Synthesis and Characterization of Mono- and Trinuclear Complexes of BF2+ Bridged Macrocycles

Dibenzo[e,k]-2,3-bis(hydroxyimino)-1,4-dithia-7,10-diaza-2,3,8,9-tetrahydrocyclododecine (H₂L) has been prepared from 1,2-bis(o-mercaptoanilino) ethane ( 4 ) and (E,E)-dichloroglyoxime. A mononuclear complex with a metal: ligand ratio of 1:2 has been isolated for cobalt(III). The Co^III complex of H₂L has been prepared with L′ = 2,6-lutidine, and with a chlorine ion as axial ligands. In addition to that, the synthesis of a new cobalt complex which contains BF₂⁺ bridges is achieved with the bis(E,E)-dioxime ligand. The trinuclear complex of this Co^III complex has been obtained by the reaction of BF₂⁺ bridged Co^III complex with Pd[bis(benzonitrile)]Cl₂. The structures of these complexes and (E,E)-dioxime were identified by using elemental analysis, ¹H and ¹³C-NMR, IR and MS spectral data.     

Synthesis and Physicochemical Investigation of Nickel (II). Complexes with salicylaldehyde S-methylthiosemicarbazone

Salicylaldehyde S-methylthiosemicarbazone (H₂L) in the presence of ClO₄– forms with Ni^II the paramagnetic octahedral bis(ligand) chelate complexes while in the presence of NCS^?, CH₃COO^?, Py and γ-Pic it gives diamagnetic square planar mono(ligand) chelate complexes. In the paramagnetic complexes H₂L is coordinated as a neutral molecule (H₂L) and monoanion (HL^?), and in diamagnetic ones only as a monoanion, except the complex obtained in the presence of CH₃COO^?, where it is coordinated as a dianion (L^2?). The last form of the ligand is the result of deprotonation, besides OH-, the NH₂-group. The complexes have been characterized by elemental analysis, magnetic measurements, i.r. and diffuse-reflection spectra, molar conductivity and TG analysis.     

Synthesis,crystal structure,antioxidation and DNA-binding properties of a dinuclear copper(II) complex with bis(N-salicylidene)-3-oxapentane-1,5-diamine

A Schiff base bis(N-salicylidene)-3-oxapentane-1,5-diamine (H₂L) and its Cu(II) complex, [Cu₂(L)₂]?CHCl₃, have been synthesized and characterized by physicochemical and spectroscopic methods. Single-crystal X-ray analysis revealed that the complex is a centrosymmetric binuclear neutral entity, in which Cu(II) is a five-coordinate in a distorted trigonal bipyramidal geometry. The DNA-binding properties of the free ligand and the complex have been investigated by electronic absorption, fluorescence, and viscosity measurements. The results suggest that the H₂L and the complex to DNA via the intercalation mode and the binding affinity of the complex were higher than that of the H₂L. The intrinsic binding constants K_b of the ligand and the complex are 2.2 × 10⁴ and 2.7 × 10⁴ M^?1, respectively. Antioxidant assay in vitro shows the Cu(II) complex possesses significant antioxidant activities and better scavenging activity than the H₂L and other antioxidants.     

Synthesis,characterization, crystal structure,electrochemical properties and electrocatalytic activity of an unexpected nickel(II) Schiff base complex derived from bis(acetylacetonato)nickel(II), acetone and ethylenediamine

The synthesis, crystal structure and electrochemical properties of a Ni(II) Schiff base complex, [Ni(L)]PF₆ (where L is 2,4,9,11,11-pentamethyl-2,3,4 triaza-1-one-4-amine) are reported herein. The complex has been characterized by its electrochemical behavior, X-ray crystallographic structural analysis, physio-chemical methods and spectroscopic techniques. Electrospray mass spectroscopic analysis gives a dominant ion peak with m/z = 296 which corresponds to the {[Ni(L)]PF₆–HPF₆}⁺ fragment. Cyclic voltammograms for [Ni(L)]PF₆, obtained in DMF (0.1 M Bu₄NPF₆) at a glassy carbon electrode with a scan rate of 100 mV s^?1, exhibit reversible ([Ni^II(L)]⁺/[Ni^I(L)]) reduction and chemically irreversible ([Ni^II(L)]⁺/[Ni^III(L)]²⁺→ electroactive product) oxidation processes at ?2.05 and 0.62 V, respectively. The diffusion coefficient, calculated using the Randles–Sevcik relationship, is 9.7 × 10^?6 cm² s^?1. Electrochemical studies reveal that the Ni^I reduced form of the complex is capable of catalyzing CO₂ reduction at a potential that is thermodynamically more favorable than for the reduced [Ni(N,N′-ethylenebis(acetylacetoneiminato)]complex. Spectroelectrochemical analyses following bulk electrolysis of [Ni(L)]PF₆ under CO₂ revealed the formation of oxalate and bicarbonate.     

