Concentration-controlled Zn(II) compounds constructed from N-tosyl-L-glutamic acid and 1,10-phenanthroline

By controlling the concentration of the reaction system, two zinc(II) complexes, [Zn₂(tsgluO)₂(phen)₂]_n (1) and [Zn₂(tsgluO)₂(phen)₂(H₂O)₂] (2) (H₂tsgluO = N-tosyl-L-glutamic acid, phen = 1,10-phenanthroline), have been synthesized under hydrothermal conditions and characterized by elemental analysis, infrared spectra, thermogravimetric analysis, and single-crystal X-ray diffraction. Complexes 1 and 2 both crystallize in the triclinic space group P-1. Complex 1 exhibits a 1-D double-chain structure. Complex 2 has a dinuclear structure which is extended by hydrogen-bonding interactions to form a 2-D supramolecular network. The structural difference indicates that the concentration plays a crucial role in modulating structures of coordination complexes. The two compounds also show intense fluorescence at room temperature.     

Four Zn(II)/Cd(II) coordination polymers derived from isomeric benzenedicarboxylates and 1,6-bis(triazol)hexane ligand: synthesis,crystal structure,and luminescent properties

Four coordination polymers, [Zn(o-bdc)(bth)_0.5(H₂O)] _n (1), [Cd(o-bdc)(bth)_0.5(H₂O)] _n (2), [Zn(m-bdc)(bth)] _n (3), and [Cd(p-bdc)(bth)?·?(H₂O)₂] _n (4) (where o-bdc?=?1,2-benzenedicarboxylate, m-bdc?=?1,3-benzenedicarboxylate, p-bdc?=?1,4-benzenedicarboxylate, and bth?=?1,6-bis(triazol)hexane), have been hydrothermally synthesized and structurally characterized. Both 1 and 2 are isostructural, featuring two binodal architectures: (6³)(6⁵·8) topology in terms of o-bdc and Zn^II/Cd^II as three- and four-connected nodes. Complex 3 shows a 2-D (4,4) network with the Zn?···?Zn?···?Zn angle of 57.84°, whereas 4 exhibits planar 2-D (4,4) network. These 2-D networks of 3 and 4 are extended by supramolecular interactions, such as CH?···?π/π–π stacking and hydrogen-bonding into 3-D architecture. A structural comparison of these complexes demonstrates that the dicarboxylate building blocks with different dispositions of the carboxyl site play a key role in governing the coordination motifs as well as 3-D supramolecular lattices. Solid-state properties such as photoluminescence and thermal stabilities of 1–4 have also been studied.     

Syntheses, crystal structures and fluorescent properties of Cd(II), Hg(II) and Ag(I) coordination polymers constructed from 1H-1,2,4-triazole-1-acetic acid

Three new d¹⁰ coordination polymers, namely [Cd(taa)Cl]_n1, [Hg(taa)Cl]_n2, and [Ag_1.5(taa)(NO₃)_0.5]_n3 (taa=1H-1,2,4-triazole-1-acatate anion) have been prepared and characterized by elemental analysis, IR, and single crystal X-ray diffraction. Compound 1 consists of two-dimensional layers constructed by carboxyl-linked helical chains, which are further linked through carboxyl group to generate a unique 3D open framework. Topological analysis reveals that the structure of 1 can be classified as an unprecedented (3,8)-connected network with the Schläfli symbol (4.5²)₂(4².5⁸.6¹⁴.7³.8). Compound 2 manifests a doubly interpenetrated decorated α-polonium cubic network with the Schläfli symbol of (4¹⁰.6².8³). Compound 3 consists of 2D puckered layers made up of Ag centers and taa⁻ bridges. In addition, all of these compounds are photoluminescent in the solid state with spectra that closely resemble those of the ligand precursor.     

