Xian-Fu Zheng

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.

Counteranion's effects on the structures of supramolecular silver coordination compounds of one asymmetric and one biting organic ligands

Reactions of one asymmetric ligand 1,6-dihydro-2-methyl-6-oxo-(3,4′-bipyridine)-5-carbonitrile (L1) with AgX (X = NO3−, BF4−, AsF6−, SbF6−) afforded two 1-D interpenetrating coordination polymers {[Ag2(L1)3]2·(CH3OH)3·(AsF6)4}n (1) and {[Ag2(L1)3]2·(SbF6)4}n (2), and two monomers [Ag(L1)2]·(NO3) (3) and [Ag(L1)2]·(CH3OH) (BF4) (4). The structural similarity between compounds 1 and 2, and the structural difference between compounds 1 and 2 and compounds 3 and 4 give evidences that the sizes of counteranions with the same polyhedron sometimes can not affect the supramolecular structures, but the polyhedra of counteranions sometimes can. The self-assembly of one angular ligand 1,3,4-thiadiazole-2,5-di-2-pyridyl (L2) with AgX (X = BF4−, ClO4−, PF6−, AsF6−, NO3−, SbF6−) produced five di-nuclear and one mono-nuclear silver(I) coordination compounds. In the three dinuclear compounds [Ag2(L2)2](BF4)2 (5), [Ag2(L2)2](ClO4)2 (6), and [Ag2(L2)2](PF6)2 (7), there are medium Ag–Ag interactions between two adjacent dimers, leading to a 1-D supramolecular chain. In the other two dimers [Ag2(L2)2](AsF6)2 (8) and [Ag2(L2)2](NO3)2(CH3OH) (9), however, no Ag–Ag interactions were found. When changing counteranion to the very large one SbF6−, the silver complex of L2 is a monomer [Ag(L2)2](SbF6) (10). The supramolecular structural diversity of compounds 7, 8, and 10, resulting from the volume changes of the octahedral counteranions shows that the sizes of counteranions with the same polyhedron can sometimes affect the supramolecular structures.

Syntheses and crystal structures of two Zn(II) complexes, [Zn(Fura)2(2,2′-bipy)(H2O)] and [Zn(μ-dnbc)2] (Fura=Furoic acid, 2,2′-bpy=2,2′-bipyridine, dnba=3,5-dinitrobenzoic acid)

Two Zn(II) complexes, [Zn(Fura)2(2,2′-bpy)(H2O)] (1) and [Zn(µ-dnbc)2] (2), have been synthesized and characterized by X-ray diffraction and IR spectra. 1 is a quaternary Zn(II) complex with ZnN2O3 configuration distorted square pyramid geometry; 2 is a Zn(II) coordination polymer with 1D double-helical chains bridged by 3,5-dinitrobenzoic acid.

Two cadmium(II) 1-D coordination polymers, {[Cd2(μ-Cl)4Cl2(CH3OH)(H2O)] · (H-aql)2} n and [Cd(μ-Cl)2(aql)] n : synthesis, crystal structures and fluorescent properties

Two Cd(II) 1-D chain coordination polymers with Cd–Cl-Cd–Cl 1-D chains as bases, one connected to protonated 8-aminoquinoline by intermolecular hydrogen bonds {[Cd2(μ-Cl)4(Cl)2(CH3OH)(H2O)]·(H-aql)2} n (1) (aql = 8-aminoquinoline) and the other to 8-aminoquinoline [Cd(μ-Cl)2(aql)] n (2), have been synthesized and structurally characterized by single-crystal X-ray analysis. 1 belongs to the monoclinic system with space group P2(1)/m and 2 belongs to the monoclinic system with space group C2/c. Fluorescent properties of aql, 1, and 2 showed that the fluorescence spectrum (λmax = 386 nm) of 1 is mainly of aql ππ* character. The fluorescence spectrum of 2 which emits blue-green light (λmax = 497 nm) mainly involves a metal-perturbed intraligand ππ* transition from strong covalent bonds. Thermal stabilities of 1 and 2 have also been studied.

A Novel 1‐D Stacking Z‐Type Supramolecular Complex, [Ni(sphs)(iz)] · EtOH (sphs=4‐(N‐Salicylaldehyde Schiff Base) Benzeneformylhydrazone‐N′‐salicylaldehyde, iz=Imidazole), Constructed by Hydrogen Bonds

A new ligand, 4‐(N‐salicylaldehyde Schiff base) benzeneformylhydrazone‐N′‐salicylaldehyde (H3L), and a new quaternary complex 1, [Ni(sphs)(iz)] · EtOH (sphs=H3L, iz=imidazole), has been designed and synthesized. The structural unit of complex 1 consists of the following groups: one Ni(II), one molecular H3L, one imidazole and one ethanol. It belongs to the orthorhombic system and has a Pbca space group. One deprotonated oxygen in enol‐form, one deprotonated oxygen of hydroxyl and one nitrogen of metheleneimine for H3L and one nitrogen atom of imidazole coordinated to central Ni with two oxygen and two nitrogen in anti‐form, respectively, constructed distorted square geometry, an ethanol existed in crystal lattice. There are intramolecular and intermolecular hydrogen bonds in the crystal structure.

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.

Syntheses and Crystal Structures of Fe(III) and Mn(III) Complexes with Salen Ligands: [Fe(salen)CL] · CH3CN and [Mn(salen)(SCN)(CH3OH)] · CH3CN

Fe(III) and Mn(III) complexes with salen possessing appended ligands, [Fe(salen)Cl] · CH3CN(1) and [Mn(salen)(SCN)CH3OH]·CH3CN(2) [salen=N, N′‐bis(2‐hydroxylphenyl)‐o‐phenylene‐diamine], have been synthesized, and their crystal structures have been determined by X‐ray diffraction analyses. The complex (1) belong to triclinic system with space group P‐1, its structural unit has Fe(III)N2O2Cl configuration with distorted quadrangle pyramid geometry. The complex (2) belong to monoclinic system with space group P2(1)/c, its structural unit has MnN3O3 configuration with distorted octahedron geometry.

(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.

Synthesis, Crystal Structure, and Fluorescence Property of a Cadmium Complex with Pyridine‐2‐carboxaldehyde‐2‐hydroxybenzoylhydrazone and 1,10‐Phenanthroline

One novel Cd(II) complex with pabh and phen, [Cd(pabh)(phen)Cl], (pabh=Pyridine‐2‐carboxaldehyde‐2‐hydroxybenzoyl hydrazone, phen=1,10‐phenanthroline), has been synthesized. The crystal structure was determined by X‐ray single crystal diffraction. It belongs to a monoclinic system with space group p21n. Fluorescence properties of complex and ligands have also been researched.

Synthesis, Crystal Structure and Properties of a Novel Cu(II)Complex with α‐Furan Carboxylate, [Cu(fura)2(bpy)(H2O)], (fura=α‐Furan Carboxylate, bpy=2,2′‐bispyridine)

A novel Cu (II) complex with α‐furan carboxylate and 2,2′‐bispyridine, [Cu(fura)2(bpy)(H2O)], was synthesized. Its crystal structure was determined by X‐ray diffraction analysis, and it belongs to the monoclinic system and space group P2(1)/c with CuO3N2 architecture. The crystal structural unit constructs distorted quadrangle pyramid geometry. The fluorescent and thermal properties of the complex were also studied.