Synthesis and Structural Characterization of two Novel Copper(I) Complexes with Oxygen Donor

Two novel copper(I) complexes with Cu‐O bonds, [Cu₂L₂(PPh₃)₂](BF₄)₂ ( 1 ) and [Cu(L)(dppeo)](BF₄) ( 2 ) ( L = 6‐(4‐diethylmethylphosphonatephenyl)‐2,2′‐bipyridine, dppeo = bis(diphenylphosphino)ethane monoxide), have been prepared and their structures characterized. In the binuclear complex 1 , the ligand L serves as tridentate donor with the N, N′ and O as coordination atoms, and the two Cu^I atoms are bridged through both P = O donor atoms in different ligand L with a triphenylphosphine molecule as auxiliary ligand. While in mononuclear complex 2 , both ligands L and dppeo behave as bidentate with N^∧N from L and P^∧O from dppeo chelating to Cu^I atom.     

Synthesis,Structures and Spectroscopic Properties of Platinum(II), Palladium(II) and Copper(I) Halide Complexes with Pyrimidine‐phosphine Ligand

The reactions of pyrimidine‐phosphine ligand N‐[(diphenylphosphino)methyl]‐2‐pyrimidinamine ( L ) with various metal salts of Pt^II, Pd^II and Cu^I provide three new halide metal complexes, Pt₂Cl₄(μ‐L)₂·2CH₂Cl₂ ( 1 ), Pd₂Cl₄(μ‐L)₂ ( 2 ), and [Cu₂(μ‐I)₂L₂]_n ( 3 ). Single crystal X‐ray diffraction studies show that complexes 1 and 2 display a similar bimetallic twelve‐membered ring structure, while complex 3 consists of one‐dimensional polymeric chains, which are further connected into a 2‐D supramolecular framework through hydrogen bonds. In the binuclear complexes 1 and 2 , the ligand L serves as a bridge with the N and P as coordination atoms, but in the polymeric complex 3 , both bridging and chelating modes are adopted by the ligand. The spectroscopic properties of complexes 1 ‐ 3 as well as L have been investigated, in which complex 3 exhibits intense photoluminescence originating from intraligand charge transfer (ILCT) π→π* and metal‐to‐ligand charge‐transfer (MLCT) excited states both in acetonitrile solution and solid state, respectively.     

Structural and theoretical studies of (E,E)-benzaldehyde azine and its rhenium(IV) complex

The azine bridged dicatechol ligand (E,E)-benzaldehyde azine (H₄L) was fully characterized by X-ray analysis. The reaction of [ReCl₆]²⁻ with this compound was studied and the novel Re(IV) complex (HNEt₃)(NBu₄)[ReCl₄(H₂L)] was prepared and characterized. The structure and spectroscopy of the compound H₄L and its Re(IV) complex were studied experimentally and by means of density functional calculations.     

Synthesis of a palladium(II) complex of a <Emphasis Type="Italic">N</Emphasis>-heterocylic carbene via transmetalation: crystal structure and antibacterial studies

An Ag(I)-N-heterocylic carbene (NHC) complex, [Ag(L)₂]PF₆ (L = 1-(2′-methylbenzyl)-3-(2″-propyl)benzimidazolium), was used as a transfer agent for the synthesis of a Pd(II)–NHC complex, formulated as [PdCl(L)₂(MeCN)]PF₆ (Pd1). The complex Pd1 was characterized by ¹H and ¹³C NMR, FTIR spectroscopy and elemental analysis. Single crystal X-ray diffraction analysis reveals that the Pd(II) atom has a square planar geometry. This complex was screened for its antibacterial potential against the Gram-negative bacteria Escherichia coli (ATCC 25922) and the Gram-positive bacteria Staphylococcus aureus (ATCC 12600). These results are compared with those obtained for a standard antibiotic, ampicillin, and also the corresponding Ag(I)–NHC complex.     

