Cyanide-bridged complexes based on dinuclear Cu(II)-M(II) [M = Pb and Cu] building blocks: Synthesis, crystal structures and magnetic properties

Four cyanide-bridged heterometallic complexes {[CuPb(L 1 )][Fe III (bpb)(CN) 2 ]} 2 ·(ClO 4 ) 2 ·2H 2 O·2CH 3 CN (1), {[CuPb(L 1 )] 2 [Fe II (CN) 6 ](H 2 O) 2 }·10H 2 O (2), {[Cu 2 (L 2 )][Fe III (bpb)(CN) 2 ] 2 }·2H 2 O·2CH 3 OH (3) and {[Cu 2 (L 2 )] 3 [Fe III (CN) 6 ] 2 (H 2 O) 2 }·10H 2 O (4) have been synthesized by treating K[Fe III (bpb)(CN) 2 ] [bpb 2-=1,2-bis(pyridine-2-carboxamido)benzenate] and K 3 [Fe III (CN)] 6 with dinuclear compartmental macrocyclic Schiff-base complexes [CuPb(L 1 )] (ClO 4 ) 2 or [Cu 2 (L 2 )]·(ClO 4 ) 2 , in which H 2 L 1 was derived from 2,6-diformyl-4-methyl-phenol, ethylenediamine, and diethylenetriamine in the molar ratio of 2:1:1 and H 2 L 2 from 2,6-diformyl-4-methyl-phenol and propylenediamine in the molar ratio of 1:1. Single crystal X-ray diffraction analysis reveals that compound 1 displays a cyclic hexanuclear heterotrimetallic molecular structure with alternating [FeⅢ (bpb)(CN) 2 ]- and [CuPb(L 1 )] 2+ units. Complex 2 is of a neutral dumb-bell-type pentanuclear molecular configuration consisting of one [Fe(CN)6] 4- anion sandwiched in two [CuPu(L 1 )] 2+ cations, and the pentanuclear moieties are further connected by the hydrogen bonding to give a 2D supramolecular framework. Heterobimetallic complex 3 is a tetranuclear molecule composed of a centrosymmetric [Cu 2 (L2)] 2+ segment and two terminal cyanide-containing blocks [FeⅢ (bpb)(CN)2 ]- . Octanuclear compound 4 is built from two [Fe(CN)6]3- anions sandwiched in the three [Cu 2 L 2 ] 2+ cations. Investigation of their magnetic properties reveals the overall antiferromagnetic behavior in the series of complexes except 2.     

Synthesis and characterization of some novel ruthenium(II) complexes containing thiolate ligands

Reactions of the ruthenium complexes [RuH(CO)Cl(PPh₃)₃] and [RuCl₂(PPh₃)₃] with hetero-difunctional S,N-donor ligands 2-mercapto-5-methyl-1,3,5-thiadiazole (HL¹), 2-mercapto-4-methyl-5-thiazoleacetic acid (HL²), and 2-mercaptobenzothiazole (HL³) have been investigated. Neutral complexes [RuCl(CO)(PPh₃)₂(HL¹)] (1), [RuCl(CO)(PPh₃)₂(HL²)] (2), [RuCl(CO)(PPh₃)₂(HL³)] (3), [Ru(PPh₃)₂(HL¹)₂] (4), [RuCl(PPh₃)₃(HL²)] (5), and [RuCl(PPh₃)₃(HL³)] (6) imparting κ²-S,N-bonded ligands have been isolated from these reactions. Complexes 1 and 4 reacted with diphenyl-2-pyridylphosphine (PPh₂Py) to give neutral κ¹-P bonded complexes [RuCl(CO)(κ¹-P-PPh₂Py)₂(HL¹)] (7), and [Ru(κ¹-P-PPh₂Py)₂(HL¹)₂] (8). Complexes 1-8 have been characterized by analytical, spectral (IR, NMR, and electronic absorption) and electrochemical studies. Molecular structures of 1, 2, 4, and 7 have been determined crystallographically. Crystal structure determination revealed coordination of the mercapto-thiadiazole ligands (HL¹-HL³) to ruthenium as κ²-N,S-thiolates and presence of rare intermolecular S-S weak bonding interaction in complex 1.     

