Two luminescent frameworks constructed from lead(II) salts with carboxylate ligands containing dinuclear lead(II) units

Two luminescent Pb(II) coordination frameworks containing dinuclear lead(II) units, [Pb(PYDC)(H₂O)]_n (1) and [Pb(HPHT)]_n (2) have been prepared by the self-assembly of lead(II) salts with pyridinecarboxylate and benzenecarboxylate. Single-crystal X-ray diffraction analyses reveal that compound 1 is a three-dimensional architecture consisting of Pb₂O₂ dimeric building units, whereas compound 2 is a two-dimensional layer structure containing one-dimensional lead-oxide chains. The luminescent properties of 1 and 2 have been investigated in the solid state at room temperature, indicating structure-dependent photoluminescent properties of the coordination frameworks.     

Syntheses,crystal structures,and luminescent properties of two cadmium(II) complexes based on bis(imidazole) and dicarboxylate

Two complexes, [Cd(ip–OH)(H₂biim)(H₂O)][Cd(ip–OH)(H₂biim)(H₂O)₃]·8(H₂O) (1) and [Cd(Himdc)(H₂biim)] _n (2) (H₂ip–OH?=?5-hydroxylisophthalic acid, H₂biim?=?2,2’-biimidazolate, H₃imdc?=?4,5-imidazoledicarboxylic acid), have been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction. 1 is a 3-D supramolecular network constructed by 0-D and 1-D motifs through hydrogen bonds and π?π interactions. Complex 2 is a 1-D zigzag polymeric coordination chain and the chains are connected to form a 3-D supramolecular network by hydrogen bonds. The complexes were characterized by elemental and thermogravimetric analyses. Fluorescence was also investigated.     

Synthesis,characterization, molecular modeling,and thermal analyses of bioactive Co(II) and Cu(II) complexes with diacetylmonoxime and different amines

Condensation of diacetylmonoxime with 2-amino-5-mercapto-1,3,4-thiadiazole, 2-amino-1,3,4-thiadiazole or 3-amino-5-methylisoxazole in the presence of Co(II) and Cu(II) salts with different anions produced nine complexes. The synthesized complexes have been characterized by elemental analyses, molar conductivities, thermal analyses, magnetic moments, IR, electron spin resonance, and UV-Vis spectral studies. The spectral data show that sulfur, oxygen, and nitrogen participate in chelation with the metal ions. The complexes are tetrahedral, octahedral, or square planar based on the amine used and the nature of anion. Molar conductance measurements of the complexes in DMF indicate non-electrolytes. CS Chem 3-D Ultra Molecular Modeling and Analysis Program has been used for optimization of the molecular structures of some complexes. In vitro cytotoxicities of the complexes were tested against different carcinoma cell lines. Antimicrobial activities of the complexes were screened against Gram-positive (Staphylococcus aureus), Gram negative bacteria (Escherichia coli), and fungal species (Aspergillus flavus, Candida albicans, and Microsporum canis).     

Iminoimidazole‐based Co(II) and Fe(II) complexes: Syntheses,characterization, and catalytic behaviors for isoprene polymerization

A stereoselectivity switchable polymerization of isoprene has been developed, which is catalyzed by iminoimidazole‐Co(II) and ‐Fe(II) complexes. The influence of substituents ranging from electron donating to the electron withdrawing on the iminoimidazole‐Co(II) and ‐Fe(II) catalysts is investigated for isoprene polymerization. Two sets of iminoimidazole‐Co(II) and ‐Fe(II) complexes have been prepared and fully characterized. X‐ray crystallography analysis reveals that the complexes Co1 and Fe1 adopt distorted tetrahedral geometries. In the presence of AlEt₂Cl as co‐catalyst, all the Co(II) complexes are active and the catalytic activity is highly dependent on the molar ratio of Al/Co. All the Co(II) complexes exhibit higher activities at low Al/Co ratio. Compared with the Co(II) complexes, the Fe(II) complexes are essentially inactive under the identical condition. However, on activation with combination of AlEtCl₂ and [Ph₃C][B(C₆F₅)₄], both Co(II) and Fe(II) complexes display high activities with good conversions of isoprene (up to >99%). Additionally, low molecular weight and high trans‐1,4‐unit (>96%) selectivity are characteristics of the resultant polyisoprene. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 767–775     

