Chun-Hong Kou

Tuning of unusual secondary ligands to construct fluorescent zinc coordination polymers of an unsymmetrical pyridylbenzoate ligand from 1D chain to interdigital or porous 2D layers and interpenetrated 3D frameworks

Four dicarboxylic acids and nitrilotriacetic acid as secondary ligands have been used to tune the zinc(II)-organic frameworks constructed by an unsymmetrical pyridylbenzoate ligand, 3-pyrid-4-ylbenzoic acid (HL1). Interestingly, malonic acid (H2L2), nitrilotriacetic acid (H3L3), and succinic acid (H2L4), not coordinating to the metal centers and not even existing in the resultant coordination polymers can, however, tune the coordinating modes of L1 and zinc ions, and then the frameworks of their coordination polymers from interdigital 2D layers of [Zn5(L1)10(H2O)3.5]n (1), to porous 2D distorted square grids of [Zn(L1)2(H2O)1.5]n (2), and 4-fold interpenetrated 3D diamond networks of [Zn(L1)2]n (3), respectively. Especially, the topology of 1 displays an unprecedented (3,4)-connected 2D trilayer net with the Schlafli symbol of (62.8)2(6.84.10). For 2, there are 0.7 × 0.8 nm2 1D channels hosting water molecules. Besides, pimelic acids (H2L5) act as bridges for zinc dimeric constructing units and terminers for the 1D chain constructed by dimeric nodes and antiparallel double L1 spacers for [Zn2(L1)2(L5)]n (4). By contrast, terephthalic acids (H2L6) acting as bridges link similar 1D chains in 4 to construct interdigital 2D layers for [Zn2(L1)2(L6)]n (5). Finally, these five coordination polymers all exhibit strong fluorescent emissions at room temperature and high thermal stabilities.

One Cadmium(II) Complex of a New Polydentate Double Schiff Base Ligand Derived from 1,10-phenanthroline: Syntheses, Structures, and Fluorescent Property

One Cd(II) complex of a new polydentate double Schiff base ligand 1,10-phenanthroline-2,9-dicarboxaldehyde-di-picolinohydrazone (L), [Cd(L)(SCN)2], was synthesized and structurally characterized. This compound belongs to a monoclinic system with space group C2/c. In this monomer, the cadmium metal center is coordinated to four nitrogen atoms and two oxygen atoms from one organic ligand L acting as a hexadentate chelate, and two nitrogen atoms from two distinct SCN− anions, forming an uncommon distorted hexagonal bipyramid coordination geometry. Furthermore, fluorescent and thermal properties of the complex were performed on the powder sample. The complex strongly emits at 467 nm with the excitation of 410 nm and is thermally stable up to 300°C, and thus can be utilized as one potential fluorescent material.

catena-Poly[[[N′-(4-cyano­benzyl­idene)nicotinohydrazide)silver(I)]-μ-N′-(4-cyano­benzyl­idene)nicotinohydrazide] hexa­fluorido­phosphate]

In the title polymer, {[Ag(C14H10N4O)2]PF6}n, each AgI ion is coordinated by two N atoms from two pyridyl rings of independent N′-(4-cyanobenzylidene)nicotinohydrazide ligands, and one N atom from one carbonitrile group of a symmetry-related ligand in a distorted T-shaped geometry. The ligands exhibit two modes of coordination. One acts as a bridge connecting Ag atoms to form one-dimensional chains along [01]. The other acts as a terminal monodentate ligand, coordinating to Ag through its pyridyl N atom. Two neighbouring antiparallel chains in the crystal are connected through N—H⋯O hydrogen bonds. Other adjacent chains are packed via Ag⋯O interactions, with Ag⋯O separations of 2.876 (2) Å. In addition, PF6 − counter-anions interact with the hydrazone groups through N—H⋯F hydrogen bonds. The PF6 − anion is disordered over two sites, with occupancies of 0.773 (8) and 0.227 (8).

Two Cd(II) Complexes with One New Polydentate Double Schiff Base Ligand Derived from 1,10-phenanthroline and Two Anionic Ligands: Syntheses, Structures, and Fluorescent Properties

Two Cd(II) coordination compounds of a polydentate double Schiff base ligand 1,10-phenanthroline-2,9-dicarboxaldehyde-di-2-hydroxybenzoylhydrazone (L), [Cd(L)(dca)2]·0.5H2O (dca = dicyanamide) (1) and [Cd(L)(SCN)2]·CHCl3·DMF (DMF = N, N′-dimethylformamide) (2) were synthesized and structurally characterized. Compounds 1 and 2 crystallized in monoclinic system with the space group C2/C and P21/n, respectively. The ligand L, acting as a hexadentate chelate, is coordinated to one Cd(II) atom with rare hexagonal bipyramid coordination geometry in these two compounds. Fluorescent measurements showed that these two compounds all strongly emit at 570 nm with the excitation of ultraviolet light at 360 nm.