Synthesis, crystal structures, and magnetic properties of tetranuclear nickel(II) and copper(II) complexes with tridentate Schiff bases

Two cubane-type tetranuclear nickel(II) and copper(II) complexes, [Ni₄(L¹)₄(CH₃OH)₄] (1) and [Cu₄(L²)₄]·H₂O (2), where L¹ and L² are the dianionic forms of the tridentate Schiff bases 4-nitro-2-[(2-hydroxyethylimino)methyl]phenol (H₂L¹) and 5-methoxy-2-[(2-hydroxyethylimino)methyl]phenol (H₂L²), respectively, have been synthesized and characterized by physicochemical methods and single-crystal X-ray diffraction. The magnetic properties of the complexes show the presence of ferromagnetic interactions for complex 1 and antiferromagnetic interactions for complex 2, mediated by hydroxyl bridges.     

Ten complexes constructed by two reduced Schiff base tetraazamacrocycle ligands: syntheses,structures, magnetic and luminescent properties

Ten new complexes, [Cu₂(L¹)(NO₃)₂]·2H₂O (1), [Cu₄(L¹)₂]·4ClO₄·H₂O (2), [Cu₂(L¹)(H₂O)₂]·(adipate) (3), [Cu₆(L¹)₂(m-bdc)₄]·2DMF·5H₂O (4), [Cu₂(L¹)(Hbtc)]·5H₂O (5), [Cu₂(L¹)(H₂O)₂]·(ntc)·3H₂O (6), [Co₂(L²)]·[Co(MeOH)₄(H₂O)₂] (7), [Co₃(L²)(EtOH)(H₂O)] (8), [Ni₆(L²)₂(H₂O)₄]·H₂O (9) and [Zn₄(L²)(OAc)₂]·0.5H₂O (10), have been synthesized. 1 displays a [Cu₂(L¹)(NO₃)₂] monomolecular structure. 2 shows a supramolecular chain including [Cu₂L¹]²⁺. In 3, two Cu(II) ions are connected by L¹ to form a [Cu₂(L¹)(H₂O)₂]²⁺ cation. In 4, the m-bdc anions bridge Cu(II) ions and L¹ anions to form a layer. Both 5 and 6 display 3-D supramolecular structures. 7 consists of both [Co₂L²]^2? and [Co(MeOH)₄(H₂O)₂]²⁺ units. 8 and 9 show infinite chain structures. In 10, Zn(II) dimers are linked by L² to generate a 3-D framework. The magnetic properties for 4 and 8 and the luminescent property for 10 have been studied.     

Altering the Activity of Catechol Oxidase Model Compounds by Electronic Influence on the Copper Core

The catecholase activity of the dicopper(II) complexes [Cu₂(L¹)(μ‐OCH₃)(NCCH₃)₂](PF₆)₂·H₂O·CH₃CN ( 1 ), [Cu₂(L²)(μ‐OH)(MeOH)(NCCH₃)](BF₄)₂ ( 2 ), [Cu₂(L³)(μ‐OMe)(NCCH₃)₂](BF₄)₂·2CH₃CN·H₂O ( 3 ), [Cu₂(L²)(μ‐OAc)₂]BF₄·H₂O ( 4 ), [Cu₂(L⁴)(μ‐OAc)₂]ClO₄ ( 5 ) and [Cu₂(L⁵)(μ‐OMe)(NCCH₃)₃(OH₂)](ClO₄)₂·2CH₃OH·CH₃CN ( 6 ) consisting of varying para‐substituted phenol ligands HL¹ = 4‐trifluoromethyl‐2,6‐bis((4‐methylpiperazin‐1‐yl)methyl)phenol, HL² = 4‐bromo‐2,6‐bis((4‐methyl‐1,4‐diazepan‐1‐yl)methyl)phenol, HL³ = 4‐bromo‐2‐((4‐methyl‐1,4‐diazepan‐1‐yl)methyl)‐6‐((4‐methylpiperazin‐1‐yl)methyl)phenol, HL⁴ = 2,6‐bis((4‐methylpiperazin‐1‐yl)methyl)‐4‐nitrophenol and HL⁵ = 4‐tert‐butyl‐2,6‐bis((4‐methylpiperazin‐1‐yl)methyl)phenol was studied. The main difference within the six complexes lies in the individual copper–copper separation that is enforced by the chelating side arms of the phenolate ligand entity and more importantly in the exogenous bridging solvent, hydroxide, methanolate or acetate ions. The distance between the copper cores varies from 2.94Å in 1 to 3.29Å in 5 . The catalytic activity of the complexes 1 – 6 towards the oxidation of 3,5‐di‐tert‐butylcatechol was determined spectrophotometrically by monitoring the increase of the 3,5–di‐tert‐butylquinone characteristic absorption band at about 400 nm over time saturated with O₂. The complexes are able to oxidize the substrate 3,5‐di‐tert‐butylcatechol to the corresponding o‐quinone with distinct catalytic activity (k_cat between 92 h^?1 and 189 h^?1), with an order of decreasing activity 6 > 5 > 1 , 2 , 4 ≥ 3 . A kinetic treatment of the data based on the Michaelis‐Menten approach was applied. A correlation of the catecholase activities with the variation of the para‐ substituents as well as other effects resulting from the copper core distances is discussed. [Cu₂(L⁵)(μ‐OMe)(NCCH₃)₃(OH)₂](ClO₄)₂·2CH₃OH·CH₃CN ( 6 ) exhibited the highest activity of the six complexes as a result of its high turnover rate.     