Structural and physicochemical characteristics of chelate nickel(II) compounds based on 1,2,3-triketone (hydrazone)imines

The crystal structures of the chelates Ni^IIL (L²⁻ are the N,N′-(o-phenylene)-bis[4-(4-methylphenyl)hydrazono-3-oxo-1,1,2,2-tetrafluorononane-5-iminate], N,N′-ethylene-bis[3-(4-methylphenyl)hydrazono-4-oxo-5,5,6,6,7,7,8,8-octafluorooctane-2-iminate], or N,N′-ethylene-bis(4-hydroxy-5,5,6,6,7,7,8,8-octafluoro-3-octene-2-iminate) anions) were studied by X-ray diffraction. Magnetic measurements and ESR spectroscopic studies revealed the appearance of paramagnetism due to a tetrahedral distortion of the coordination unit and also the unusual behavior of the effective magnetic moment at low temperatures. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 103–109, January, 2007.     

Synthesis and structural characterization of a new polymeric zinc(II) complex with thiophene-2-carboxylic acid

A new polymeric zinc(II) complex with thiophene-2-carboxylic acid (α-tpc) of composition [Zn₂(C₂₀H₁₂O₈S₄)] _n was obtained and structurally characterized by X-ray diffraction, thermal analysis, nuclear magnetic resonance (NMR), and infrared spectroscopies. Upfield shift in the ¹H-NMR spectrum is explained by the crystalline structure, which shows the thiophene rings overlapping each other in parallel pairs. The compound crystallizes in the monoclinic system, space group P2₁/c, with a = 9.7074(4) Å, b = 13.5227(3) Å, c = 18.9735(7) Å, β = 95.797(10)°, and Z = 4. Three α-tpc groups bridge between two Zn(II) ions through oxygens and the fourth one bridges between one of these ions and the third one, symmetry related by a twofold screw axis. This arrangement gives rise to infinite chains along the crystallographic a direction. The metal atoms display an approximate tetrahedral configuration. The complex is insoluble in water, ethanol, and acetone, but soluble in dimethyl sulfoxide.     

HgII-containing MOFs constructed from bis-benzimidazole-based ligand with highly selective anion-exchange capacity

Two Hg(II)-containing metal–organic frameworks (MOFs) based on 1,1′-(1,5-pentanediyl)bis-1H-benzimidazole (pbbm), {[HgBr₂(pbbm)]?·?DMF} _n (1) and [HgI₂(pbbm)]₂ (2), have been constructed to explore new and potent ion-exchange materials. Single-crystal X-ray diffraction shows that 1 features a 1-D zigzag chain framework, while 2 presents a dimeric structure in which two Hg(II) cations are bridged by two pbbm ligands. The significant differences of these MOFs indicate that the counteranions have impact on assembling and structures of the resultant MOFs. Remarkably, coordinated Br^? in 1 can be replaced completely when the solid polymer is treated with an aqueous solution containing I^?. Confirmation of retention of structure is provided by FT-IR spectra and the XRPD pattern. The thermal stabilities of 1 and 2 have also been investigated.     

Syntheses,structures and luminescent properties of two Zn(II) complexes of N-2-nitrobenzenesulfonyl-glycine acid

Two luminescent zinc coordination complexes [Zn₂(2-NBS-gly)₄(H₂O)₄]?·?2H₂O (1), and Zn(Im)₂(2-NBS-gly)₂ (2), (2-NBS-glyH?=?N-2-nitrobenzenesulfonyl-glycine acid, Im?=?imidazole) have been synthesized and their crystal structures determined by X-ray crystallography. The Zn(II) in 1 is a five-coordinate geometry and can be described as a slightly distorted square-pyramid; complex 2 is four-coordinate, forming a distorted tetrahedron. Through hydrogen bonding, complex 1 forms a 2-D network and complex 2 forms a zigzag chain. Fluorescent analyses show that both 1 and 2 exhibit photoluminescence in the solid state and may be potential candidates for photoactive materials.     