Crystal structure,DNA-binding,and fluorescence properties of cadmium(II) complex with N-(2-acetic acid)salicyloyl hydrazone and imidazole

A novel cadmium(II) complex with N-(2-acetic acid)salicyloyl hydrazone (C₉H₈N₂O₄, H₃L) and imidazole (Im) was prepared and characterized. The crystal structures of ligand H₃L and cadmium(II) complex were determined by X-ray single-crystal diffractometry. The complex consists of three binuclear neutral unattached units. One of Cd²⁺ is six-coordinated by the carboxylic O atom, acylic O atom, and azomethinic N atom of one ligand H₃L (HL²⁻ form), carboxylic O atom from the other ligand H₃L by the μ₂-bridging form and N atoms from two imidazoles, but the other five Cd²⁺ ions all are seven-coordinated more than an O atom from coordinated water molecule compared with six-coordinated Cd²⁺. HL²⁻ acts as tridentate ligand forming two stable five-numbered rings and sharing one side in the keto form for each ligand, and the carboxyl groups of two HL²⁻ ligands are coordinated via the μ₂-bridging form. The coordination polyhedron around Cd²⁺ was described as a octahedron or pentagonal bipyramidal. The inter- and intramolecular hydrogen bonds resulted in a three- dimensional network and provided extrastability for the structure. The complex exhibits good fluorescence properties. The complex was also searched for the interaction with CT-DNA by electronic absorption titration and emission titration. The results show that the complex is bound to calf thymus DNA mainly by intercalation.     

Enhanced Photostability of a Ruthenium(II) Polypyridyl Complex under Highly Oxidizing Aqueous Conditions by Its Partial Inclusion into a Cyclodextrin

The complex [Ru(bpy)₂L]²⁺, where bpy=2,2′‐bipyridine, L=4‐(phenylethynyl)‐2,2′‐bipyridine, was prepared in its racemic and resolved forms (Δ and Λ). The phenylethynyl unit on the bipyridine for the complex acts as a binding site for α‐cyclodextrin in water (1:1 complex, K=3390 L mol^?1) or β‐cyclodextrin (2:1 complex, K₁=887 L mol^?1, K₂=8070 L mol^?1). The presence of the cyclodextrin provides partial protection to the complex under light‐activated water oxidation conditions.     

Metal-ligand coordination and antiradical activity of a trichromium(III) complex with the flavonoid naringenin

The trinuclear chromium(III) complex [Cr₃O(CH₃CO₂)₆(L)(H₂O)₂] (where L is the monoanion of the flavonoid naringenin) was synthesized and characterized. Density functional theory (DFT) calculations and quantum theory of atoms in molecules (QTAIM) analysis show that the flavonoid binds to Cr^III as an O,O-bidentate ligand via the 5-hydroxy and 4-oxo groups. Reactions with 2,2-diphenyl-1-picrylhydrazyl (DPPH) indicate that the antiradical activity of this flavonoid-metal complex is enhanced in comparison with uncoordinated naringenin.     

The synthesis and characterization of a new (E,E)-dioxime and its mono and heterotrinuclear complexes containing dioxadithiadiazamacrobicyclic moieties

A new (E,E)-dioxime (2Z,3Z)-1,4,7,8,15,16-hexahydro-9,14-(ethanothioethanothioethano)quinoxalino[6,7-e] [4,7,1,10]benzodioxadiazacyclododecine-2,3,19,26-tetrone2,3-dioxime (H₂L) has been synthesized by reacting cyanogen-di-N-oxide with 2,3-diamino-6,7,14,15-tetrahydro-8,13-(ethanothioethanothioethano)dibenzo[b,h] [1,4,7,10]dioxadiazacyclodecine-17,24-dione (6). Mononuclear complexes (8, 9) of this ligand have been synthesized by reacting the vic-dioxime (H₂L) with NiCl₂ · 6H_2O and COCl₂ · 6H₂O respectively. The BF ₂ ⁺ capped cobalt(III) complex (10) of the new (E,E) vic-dioxime has been synthesized by using as precursor a hydrogen-bridged mononuclear cobalt(III) complex (9). The heterotrinuclear complex (11) has been prepared by reacting one mononuclear cobalt(III) complex (10) with [Cu(MeCN)₄]PF₆. The new compounds were characterized by a combination of elemental analysis, ¹H- and ¹³C-n.m.r, i.r. and m.s. spectral data.     