Three new coordination complexes of cobalt(III), manganese(II), and copper(II) with N,N,O-donor hydrazone ligands: syntheses and structural characterizations

Three new coordination complexes, 2{[Co(L¹)₂]ClO₄} · 0.5CH₃OH (1), [Mn(L²)₂] (2), and [Cu(HL²)(L²)]ClO₄ · 2H₂O (3) have been synthesized from two tridentate N,N,O-donor hydrazone ligands HL¹, 2-acetylpyridine-salicyloylhydrazone, and HL², 2-benzoylpyridine-salicyloylhydrazone, respectively and thoroughly characterized by elemental analysis, FT-IR, UV–Vis, electrochemical, and room temperature magnetic susceptibility measurements. Structures of the complexes have been unequivocally established by single crystal X-ray diffraction technique. Structural analysis reveals that 1 consists of two chemically similar but crystallographically independent cationic [Co(L¹)₂]⁺ units and 2 consists of a neutral [Mn(L²)₂] molecule while 3 consists of a cationic [Cu(HL²)(L²)]⁺ unit. Metal ions display distorted octahedral geometry in 1 and 2 while in 3 it shows a distorted square pyramidal geometry. Ligand conformations around the metal ions are stabilized by the presence of intra-ligand hydrogen bonding in all the complexes. Structure of 3 reveals that a perchlorate ion linked to the complex by hydrogen bonding via a water molecule.     

Copper(I) and copper(II) complexes with pyrazine-containing pyridylalkylamide ligands N-(pyridin-2-ylmethyl)pyrazine-2-carboxamide and N-(2-(pyridin-2-yl)ethyl)pyrazine-2-carboxamide

Four copper(II) complexes and one copper(I) complex with pyridine-containing pyridylalkylamide ligands N-(pyridin-2-ylmethyl)pyrazine-2-carboxamide (HL^pz) and N-(2-(pyridin-2-yl)ethyl)pyrazine-2-carboxamide (HL^pz?) were synthesized and characterized. The X-ray crystal structures of [Cu₂(L^pz)₂(4,4?-bipy)(OTf)₂] (1, OTf?=?trifluoromethanesulfonate, 4,4?-bipy?=?4,4?-bipyridine) and [Cu(L^pz)(py)₂]OTf·H₂O (2, py?=?pyridine) revealed binuclear and mononuclear molecular species, respectively, while [Cu(L^pz)(μ₂-1,1-N₃)]_n (3), [Cu(L^pz?)(μ₂-1,3-N₃)]_n (4), and [Cu(HL^pz)Cl]_n (5) are coordination polymer 1-D chains in the solid state.     

Structural and spectral studies of some coordination complexes of a phenol-functionalized diazamesocyclic ligand 1,4-bis-(3-tert-butyl-5-methyl-2-hydroxybenzyl)-1,4-diazacycloheptane (H2L)

A series of four-coordinated monomeric Cu^II, Co^II, and Ni^II complexes of a tetradentate diazamesocyclic ligand containing bulky phenolate donor pendants, [CuL] (1), [Cu(HL)]ClO₄ (2), [CoL] (3), and [NiL] (4), where H₂L=1,4-bis-(3-tert-butyl-5-methyl-2-hydroxybenzyl)-1,4-diazacycloheptane, have been synthesized and characterized by elemental analyses, IR, UV–vis and ESR spectra. The crystal structure of complex 1 has been determined by X-ray diffraction analysis.     