Syntheses,structures, and properties of CdII and CoII complexes with 5-(pyridin-4-yl)isophthalate

A N-donor containing carboxylic ligand, 5-(pyridin-4-yl)isophthalic acid (H₂L), was applied to construct two new coordination polymers [Cd(L)(DMF)] _n (1, DMF?=?N,N-dimethylformamide) and {[Co(L)(H₂O)₂]?·?0.5CH₃OH?·?1.5H₂O} _n (2) under different conditions. The complexes were characterized by IR, elemental, and thermogravimetric analyses, powder and single crystal X-ray diffraction. In 1 each L^2? links four Cd^II to form a 3-D framework, while in 2 each L^2? connects three metals to form a 2-D layer structure, which is further connected together by hydrogen bonds to form a 3-D architecture. The thermal stability of the complexes and the photoluminescence of 1 were investigated.     

Synthesis,crystal structure and properties of a silver(I) complex with 2-(1H-1,2,4-triazol-1-yl) acetic acid

The treatment of 2-(1H-1,2,4-triazol-1-yl) acetic acid (Htza) with AgClO₄ resulted in [Ag₃(tza)₂(ClO₄)] _n . Its crystal structure was characterized by X-ray crystallography. Each pair of adjacent Ag1 atoms, separated at 2.954 Å, is bridged by the bidentate carboxylate. Each Ag2 is coordinated in an exactly linear geometry by two triazole nitrogens from two tza^? ligands. Solid state fluorescent measurements have a ligand-based emission at 415 nm. Thermal properties were also investigated.     

Syntheses,crystal structures,and fluorescence properties of two isomorphic binuclear compounds incorporating N-acetyl-N-phenylglycinate with N-donor co-ligands

In this study, two new isomorphic binuclear compounds, [Ln(µ-NAP)₄(NAP)₂(phen)₂]?·?H₂O (1) and (2) (Ln?=?Eu, Tb, NAP?=?N-acetyl-N-phenylglycinate; phen?=?1,10-phenanthroline), have been synthesized and characterized by infrared spectroscopy, elemental analysis, and X-ray crystallography. These compounds crystallize in a triclinic form with space group Pī with a?=?11.7519(11), b?=?13.4293(12), c?=?14.0686(13)?Å, V?=?1992.7(3)?ų, and Z?=?1. Single-crystal X-ray structural analysis reveals that 1 is binuclear, assembled into a 3-D supramolecular network with self-complementary double hydrogen-bonding interactions and aromatic π–π interactions. Fluorescence properties of 1 and 2 are also discussed.     

Magnetic Nitrogen-Doped Porous Carbon Nanocomposite for Pb(II) Adsorption from Aqueous Solution

We report in the present study the in situ formation of magnetic nanoparticles (Fe₃O₄ or Fe) within porous N-doped carbon (Fe₃O₄/N@C) via simple impregnation, polymerization, and calcination sequentially. The synthesized nanocomposite structural properties were investigated using different techniques showing its good construction. The formed nanocomposite showed a saturation magnetization (M_s) of 23.0 emu g⁻¹ due to the implanted magnetic nanoparticles and high surface area from the porous N-doped carbon. The nanocomposite was formed as graphite-type layers. The well-synthesized nanocomposite showed a high adsorption affinity toward Pb²⁺ toxic ions. The nanosorbent showed a maximum adsorption capacity of 250.0 mg/g toward the Pb²⁺ metallic ions at pH of 5.5, initial Pb²⁺ concentration of 180.0 mg/L, and room temperature. Due to its superparamagnetic characteristics, an external magnet was used for the fast separation of the nanocomposite. This enabled the study of the nanocomposite reusability toward Pb²⁺ ions, showing good chemical stability even after six cycles. Subsequently, Fe₃O₄/N@C nanocomposite was shown to have excellent efficiency for the removal of toxic Pb²⁺ ions from water.     

