Sheng-Chun Chen

Solvent-mediated assembly of chiral/achiral hydrophilic Ca(II)-tetrafluoroterephthalate coordination frameworks: 3D chiral water aggregation, structural transformation and selective CO2 adsorption

The spontaneous self-assembly reactions of 2,3,5,6-tetrafluorobenzenedicarboxylic acid (H2BDC-F4) with Ca(NO3)2·4H2O in different solvents resulted in the generation of hydrophilic 3D chiral and achiral Ca(II)–organic frameworks {[Ca4(BDC-F4)4(H2O)4]·4H2O}n (1) and [Ca(BDC-F4)(MeOH)2]n (2), respectively. Complex 1 exhibits higher water solubility compared to 2, and further dissolution of 1 in water results in a new achiral crystal, [Ca(BDC-F4)(H2O)4]n (3). All complexes have been characterized by elemental analysis, IR spectroscopy, and single-crystal and powder X-ray diffraction techniques. Complex 1 crystallizes in the tetragonal P41212 chiral space group and features a rare binodal 5-connected network, directed by a unique 3D chiral (10,3)-a water aggregation consisting of two distinct helical arrays. Complex 2 crystallizes in the space group C2/c and has a binodal 4-connected pts net. Complex 3 crystallizes in the space group P21/m and presents a 2D layer framework containing the unprecedented polymeric [CaII–H2O]n chain based on triple μ2-O aqua bridges. The structural discrepancies illustrate the solvent-induced effect on the construction and structural transformation of chiral and achiral coordination frameworks. Moreover, gas (N2 and CO2) adsorption studies show that the dehydrated framework 1a exhibits excellent selective CO2 gas uptake at 195 K.

Alkali-metal-regulated construction of superhydrophilic ZnII and CdII coordination polymers with perhalogenated terephthalate ligands

By simply introducing different alkali metal ions as structure-directing agents, four new coordination polymers with the formulae [Cd3(BDC-F4)3(DMF)2(MeOH)6]n (1), [Cd(BDC-F4)(DMF)2(H2O)2]n (2), [Zn2Na2(BDC-Cl4)3(DMF)4(μ2-MeOH)]n (3) and [ZnK(BDC-Cl4)1.5(DMF)(Me2NH)]n (4) (BDC-F4 = 2,3,5,6-tetrafluoro-benzenedicarboxylate; BDC-Cl4 = 2,3,5,6-tetrachloro-benzenedicarboxylate; DMF = dimethylformamide and Me2NH = dimethylamine) have been synthesized and structurally characterized. Complex 1 presents an open three-dimensional (3D) 3-nodal (3,4)-connected framework, 2 has a one-dimensional (1D) chain structure, 3 features a 3D 4-nodal (3,4,5,6)-connected coordination network constructed from the new ZnII–NaI heterometallic tetranuclear cluster, and 4 shows a 3D 4-nodal (3,5,6)-connected network based on the unique ZnII–KI heterometallic tetranuclear cluster. The results reveal the significant influence of alkali-metal ions on the structural topologies of complexes 1–4. Interestingly, compounds 1–4 all exhibit high water solubility, and futher evaporation of their water solution will result in a 1D coordination polymer {[Cd4(BDC-F4)4(H2O)11]·3.5H2O}n (5) consisting of the unprecedented polymeric [CdII–H2O]n chain, and a zero-dimensional (0D) complex [Zn(H2O)6]·(BDC-Cl4)·4H2O (6) containing the discrete [Zn(H2O)6]2+ cationic and BDC-Cl4 dianionic moieties. Furthermore, the solution chemistry of complexes 5 and 6 has been investigated by electrospray ionization (ESI) mass spectrometry and molar electrical conductivity. The photoluminescent properties of complexes 1–6 have also been explored, which interestingly indicate a strong blue emission of complex 1 in the solid state at room temperature.