Tuning the bridging modes of Cu-azido complexes with Schiff bases by varying the terminal groups

Three azido-bridged copper(II) complexes, [Cu₂(L¹)₂(μ_1,1,3-N₃)₂] _n ·2nH₂O (1), [Cu₄(L²)₄(μ_1,1-N₃)₂(μ_1,1,3-N₃)₂] _n (2), and [Cu₂(L³)₂(μ_1,1-N₃)₂] (3), where L¹, L², and L³ are the deprotonated forms of 4-bromo-2-[(2-methylaminoethylimino)methyl]phenol (HL¹), 4-bromo-2-[(2-ethylaminoethylimino)methyl]phenol (HL²), and 4-bromo-2-[(2-isopropylaminoethylimino)methyl]phenol (HL³), respectively, have been prepared and structurally characterized by single-crystal X-ray diffraction analysis and IR spectra. The slight differences in the terminal groups of the Schiff bases lead to different bridging modes of the azido groups.     

Syntheses,structures, in vitro cytotoxicities and DNA-binding properties of four copper complexes based on a phenyl 2-pyridyl ketoxime ligand

Four complexes [Cu₆L₆(µ₄–O)₂(dca)₂] (1), [Cu₃L₃(µ₃–OH)Cl₂] (2), [Cu₃L₃(µ₃–OH)(OAc)₂]·py (3) and [Cu₂L₄] (4) (HL = phenyl 2-pyridyl ketoxime; dca = dicyanamide anion) have been synthesized and characterized by physicochemical and spectroscopic methods. The structures of all three complexes consist of a single or off-set stacked inverse 9-MC-3 metallacrown formed by three L^? ligands and three Cu atoms, and all of the Cu atoms are located in square planar or square pyramidal geometries with different apical ligands. In complex 4, four L^? ligands link two Cu atoms to form a dinuclear structure, and the Cu atoms adopt square pyramidal coordination geometry. The in vitro cytotoxicities against four cell lines (A549, HL-60, HT-29 and HCT-116) have been assayed by colorimetric MTT assay. In addition, all four complexes interact strongly with calf thymus DNA, which may be directly responsible for their antitumor activities.     

Novel tetranuclear cubane-like Co(II) complexes involving chelate phosphoramide ligands

Interaction of cobalt(II) ions and sodium carbacylamidophosphates Na(L) (HL=PhC(O)NHP(O)(NR₂)₂; where NR₂ are morpholyl, HL¹; NMe₂, HL²; NEt₂, HL³) in methanol solution afforded polynuclear alkoxo complexes [Co₄{L¹}₃(OCH₃)₄(OH)(H₂O)₅·3H₂O] 1 and [Co₄{L}₄(OCH₃)₄(CH₃OH)₄] (L=L² 2, L³ 3). Data of spectral and TGA studies are presented. Coordination compounds 1 and 3 have been characterized by means of X-ray diffraction. Both the structures consist of tetranuclear cubane alkoxo clusters with methoxide ions bridging three metal centers (CoO 2.068(3)–2.093(4) Å) and phosphorylic ligands coordinated in a bidentatechelate fashion via the carbonyl oxygen atoms (CoO 1: 2.050(2); 3: 2.031(4) Å) and the phosphoryl groups (2.093(2) and 2.106(4) Å). Isolation of these cubane alkoxo complexes is an important proof for close resemblance in behavior of carbacylamidophosphate systems and β-diketonates towards transition metal ions.     

