Hai-Fu Guo

Structural diversity of a series of coordination polymers built from 5-substituted isophthalic acid with or without a methyl-functionalized N-donor ligand

The reaction of X-H2BDC (X = H, Br, NO2 and CH3) and methyl-functionalized dmbpy ligands with metal salts under different solvent media conditions generates nine structurally diverse zinc(II)/cadmium(II)-based coordination polymers (CPs), {[Zn2(BDC)2(DMF)3]·DMF}n (1), [Zn(BDC)2(dmbpy)]n (2), {[(Me2NH2)2Zn3(Br-BDC)4]·3DMF·3H2O}n (3), [Zn2(Br-BDC)2(dmbpy)]n (4), {[Zn13(NO2-BDC)8(μ3-OH)2(μ2-OH)6(H2O)4]·12H2O·2NO3}n (5), [Zn2(NO2-BDC)2(dmbpy)(H2O)2]n (6), {[Cd(NO2-BDC)(dmbpy)0.5(H2O)]·(ACN)·H2O}n (7), [Zn(CH3-BDC)(dmbpy)0.5(H2O)]n (8), and [Zn(CH3-BDC)(dmbpy)0.5]n (9) (H2BDC = isophthalic acid, Br-H2BDC = 5-bromoisophthalic acid, NO2-H2BDC = 5-nitroisophthalic acid, CH3-H2BDC = 5-methylisophthalic acid, dmbpy = 2,2′-dimethyl-4,4′-bipyridine, DMF = N,N-dimethylformamide, ACN = acetonitrile). All the compounds are synthesized using dual linkers (X-H2BDC and dmbpy). 1 and 7–8 show a 2D (4,4) network when dinuclear metal ions and ligands are regarded as nodes and linkers, respectively. 2 is a wave-like chain with BDC ligands alternately pointing up and down. CPs 3–6 and 9 all exhibit 3D networks with 5-connected sqp, 6-connected jsm, 6-connected pcu, (3,4)-connected dmc and 6-connected jsm topologies, respectively. Furthermore, luminescence, thermogravimetric and chemical stability properties of these CPs were investigated. The results suggest that both organic ligands and solvent media influence the final resulting CPs.

Structures, luminescence, and antibacterial studies of two transition metal complexes involving Schiff bases

Two new transition metal complexes of Schiff bases, [Pd2(L1)2Cl2] (1) and [Zn(L2)2] (2), [L1 = N-(4-fluorobenzylidene)-2,6-diisopropylbenzenamine and L2 = 2,4-dibromo-6-((E)(mesitylimino)methyl)phenol], have been synthesized solvothermally and characterized by elemental analysis, IR-spectroscopy, thermogravimetric analysis, powder X-ray diffraction, UV-vis absorption spectra, and single-crystal X-ray diffraction. Complex 1 is a μ-chloro-bridged dinuclear cyclometallated Pd(II) complex, whereas 2 is mononuclear with the ZnII tetrahedrally coordinated by two L2. Both 1 and 2 display photoluminescence in the solid state at 298 K (fluorescence lifetimes τ = 22.516 ns at 468 nm for 1, τ = 3.697 μs at 490 nm for 2). These Schiff bases and their metal compounds have been screened for antibacterial activity against several bacteria, and the results are compared with the activity of penicillin.

1-D Chain lanthanide coordination polymers based on mixed 2,4-dichlorophenoxyacetate and 1,10-phenanthroline ligands: crystal structures and luminescent properties

Two new isostructural 1-D lanthanide coordination polymers, {[Ln(2,4-dcp)3(phen)] n [(Ln = Eu (1); Tb (2)], [2,4-dcp = 2,4-dichlorophenoxyacetate, phen = 1,10-phenanthroline], were obtained under hydrothermal conditions and characterized by IR spectroscopy, elemental analyses, thermogravimetry analyses, powder X-ray diffraction, and single-crystal X-ray diffraction. Both structures exhibit similar 1-D infinite chains with a {Ln2(2,4-dcp)6(phen)2} dimeric repeat unit, with lanthanides in an eight-coordinate environment. The results of thermal analysis indicate that 1 and 2 are quite stable to heat. 3-D fluorescence spectra of 1 and 2 were detected at room temperature under excitation and the emission wavelengths of 250–460 nm and 420–750 nm with the same interval of 5 nm, respectively. Interestingly, 1 and 2 possess longer fluorescence lifetimes than other complexes (τ = 1.61 ms for 1 at 611 nm; 1.79 ms for 2 at 543 nm).

