimb)]·H2O}n (4), and {[Cd2(DDB)(p-bimb)]·2.5H2O·0.5(p-H2bimb)}n (5), have been obtained and characterized. Complex 1 is a 3D 3-fold interpenetrating (3,4)-c {83}2{85·9}-vtx net. Based on the binuclear {Mn2(COO)2} SBUs, as well as the trinuclear {Mn3(COO)4(μ2-H2O)2} SBUs, complex 2 shows a 3D 3,4,6-c 3,4,6T10 net with a point symbol of {3·72}2{32·73·8}{32·76·86·10}. Complex 3 displays an unprecedented 3D (3,4,4)-c net with a point symbol of {6·82}2{64·82}2{8·104·12} based on the binuclear {Cd2(COO)4} SBUs. Complex 4 shows an interesting 3D (3,10)-c {410·632·83}{43}2 net based on the quadrilateral tetranuclear {Cd4(COO)8} SBUs. Complex 5 exhibits a linear tetranuclear {Cd4(COO)4} SBU-based 3D (4,10)-c deh1 net with a point symbol of {3·45}2{34·412·510·614·73·82}. A variable temperature magnetic susceptibility investigation indicated that antiferromagnetic interactions exist between the neighbouring metal ions in 1 and 2. Fluorescence measurements showed that 3–5 are promising luminescence sensors for the detection of Cr(VI) anions (CrO42− and Cr2O72− anions) in aqueous solution.