Synthesis, crystal structure and magnetism of [Mn(tfbdc)(MeOH)4] (tfbdc = tetrafluoroterephthalate)

[Mn(tfbdc)(MeOH)4] was synthesized by reaction of tetrafluoroterephthalatic acid with manganese(II) perchlorate hexahydrate in methanol. The complex was characterized by elemental analysis, IR spectra, magnetism, and X-ray single crystal structure analysis. This complex crystallizes in the monoclinic system with space group C2/c. Mn(II) has a distorted octahedral geometry coordinated by two oxygens from two tetrafluoroterephthalate (tfbdc) and four MeOH molecules. Each tfbdc ligand bridges two Mn(II) ions in end-to-end fashion, forming a zigzag chain. These chains are connected by hydrogen bonds, forming a 2-D supramolecular network. Magnetic susceptibility data from 300–1.8 K show that there is a weak antiferromagnetic exchange between Manganese(II) ions.

Three metal complexes derived from 3-methyl-1H-pyrazole-4-carboxylic acid: synthesis, crystal structures, luminescence and electrocatalytic properties

Mononuclear complexes [Cd(HMPCA)2(H2O)4] (1) and [Co(H2MPCA)2(DMF)2(H2O)2]Cl2 (2), and 3D coordination polymer [Cd3Cl2(HMPCA)4(H2O)2]·2H2O (3) (H2MPCA = 3-methyl-1H-pyrazole-4-carboxylic acid) were synthesized and characterized by elemental analysis, IR spectra, thermogravimetric analysis, and X-ray single-crystal structure analysis. In 3, HMPCA− anions bridged trinuclear Cd(II) ions clusters to form an 8-connected 3D network with channels. The complexes all display green fluorescence in the solid state. As a bifunctional catalyst, complex 2 exhibited excellent catalytic activity for oxygen evolution reaction (OER), and certain catalytic activity for oxygen reduction reaction (ORR).

Influence of solvent on the structures of two copper(II) coordination polymers with tetraiodoterephthalate: syntheses, crystal structures, and properties

Two CuII coordination polymers {[Cu(BDC-I4)(MeOH)4](H2BDC-I4)(MeOH)2} n (1) and [Cu(BDC-I4)(dioxane)(MeOH)2] n (2) with a rigid periodinated ligand 2,3,5,6-tetraiodo-1,4-benzenedicarboxylic acid (H2BDC-I4) have been synthesized and characterized by elemental analysis, IR spectroscopy, and X-ray crystallography. Complex 1 presents a one-dimensional (1-D) linear structure, further assembled to form a two-dimensional (2-D) layer through inter-chain O–H I, O–H O, or C– weak interactions. Complex 2 shows a 1-D zigzag structure that is extended into a 2-D supramolecular network by intermolecular O–H O hydrogen bonds. The CuII in 1 has a distorted octahedral (CuO6) coordination sphere, whereas CuII in 2 displays a nearly ideal square-pyramidal (CuO5) coordination. The structural differences between 1 and 2 imply that solvent plays an important role in the construction of coordination architectures. In addition, the luminescent properties of H2BDC-I4, 1 and 2 in the solid state were investigated.

K(I)-M(II) (M = Co, Mn) heterometallic-(perfluorinated) organic frameworks containing inorganic layered K–O–M linkages: synthesis, crystal structure, and magnetic properties

Reactions of a perfluorinated ligand, tetrafluorophthalic acid (o-H2BDC-F4), with KNO3 and M(OAc)2 (M = Co, Mn) led to the formation of perfluorinated metal-organic frameworks [CoK2(o-BDC-F4)2(MeOH)]n (1) and [MnK2(o-BDC-F4)2(DMF)]n (2). The structures were characterized by elemental analyses, infrared spectra, and single-crystal X-ray diffraction. Both complexes show similar 2-D heterometallic-organic frameworks containing unusual layered inorganic K–O–M connectivities. For 1 and 2, ortho fluorines of o-BDC-F4 are bound to the K(I) ion, while the other fluorines participate in the linkage of adjacent coordination layers forming 3-D supramolecular architectures via intermolecular FF interactions. Spectroscopic, thermal, and fluorescence properties have been investigated. Variable-temperature magnetic susceptibility studies indicate that 1 displays a weak antiferromagnetic effect between adjacent Co(II) ions. Graphical abstract

Anion Effect on the Structural Diversity of 1-D and 2-D Zinc(II) Coordination Polymers with a Flexible Fluorinated Bis(imidazole) Ligand