一种含吲哚咪唑基Ru(II)配合物的酸碱性质和与DNA相互作用的研究

合成了一个新的Ru(II)配合物[Ru(bpy)₂(H₂iip)](ClO₄)₂•5H₂O [bpy＝2,2'-联吡啶, H₂iip＝2-吲哚基-咪唑并[4,5-ƒ][1,10]-邻菲罗啉]. 通过酸碱滴定发射光谱测定了该配合物的表观电离常数; 用紫外可见光谱、荧光光谱、稳态荧光淬灭、溴化乙锭竞争键合、粘度测量和DNA裂解实验研究了配合物与DNA的相互作用性质. 结果表明配合物以经典的插入模式与DNA键合, 键合常数K_b＝(5.97±0.27)×10⁵ mol^－1•L (50 mmol/L NaCl).     

Electrocatalytic Hydrogen Production by a Nickel(II) Complex with a Phosphinopyridyl Ligand

A novel nickel(II) complex [Ni(L)₂Cl]Cl with a bidentate phosphinopyridyl ligand 6‐((diphenylphosphino)methyl)pyridin‐2‐amine (L) was synthesized as a metal‐complex catalyst for hydrogen production from protons. The ligand can stabilize a low Ni oxidation state and has an amine base as a proton transfer site. The X‐ray structure analysis revealed a distorted square‐pyramidal Ni^II complex with two bidentate L ligands in a trans arrangement in the equatorial plane and a chloride anion at the apex. Electrochemical measurements with the Ni^II complex in MeCN indicate a higher rate of hydrogen production under weak acid conditions using acetic acid as the proton source. The catalytic current increases with the stepwise addition of protons, and the turnover frequency is 8400 s^?1 in 0.1 m [NBu₄][ClO₄]/MeCN in the presence of acetic acid (290 equiv) at an overpotential of circa 590 mV.     

Synthesis,Characterization and Crystal Structure of an Unsymmetric Samarium(III) Cryptate

Abstract

The complex [Sm(H₃L)(NO₃)(H₂O)](NO₃)₂ · H₂O was synthesized by the (2+3) condensation of tris(2-aminoethyl)amine with 2,6-diformyl-4-chlorophenol in the presence of Sm³⁺. Its crystal structure has been determined. In the complex the coordination number of Sm³⁺ is nine. A water molecule is encapsulated in the cryptate as a guest, confirmed by electrospray mass spectrometry, thermal analysis and the X-ray crystal structure.     

Synthesis,structure, and properties of a coordination polymer based on N- and O-donors

A ternary coordination polymer, [Cd(L)(pbda)_0.5] _n [HL?=?3,5-bis(2-pyridylmethyl)aminobenzoic acid, pbda?=?dianion of 1,4-benzenedicarboxylic acid], has been synthesized and characterized by elemental analysis, FT-IR spectroscopy, powder X-ray diffraction, thermogravimetric analysis, and single-crystal X-ray diffraction analysis. The single-crystal X-ray crystallography reveals that the complex is a 2-D wave-like network. The cadmium has an unsymmetrical seven-coordinate [CdN₂O₅] geometry, coordinated by two nitrogens and five oxygens from L^? and pbda. Hydrogen bonds between the uncoordinated (2-pyridylmethyl)amino groups from adjacent layers form dimers across the inversion center, superposing different layers to construct a 3-D framework. To the best of our knowledge, [Cd(L)(pbda)_0.5] _n represents the first example of a complex containing 3,5-bis(2-pyridylmethyl)aminobenzoate.     

