Xiang-Yang Hou

Syntheses, crystal structures, and photoluminescent properties of two new Cd(II) coordination polymers based on biphenyl-2,2′,4,4′-tetracarboxylate and dipyridyl-containing ligands

Two new Cd(II) coordination polymers, [Cd2(btc)(dpe)1.5(H2O)]n (1) and [Cd2(btc)(bpp)(H2O)]n (2), were prepared by the hydrothermal reaction of cadmium nitrate with H4btc (H4btc = biphenyl-2,2′,4,4′-tetracarboxylic acid) in the presence of 1,2-di(4-pyridyl)ethylene (dpe) and = 1,2-bis(4-pyridyl)propane (bpp), respectively, structurally characterized by single-crystal X-ray diffraction, and further characterized by elemental analysis, IR spectroscopy, and thermogravimetric analysis. In 1, btc4− connect six Cd2+ ions, forming a 3-D (3,3,6)-connected [Cd2(btc)] net, and further connected by 1-D [Cd(dpe)]n chains to construct the final (4,5,6)-connected (42.52.65.7)(43.62.7)(45.53.64.72.8) net. In 2, a 3-D [Cd2(btc)] net is also constructed from btc4− connecting six Cd2+ ions, giving a 3-D (3,4,7)-connected network. The overall structure of 2 can be regarded as a (4,4,6)-connected (45.64) (42.5.62.8) (43.54.67.7) framework with bpp linking adjacent Cd ions. Structural comparisons show that the secondary auxiliary N-donors have important effects on the final structure and properties. Photoluminescent properties of 1 and 2 are also discussed.

Synthesis, characterization, and crystal structures of two Ag (I) coordination polymers based on biphenyl-2,2′,4,4′-tetracarboxylate

In this article, [Ag8(btc)2(2,2′-bpy)2] n (1) and [Ag4(btc)(phen)2] n (2) (H4btc = biphenyl-2,2′,4,4′-tetracarboxylic acid, 2,2′-bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline) have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectra, thermogravimetric analyses, and single-crystal X-ray diffraction. Complex 1 shows a 3-D framework containing a 2-D bilayer network constructed from (btc)4− with Ag (I), whereas 2 features a 2-D supramolecular bilayer network. The differences of the two complexes demonstrate that nitrogen-containing chelating ligands have a significant effect on the formation and structure of the resulting complexes. Electrochemistry properties of 1 were also studied.

Syntheses, crystal structures, and luminescence of two new coordination polymers based on biphenyl-2,2′,4,4′-tetracarboxylate

Two new coordination polymers, [Zn(H2btc)(4,4′-bpy)2] n (1) and {[Cd(H2btc) (terpy)] · H2O} n (2) (H4btc = biphenyl-2,2′,4,4′-tetracarboxylic acid, 4,4′-bpy = 4,4′-bipyridine, terpy = terpyridine), have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectra, and single-crystal X-ray diffraction. Complexes 1 and 2 are 1-D chains linked through partially deprotonated H4btc. The adjacent 1-D chains of 1 are further formed into 2-D supramolecular architecture through inter-chain N–H···O hydrogen bonds. In contrast, due to a different auxiliary ligand, the 1-D chains of 2 are further extended into 3-D supramolecular framework through inter-chain O–H···O hydrogen bonds. Thermal stabilities and luminescence of 1 and 2 were also studied.

Synthesis and characterization of two- and three-dimensional coordination polymers built with 3,5-bis(4′-carboxy-phenyl)-1,2,4-triazole and/or 1,4-bis(imidazol-1-ylmethyl)benzene

Two new coordination polymers, [Cd(bct)(H2O)]·(H2O) (1) and [Zn(bct)(bip)]·2(H2O) (2) (H2bct = 3,5-bis(4′-carboxy-phenyl)-1,2,4-triazole, bip = 1,4-bis(imidazol-1-ylmethyl)benzene), have been synthesized. Their structures have been determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, IR spectroscopy, and thermogravimetric analysis. Compound 1 is a two-dimensional structure with double-layered network, where bct ligands adopt a μ 4 -k 1,k 1,k 1,k 1 bridging mode linking four five-coordinate Cd ions. Compound 2 exhibits a three-dimensional framework consisting of double-layered helical chains with the bct and bip adopting μ 3 -k 1,k 1,k 1 and μ 2 -k 1,k 1 bridging mode, respectively. Complexes 1 and 2 exhibit intense emissions at 399 and 441 nm, respectively.