Butterfly and chair clusters using N,O-chelating ligands: A combined crystallographic and mass spectrometric study

The organic ligand (1-methyl-1H-benzo[d]imidazol-2-yl)methanol (HL¹) was used to react with Cu(ClO₄)₂·6H₂O and triethylamine at 80°C to afford the complex [Cu₄(L¹)₆]·(ClO₄)₂·CH₃CN ( 1 ). Every four-coordinated Cu(II) ion is surrounded with NO₃ coordinated environment, and every five-coordinated Cu(II) ion is surrounded with N₂O₃ coordinated environment. Changing the metal salt to Zn(NO₃)₂·6H₂O, and after adding CH₃COONa, afforded the complex [Zn₄(L¹)₄(NO₃)₂(CH₃COO)₂] ( 2 ), in which every five-coordinated Zn(II) ion is surrounded with NO₄ coordinated environment. High-resolution electrospray ionization mass spectrometry results revealed that complex 1 broke into the most stable fragment [Cu₂(L¹)₃]⁺, and it also can assemble high nuclear peaks in solution. For complex 2 , it was found that the complex exhibited different component distribution in solution. Not only were there substitutions between coordinated anions, but the high nuclear peaks could also be detected.     

Synthesis,characterization, thermal,and antimicrobial studies of binuclear metal complexes of sulfa-guanidine Schiff bases

A series of metal complexes of Schiff bases derived from condensation of sulfa-guanidine with 1-benzoylacetone (H₂L¹), 2-hydroxybenzophenol (H₂L²), dibenzoylmethane (H₂L³), 5-methylisatine (H₂L⁴), and 1-methylisatine (H₂L⁵) have been synthesized. The complexes are characterized by elemental analysis, molar conductance, magnetic moment measurements, IR, UV–Vis, ¹H NMR, and ESR spectra, as well as thermogravimetric analysis. The low molar conductance values indicate the complexes are nonelectrolytes. IR and ¹H NMR spectra show that H₂L¹–H₂L⁵ are coordinated to metal ions by two bidentate centers. Mn(II), Co(II), Ni(II), and Cu(II) complexes display paramagnetic behavior, whereas the Zn(II)-complex was diamagnetic. All studies confirm the formation of an octahedral geometry for [Cu₂L¹(AcO)₂(H₂O)₆] · 3H₂O (1), [Mn₂L⁴(AcO)₂(H₂O)₆] · 2H₂O (6), [Ni₂L⁴(AcO)₂(H₂O)₆] · 2H₂O (8), a tetrahedral geometry for [Cu₂L²(AcO)₂(H₂O)₂] (2), [Cu₂(L⁴)₂] (4), [Co₂(L⁴)₂] · 2H₂O (7) and [ZnHL⁴(AcO)(H₂O)] · 2H₂O (9) and a trigonal bipyramid geometry for [Cu₂L³(AcO)₂(H₂O)₄] (3) and [Cu₂HL⁵(AcO)₃(H₂O)₃] · H₂O (5). H₂L⁴ was most effective on Gram negative, Gram positive bacteria, and fungi (diameters inhibition zone ranged between 10.5–27.5 mm) after 24 and 48 h, respectively. Complex 8 showed moderate antimicrobial activity. Its minimum inhibitory concentration (MIC) against Escherichia coli, Bacillus subtilis, Candida albicans and Aspargllus flavas was 20 mg L^–1. The compound proved to be of moderate toxicity and its LD₅₀ was 20 mg L^–1.     

Synthesis,characterization, DNA-binding,and antioxidant activities of four copper(II) complexes containing N-(3-hydroxybenzyl)-amino amide ligands

Four new substituted amino acid ligands, N-(3-hydroxybenzyl)-glycine acid (HL₁), N-(3-hydroxybenzyl)-alanine acid (HL₂), N-(3-hydroxybenzyl)-phenylalanine acid (HL₃), and N-(3-hydroxybenzyl)-leucine acid (HL₄), were synthesized and characterized on the basis of ¹H NMR, IR, ESI-MS, and elemental analyses. The crystal structures of their copper(II) complexes [Cu(L₁)₂]·2H₂O (1), [Cu(L₂)₂(H₂O)] (2), [Cu(L₃)₂(CH₃OH)] (3), and [Cu(L₄)₂(H₂O)]·H₂O (4) were determined by X-ray diffraction analysis. The ligands coordinate with copper(II) through secondary amine and carboxylate in all complexes. In 2, 3, and 4, additional water or methanol coordinates, completing a distorted tetragonal pyramidal coordination geometry around copper. Fluorescence titration spectra, electronic absorption titration spectra, and EB displacement indicate that all the complexes bind to CT-DNA. Intrinsic binding constants of the copper(II) complexes with CT-DNA are 1.32?×?10^6?M^?1, 4.32?×?10^5?M^?1, 5.00?×?10^5?M^?1, and 5.70?×?10^4?M^?1 for 1, 2, 3, and 4, respectively. Antioxidant activities of the compounds have been investigated by spectrophotometric measurements. The results show that the Cu(II) complexes have similar superoxide dismutase activity to that of native Cu, Zn-SOD.     