Synthesis and structural characterization of mono- and dinuclear NiII and PdII complexes derived from tetradentate 1,7-bis-(pyridin-2-yl)-2,6-diaza-1,6-heptadiene

The reaction of Schiff base 1,7-bis-(pyridin-2-yl)-2,6-diaza-1,6-heptadiene (L) with either NiCl₂·6H₂O or [Pd^IICl₂(CH₃CN)₂]/Na[BF₄] in 1?:?1 stoichiometry yielded mononuclear ionic complexes, trans-[Ni^II(L)(H₂O)₂]Cl₂·3H₂O (1·3H₂O) and [Pd^II(L)][BF₄]₂ (2), respectively; the reaction of L with [Pd^IICl₂(CH₃CN)₂] in 1?:?2 ratio yielded dinuclear cis-[Pd^II ₂(μ-L)Cl₄] (3). Complexes 1–3 were characterized by vibrational spectroscopy and X-ray diffraction; diamagnetic 2 and 3 were also characterized by NMR in solution. The molecular structures of 1 and 2 displayed tetradentate coordination of L with formation of two five-membered and one six-membered chelate rings for both complexes. In 3, L showed bidentate coordination mode for each pyridylimine toward Pd^II. Complex 1 has distorted octahedral geometry around Ni^II and an extended hydrogen-bond network; distorted square planar geometry around Pd^II in 2 and 3 was observed.     

Copper(II) complex of monobasic tridentate ONN donor ligand: synthesis,encapsulation in zeolite-Y,characterization, and catalytic activity

Reaction between CuCl₂ and (Z)-2-(1-(2-(1H-benzo[d]imidazol-2-yl)ethylimino)ethyl)phenol (Hhap-aebmz) derived from o-hydroxyacetophenone (Hhap) and 2-aminoethylbenzimidazole (aebmz) gives [Cu^II(hap-aebmz)Cl]. Elemental analysis, magnetic susceptibility, spectral (IR and electronic) data, and single crystal X-ray studies confirm the distorted square planar structure of the complex. [Cu^II(hap-aebmz)Cl] has been encapsulated in the nano-cavity of zeolite-Y and its encapsulation is ensured by various physico-chemical techniques. The encapsulated complex has been used as a catalyst for oxidation of cyclohexene and phenol in the presence of H₂O₂. With nearly quantitative oxidation of cyclohexene, the selectivity of the oxidation products follows the order, 2-cyclohexene-1-ol (44%)?>?2-cyclohexene-1-one (40%)?>?cyclohexeneoxide (12%)?>?cyclohexane-1,2-diol (4%). Oxidation of phenol (65.7%) gives catechol (66.1%)?>?hydroquinone (32.9%).     

Synthesis and characterization of two 3-D polymeric lanthanide complexes constructed from 1,2,4,5-benzenetetracarboxylic acid

Two new 3-D lanthanide coordination polymers, [CeK(btec)(H₂O)₂] _n (1), [Ho(btec)_0.5(ad)_0.5(H₂O)] _n (2) (H₄btec?=?1,2,4,5-benzenetetracarboxylic acid, H₂ad?=?adipic acid), have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Structural analyses reveal that both complexes crystallized in monoclinic space group P2₁/c and possessed 3-D net-structures. In 1, btec adopts two types of coordination modes: µ₁₂–η²:η²:η²:η¹:η²:η²:η²:η¹ bridging mode linking six Ce(III) ions and six K⁺ ions and the other µ₈–η¹:η²:η²:η¹:η¹:η²:η²:η¹ bridging mode connecting four Ce(III) ions and four K⁺ ions. In 2, btec adopts a µ₆-bridging with each carboxylate group of btec ligand in a µ₂–η¹–η² mode, the adipate is µ₄-bridging with each carboxylate µ₂–η¹–η¹-monodentate. The topological analysis shows that 1 can be simplified to a 3-nodal net with the Schläfli symbol {3²,4⁸,5³,6²}₄{3⁴,4¹²,5¹²}{4³⁸,6²⁶,8²} and 2 can be simplified to a 3-nodal network with the Schläfli symbol {4²,8⁴}{4⁶,6⁶,8³}{4⁷,6³}₂. The thermogravimetric analyses and the X-ray powder diffraction of 1 and 2 are discussed.     

