Yucang Liang

Solvothermal syntheses and crystal structures of two metal coordination polymers with double-chain structures

Two polymeric complexes, [Cu2(btec)(phen)2]n·(H2O)n (1) and [Cd4(btec)2(phen)4(H2O)4]n (2 )( H 4btec = 1,2,4,5-benzenetetracarboxylic acid; phen =1,10-phenanthroline), were synthesized by solvothermal reactions at 140 °C. Both complex 1 and 2 possess infinite double-chain structures, in which each Cu(II) center has a tetrahedral configuration and the Cd(II) centers adopt triangular prismatic and square-based pyramidal configurations simultaneously. The inter-chain face to face – interactions among the aromatic rings of phen and the hydrogen bond interactions between aqua molecules and carboxyl O atoms result in 3-D networks in the two complexes. The ESR spectra study of complex 1 shows that there is negligibly small long-range super-exchange interactions between the Cu(II) atoms via benzenecarboxylate bridging.

Syntheses and characterizations of two novel Ln(III)–Cu(II) coordination polymers constructed by Pyridine-2,4-dicarboxylate ligand

Abstract Two novel three dimension Ln(III)–Cu(II) coordination polymers [Gd 2 Cu(pydc) 4 (H 2 O) 6 ] n and [Sm 2 Cu 3 (pydc) 6 (H 2 O) 6 ] n were prepared by the hydrothermal reactions of CuO, Ln 2 O 3 (Ln = Gd, Sm), H 2 pydc (H 2 pydc = 2,4-pyridinedicarboxylic acid) and characterized by single-crystal X-ray diffraction analysis.

Intramolecular Hydroamination/Cyclization of Aminoalkenes Catalyzed by Ln(N(SiMe3)2)3 Grafted onto Periodic Mesoporous Silicas

Homoleptic rare-earth metal silylamide complexes Ln[N(SiMe(3))(2)](3) (Ln = Y, La, Nd) were grafted onto a series of partially dehydroxylated periodic mesoporous silica (PMS) supports, SBA-15(-500) (d(p) = 7.9 nm), SBA-15LP(-500) (d(p) = 16.6 nm), and MCM-41(-500) (d(p) = 4.1 nm). The hybrid materials Ln[N(SiMe(3))(2)](3)@PMS efficiently catalyze the intramolecular hydroamination/cyclization reaction of 2,2-dimethyl-4-penten-1-amine. Under the prevailing slurry conditions the metal size (Y > La > Nd), the pore size, and the particle morphology affect the catalytic performance. Material Y[N(SiMe(3))(2)](3)@SBA-15LP(-500) displayed the highest activity (TOF = up to 420 h(-1) at 60 °C), with the extralarge pores minimizing restrictive product inhibition and substrate diffusion effects. The catalytic activity of Y[N(SiMe(3))(2)](3)@SBA-15LP(-500) is found to be much higher than that of the molecular counterpart (TOF = up to 54 h(-1)), and its recyclability is demonstrated.

Hydrothermal syntheses, structural characterizations and magnetic properties of cobalt(II) and manganese(II) coordination polymeric complexes containing pyrazinecarboxylate ligand

Two novel coordination polymeric complexes [Co(pzca) 2 (H 2 O)] n ( 1 ) and [Mn(pzca) 2 ] n ( 2 ) (pzca=2-pyrazinecarboxylate) have been synthesized by hydrothermal reaction of M(CH 3 COO) 2 ·4H 2 O (M=Co, Mn) and 2-pyrazinecarboxylic acid. The complex 1 displays an infinite zigzag chain structure in which each cobalt(II) center was coordinated by three nitrogen and three oxygen atoms to generate a CoN 3 O 3 octahedral geometry. The existence of hydrogen bond leads to the formation of the interpenetrating stacking structure. Complex 2 indicates a two-dimensional layer structure through the linkage of bridging oxygen atom of pzca ligand. Each Mn(II) center exhibits a distorted octahedral coordination environment with four oxygen atoms and two nitrogen atoms. The distances of adjacent Mn(II) atoms are 3.503 and 5.654 A, respectively. The magnetic property analyses reveal that both complexes show weak antiferromagnetic exchange interactions between the metal centers.