Positional isomeric and N-donor auxiliary chelating ligand effect on engineering crystalline architectures of four lead(II) complexes with diverse fluorescent properties

This work presents an investigation on the positions of the substituent and N-donor auxiliary chelating ligand (bipy/phen) effect on engineering of crystalline architectures of four Pb(II) complexes with a pair of methyl-substituted 3-sulfobenzoic isomers: [Pb(4-msba)(phen)(H₂O)] (1), [Pb(4-msba)(bipy)(H₂O)]·H₂O (2), [Pb(5-msba)(phen)₂]·9H₂O (3), and [Pb₂(5-msba)₂(bipy)₂(H₂O)₂] (4) (4/5-msba?=?4/5-methyl-3-sulfobenzoate, phen?=?1,10-phenanthroline and bipy?=?2,2′-bipyridine). The lead(II) ions exhibit hemidirected geometry in 1–4. The positions of the methyl as well as the auxiliary chelating ligands influence coordination modes of the sulfonates and thus determine the architectures. As the position of methyl in aromatic ring changes from 4 to 5, the structures change from 2-D sheet-like compounds for 1 and 2 to 0-D dimeric species for 3 and 4. A water cluster (H₂O)₁₈ exists in 3, which further assembles into a water tape with a new pattern T4(3)4(3)10(3)A4. Complex 3 loses crystallinity rapidly in the open air and turns into [Pb(5-msba)(phen)₂]·2H₂O (3A). Thermal stabilities and solid state fluorescent properties of 1, 2, 3A, and 4 have been studied.     

Syntheses, structures and magnetic properties of five iron(II) coordination polymers with flexible bis(imidazole) and bis(triazole) ligands

Five iron(II) coordination polymers, {[Fe(bte)₂(NCS)₂][Fe(bte)(H₂O)₂(NCS)₂]}_n (1), [Fe(bime)(NCS)₂]_n (2), [Fe(bime)(dca)₂]_n (3), [Fe(bime)₂(N₃)₂]_n (4) and [Fe(btb)₂(NCS)₂]_n (5), were synthesized using the flexible ligands 1,2-bis(1,2,4-triazol-1-yl)ethane (bte), 1,2-bis(imidazol-1-yl)ethane (bime) and 1,4-bis(1,2,4-triazol-1-yl)butane (btb), together with NCS⁻, dicyanamide (dca) and N₃⁻. The compound 1 contains two kinds of motifs (double chain and single chain) and forms a three-dimensional hydrogen bonded network; 2 and 3 contain one-dimensional triple chains; and 4 and 5 form two-dimensional (4, 4) networks. The coordination anions (NCS⁻, dca and N₃⁻) and the structural characteristics of the ligands (bte, bime and btb) play an important role in the assembly of the topologies. Magnetic studies reveal that 1-5 remain in the high-spin state over the whole temperature range 2-300 K and no detectable spin-crossover is observed.     

Struktur eines Blei(II)‐Komplexes mit verknüpften Monothioquadratationen als Liganden

A Lead(II) Complex with Linked Monothiosquarate Ions as Ligands The thiosquarate ligand bis‐1,2‐(2‐hydroxy‐3,4dione‐cyclobut‐1‐enylsulfanyl)‐ethane and its lead(II) complex have been prepared. According to the crystal structure analysis the complex has a unique layer structure in the solid state. The layers consist of a superposition of cyclic dimeric complexes and of chain like polymeric complexes. The shortest nonbonding Pb…Pb distances are 4.0 Å.     

Synthesis and crystal structures of two lead(II) complexes of 4,4,4-trifluoro-1-naphthyl-1,3-butanedione ligand,subtle interplay of weak intermolecular interactions

[Pb₂(tfnb)₄ (µ-CH₃OH)] _n (1) and [Pb₂(dmp)₂(tfnb)₄] (2) (tfnb and dmp are the abbreviations for 4,4,4-trifluoro-1-naphthyl-1,3-butanedionate and 2,9-dimethyl-1,10-phenanthroline) have been synthesized and characterized by elemental analysis, IR, ¹H NMR spectroscopy, and thermal analysis. The single-crystal structure of 1 shows that the complex forms two 1-D polymeric networks containing four types of Pb²⁺ with coordination numbers seven for Pb(1) and Pb(3), five for Pb(2), and six for Pb(4). The single-crystal structure of 2 shows that the complex forms a dinuclear complex with eight-coordinate Pb(II). The supramolecular features in this complex are guided by lone-pair activity and the control of weak directional intermolecular interactions and aromatic π–π stacking interactions.     