Dinuclear Schiff-base copper(II) complexes with various bridging groups

Three new centrosymmetric dinuclear copper(II) complexes, [Cu₂Cl₂(L¹)₂] (1), [Cu₂(μ _1,3-NCS)₂(L²)₂] (2), and [Cu₂(μ _1,1-N₃)₂(L³)₂] (3), where L¹, L², and L³ are the deprotonated forms of the Schiff bases 1-[(2-propylaminoethylimino)methyl]naphthalen-2-ol (HL¹), 1-[(3-methylaminopropylimino)methyl]naphthalen-2-ol (HL²), and 2-[(2-isopropylaminoethylimino)methyl]phenol (HL³), respectively, have been prepared and characterized by elemental analysis, IR spectra, and single-crystal X-ray crystallography. Each Cu is coordinated by the three donors of the Schiff bases and by two bridging groups, forming a square-pyramidal geometry.     

Synthesis,crystal structures,and properties of copper(II) dicarboxylate complexes with [bis(2-pyridylcarbonyl)amido]

Four new complexes, [Cu₂(Bpca)₂(L¹)(H₂O)₂] · 3H₂O (I), [Cu₂(Bpca)₂(L²)(H₂O)₂] (II), [Cu₂(Bpca)₂(L³)] · 2H₂O (III), [Cu₂(Bpca)₂(L¹)(H₂O)] · 2H₂O (IV) (Bpca = bis(2-pyridylcarbonyl)amido, H₂L¹ = glutaric acid, H₂L² = adipic acid, H₂L³ = suberic acid, H₂L⁴ = azelaic acid) have been synthesized and characterized by single-crystal X-ray diffraction methods (CIF files CCDC nos. 1432836 (I), 1432835 (II), 817411 (III), and 817412 (IV)), elemental analyses, IR spectra. Structural analyses reveal that compounds I, II, and IV have similar structures [Cu(Bpca)]⁺ units bridged by dicarboxylate forming dinuclear units, whereas the dinuclear of compound III are edge-shared through two carboxylate oxygen atoms of different suberate anions. Hydrogen bonds are response for the supramolecular assembly of compounds I to IV. The temperature-dependent magnetic property of III was also investigated in the temperature range of 2 to 300 K, and the magnetic behaviour suggests weak antiferromagnetic coupling exchange.     

Structure Modulation in Four New Coordination Polymers by In Situ Ligands Synthesis of Anthracene Derivatives and Various Auxiliary N-donor Ligands

Four novel coordination polymers, [Zn(HL¹)₂(phen)₂]·2CH₃OH·2H₂O (1), [ZnCl(HL¹)(4,4′-bipy)_0.5] _n (2), [Cd(HL¹)(L²)_0.5(2,2′-bipy)₂]·3H₂O (3), [Zn(L³)_0.5(N₃)_1.5(phen)] _n (4) (H₂L¹ = 9-(1H-tetrazole-5-yl)-10-carboxyl anthracene, H₂L² = 9,10-di-(1H-tetrazole-5-yl) anthracene, HL³ = 9-(1H-tetrazole-5-yl)-10-cyan anthracene, 1,10-phen = 1,10-phenanthroline, 4,4′-bipy = 4,4′-bipyridine, 2,2′-bipy = 2,2′-bipyridine), have been constructed by in situ ligands synthesis system. The formation of tetrazole-based ligands H₂L¹, H₂L² and H₂L³ involves the in situ Sharpless [2 + 3] cycloaddition reaction between 9,10-dicyanoanthracene (DCA) and NaN₃ in the presence of Zn²⁺/Cd²⁺ ions as Lewis-acid catalysts under hydro/solvothermal conditions. At the same time, there is also another in situ carboxyl ligand synthesis reaction by hydrolysis from nitrile in compounds 1 and 2. The four compounds have been characterized by elemental analysis, IR and single-crystal X-ray diffraction analysis. Compound 1 exhibits a butterfly-shaped mononuclear structure. Compound 2 represents a 2D framework constructed by six-membered {Zn₆} rings as secondary building units (SBUs). Compound 3 presents a dinuclear {Cd₂} structure with two butterflies “flying side by side” fashion. While compound 4 displays a 1D chain structure based on a dinuclear {Zn₂} SBUs. Moreover, the luminescence properties of 1–4 have been also investigated.     

