Kun-Lin Huang

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.

Three pillared-layered inorganic–organic hybrid polymers with efficient luminescence

Three pillared-layered inorganic–organic hybrid polymers, namely, [Cu2(4,4′-Hbpt)(SCN)2]n (1), [Cd(4,4′-Hbpt)(SCN)2]n (2), and [Cd(4,4′-Hbpt)(SCN)2·CH3CN]n (3) were synthesized via layer diffusion methods. In all three complexes, there exist 2-D neutral wave-like d10 metal thiocyanate layers (for 1, [Cu2(SCN)2]n, and for 2 and 3, [Cd(SCN)2]n) with (4, 4) topology, which are further connected by bidentate 4,4′-Hbpt ligands to form 3-D structures with the primitive cubic topology. The results of photoluminescence and thermogravimetric analyses indicate that the three complexes are good candidates as luminescent materials. This paper provides a strategy to synthesize a novel family of pillared-layered inorganic–organic hybrid polymers constructed with layered d10 metal thiocyanate layers and conjugated organic spacers at the molecular engineering level, as well as the discovery of new patterns of crystallization at the crystal engineering level.

A binuclear zinc polymer with paddlewheel building units and intersecting helical chains based on a flexible 4-[(carboxymethyl)sulfanyl]benzoic acid ligand.

The asymmetric unit of the title compound, poly[{μ(4)-4-[(carboxylatomethyl)sulfanyl]benzoato}(N,N-dimethylformamide)zinc], [Zn(C(9)H(6)O(4)S)(C(3)H(7)NO)](n), consists of one crystallographically independent Zn(II) cation, one 4-[(carboxylatomethyl)sulfanyl]benzoate (L(2-)) ligand and one coordinated dimethylformamide (DMF) molecule. The zinc ion is coordinated by five O atoms from four separate L(2-) ligands and one DMF molecule, and the ZnO(5) unit displays a distorted square-based-pyramidal geometry. Two ZnO(5) units form a binuclear zinc-tetracarboxylate paddlewheel cluster, and these are bridged by L(2-) ligands to generate an intersecting helical chain (Zn(2+) ions as nodes), which is composed of right-handed (P) and left-handed (M) helices. Weak C-H···O hydrogen bonds extend the one-dimensional coordinated chain into a weakly bound three-dimensional supramolecular architecture.

Crystal structure of catena-poly[[di-aqua-cadmium(II)]-μ-3,3'-(1,3-phenyl-ene)diacrylato].

In the crystal of the title polymeric complex, [Cd(C12H8O4)(H2O)2]n, the CdII cation, located on a twofold rotation axis, is coordinated by two water molecules and chelated by two phenylenediacrylate anions (mpda) in a distorted octahedral geometry. The mpda anions bridge the CdII cations, forming helical chains propagating along the c-axis direction. The mpba anion has twofold symmetry with two benzene C atoms located on the twofold rotation axis. In the crystal, O—H⋯O hydrogen bonds link the polymeric helical chains into a three-dimensional supramolecular architecture.

Poly[diaqua­[μ6-4,4′-(1,4-phenyl­ene)bis­(2,6-dimethyl­pyridine-3,5-dicarboxyl­ato)]dilead(II)]

The asymmetric unit of the title Pb-based coordination polymer, [Pb2(C24H16N2O8)(H2O)2]n, consists of one PbII cation, half of a 4,4′-(1,4-phenylene)bis(2,6-dimethylpyridine-3,5-dicarboxylate (L 4−) ligand and one coordinating water molecule. The centers of the benzene ring of the ligand and the four-membered Pb/O/Pb/O ring are located on centers of inversion. The PbII ion is coordinated in form of a distorted polyhedron by seven O atoms from four separate L 4− ligands and by one water O atom. The PbO7 polyhedra share O atoms, forming infinite zigzag [PbO4(H2O)]n chains along [100] that are bridged by L 4− ligands, forming a two-dimensional coordination network parallel to (001). O—H⋯O hydrogen bonds involving the water molecule are observed.

A new two-dimensional supra­molecule composed of μ-2,6-dimethyl­pyridine-3,5-dicarboxyl­ato-κ4O3,O3′:O5,O5′-bis­[chloro­(1,10-phenanthroline-κ2N,N′)zinc(II)]

In the binuclear title molecule, [Zn(2)(C(9)H(7)NO(4))Cl(2)(C(12)H(8)N(2))(2)], the two metal centres are bridged by a 2,6-dimethylpyridine-3,5-dicarboxylate ligand. The binuclear unit is extended to form a two-dimensional supramolecular motif via pi-pi stacking interactions between neighbouring phenanthroline rings.