Bis[N'-(3-cyano-benzyl-idene)isonicotino-hydrazide]silver(I) trifluoro-acetate.

In the title compound, [Ag(C14H10N4O)2]CF3CO2, the AgI ion is coordinated by two N atoms of the pyridine rings of two N′-(3-cyanobenzylidene)isonicotinohydrazide ligands in a nearly linear geometry. In the crystal structure, a combination of close contacts formed via Ag⋯N interactions [Ag⋯N = 3.098 (2) and 3.261 (2) Å] from symmetry-related molecules and intermolecular N—H⋯O hydrogen bonds between CF3CO2 − anions and the hydrazone groups of two ligands give rise to chains. Furthermore, there are Ag⋯O interactions with a separation of 2.765 (2) Å between chains. The F atoms of the CF3CO2 − anion are disordered over two sites with refined occupancies of 0.593 (5) and 0.407 (5).

Dichlorido(2,9-dimeth­oxy-1,10-phenanthroline-κ2N,N′)zinc(II)

In the crystal structure of the title compound, [ZnCl2(C14H12N2O2)], the ZnII center is four-coordinated by two N atoms from one 2,9-dimethoxy-1,10-phenanthroline ligand and two Cl atoms. The coordination geometry is distorted tetrahedral, as the Zn—N bond distances are shorter than the Zn—Cl distances, and the Cl—Zn—N and Cl—Zn—Cl bond angles are much larger than the N—Zn—N angle. For the ligand, the O and C atoms of the methoxy groups are almost in the plane defined by the phenanthroline ring. The two O atoms deviate from the phenanthroline mean plane by 0.076 (2) and 0.084 (2) Å, and the two methyl C atoms deviate from the phenanthroline mean plane by 0.035 (3) and 0.361 (3) Å. There are medium π–π stacking interactions between two parallel phenanthroline rings with a centroid–centroid distance of 3.7860 (2) Å and a dihedral angle between the plane defined by the two parallel phenanthroline rings of 1.13 (5)°.

(2,9-Dieth­oxy-1,10-phenanthroline-κ2N,N′)bis­(thio­cyanato-κN)cobalt(II)

In the title complex, [Co(NCS)2(C16H16N2O2)], the CoII ion is coordinated by two N atoms from one 2,9-diethoxy-1,10-phenanthroline ligand and two N atoms from two different thiocyanate ligands in a distorted tetrahedral environment. The Co—N bonds involving the thiocyanate ligands are significantly shorter than the other two Co—N bonds. The atoms of one of the ethoxy groups are essentially coplanar with the phenanthroline ring [N=C—O—C = 178.8 (4)°], while the other ethoxy group is slightly twisted from the phenanthroline ring plane [N=C—O—C = 167.2 (4)°]. In the crystal structure, there is a weak π–π stacking interaction between two symmetry-related phenanthroline rings with a centroid–centroid distance of 3.706 (4) Å.

One-Dimensional Zinc and Cadmium Coordination Polymers Constructed by Dicyanamide Anions: Synthesis, Crystal Structure, and Fluorescent Property

Two new one-dimensional coordination polymers, [Zn(L)2 (C2N3)2] n and [Cd(L)2(C2N3)2] n (L = 4-Cyanobenzylidene nicotinohydrazide, C2N3 = dicyanamide anions), have been synthesized and structurally characterized. These two compounds are isomorphs. Each metal center is coordinated to six nitrogen atoms from two L molecules and four dicyanamide anions, defining distorted octahedral coordination geometry. Dicyanamide anions acting as linear bridging ligands connect metal centers to form 1D chains along the crystallographic a axis. Furthermore, an interesting (3,4)-connected (83)2(85.10)-tfc topology of supramolecular 3D networks through hydrogen bonds based on 1D chains is constructed. Luminescent property of the Zn(II) coordination polymer has also been studied.

One Supramolecular 3D Framework based on 1D Coordination Polymer of Cobalt(II) with 1,3-Bis(4-pyridyl)propane (bpp) Pillared by bpp Ligands: Synthesis, Crystal Structure and Magnetic Properties

One Co(II) 1D chain coordination polymer {[Co(bpp)2(H2O)2] (bpp)3· (H2O)· (ClO4)2}n (bpp = 1,3-Bis(4-pyridyl)propane) has been synthesized and structurally characterized by single-crystal X-ray analysis. This compound belongs to orthorhombic system with space group Pccn. 1D chains are packed through π −π interactions and linked together by bpp ligands through hydrogen bonds to construct 2D layers. Organic ligand molecules are pillared among these parallel 2D layers to construct a 3D supramolecular inorganic-organic hybrid framework. Organic ligand bpp in this compound exhibits three unusual comformations. Studies on magnetic properties of this compound show that it presents weakly antiferromagnetic behavior.

CCDC 715488: Experimental Crystal Structure Determination

Related Article: Xinsheng Wan, Caoyuan Niu, Xianfu Zheng, Chunhong Kou|2008|Z.Kristallogr.-New Cryst.Struct.|223|279|