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1.
Reactions of FeII, CoII, NiII, and ZnII salts with 6-quinolinecarboxylic acid (HL) under the hydrothermal conditions afford three monomeric complexes [M(L)2(H2O)4] (M = FeII for 1, CoII for 2, and NiII for 3) and a 1-D polymeric species {[Zn(L)2(H2O)] · H2O}n (4). The crystal structures of the ligand HL and these four complexes have been determined by using the X-ray single-crystal diffraction technique. The results suggest that complexes 1-3 are isostructural, displaying novel 3-D pillar-layered networks through multiple intermolecular hydrogen bonds, whereas in coordination polymer 4, the 1-D comb-like coordination chains are extended to generate a hydrogen-bonded layer, which is further reinforced via aromatic stacking interactions. Solid-state properties such as thermal stability and fluorescence emission of the polymeric ZnII complex 4 have also been investigated. 相似文献
2.
Three distinct coordination complexes, viz. {[Cu(μ-L)2] · (H2O)4}n (1), [Ni(L)2(CH3OH)2] (2), and [Zn(L)2(H2O)2] · (H2O)2 (3), have been prepared by the reactions of metal nitrates with isoquinoline-3-carboxylic acid (HL). X-ray single-crystal diffraction suggests that 1 is a 1D chain coordination polymer in which the CuII ions are connected by carboxylates, whereas complexes 2 and 3 represent discrete mononuclear species. In all the cases, the coordination entities are further organized via hydrogen-bonding interactions to generate multifarious supramolecular networks. Remarkably, a well-resolved 1D water morphology is observed for the first time in the crystalline lattice of 1 along [1 0 0], which consists of edge-sharing tetrameric subunits and stabilized by the metal-organic host surroundings. 相似文献
3.
Hong-Ying Zang Guang-Sheng Yang Guang-Juan Xu Dong-Ying Du Lei Chen Li-Kai Yan 《Inorganica chimica acta》2010,363(1):118-1872
Four octamolybdate-based compounds, that is, CuII2(L1)4(Mo8O26) (1), CuII2(HL2)4(Mo8O26)2 (2), [CuIIL2(H2O)(Mo8O26)0.5]·2H2O (3) and [CuIIL2(H2O)(Mo8O26)0.5]·2H2O (4) (L1 = 2-(2-pyridyl)imidazole, L2 = 2-(1-(pyridine-3-ylmethyl)-1H-imidazol-2-yl)pyridine), have been hydrothermally synthesized via changing the reaction conditions and structurally characterized by single-crystal X-ray diffraction. With L1 ligand, we obtained compound 1, which is a 0D molecule and extends to a 3D supramolecular structure via hydrogen-bonding interactions. By using L2 instead of L1 ligand, compound 2 comes into being which is as well a discrete molecule and further extended to a 3D supramolecular structure by hydrogen bonds. Intriguingly, compounds 3 and 4 are supramolecular isomers: the former is a 2D 4-connected network and the latter is a 3D (3,4)-connected framework. The measurements of diffuse reflectance for compounds 1-4 indicate that they are potential wide gap semiconductors. 相似文献
4.
Jun-Jie Wang 《Inorganica chimica acta》2010,363(7):1377-1385
In our continuing efforts to explore the effects of substituent groups of ligands in the formation of supramolecular coordination structures, seven new CuII complexes formulated as [Cu2(L1)4(DMF)2] (1), {[Cu2(L1)4(Hmta)](H2O)0.75}∞ (2), [Cu2(L2)4(2,2′-bipy)2] (3), [Cu2(L3)4(H2O)2] (4), [Cu2(L3)4(Hmta)]∞ (5), [Cu2(L3)4(Dabco)]∞ (6) and [Cu2(L3)4(Pz)]∞ (7) with three monocarboxylate ligands bearing different substituent groups HL1-HL3 (HL1 = phenanthrene-9-carboxylic acid, HL2 = 2-phenylquinoline-4-carboxylic acid, HL3 = adamantane-1-carboxylic acid, Hmta = hexamethylenetetramine, 2,2′-bipy = 2,2′-bipyridine, Dabco = 1,4-diazabicyclo[2.2.2] octane and Pz = pyrazine), have been prepared and characterized by X-ray diffraction. In 1, 2 and 4-7, each CuII ion is octahedrally coordinated, and carboxylate acid acts as a syn-syn bridging bidentate ligand. While each CuII ion in 3 is penta-coordinated in a distorted square-pyramidal geometry. 1 and 4 both show a dinuclear paddle-wheel block, while 2, 5, 6 and 7 all exhibit an alternated 1D chain structure between dinuclear paddle-wheel units of the tetracarboxylate type Cu2-(RCO2)4 and the bridging auxiliary ligands Hmta, Dabco and Pz. Furthermore, 3 has a carboxylic unidentate and μ1,1-oxo bridging dinuclear structure with the chelating auxiliary ligand 2,2′-bipy. Moreover, complexes 1-6 were characterized by electron paramagnetic resonance (EPR) spectroscopy. 相似文献
5.