Supramolecular Influences on Metal Ion Coordination: Lead(II) under Eight-coordination

Crystal structure determinations on the “acid salt” of Pb(II) and dipicolinic acid (pyridine-2,6-dicarboxylic acid, dipicH²), regarded as composed of dimer entities, [Pb²(dipic)²(dipicH²)²(OH²)⁶], 1, infinitely cross-linked, and on the complex of 2,4-dinitrophenol (2,4-DNPH), a simpler coordination polymer, [Pb(2,4-DNP)²]n, 2, show both solid state structures to be influenced by π-stacking of the ligands. Although the Pb(II) coordination environment in 1 can be regarded as “hemidirected” and that in 2 as “holodirected”, it is argued that inter-dimer stacking interactions, rather than lone pair effects, are responsible for the distorted 9-coordination of Pb in 1. In 2, Pb adopts close-to-cubic 8-coordination.     

Syntheses,crystal structures,and photophysical properties of two 2-D coordination polymers with different geometries of lead(II)

Two complexes constructed from aromatic acid and N-heterocyclic ligands have been synthesized by hydrothermal reaction: [Pb(cipt)(NDC)]_n (1) [cipt?=?2-(3-chlorophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline, NDC?=?naphthalene-1,4-dicarboxylic acid] and [Pb(ipm)(BDC)₂]_n (2) [BDC?=?terephthalic acid, ipm?=?5-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)-2-methoxyphenol]. Single-crystal X-ray analysis shows that 1 exhibits an interesting arm-shaped chain structure. 1-D ladder chain structure is formed by N–H···O bonding interactions and further into a 2-D network by N–H···O hydrogen bonds and interchain π–π stacking interactions. Complex 2 shows a 2-D butterfly wings structure, which has been rarely reported. The structure in 2 has intermolecular N–H···O interactions, which help in construction of the 3-D framework. In 1, the coordination sphere of Pb(II) is hemi-directed, whereas the Pb(II) geometry in 2 is holo-directed. The solid-state fluorescence spectra of 1 and 2 are also investigated, as well as the ligands cipt and ipm.     

Unreported coordination behaviour of a bis(semicarbazone) ligand in a lead(II) complex

A novel lead(II) complex with the Schiff base benzil bis(semicarbazone), [Pb(LH₂)₂(NO₃)]NO₃ · 1/2H₂O, has been synthesised and structurally characterized as well as the free ligand. The coordination number of Pb(II) is seven provided by two neutral ligand molecules and one nitrato group. The most interesting characteristic of this complex is the different behaviour observed in the two bis(semicarbazone) molecules. One of them is a N₂O₂ chelate ligand, whereas the other one is bonded to the lead ion only through one of the semicarbazone branches. The seventh position in the lead coordination sphere is provided by one oxygen atom from a nitrato ligand.     

Syntheses and characterization of nickel(II), zinc(II) and palladium(II) complexes derived from three pyrazole-based polydentate ligands

Two pyrazole-based polydentate ligands, 1,3-bis(5-methyl-3-phenylpyrazol-1-yl)-propan-2-ol (Hmppzpo) and 1,3-bis(5-methyl-3-p-isopropylphenylpyrazol-1-yl)-propan-2-ol (Hmcpzpo), have been synthesized. A third ligand, 1,3-bis(3,5-dimethylpyrazol-1-yl)-propan-2-ol (Hdmpzpo), has been synthetically modified. Seven new M(II) coordination compounds of general formula M₂L₂X₂ (M?=?Zn, Ni; X?=?NO₃ or ClO₄; L?=?dmpzpo, mppzpo or mcpzpo) or MLX (M?=?Pd; L?=?dmpzpo; X?=?Cl) were synthesized and structurally characterized by elemental analysis and FT-IR analysis. The crystal structures of [Zn₂(μ-dmpzpo-O,N,N′)₂(NO₃)₂]?·?2H₂O (1?·?2H₂O), [Ni₂(μ-dmpzpo-O,N,N′)₂(CH₃CN)₂](ClO₄)₂ (2) and Pd(μ-dmpzpo-N,N′)Cl₂ (4) were determined by single-crystal X-ray crystallography. The crystal structures show that complexes 1?·?2H₂O and 2 are center-symmetric dinuclear compounds, with two metal ions bridged by two alkoxo groups and each metal ion with a distorted square-pyramidal environment. The palladium complex, 4, displayed square-planar coordination geometry around the Pd(II) ion with trans arrangement.     