Synthesis,crystal structure and spectral characterization of Co(II) complexes with acylpyrazolone ligands

The three new Cobalt(II) complexes [Co(L¹)₂(H₂O)₂] (1), [Co(L²)₂(H₂O)₂] (2), and [Co(L³)₂(H₂O)₂] (3) have been synthesized by interaction of acyl pyrazolone ligands, 4-(4-chlorobenzoyl)3-methyl1-phenyl1H-pyrazole5(4H)-one (HL¹), 4-(4-chlorobenzoyl)1-(3-chlorophenyl)3-methyl1H-pyrazole5(4H)-one (HL²) and 5-methyl4-(4-methylbenzoyl)2-phenyl2,4-dihydro3H-pyrazole3-one (HL³) with CoCl₂.6H₂O. The complexes were screened using FTIR, UV–Vis, TGA, and Single Crystal X-ray diffraction spectroscopic techniques. A relative study of the ligands’ FTIR spectra and their metal complexes reveal the formation, sifting, and disappearance of several bands during complexation. Other interpretations stipulated that these three complexes are mononuclear and exhibited octahedral geometry around Co²⁺.Triclinic crystal system, Distortion in Octahedral geometry, and Intermolecular hydrogen bonding confirmed by Single-crystal XRD analysis of [Co(L³)₂(EtOH)₂] complex.     

Binuclear zinc(II) complexes with the anti-inflammatory compounds salicylaldehyde semicarbazone and salicylaldehyde-4-chlorobenzoyl hydrazone (H2LASSBio-1064)

Complexes [Zn₂(HL¹)₂(CH₃COO)₂] (1) and [Zn₂(L²)₂] (2) were synthesized with salicylaldehyde semicarbazone (H₂L¹) and salicylaldehyde-4-chlorobenzoyl hydrazone (H₂LASSBio-1064, H₂L²), respectively. The crystal structure of (1) was determined. Upon recrystallization of previously prepared [Zn₂(HL²)₂(Cl)₂] (3) in 1:9 DMSO:acetone crystals of [Zn₂(L²)₂(H₂O)₂]·[Zn₂(L²)₂(DMSO)₄] (3a) were obtained. The crystal structure of 3a was also determined. All crystal structures revealed the presence of phenoxo-bridged binuclear zinc(II) complexes.     

Three salicylaldehyde derivative Schiff base Zn<Superscript>II</Superscript> complexes: synthesis,DNA binding and hydroxyl radical scavenging capacity

Three new Schiff base ligands N-(3-formyl-5-methylsalicylidene)-2-aminoethanol (H₂L¹), N-(3-hydroxylmethyl-5-methylsalicylidene)-2-aminoethanol (H₃L²), 2,6-bis(o-carboxyphenyliminomethene)-4-methylphenol (H₃L³) and their binuclear Zn^II complexes [Zn₂(HL¹)₂]Cl₂ · 2H₂O (ZnHL¹), [Zn₂(H₂L²)₂]Cl₂ · H₂O (ZnH₂L²) and [Zn₂(HL³)Cl₂] · H₂O (ZnHL³) were synthesized and characterized by ¹H-NMR, elemental analysis, IR and molar conductivity. The results suggest, in every case, two Zn²⁺ ions were bridged by phenolic OH group oxygen, forming a binuclear complex. The binding properties of these complexes to calf thymus DNA (ct-DNA) were investigated. Absorption and fluorescence spectra are together suggestive that both ZnHL¹ and ZnHL³ interact with ct-DNA through intercalative mode, while ZnH₂L² interact with ct-DNA by non-intercalative interaction. Moreover, ZnHL³ can bind to ct-DNA more strongly than ZnHL¹. These complexes also exhibited good scavenging activity on the hydroxyl radical (•OH), which are better than those of their corresponding ligands.