Jana Jašková Dušan Mikloš Vladimír Jorík Barbora Kaliňáková Jozef Švorec Jerzy Mrozinski Milan Melník 《Inorganica chimica acta》2007,360(8):2711-2720
Synthesis and characterization of six new complexes [Cu{2,6-(MeO)2nic}2(H2O)]2 (1), [Cu{2,6-(MeO)2nic}2(H2O)]2 · 3DMF (2), where 2,6-(MeO)2nic is 2,6-dimethoxynicotinate and DMF is N,N-dimethylformamide, [Cu(3-pyacr)2(H2O)2]n (3), where 3-pyacr is trans-3-(3-pyridyl)acrylate, [Cu(en)2(H2O)2]X2, where X is 2,6-(MeO)2nic (4) or 3-pyacr (5) and en is ethylenediamine, and [Cu(3-pyacr)2(dien)(μ-H2O)0.5]2 · 7H2O (6), where dien is diethylenetriamine are reported. The characterizations were based on elemental analysis, infrared, electronic and EPR spectra, and magnetic measurements over a temperature range of 1.8-300 K. Crystal structures of complexes 2, 4 and 6 have been determined by X-ray single crystal structure analysis. The available evidence supports dimeric structure of the acetate type for 1 and 2. Crystal structure of polymeric complex 3 has been determined from X-ray powder diffraction data. The 3-pyacr anions in pairs form bridges between two octahedrally surrounded copper(II) atoms in such a way that one 3-pyacr is coordinated to the first CuII by an oxygen atom of its carboxyl group and to the second CuII by the nitrogen atom of its pyridine ring, while the other is coordinated to the same two CuII atoms in a similar way, but the other way round. Environment about the copper(II) atom for 4 and 5 is a square bipyramid (4+2).In complex 6 both CuII central atoms are bridged only by an axial water molecule forming a dimeric structure with the considerably long separation of CuII atoms of 5.194 Å and the angle Cu1-O3-Cu1a of 150.79°. Moreover, results of the quantitative determination of antimicrobial activity of the complexes as well as above organic ligands alone are discussed. 相似文献
6.
Frederik Schleife 《Inorganica chimica acta》2011,374(1):521-527
The metal complexation properties of a functionalized N3O2 donor ligand H2L2, where H2L2 stands for 2,6-diacetyl-4-carboxymethyl-pyridine bis(benzoylhydrazone), are investigated by structural and spectroscopic (IR, ESI-MS and EPR) characterization of its Mn(II) and Co(II) complexes. The ligand H2L2 is observed to react essentially in the same fashion as its unmodified parent H2L1 producing mixed-ligand [M(H2L2)(Cl2)] complexes (M = MnII (1), CoII (3)) upon treatment with MCl2. Complexes [M(HL2)(H2O)(EtOH)]BPh4 (M = Mn 2, M = Co 4), incorporating the supporting ligand in the partially deprotonated form (HL2)−, are formed by salt elimination of the [M(H2L2)(Cl2)] compounds with NaBPh4. Compounds 2 and 4 are isostructural featuring distorted pentagonal-bipyramidal coordinated MnII and CoII ions, with the H2O and EtOH ligands bound in axial positions. Intermolecular hydrogen bonding interactions of the type M-OH2?O-M involving the H2O ligands and the carbonyl functions of the supporting ligand assembles the complexes into dimers. Temperature-dependent magnetic susceptibility measurements (2-300 K) show a substantially paramagnetic Curie behavior for the Mn2+ compound (2) influenced by zero-field splitting and significant orbital angular momentum contribution for 4 (high-spin CoII). The exchange coupling across the MnII-OH2?O-MnII bridges in 2 was found to be less than 0.1 cm−1, suggesting that no significant intradimer exchange coupling occurs via this path. 相似文献
7.
