Hua-Cai Fang

Metal-directed assembly of two 2-D 4d–4f coordination polymers based on elliptical triple-deck cylinders hinged by meso-double helical chains

Two 2-D 4d–4f coordination polymers based on elliptical triple-deck cylinders hinged by meso-helical chains containing an isonicotinate ligand, namely, {[Ag2Ln(IN)4(H2O)2]·(NO3)·(H2O)}n (Ln = Sm and Eu, IN− = isonicotinate), have been successfully constructed through the transformation of a single-crystal to single-crystal (SC-SC) or different metal–organic polymer units, in which the recognition between the organic ligand and two types of metal ions direct the formation of the final productions.

Temperature- and solvent-controlled dimensionality in a zinc 6-(1H-benzoimidazol-2-yl)pyridinecarboxylate system

Several 0D, 1D, and 3D metal–organic hybrid frameworks of ZnII have been synthesized by using the asymmetric ligand 6-(1H-benzoimidazol-2-yl)pyridinecarboxylic acid (HL) with control of the temperature and solvent in a solvothermal synthesis technique. In DMF, the structure at room temperature confirms that the resulting compound Zn(L)2·2(H2O) (1) is the 0D mononuclear structure, above ∼80 °C, C–N bond cleavage of partial DMF molecules induces the formation of the 1D chain-like compound {[Zn(L)(HCOO)]·2(H2O)}n (2), but on warming up to 120 and 160 °C, due to the decomposition of a large number of DMF molecules, the same reaction, respectively, gives two 3D metal–organic coordination polymers with 3D channels reported previously {[Zn(HCOO)3]−·[H2N(CH3)2]+}n (3) and [Zn(HCOO)2]n (4), in which the 3D channels of 3 contain guest [H2N(CH3)2]+ motifs, while at high temperature the 3D channels of 4 are an open stable system without any guest molecules. Replacing DMF in the above reaction by ethanol or acetonitrile, only 0D compound 1 is obtained in the range from room temperature to 160 °C. However, the same reaction in DMSO provides a 1D wave-like compound {[Zn(L)(DMSO)]·(ClO4)·H2O}n (5), in which the solvent DMSO molecule coordinates to the central metal ZnII ion. Furthermore, in three new complexes 1, 2 and 5, through π⋯π stacking and hydrogen bonding interactions, 3D supramolecular networks are assembled. It is worth noting that the existence of the twelve-membered cyclic water–perchlorate dimers [(ClO4)⋯(H2O)]22− with chair-conformation in the solid state of 5 not only increases the stability of the supramolecular structure, but also results in a stronger fluorescence signal compared with ligand HL, 1 and 2.

Construction of a novel Zn-Ni trinuclear Schiff base and a Ni2+ chemosensor.

A novel Zn-Ni heterotrinuclear Schiff base compound bearing acacen(2-) moieties was constructed through the selective assembly of a chemosensor Schiff base zinc compound with a Ni(2+) ion. Its crystal structure not only clearly explains the binding mode between the chemosensor molecule and the detected metal ion but also represents the first trinuclear complex based on a symmetric acacen(2-) base Schiff base.

Construction of three high-dimensional supramolecular networks from temperature-driven conformational isomers

Under different temperatures, the reaction mixture of the multidentate organic ligand usy-L4 and Zn(NO3)2 + NaN3 crystallized to give three conformational isomers, namely Zn(usy-L4)(η1-N3)2 (α-1, β-2 and γ-3) (usy-L4 = N,N-dimethyl-2-(pyridin-2-ylmethylimino)ethanamine). Single-crystal X-ray diffraction analyses reveal that the conformational isomerism of three compounds 1–3 stems from the different orientations of two azide groups with η1-terminal nitrogen atom coordinating to central zinc ion in reference to the basal chelating plane of ligand usy-L4, and further resulting in different supramolecular networks with two-dimensional 44 rhombic-grid for α-1, a three-dimensional 36·418·53·6 compressed-NbO framework for β-2, and a three-dimensional “dense” 424·64 topology for γ-3. Meanwhile, three isomers may be also irreversibly converted from 1 to 2, to 3 through SC-to-SC transformation driven by temperature.