Syntheses and structural characterization of silver(I) complexes with versatile heterocyclic sulfur and nitrogen donor ligands

Abstract Five versatile non-chelating heterocyclic ligands, benzimidazo[1,2-b]benzo[e]-1-thia-3-azacyclicheptane (bbch), 1,2-bis[(4-pyridinyl)-sulfanylmethyl]benzene (psb), 2,3-bis[(4-pyridinyl)-sulfanylmethyl]quinoxaline (psmq), 2-[(p-pyridinyl)-sulfanylmethyl]-pyrimidine (ppsp), and 2-[(m-pyridinyl)-sulfanylmethyl]pyrimidine (mpsp) were designed and prepared. Self-assembly between silver nitrate and bbch resulted in a coordination polymer [Ag2(bbch)2(NO3)2]n (1) with a double silver atom chain, while treatment of silver perchlorate and bbch under the same conditions generated a discrete mononuclear complex [Ag(bbch)2](ClO4) (2). A 30-membered macrocyclic complex [Ag2(psb)2](ClO4)2 (3) was obtained by the stoichiometric reaction of silver perchlorate and psb. A coordination polymer [Ag(psmq)ClO4]n (4) with a zigzag chain was obtained by the reaction of silver perchlorate and psmq. Reaction of silver nitrate with ppsp and mpsp gave rise to polymers [Ag2(ppsp)2(NO3)2]n (5) and [Ag2(mpsp)2(NO3)2]n (6) with single stranded helical chain structures.

Silver(I) complexes derived from versatile multidentate chelating ligand

Three novel Ag(I) coordination polymers, [{Ag3(bpsp)2·dmf·MeCN}(ClO4)3]n (1), [Ag2(bpsp)2](NO3)2 (2) and [{Ag4(bpsp)2(NO3)2·dmf}(NO3)2]n (3), were synthesized by self-assembly of AgX (X=ClO4−, NO3−) with bpsp (bpsp=2,6-bis[(2-pyrimidinyl)methylsulfanyl]-pyridine). X-ray single-crystal diffraction analyses showed that the versatile multidentate chelating ligand bpsp ligates coordinately flexible Ag(I) into 1 in a one-dimensional(1-D) zigzag chain polymer, 2 in a helical dimer and 3 in two independent 1-D zigzag chains (chain A and B), respectively. In 1, one bpsp ligand acts in an unusual pentadentate mode with two sulfur atoms and three nitrogen atoms from a pyridine ring and different pyrimidine rings coordinating to three different Ag atoms; the other bpsp ligand acts in a tridentate mode with three nitrogen atoms from the pyridine ring and different pyrimidine rings bridging three different Ag atoms. The bpsp ligand in 2 functions in another tridentate mode with one sulfur atom and a nitrogen atom of the pyridine ring chelating with Ag(I) and with one nitrogen atom of the pyrimidine ring ligating the other Ag(I) to form a binuclear silver(I) helicate. For chain A in 3, the bpsp ligand can serve in an unusual tetradentate fashion, in which a sulfur atom and a nitrogen atom of the pyridine ring chelate with the Ag atom to form a stable five-membered ring, and two nitrogen atoms from different pyrimidine rings bridge two Ag atoms in different directions. Similar to the bpsp molecule of pentadentate fashion in 1, bpsp molecule also serves as a pentadentate ligand in the chain B of 3. Ag atoms adopt three, one, and four different coordination fashions in 1, 2, and 3, respectively.

Solvothermal Syntheses and Characterizations of Two Isomorphous One-Dimensional Chain Complexes Constructed by Orotic Acid

Solvothermal reactions of M(OAc)2 (M = Ni, Co) with orotic acid (2,6-dioxo-1,2,3,6-tetrahydropyrimidine-4-carboxylic acid, H3L) in H2O/MeOH (1 : 1) gave rise to two new isomorphous polymeric complexes, [M(HL)(H2O)3]n [M = Ni, (4); Co, (5)], with one-dimensional chain structures. Both complexes crystallize in the orthorhombic space group P212121, with a 7.7438(7), b 7.7610(7), c 14.6528(12) A, Z 4 for (4), and a 7.7005(3), b 7.8725(3), c 14.6997(10) A, Z 4 for (5). X-Ray diffraction analysis shows that the metal ion is coordinated by nitrogen and oxygen atoms of an orotate ligand (HL2–) and water molecules in a distorted octahedral geometry. The hydrogen-bond interactions between chains leads to the formation of three-dimensional network structures.