New lead(II) complexes with N,S-ligands,including a lead pyrazolonate with unusual packing flexibility

The reaction of lead(II) acetate in methanol with thiosemicarbazones derived from β-keto esters and β-keto amides (HTSCs) afforded two lead(II) thiosemicarbazonates and numerous homoleptic ([PbL₂]) and/or heteroleptic ([Pb(OAc)L]) complexes containing deprotonated pyrazolones L⁻ formed by metal-induced cyclization of the starting HTSC ligands. All the complexes isolated were characterized by IR spectroscopy in the solid state and by ¹H and ¹³C NMR spectroscopy in DMSO solution; in addition, crystals containing [Pb(L⁶)₂] and [Pb(L⁷)₂] were examined by X-ray crystallography. [Pb(L⁶)₂] · 0.5H₂O · 0.3MeOH (HL⁶ = 4-ethyl-2,5-dihydro-3-methyl-5-oxo-1H-pyrazole-1-carbothiamide) showed three types of molecule with significant structural differences that appear to be determined by packing interactions. In all three molecules the Pb?Pb distances are very short [3.6096(8)–3.7562(8) Å], but density-functional-theoretic calculations at the B3LYP level do not support the existence of Pb–Pb bonds. In [Pb(L⁷)₂] (HL⁷ = N-ethyl-2,5-dihydro-3-methyl-5-oxo-1H-pyrazole-1-carbothiamide) all the molecules are of a single type, and they are linked in a three-dimensional network by weak intermolecular Pb?O bonds.     

Syntheses, structures and properties of dinickel(II) macrocyclic complexes with two 2-thiophenoethyl pendant arms

Three dinickel(II) macrocyclic complexes [Ni₂L(μ-OAc)]ClO₄•X (L = L¹, L² and L³) with two 2-thiophenoethyl pendant arms, have been synthesized by cyclocondensation between N,N-bis(3-aminopropyl)-2-thiophenoethylamine and 2,6-diformyl-4-R-phenol (where R = Me, Cl and F and X = MeOH, 2MeCN and H₂O, respectively), in the presence of nickel(II) ions. The complexes were characterized by elemental analysis, spectroscopic methods and X-ray diffraction techniques. The geometry around both of the Ni(II) ions in each molecule is a slightly distorted octahedral and the thiopheno groups do not coordinate to the Ni(II) ions, resulting that the complexes display contorted saddle-form configurations. The distances between the Ni?Ni centers for the complexes are 3.145, 3.171 and 3.155 Å, respectively. The influences of the substituted groups R in the benzene rings of the macrocyclic units on the structure, electrochemistry, magnetism, cleavage and antibacterial property to DNA have been investigated. The ES-MS results of the complexes confirm that [Ni₂L]²⁺ species in methanol solution are very stable because all the peaks in ES-MS spectra contain this kind of units. The reduction potentials of the complexes shift towards anode upon increasing the drawing electronic ability of substituted groups. Magnetic measurements in the 2-300 K range indicate weak antiferromagnetism for the dinuclear Ni(II) complexes and the magnetic exchange interactions enhance with the decrease of the Ni-Ni distances. These complexes exhibit cleavage activities towards plasmid pBR322 DNA and antibacterial activities.     

Sonochemical syntheses and characterization of a new nano-sized 2-D lead(II) coordination polymer as precursor for preparation of PbBr(OH) nano-structure

Nano-particles of a new 2-D Pb(II) coordination polymer, [Pb(4-pyc)(Br)(H₂O)] _n (1) (4-Hpyc = 4-pyridinecarboxylic acid), were synthesized by a sonochemical method. Crystal structure of 1 was determined by X-ray crystallography. The nano-particles were characterized by scanning electron microscopy, X-ray powder diffraction, IR spectroscopy, and elemental analyses. PbBr(OH) nano-structure was obtained by the calcination of nano-particles of 1 at 400°C.     