Jing Chen 《Inorganica chimica acta》2011,378(1):206-212
Three Cd(II) and Zn(II) coordination polymers, including {[Cd(3-bpo)(mip)(H2O)](H2O)2}n (1), {[Cd(4-bpo)(hip)(H2O)](H2O)4}n (2), and {[Zn(4-bpo)(tp)](CH3OH)}n (3) were synthesized from the reactions of CdII or ZnII nitrate with mixed organic ligands [3-bpo = 2,5-bis(3-pyridyl)-1,3,4-oxadiazole, H2mip = 5-methylisophthalic acid, 4-bpo = 2,5-bis(4-pyridyl)-1,3,4-oxadiazole, H2hip = 5-hydroxylisophthalic acid, H2tp = terephthalic acid] under the similar layered diffusion condition. The resulting crystalline materials 1-3 were characterized by IR, microanalysis, powder X-ray diffraction (PXRD) techniques. Single-crystal X-ray diffraction indicates a 1-D tubular motif for 1, a 1-D dual-track array for 2, and a 2-D grid-like pattern for 3, constructed via different metal-ligand coordination contacts. Higher-dimensional supramolecular architectures are further assembled in 1-3 via H-bonding and aromatic stacking interactions. In addition, thermal stability and fluorescence of these polymeric complexes were also investigated and discussed. 相似文献
8.
Chun-Sen Liu 《Inorganica chimica acta》2007,360(8):2532-2540
In our efforts to investigate the factors that affect the formation of coordination architectures, such as secondary coordination donors and pendant skeletons of the carboxylic acid ligands, as well as H-bonding and other weak interactions, two kinds of ligands: (a) 3-(2-pyridyl)pyrazole (L1) with a non-coordinated N atom as a H-bonding donor, a 2,2′-bipyridyl-like chelating ligand, and (b) four carboxylic ligands with different secondary coordination donors and/or pendant skeletons, 1,4-benzenedicarboxylic acid (H2L2), 4-sulfobenzoic acid (H2L3), quinoline-4-carboxylic acid (HL4) and fumaric acid (H2L5), have been selected to react with Mn(II) salts, and five new complexes, [Mn(L1)2(SO4)]2 (1), [Mn(L1)2(L2)]∞ (2), [Mn(L1)(HL3)2]∞ (3), Mn(L1)2(L4)2 (4), and [Mn(L1)2(L5)]∞ (5), have been obtained and structurally characterized. The structural differences of 1-5 can be attributed to the introduction of the different carboxylic acid ligands (H2L2, H2L3, HL4, and H2L5) with different secondary coordination donors and pendant skeletons, respectively. This result also reveals that the typical H-bonding (i.e. N-H?O and O-H?O) and some other intra- or inter-molecular weak interactions, such as C-H?O weak H-bonding and π?π interactions, often play important roles in the formation of supramolecular aggregates, especially in the aspect of linking the multi-nuclear discrete subunits or low-dimensional entities into high-dimensional supramolecular networks. 相似文献
9.
The synthesis and characterisation of two dicopper(II) and two dinickel(II) macrocyclic complexes, [CuII2LPr] (10), [CuII2LBu] (11), [NiII2LPr] (12) and [NiII2LBu] (13), are reported. The two new Schiff-base macrocycles (LPr)4− and (LBu)4− are isolated as dimetallic complexes 10-13 by the [2+2] condensation of 5,5-dimethyl-1,9-diformyldipyrromethane (9) and 1,3-diaminopropane or 1,4-diaminobutane, respectively, using Cu2+ or Ni2+ template ions. Single crystal X-ray structure determinations carried out on 10-13 show that each metal atom is in a square planar N4 geometry, being bound to two deprotonated pyrrole nitrogen atoms of one dipyrromethane unit and to the two adjacent imine nitrogen atoms. NMR spectra obtained for the two dinickel(II) complexes 12 and 13 show that in CDCl3 solution they are highly symmetrical and diamagnetic. 相似文献
10.