Syntheses and conversions of dinuclear cadmium(II) compounds containing N2O/N2O2 donor tridentate/tetradentate asymmetrical Schiff base ligands

Through different synthetic strategies, four dinuclear cadmium(II) complexes containing N2O/N2O2 donor tridentate/tetradentate asymmetrical Schiff base ligands have been synthesized and characterized. The two complexes [Cd(L1)(μ2-Cl)(CH3OH)]2 (1) and [Cd(L2)Cl]2·CH3OH (2) are constructed, respectively, from self-assembly of a Cd2+ ion with two asymmetrical Schiff base ligands, namely 2-((2-(dimethylamino)ethylimino)methyl)phenol (HL1) and 2-((2-(dimethylamino)ethylimino)methyl)-6-methoxyphenol (HL2). However, via single-crystal to single-crystal structural transformations driven by temperature, the other two corresponding compounds [Cd(L1)Cl]2 (1a) (1 → 1a) and [Cd(L2)Cl]2 (2a) (2 → 2a), with N2O2Cl and N2O3Cl donors, respectively, can be obtained. Obviously, the synthetic strategies presented in the text provide very effective methods for constructing the dinuclear CdII compounds with N2O/N2O2 donor tridentate/tetradentate asymmetrical Schiff base ligands. Meanwhile, the strong fluorescence emission of 1 and 2 makes them potentially useful photoactive materials.

Syntheses and characterization of three lanthanide(III) complexes containing pyridine-3,5-dicarboxylic acid and oxalic acid ligands

Direct reaction of pyridine-3,5-dicarboxylic acid (H2PDA) and oxalic acid (H2ox) with Ln(ClO4)3 · nH2O under hydrothermal conditions gave three 3-D coordination networks, [Ln(PDA)(ox)0.5(H2O)2] · H2O [Ln = La(1), Nd(2), and Eu(3)]. The complexes were characterized by elemental analysis (EA), X-ray single-crystal diffraction, infrared spectroscopy (IR), and thermogravimetric analysis (TGA). Single crystal X-ray diffractions shows that the compounds are isomorphous and have 3-D framework structures, in which pyridine-3,5-dicarboxylates (PDA2−) link lanthanides to give 2-D layers, which are further fabricated into a 3-D network via bis-bidentate oxalate bridging. Luminescence of 3 is investigated.

8-(Carboxy-methoxy)-quinolinium nitrate monohydrate.

In the title compound, C11H10NO3 +·NO3 −·H2O, the planar 8-carboxymethoxyquinolinium cation, the nitrate anion and the water molecule are dimerized by hydrogen bonds into square building-block units, and then further assembled into two-dimensional gently undulating supramolecular layers.

CCDC 777811: Experimental Crystal Structure Determination

Related Article: Zhi-Gang Gu, Ming-Fang Wang, Hui-Min Peng, Guo-Zhen Li, Xiao-Yi Yi, Xue Gong, Hua-Cai Fang, Zheng-Yuan Zhou, Yue-Peng Cai|2010|Inorg.Chem.Commun.|13|1439|doi:10.1016/j.inoche.2010.08.011

Methyl 2-[(4-chloro-2-meth­oxy-5-oxo-2,5-dihydro­furan-3-yl)amino]­acetate

The title compound, C8H10ClNO5, was obtained via a tandem Michael addition–elimination reaction of 3,4-dichloro-5-methoxyfuran-2(5H)-one and glycine methyl ester in the presence of triethylamine. The molecular structure contains an approximately planar [maximum atomic deviation = 0.010 (2) Å] five-membered furanone ring. The crystal packing is stabilized by intermolecular N—H⋯O and weak C—H⋯O hydrogen bonding.

Poly[[tetraaquadi-μ3-oxalato-μ2-oxalato-diprasedymium(III)] dihydrate]

In the title compound, {[Pr2(C2O4)3(H2O)4]·2H2O}n, the three-dimensional network structure has the PrIII ion coordinated by nine O atoms in a distorted tricapped trigonal-prismatic geometry. The coordinated and uncoordinated water molecules interact with the carboxylate O atoms to consolidate the network via O—H⋯O hydrogen bonds.