Reactions of a flexible fluorinated ligand, 2,3,5,6-tetrafluoro-1,4-bis(imidazol-1-ylmethyl) benzene (Fbix), with ZnX2 (X =OAc- or NO3-) lead to the formation of the two new ZnII coordination polymers [Zn(Fbix)(OAc)2]n (1) and {[Zn2(Fbix)3(NO3)2](NO3)2(H2O)3}n (2), which have been characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Although the ZnII centers of both 1 and 2 are in a similar tetrahedral coordination geometry, each ZnII ion in 1 is surrounded by two Fbix spacers and two terminal OAc- anions to form a highly undulated chain, whereas each ZnII ion in 2 is embraced by three Fbix ligands and one NO3- anion to result in a two-dimensional cationic network. Since 1 and 2 are synthesized under the same conditions, the structural differences between them are attributable to the difference of the counterions. The solid-state properties such as thermal stability and luminescence of 1 and 2 have also been studied briefly. Graphical Abstract Anion Effect on the Structural Diversity of 1-D and 2-D Zinc(II) Coordination Polymers with a Flexible Fluorinated Bis(imidazole) Ligand

Manganese(II), nickel(II), and cadmium(II) coordination polymers with tetrafluoroterephthalate: syntheses, crystal structures, and luminescence properties

Three new coordination polymers, [Mn(BDC-F4)(DMF)2(H2O)2]n (1), [Ni(BDC-F4)(DMF)(EtOH)]n (2), and [Cd(BDC-F4)(DMF)(EtOH)]n (3), have been synthesized by assembling transition metal salts with the rigid ligand tetrafluoroterephthalic acid (H2BDC-F4) in mixed EtOH/DMF solvent at pH ca. 2. For complex 1, the octahedral coordination geometry of the MnII center is provided by two oxygen atoms from two dianionic BDC-F4 ligands, two DMF ligands and two aqua ligands, giving a 1-D linear chain array. For complex 2, the NiII center is coordinated by two dianionic BDC-F4 ligands, two EtOH ligands and two DMF ligands, resulting in a 1-D chain structure. For complex 3, the CdII center is coordinated by four dianionic BDC-F4 ligands, one EtOH ligand and one DMF ligand, generating a 2-D layered structure. The results suggest that both the metal and the solution pH play an important role in the formation of the complexes. The spectroscopic, thermal, and luminescence properties of the complexes have been investigated.

Synthesis, Crystal Structure, and Electrochemical Property of the Complex [Co(tfbdc)(DMF)2(H2O)2] (tfbdc = Tetrafluoroterephthalate; DMF = N,N-Dimethylformamide)

One complex [Co(tfbdc)(DMF)2(H2O)2] (tfbdc = tetrafluoroterephthalate) was synthesized by the reaction of tetrafluoroterephthalatic acid with cobalt(II) nitrate hexahydrate in mixture solvent. This complex was characterized by elemental analysis, infrared (IR) spectra, cyclic voltammetry, and x-ray single-crystal structure analysis. This complex crystallizes in the monoclinic system with space group P2(1)/n. The Co(II) ion has a distorted octahedral geometry coordinated by two O atoms from two tetrafluoroterephthalate (tfbdc), two O atoms from two water molecules, and two O atoms from two N,N-dimethyl formamide molecules. Each tfbdc ligand bridges two Co(II) ions in end-to-end fashion, forming a straight chain. These chains are connected by hydrogen bonds, forming a two-dimensional supramolecular network structure.

A zinc(II) coordination polymer containing single- and double-stranded helical chains: synthesis, crystal structure, and thermal and luminescence properties

Abstract A new zinc(II)-based coordination polymer {[Zn(5-fip)(tdbpy)]·(DMF)}n (1) {5-H2fip=5-fluoroisophthalic acid, tdbpy=4,4′-(2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diyl)bispyridine, DMF=dimethylformamide} has been solvothermally synthesized and structurally characterized. Single-crystal X-ray diffraction revealed that complex 1 shows a unique two-dimensional network architecture containing single-stranded [Zn(5-fip)]n and double-stranded helical [Zn(tdbpy)]n chains. The thermal and luminescence properties of complex 1 have also been studied.