Syntheses and structural characterizations of three transition metal coordination complexes based on flexible 2,4-dichlorophenoxyacetate (2,4-DCP)

Three transition metal coordination complexes, {[Co(2,4-DCP)2(μ 2-H2O)(H2O)2] · (H2O)2} n (1), [Zn(2,4-DCP)(IN)] n (2), and [Mn2(2,4-DCP)3(DMPY)2(μ 2-H2O)(H2O)] · (2,4-DCP) · 0.2(H2O) (3) (2,4-DCP = 2,4-dichlorophenoxyacetate, IN = isonicotinate, DMPY = 5,5′-dimethyl-2,2′-bipyridine), have been prepared under hydrothermal conditions and characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, and single-crystal X-ray diffraction. Complex 1 displays a 1-D chain through cobalt and bridging water molecules with Co ··· Co distance of 4.028(2) Å. Complex 2 shows a 2-D (4,4) net, which is extended into a 3-D supramolecular framework by weak hydrogen-bonding interactions. Complex 3 consists of discrete dinuclear cations, 2,4-DCP counter ions and free water molecules, which are assembled into a packing structure through π ··· π stacking of inversion-related DMPY ligands and hydrogen bonds. Magnetic susceptibility measurements show weak antiferromagnetic interactions in 1. The photoluminescence and lifetime of 2 in the solid state have also been studied.

Hydrothermal synthesis, crystal structure, and photoluminescence of a new 2D cadmium(II) complex: {Cd(C8H5O3Cl2)2(C10H8N2)}n

One new cadmium coordination polymer, [Cd(2,4-Dcp)2(4,4-Bipy)]n (I) (2,4-HDcp = 2,4-dichlorophenoxyacetic acid, 4,4′-Bipy = 4,4′-bipyridine) with 2D layer structure, has been prepared by the hydrothermal synthesis and characterized by elemental analysis, IR, TGA and single-crystal X-ray diffraction. Complex I crystallizes belong to monoclinic system and has C2/c space group. Each Cd2+ ion is six-coordinated and located at an octahedral geometry. The Cd2+ ions are linked by bidentate 2,4-Dcp groups into a linear chain in which the benzene rings of 2,4-Dcp ligands point alternately up and down. These chains are further connected into a sandwich-like layer though 4,4′-Bipy ligands. Furthermore, the photoluminescence and life-time of I in the solid state have been studied.

Structure and characterization of A 2D cobalt(II) complex [Co(L)2] n (L = 3-nitro-5-(pyridine-4-yl)benzoate)

The self-assembly of unsymmetrical tecton 3-nitro-5-(pyridin-4-yl)benzoic acid (HL)with cobalt chloride under hydrothermal conditions affords a new 2D coordination polymer [Co(L)2]n (1, L = 3-nitro-5-(pyridin-4-yl)benzoate), which is characterized by elemental analysis, infrared spectroscopy, thermogravimetric analysis, powder X-ray diffraction analysis, and single crystal X-ray diffraction. Compound 1 is of the triclinic system, space group P-1 with a = 9.7857(12) Å, b = 10.3417(13) Å, c = 10.8463(13) Å, α = 85.155(2)°, β = 74.785(2)°, γ = 88.962(2)°, V = 1055.4(2) Å3. The crystal structural analysis of complex 1 shows that the cobalt center is six-coordinated in an octahedral geometry by four O atoms from four different L ligands and two N atoms from two different L ligands; the Co(II) cations are bridged by μ3-L into an interesting two-dimensional network structure. It should be pointed out that the thermal analysis results indicate that complex 1 is quite stable up to 420°C.

(E)-N-(2,4-Dichloro-benzyl-idene)-2,5-dimeth-oxy-aniline.

In the title compound, C15H13Cl2NO2, which was obtained by a condensation reaction of 2,5-dimethoxyaniline and 2,4-dichlorobenzaldehyde, the dihedral angle between the benzene rings is 51.94 (2)°. The 2,5-dimethoxyphenyl and 2,4-dichlorophenyl groups are attached to the ends of the N=C group in an E conformation. Intramolecular C—H⋯Cl and C—H⋯N contacts are observed. In the crystal, molecules are linked by C—H⋯O hydrogen bonds, forming chains parallel to the b axis.

trans-Dichloridobis(2,4-dimethylaniline-κN)palladium(II)

In the title compound, [PdCl2(C8H11N)2], the PdII atom is located on a crystallographic inversion center and adopts a square-planar coordination geometry, with pairs of equivalent ligands in trans positions. In the crystal, adjacent molecules are linked with each other through weak N—H⋯Cl hydrogen bonds and π–π stacking interactions between the phenyl rings [shortest centroid–centroid distance = 3.720 (2) Å], leading to the formation of layers parallel to the a-axis direction.