Synthesis and characterization of polymeric Ni(II) complexes of 4-(4-aminobenzyl)benzenamine (abba) and 4-(4-aminophenylthio)benzenamine (aptba) with thiocyanate

Two one-dimensional complexes, [Ni(SCN)₂(abba)₂] _n (abba?=?4-(4-aminobenzyl)benzenamine) (1) and [Ni(SCN)₂(aptba)₂] _n (aptba?=?4-(4-aminophenylthio)benzenamine) (2), were synthesized and characterized by EA, IR, X-ray crystallography and thermal analysis. The single crystal X-ray structural analyses of 1 and 2 show the complexes to be 1D chain polymers as a result of dibenzenamine (dba) bridging. Each Ni is six-coordinate and adopts a slightly distorted octahedral geometry with four N atoms from four dba ligands and two N atoms from two NCS-groups. Adjacent Ni atoms and two dba ligands form a 24-membered macrocycle. Thermogravimetric analysis and differential thermogravimetric analysis of 2 show that the thermal decomposition of 2 includes four transitions.     

Synthesis and structural characterization of mixed carbene-carboxylate complexes of palladium(II)

Mixed carbene-carboxylate complexes of Palladium(II) have been prepared by reacting {1,1^′-dimethyl-3,3^′-methylenediimidazoline-2,2^′-diylidene} palladium(II) diiodide (1) [Angew. Chem. 107 (1995) 2602; Angew. Chem. Int. Ed. Engl. 34 (1995) 2371; J. Organomet. Chem. 557 (1998) 93] with AgO₂CR, where R=CF₃, CF₂CF₃ and CF₂CF₂CF₃. In this manner, {1,1^′-dimethyl-3,3^′-methylenediimidazoline-2,2^′-diylidene} palladium(II) bis(trifluo-roacetate) (2), {1,1^′-dimethyl-3,3^′-methylenediimidazoline-2,2^′-diylidene} palladium(II) bis(pentafluoropropionate) (3) and {1,1^′-dimethyl-3,3^′-methylenediimidazoline-2,2^′-diylidene} palladium(II) bis(heptafluorobutyrate) (4) were obtained. All three complexes were fully characterized by ¹H-, ¹³C- and ¹⁹F NMR spectroscopy as well as ESI mass spectrometry. X-ray crystal structure analyses of complexes 3 and 4 reveal mononuclear species with a square planar metal center coordinated by a cis-chelating dicarbene and two monodentate carboxylate ligands. The results show that the introduction of a cis-chelating N,N-heterocyclic carbene ligand stabilizes the palladium-carboxylate moiety effectively.     

Synthesis,characterization and screening of biological activity of Zn(II), Fe(II) and Mn(II) complexes with trithiocyanuric acid

New Zn(II), Fe(II) and Mn(II) complexes with a combination of nitrogen-donor ligands and trithiocyanuric acid (ttcH₃) were prepared and characterized by elemental analysis, IR and UV–Vis spectroscopies. The antitumor activity of the prepared complexes, together with already known Ni(II) species, were assayed in vitro against G-361 (human malignant melanoma), HOS (human osteogenic sarcoma), K-562 (human chronic myelogenous leukaemia) and MCF-7 (human breast adenocarcinoma) tumor cell lines. The IC₅₀ values of the Fe(II) and Mn(II) compounds turned out to be lower than those of cisplatin and oxaliplatin. The antimicrobial activities were evaluated by MIC against bacteria (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus faecalis). The molecular structure of [Zn(taa)(ttcH)] · H₂O (taa = tris(2-aminoethyl)amine) was determined by X-ray diffraction. The central atom is pentacoordinated by four N atoms of taa and one N atom of the ttcH dianion.