Periodic mesoporous organosilicas : mesophase control via binary surfactant mixtures

A series of ordered periodic mesoporous organosilicas (PMOs) with cubic and hexagonal symmetry was synthesized from organosilica precursor 1,2-bis(triethoxysilyl)ethane (BTEE) by using cationic surfactants [CH3(CH2)17NMe3]+Br− (C18TABr) or [CH3(CH2)17NMe2(CH2)3NMe3]2+2Br− (C18-3-1) or binary mixtures herefrom as structure-directing agents (SDAs). Under the prevailing basic reaction conditions, the commercially available quaternary alkyltrimethylammonium salt C18TABr selectively gave materials PMO[MCM-41]-n with hexagonal symmetry (space group P6mm). Depending on the surfactant concentration, the materials obtained from divalent C18-3-1 displayed cubic (PMO[SBA-1]-n with space group Pm3n) or disordered hexagonal structure (mixed phase). Fine-tuning of the total amount and molar ratio of surfactant mixtures of C18-3-1 and C18TABr also accomplished an effective mesophase control of ordered organosilicas PMO[MCM-41]-n and PMO[SBA-1]-n. For a given gel composition, such a mesophase transformation occurred also by addition of inorganic salt KF (hexagonal → cubic) and addition of organic expander molecule mesitylene, TMB (cubic → hexagonal). All of the PMOs were characterized by powder X-ray diffraction, transmission electron microscopy (TEM), scanning electron microscopy (SEM), nitrogen physisorption, FTIR spectroscopy, and 29Si and 13C CP MAS NMR spectroscopy. The hexagonal PMOs displayed BET surface areas in the range of 500–1030 m2 g−1, pore volumes as large as 1.62 cm3 g−1, and pore diameters ranging from 29 to 52 A. Materials PMO[SBA-1]-n exhibited BET surface surface areas in the range of 570 to 800 m2 g−1, pore volumes between 0.51 and 1.08 cm3 g−1, and pore sizes ranging from 29 to 40 A. Representative PMO samples indicated silanol group populations in the range of 0.6–0.9 OH per nm2 by tetramethyldisilazane silylation (carbon analysis).

Hydrothermal synthesis and structural characterization of a novel gadolinium(III) coordination polymer [Gd(Hdtpc)(OH)(H 2 O)] n

Abstract Hydrothermal reaction of Gd2O3 with orotic acid (2,6-dioxo-1,2,3,6-tetrahydropyrimidine-4-carboxylic acid, H3dtpc) yielded a novel polymeric complex [Gd(Hdtpc)(OH)(H2O)]n (1) possessing the three-dimensional network constructed by eight-coordinate Gd(III) centers. The whole structure of 1 can be viewed as Gd(III) chains linked by orotate spacers. Crystallographic data for the complex: orthorhombic, space group Pna21, a=10.0654(10), b=16.5208(17), c=4.6223(5) A, V=768.64(14) A3, Z=4, D c =2.993 gcm −3 .

Hydrothermal synthesis and characterization of the coordination polymer [Zn(bbdc)(H2O)]n (bbdc=4,4′-bibenzene-dicarboxylate) possessing a 3D network structure

Abstract A Zn coordination polymer [Zn(bbdc)(H2O)]n (bbdc=4,4′-bibenzene-dicarboxylate) with 3D network structure was prepared by the hydrothermal reaction of Zn(CH3CO2)·2H2O,H2bbdc and H2O in a molar ratio of 1:1:1556 at 170°C and characterized by single-crystal X-ray diffraction analysis. Each Zinc(II) center was coordinated by three oxygen atoms from bbdc ligand and one oxygen atom from water molecule to display a slightly distorted tetrahedral geometry.