Three new o-thioetherphenol ligands have been synthesized: 1,2-bis(3,5-di-tert-butyl-2-hydroxyphenylsulfanyl)ethane (H2bse), 1,2-bis(3,5-di-tert-butyl-2-hydroxyphenylsulfanyl)benzene (H2bsb), and 4,6-di-tert-butyl-2-phenylsulfanylphenol (Hpsp). Their complexes with copper(II) were prepared and investigated by UV-Vis-, EPR-spectroscopy; their electro- and magnetochemistry have also been studied: [CuII(psp)2] (1), [CuII2(bse)2] (2), [CuII2(bsb)2] (3), [CuII(bsb)(py)2] (4). The crystal structures of the ligands H2bse, H2bsb, Hpsp and of the complexes 1, 2, 3, 4 have been determined by X-ray crystallography. 相似文献
11.
The reactions of 2,5-bis(pyrazinyl)-1,3,4-oxadiazole (bpzo) with CdII or CoII salt in the presence of thiocyanate afford two distinct complexes, a 1-D coordination array [Cd(bpzo)2(SCN)2]n (1) and a 3-D hydrogen-bonded supramolecular network [Co(bpzo)2(SCN)2(H2O)2](CH3CN)2(H2O)2 (2). X-ray single-crystal structural determination reveals that the extended networks of complexes 1 and 2 are manipulated via different directional propagating forces. In 1, the adjacent CdII centers are bridged by a pair of μ1,3-SCN− anions to form a 1-D array, whereas in 2, the monomeric CoII coordination entities are hydrogen-bonded into a novel 3-D architecture in which the thiocyanate ions take the only N-binding mode. In both cases, bpzo behaves as monodentate terminals. These results indicate that the choice of metal ions does play a critical role in the supramolecular assembly. The structural and binding features of bpzo in all related compounds have also been discussed. 相似文献
12.
Two oxime-functionalized diazamesocyclic derivates, namely, N,N′-bis(acetophenoneoxime)-1,4-diazacycloheptane (H2L1) and N,N′-bis(acetophenonoxime)-1,5-diazacyclooctane (H2L2), have been prepared and characterized. Both ligands (obtained in the hydrochloride form) can form stable metal complexes with CuII and NiII salts, the crystal structures of which were determined by X-ray diffraction technique. The reactions of H2L1 with Cu(ClO4)2 and Ni(ClO4)2 afford a penta-coordinated mononuclear complex [Cu(H2L1)Cl] · ClO4 (1) and a four-coordinated monomeric [Ni(HL1)] · ClO4 (2), in which the ligand is monodeprotonated. The ligand H2L2 also forms a quite similar mononuclear [Ni(HL2)] · ClO4 complex with Ni(ClO4)2, according to our previous work. However, reactions of different CuII salts [Cu(ClO4)2, CuCl2 and Cu(NO3)2 for 3, and CuSO4 for 4] with H2L2 in the presence of NaClO4 yield two unusual mono-μ-Cl dinuclear CuII complexes [Cu2(HL2)2Cl] · (ClO4) (3), and [Cu2(H2L2)(HL2)Cl] · (ClO4)2 · (H2O)(4). These results indicate that the resultant CuII complexes (1, 3 and 4) are sensitive to the backbones of diazamesocycles and even auxiliary anions. 相似文献
13.
Palladium [PdCl2(L)] complexes with N-alkylpyridylpyrazole derived ligands [2-(5-trifluoromethyl-1H-pyrazol-3-yl)pyridine (L1), 2-(1-ethyl-5-trifluoromethyl-1H-pyrazol-3-yl)pyridine (L2), 2-(1-octyl-5-trifluoromethyl-1H-pyrazol-3-yl)pyridine (L3), and 2-(3-pyridin-2-yl-5-trifluoromethyl-pyrazol-1-yl)ethanol (L4) were synthesised. The crystal and molecular structures of [PdCl2(L)] (L = L2, L3, L4) were resolved by X-ray diffraction, and consist of monomeric cis-[PdCl2(L)] molecules. The palladium centre has a typical square-planar geometry, with a slight tetrahedral distortion. The tetra-coordinate metal atom is bonded to one pyridinic nitrogen, one pyrazolic nitrogen and two chlorine ligands in cis disposition. Reaction of L (L2, L4) with [Pd(CH3CN)4](BF4)2, in the ratio 1M:2L, gave complexes [Pd(L)]2(BF4)2. Treatment of [PdCl2(L)] (L = L2, L4) with NaBF4 and pyridine (py) and treatment of the same complexes with AgBF4 and triphenylphosphine (PPh3) yielded [Pd(L)(py)2](BF4)2 and [Pd(L)(PPh3)2](BF4)2 complexes, respectively. Finally, reaction of [PdCl2(L4)] with 1 equiv of AgBF4 yields [PdCl(L4)](BF4). 相似文献
14.