Coordination polymers of CuII and NiII with 3-pyridin-3-yl-benzoate: crystal structures and magnetic properties

Coordination polymers of CuII and NiII with 3-pyridin-3-yl-benzoic acid (3,3-Hpybz), {[Cu(3,3-pybz)2(CH3OH)]·(DMF)} n (1) and {[Ni(3,3-pybz)2(H2O)] · (H2O)} n (2), were synthesized and characterized by single-crystal X-ray diffraction, thermogravimetric analyses, elemental analysis, and IR spectroscopy. In 1, CuII ions are linked by paired 3,3-pybz ligands to generate an infinite 1-D double-strand chain. However, NiII ions in 2 are linked by the 3,3-pybz to form a 2-D corrugated network with a simple (4,4) topology; these 2-D layers are further enlarged to form the final 3-D supramolecular edifice via strong aromatic π–π stacking interactions and O–H ··· O hydrogen bonds. Magnetic properties of 1 and 2 have also been investigated.

Six lanthanide(III) coordination polymers with 3,5-bis(4′-carboxy-phenyl)-1,2,4-triazole: syntheses, structures, and photoluminescence

Six 3-D lanthanide(III)-metal-organic frameworks (MOFs) through multidentate 3,5-bis(4′-carboxy-phenyl)-1,2,4-triazole (H2BCPT); acetic acid (HOAc); and corresponding trivalent rare earth chloride, {[Ln(BCPT)(OAc)(H2O)]·(H2O)}n (Ln = Nd3+ (1); Sm3+ (2), Gd3+ (3), Tb3+ (4), Ho3+ (5), Yb3+ (6)), have been synthesized. MOFs 1–6 were characterized via FT-IR spectroscopy, elemental analysis, X-ray single-crystal diffraction, thermal analysis, and fluorescence. MOFs 1–6 are isomorphous, which can be described as a 3-D construction containing a dinuclear cluster [Tb2(CO2)2(O)2]. The 3-D structure with (4,4) topologies have been extended through BCPT2− using μ4-kO;kO;kO;kO coordination modes. Solid-state luminescence of 1–4 and 6 shows the characteristic bands of Nd3+, Sm3+, Tb3+, and Yb3+ from visible to near-infrared spectral regions.

Fine-tuning the effects of auxiliary ligands on two trigonal-bipyramid cobalt(II) complexes exhibiting field-induced slow magnetic relaxation

Two penta-coordinate Co2+ complexes, namely [Co(PDA)(H2O)2] (1) and [Co(PDA)(1,2-BIYB)0.5(H2O)]·(H2O) (2), (H2PDA = pyridine-3,5-dicarboxylate, 1,2-BIYB = 1,2-bis(imidazol-1-ylmethyl) benzene), which have similar ligand fields except for their local symmetries due to the different coordination atoms of Co2+, were synthesized, structurally analyzed, and magnetically investigated. Complexes 1 and 2 possess 3D supramolecular structures in which the 2D structures are further cross-linked by hydrogen bonds. Complex 1 can be observed to transform into 2 in the presence of 1,2-BIYB coligand, and 1 and 2 have distortion trigonal bipyramid geometries when the space group of Co2+ ion changes from C2/c in 1 to P2(1)/c in 2. Meanwhile, the average equatorial Co–O/N bond distances of CP 1 (2.1655 A) are clearly larger than its axial Co–O bond distances (2.0704 A); for CP 2, the average equatorial Co–O/N bond distances (2.0814 A) are slightly shorter than the axial Co–O/N bond distances (2.0896 A), which leads to different axial compression and distortion of the trigonal bipyramid metal environment. Fine-tuning of the structures arising from the auxiliary ligands has a definite impact on the magnetic properties of compounds 1 and 2. Both compounds share easy-plane magnetic anisotropies of their central Co2+ ions (D = 16 cm−1 for 1 and D = 59 cm−1 for 2) and different slow magnetic relaxations of magnetization with applied magnetic fields of 1500 Oe and 3000 Oe, respectively.