Synthesis,characterization, and antitumor properties of ruthenium(II) anthraquinone complexes

Three new Ru(II) complexes, [Ru(dmb)₂(ipad)](ClO₄)₂ (dmb = 4,4′-dimethyl-2,2′-bipyridine, ipad = 2-(anthracene-9,10-dione-2-yl) imidazo[4,5-f][1,10]phenanthroline, 1), [Ru(dmp)₂(ipad)](ClO₄)₂ (dmp = 2,9-dimethyl-1,10-phenanthroline, 2), and [Ru(dip)₂(ipad)](ClO₄)₂ (dip = 4,7-diphenyl-1,10-phenanthroline, 3), have been synthesized and characterized. The three Ru(II) complexes intercalate with the base pairs of DNA. The in vitro antiproliferative activities and apoptosis-inducing characteristics of these complexes were investigated. The complexes exhibited cytotoxicity against various human cancer cell lines. BEL-7402 cells displayed the highest sensitivity to 1, accounted for by the greatest cellular uptake. Complex 1 was shown to accumulate preferentially in the nuclei of BEL-7402 cells and cause DNA damage and induce apoptosis, which involved cell cycle arrest and reactive oxygen species generation.     

Synthesis,characterization, and electrochemical study of two new macroacyclic Schiff bases and their copper(II) and zinc(II) complexes

Two new potentially octadentate N₂O₆ Schiff-base ligands 2-((E)-(2-(2-(2-((E)-2-hydroxy-3-methoxybenzylideneamino)phenoxy)phenoxy)phenylimino)methyl)-6-methoxyphenol H₂L¹ and 2-((E)-(2-(2-(2-((E)-2-hydroxy-3-methoxybenzylideneamino)phenoxy)-4-tert-butylphenoxy)phenylimino)methyl)-6-methoxyphenol H₂L² were prepared from the reaction of O-Vaniline with 1,2-bis(2′-aminophenoxy)benzene or 1,2-bis(2′-aminophenoxy)-4-t-butylbenzene, respectively. Reactions of H₂L¹ and H₂L² with copper(II) and zinc(II) salts in methanol in the presence of N(Et)₃ gave neutral [CuL¹]?·?0.5CH₂Cl₂, [CuL²], [ZnL¹]?·?0.5CH₂Cl₂, and [ZnL²] complexes. The complexes were characterized by IR spectra, elemental analysis, magnetic susceptibility, ESI–MS spectra, molar conductance (Λ_m), UV-Vis spectra and, in the case of [ZnL¹]?·?0.5CH₂Cl₂ and [ZnL²], with ¹H- and ¹³C-NMR. The crystal structure of [ZnL¹]?·?0.5CH₂Cl₂ has also been determined showing the metal ion in a highly distorted trigonal bipyramidal geometry. The electrochemical behavior of H₂L² and its Cu(II) complex, [CuL²], was studied and the formation constant of [CuL²] was evaluated using cyclic voltammetry. The logarithm value of formation constant of [CuL²] is 21.9.     

Syntheses and characterization of different zinc(II) oxide nano-structures from direct thermal decomposition of 1D coordination polymers

Three zinc(II) nitrite coordination polymers, [Zn(4-bpdb)(NO₂)₂]_n (1), {[Zn(3-bpdb)(NO₂)]·0.5H₂O}_n (2) and [Zn(3-bpdh)(NO₂)₂]_n (3), 4-bpdb = 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene, 3-bpdb = 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene and 3-bpdh = 2,5-bis(3-pyridyl)-3,4-diaza-2,4-hexadiene} were prepared and characterized by elemental analyses and IR spectroscopy. Compound 3 was structurally characterized by single-crystal X-ray diffraction and is one-dimensional polymer with coordination environments of distorted octahedral, ZnN₂O₄. The thermal stabilities of compounds 1–3 were studied by thermal gravimetric (TG) and differential thermal analyses (DTA). Direct calcination of the compounds 1–3 at 600 °C under air atmospheres yields different morphologies of nano-sized ZnO.