Xian-He Bu He LiuMiao Du Keith Man-Chung WongVivian Wing-Wah Yam 《Inorganica chimica acta》2002,333(1):32-40
The complexes of Cu(I), Cu(II), Ni(II), Zn(II) and Co(II) with a new polypyridyl ligand, 2,3-bis(2-pyridyl)-5,8-dimethoxyquinoxaline (L), have been synthesized and characterized. The crystal structures of these complexes have been elucidated by X-ray diffraction analyses and three types of coordination modes for L were found to exist in them. In the dinuclear complex [Cu(I)L(CH3CN)]2·(ClO4)2 (1), L acts as a tridentate ligand with two Cu(I) centers bridged by two L ligands to form a box-like dimeric structure, in which each Cu(I) ion is penta-coordinated with three nitrogen atoms and a methoxyl oxygen atom of two L ligands, and an acetonitrile. In [Cu(II)L(NO3)2]·CH3CN 2, the Cu(II) center is coordinated to the two nitrogen atoms of the two pyridine rings of L which acts as a bidentate ligand. The structures of [Ni(II)L(NO3)(H2O)2]·2CH3CN·NO3 (3), [Zn(II)L(NO3)2 (H2O)]·2CH3CN (4) and [Co(II)LCl2(H2O)] (5) are similar to each other in which L acts as a tridentate ligand by using its half side, and the metal centers are coordinated to a methoxyl oxygen atom and two bipyridine nitrogen atoms of L in the same side. The formation of infinite quasi-one-dimensional chains (1, 4 and 5) or a quasi-two-dimensional sheet (2) assisted by the intra- or intermolecular face-to-face aryl stacking interactions and hydrogen bonds may have stabilized the crystals of these complexes. Luminescence studies showed that 1 exhibits broad, structureless emissions at 420 nm in the solid state and at 450 nm in frozen alcohol frozen glasses at 77 K. Cyclic voltammetric studies of 1 show the presence of an irreversible metal-centered reduction wave at approximately −0.973 V versus Fc+/0 and a quasi-reversible ligand-centered reduction couple at approximately −1.996 V versus Fc+/0. The solution behaviors of these complexes have been further studied by UV-Vis and ESR techniques. 相似文献
15.
Marina V. Kirillova 《Inorganica chimica acta》2007,360(2):506-512
The heteronuclear water-soluble and air-stable compounds [M(H2O)5M′(dipic)2] · mH2O (M/M′ = CuII/CoII (1), CuII/NiII (2), CuII/ZnII (3), ZnII/CoII (4), NiII/CoII (5), m = 2-3; H2dipic = dipicolinic acid) have been prepared by self-assembly synthesis in aqueous solution at room temperature, and characterized by IR, UV-Vis and atomic absorption spectroscopies, elemental and X-ray diffraction single crystal (for 1 and 2) analyses. 1-5 represent the first examples of heteronuclear dipicolinate compounds with 3d metals. Extensive H-bonding interactions involving all aqua ligands, dipicolinate oxygens and lattice water molecules further stabilize the dimetallic units by linking them to form three-dimensional polymeric networks. 相似文献
16.