Silver(I) coordination polymer based on anthraquinone-2,6-disulfonate: synthesis, crystal structure, and luminescent properties

Self-assembly of anthraquinone-2,6-disulfonic acid disodium salt (Na2a-2,6-dad) and AgNO3 under hydrothermal conditions resulted in an unprecedented coordination complex, which was characterized by single-crystal X-ray analyses, elemental analyses, IR spectra, TG analyses, and fluorescence investigations. Complex 1 is a 3-D coordination polymer, where a-2,6-dad and Ag–Ag bonds play vital roles. Two sulfonate groups of a-2,6-dad are μ 4- and μ 5-bridges. The unique packing environments of the Ag ions and Ag–Ag bonds lead to 1-D chains consisting of eight- and four-membered rings for Ag1 and Ag1, Ag2 and Ag2 connection, respectively.

The 3D supramolecular architecture of copper(II) 6-methyl-2-pyridone-4-carboxylate: synthesis, structure, magnetic behavior and DFT studies

Abstract The reaction of Cu(NO3)2·3H2O and 6-methyl-2-pyridone-4-carboxylic acid (Hhmpca) under hydrothermal condition produced a new copper(II) coordination polymer [Cu(hmpca)2(H2O)2]·4H2O (1), which has been characterized by elemental analysis, infrared spectroscopy, thermogravimetric analysis and single-crystal X-ray diffraction. The Cu(II) ions are linked by coordinating water molecule bridges to generate a polymeric chain, and adjacent chains are connected to form a layer structure through interchain N–H···O hydrogen bonding. Because of the strong hydrogen bonds of free water molecules, ladder-shaped water chains are produced. Further, the layers and the water chains are linked into a three-dimensional supramolecular structure through strong O–H···O hydrogen bonds. Magnetic susceptibility measurements have indicated that compound 1 shows antiferromagnetic interactions between the adjacent Cu(II) ions. Based on the crystal structure data, compound 1 was analyzed using hybrid density functional theory (DFT) methods at the B3LYP/6-31G(d) level, and a DFT-broken symmetry approach was applied to study the magnetic coupling behavior. The calculated exchange coupling constant J is in good agreement with the experimental data.

A novel microporous Tb-MOF fluorescent sensor for highly selective and sensitive detection of picric acid

A new three-dimensional metal–organic framework (MOF) sensor with molecular formula (C2H6NH2)2[Tb2(ptptc)2(DMF)(H2O)]·DMF·6H2O (complex 1) has been constructed from terphenyl-3,3′,5,5′-tetracarboxylic acid (H4ptptc) and terbium nitrate under solvothermal conditions. The structure of complex 1 was characterized by single-crystal X-ray diffraction analysis (XRD), elemental analysis, IR spectroscopy and thermogravimetric (TG) analysis, and the purity was further confirmed by powder X-ray diffraction (PXRD) analysis. XRD analysis reveals that complex 1 crystallizes in a triclinic system P space group and consists of a three-dimensional anionic network which has one-dimensional channels. Fluorescence titration experiments showed that complex 1 displayed real-time, highly selective and sensitive fluorescence quenching behavior towards picric acid with a nanomolar scale experimental detection limit (100 nM). Recycling titration experiments suggested that the as-synthesized probe has good reversibility and can be used for at least five cycles in fluorescence titration experiments without obvious fluorescence intensity reduction or framework structure destruction. Furthermore, the high selectivity and sensitivity as well as good recyclability of complex 1 make it a potential fluorescent sensor for picric acid.