Xiao-Li Chen Qing-Ran Wu Feng Fu Yuan-Yuan Hui Gang-Lin Xue 《Inorganica chimica acta》2010,363(2):360-3894
Three novel d10 metal coordination polymers, {[Cd(H2odpa)(phen)2]·H2O}n (1), [Cd2(odpa)(phen)(H2O)2]n (2), {[Zn4(odpa)2(phen)2(H2O)2]·H2O}n (3), (H4odpa = 4,4′-oxydiphthalic acid, phen = 1,10-phenanthroline) were obtained with different metal/ligand ratios through hydrothermal method and characterized. Compound 1 forms a one dimensional zigzag chain, in which two phen ligands chelate to one cadmium atom. Compound 2 shows a three dimensional network structure comprised of new tetranuclear cadmium clusters as the nodes and (odpa)4− anions as the linkers, exhibits an unusual topological structure. Compound 3 is an unprecedented three dimensional polymer based on octanuclear zinc clusters cross-linked by (odpa)4− anions. In 1-3, central CdII/ZnII ions and (odpa)4− ligand display completely different coordination modes and conformations. In addition, the thermal stabilities and photoluminescence properties of 1-3 were also studied. 相似文献
17.
Reaction of M(OAc)2 (MII = CuII for 1, CoII for 2, and PbII for 3) with pyridine-2,6-dicarboxylic acid (H2pydc) in presence of a dipyridyl spacer 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (bpo) affords three novel metal-organic supramolecular networks [Cu2(bpo)(pydc)2(H2O)3] · 2.75H2O(1), [Co(bpo)(pydc)(H2O)2] · (H2O) (2) and [Pb(pydc)]n (3), which have been structurally determined by single-crystal X-ray diffraction. The dimeric Cu-pydc coordination framework bridged by a bpo spacer in 1 is hydrogen-bonded to four others to result in a two-dimensional (2-D) sheet array. The neutral monomeric molecules in 2 have an ordered 3-D stacking stabilized via hydrogen bonds and significant π-π interactions in the lattice, possessing large porous channels with the inclusion of guest solvates. In coordination polymer 3, the PbII ion takes the unusual distorted capped trigonal prismatic geometry (PbNO6) and each pydc dianion binds to four PbII centres to form a 2-D infinite network. The thermal stabilities of these complexes have also been investigated. 相似文献
18.
Li-Zhen Cai Ming-Lai Fu Ming-Sheng Wang Wen-Tong Chen Jin-Shun Huang 《Inorganica chimica acta》2006,359(14):4483-4492
Assembly of isonicotinic acid ligand (HL) with metal halide, five new hybrid complexes [CdI2(C5H4NCOOH)(C5H4NHCOO)] · H2O (1), Nan[ZnCl2(C5H4NCOO)]n · 2nH2O (2), [CdX(C5H4NCOO)]n (X = Br (3), I (4)) and [Cd3Cl2(OH)2(C5H4NCOO)2]n (5) were obtained, which display a variety of structural motifs, ranging from zero-dimensional to complicated three-dimensional networks. Complex 1 possesses an isolated unit MX2 that is further connected into 3D networks through hydrogen bonding and π-π stacking interactions. Complex 2 is characterized by an infinite one-dimensional chain of zinc atoms bridged by L− ligands. While complexes 3 and 4 possess X-bridging ∞1[CdX2/2] inorganic chains connected by L− ligands to form a 2D hybrid network structure. In the case of 5, the cadmium(II) cation is bridged by μ3-Cl atom and μ3-OH− group to form a 2-D ∞2[Cd6/2Cl6/3(μ3-OH)2] inorganic layer which is further extended into 3-D framework by bridging L− ligand via Cd-N and Cd-O bonds. The optical properties of 1, 4, and 5 in the solid state are investigated at room temperature and time-dependent DFT (TDDFT) calculation using the B3LYP functional has been performed on 1. The result indicated that the emission band of 1 is attributed to an admixture of MLCT (metal-to-ligand charge-transfer) and LLCT (ligand-to-ligand charge-transfer). 相似文献
19.
Jun-Jie Wang 《Inorganica chimica acta》2009,362(9):3147-3943
In our efforts to investigate the relationships between the structures of ligands and their complexes, two structurally related ligands, 1-(2-pyridylmethyl)-1H-benzimidazole (L1) and 1-(4-pyridylmethyl)-1H-benzimidazole (L2), and their four complexes, [Zn(L1)2Cl2] (1), [Hg(L1)Br2]∞ (2), {[Zn(L2)Cl2](CH3CN)}∞ (3) and [Hg(L2)Br2]2(CH3CN)2 (4) were synthesized and structurally characterized by elemental analyses, IR spectra and single-crystal X-ray diffraction analysis. Structural analyses show that 1 has a mononuclear structure, and 2 and 3 both take 1D structure. While 4 takes a dinuclear structure. 1, 2 and 4 were further linked into higher-dimensional supramolecular networks by weak interactions, such as C-H?Cl and C-H?Br H-bonding, C-H?π, and π?π stacking interactions. The structural differences of 1-4 may be attributed to the difference of the spatial positions of the terminal N donor atoms in the pendant pyridyl groups in L1 and L2, in which the pyridine rings may act as the directing group for coordination and the benzimidazole rings act as the directing group for π?π stacking and C-H?π interactions. The luminescent properties of the corresponding complexes and ligands have been further investigated. 相似文献
20.
The acid-base properties and Cu(II), Ni(II), Ag(I) and Hg(II) binding abilities of PAMAM dendrimer, L, and of the simple model compounds, the tetraamides of EDTA and PDTA, L1, were studied in solution by pH-metric methods and by 1H NMR and UV-Vis spectroscopy. PAMAM is hexabasic and six pKa values have been determined and assigned. PAMAM forms five identifiable complexes with copper(II), [CuLH4]6+, [CuLH2]4+, [CuLH]3+, [CuL]2+ and [CuLH-1]+ in the pH range 2-11 and three with nickel(II), [NiLH]3+, [NiL]2+ and [NiLH-1]+ in the pH range 7-11. The complex [CuLH4]6+, which contains two tertiary nitrogen and three amide oxygen atoms coordinated to the metal ion, is less stable than the analogous EDTA and PDTA tetraamide complexes [CuL1]2+, which contain two tertiary nitrogen and four amide oxygen atoms, due to ring size and charge effects. With increasing pH, [CuLH4]6+ undergoes deprotonation of two coordinated amide groups to give [CuLH2]4+ with a concomitant change from O-amide to N-amidate coordination. Surprisingly and in contrast to the tetraamide complexes [CuL1]2+, these two deprotonation steps could not be separated. As expected the nickel(II) complexes are less stable than their copper(II) analogues. The tetra-N-methylamides of EDTA, L1(b), and PDTA form mononuclear and binuclear complexes with Hg(II). In the case of L1(b) these have stoichiometries HgL1(b)Cl2, [HgL1(b)H−2Cl2]2−, [Hg2L1(b)Cl2]2+, Hg2L1(b)H−2Cl2 and [Hg2L1(b)H−5Cl2]3−. Based on 1H NMR and pH-metric data the proposed structure for HgL1(b)Cl2, the main tetraamide ligand containing species in the pH range <3-6.5, contains L1(b) coordinated to the metal ion through the two tertiary nitrogens and two amide oxygens while the structure of [HgL1(b)H−2Cl2]2−, the main tetraamide ligand species at pH 7.5-9.0, contains the ligand similarly coordinated but through two amidate nitrogen atoms instead of amide oxygens. The proposed structure of [Hg2L1(b)Cl2]2+, a minor species at pH 3-6.5, also based on 1H NMR and pH-metric data, contains each Hg(II) coordinated to a tertiary amino nitrogen, two amide oxygens and a chloride ligand while that of [Hg2L1(b)H−5Cl2]3−, contains each Hg(II) coordinated to a tertiary amino nitrogen, two amidate nitrogens, a chloride and a hydroxo ligand in the case of one of the Hg(II) ions. The parent EDTA and PDTA amides only form mononuclear complexes. PAMAM also forms dinuclear as well as mononuclear complexes with mercury(II) and silver(I). In the pH range 3-11 six complexes with Hg(II) i.e. [HgLH4Cl2]4+, [HgLH3Cl2]3+, [Hg2LCl2]2+, [Hg2LH−1Cl2]+, [HgLH−1Cl2]− and [HgLH−2Cl2]2− were identified and only two with Ag(I), [AgLH3]4+ and [Ag2L]2+. Based on stoichiometries, stability constant comparisons and 1H NMR data, structures are proposed for these species. Hence [HgLH4Cl2]4+ is proposed to have a similar structure to [CuLH4]6+ while [Hg2LCl2]2+has a similar structure to [Hg2L1(b)H−5Cl2]3−. 相似文献