New magnetic supported hydrazone Schiff base dioxomolybdenum (VI) complex: An efficient nanocatalyst for epoxidation of cyclooctene and norbornene

A new dioxomolybdenum (VI) complex with tridentate hydrazone Schiff base ligand (H₂L) derived from 2‐hydroxy‐5‐nitrobenzaldehyde and benzhydrazide was synthesized and designated as [MoO₂L (DMF)]·2H₂O. The Fe₃O₄@SiO₂‐CPS‐L‐MoO₂ (EtOH) nanocatalyst was successfully prepared by grafting H₂L ligand on modified Fe₃O₄ nanoparticles followed by reacting with MoO₂ (acac)₂. The complex and nanocatalyst were characterized by various techniques such as elemental analysis, mass, FT‐IR, UV–Vis, ¹H NMR, ¹³C{¹H}‐NMR, TGA, XRD, XPS, TEM, SEM and VSM. The catalytic activity of [MoO₂L (DMF)]2H₂O and Fe₃O₄@SiO₂‐CPS‐L‐MoO₂ (EtOH) were evaluated for the oxidation of various alkenes (cyclooctene, norbornene, cyclohexene, styrene and α‐methyl styrene) in the presence of tert‐butylhydroperoxide as oxidant. The results revealed that the catalysts were especially efficient for oxidation of cyclooctene and norbornene with 100% selectivity towards corresponding epoxide product. Fe₃O₄@SiO₂‐CPS‐L‐MoO₂ (EtOH) showed higher catalytic activity, shorter reaction time and higher turnover number (TON) compared with homogeneous complex [MoO₂L (DMF)]·2H₂O. Moreover, simple magnetic recovery from the reaction mixture and reuse for several times with no significant loss in activity were other advantages of the nanocatalyst.     

Cyan-Blue Luminescence and Antiferromagnetic Coupling of CN-Bridged Tetranuclear Complex Based on Manganese(III) Schiff Base and Hexacyanoferrate(III)

A new tetranuclear cyanide-bridged Mn^III–Fe^III complex based on manganese(III) Schiff base and hexacyanoferrate(III) units, [Mn(L)(MeOH)₂][{Mn(L)}{Fe(CN)₆}{Mn(L)(MeOH)}].2MeOH, [H₂L?=?N,N′-bis(2-hydroxy-1-naphthalidenato)-1,2-diaminopropane] (1), has been synthesized and characterized by elemental analysis, UV–Vis, FT-IR, PXRD, single crystal X-ray analyses, magnetic and photoluminescence measurements. Complex 1 consist of one trinuclear cyanido-bridged anion, in which [Fe(CN)₆]^3? anion bridge [Mn(L)]⁺ and Mn(L)(MeOH)}]⁺ cations via two C≡N groups in the cis positions, and also one isolated manganese [Mn(L)(MeOH)₂]⁺ cation. DC magnetic susceptibility and magnetization studies showed that complex 1 indicates an antiferromagnetic coupling between low-spin Fe(III) and high-spin Mn(III) through the cyanide bridges. In addition, the complex 1 displays a strong cyan-blue luminescence emission in the solid state condition at room temperature. This behavior might be seen easily from the chromaticity diagram. Thus, the complex may be a good promising cyan-blue OLED developing electroluminescent materials for flatted or curved panel display applications due to the fact that it has such features.     

Synthesis,structural characterization and catalytic potential of oxidovanadium(IV) and dioxidovanadium(V) complexes with thiazole-derived NNN-donor ligand

Reaction between the tridentate NNN donor ligand, (E)-2-(2-(1-(pyridin-2-yl)ethylidene)hydrazinyl)benzo[d]thiazole (HL), and V₂O₅ in ethanol gave a new vanadium(V) complex, [VO₂L] (1), while the similar reaction by using [V^IVO(acac)₂] as the metal source gave two different types of crystals related to compounds [VO₂L] (1) and [V^IVO(acac)L] (2). The molecular structures of the complexes were determined by single-crystal X-ray diffraction and spectroscopic characterization was carried out by means of FT-IR, UV–vis and NMR experiments as well as elemental analysis. The oxidovanadium(IV) and dioxidovanadium(V) species were used as catalyst precursors for olefin oxidation in the presence of hydrogen peroxide (H₂O₂) as an oxidant. Under similar experimental conditions, the presence of 1 resulted in higher oxidation conversion than 2.     

一种大环化合物的晶体结构及其双核铜配合物的酪氨酸酶活性研究

A ring-contracted form macrocycle, 29,30-dioxo-3,6,9,17,20,23,29,30-octaazapentacyclo[23,3,1,1^11,15,0^2,6,0^16,20]-triacontaneocta- 1 (28),9,11 (12), 13,15(30),23,25(29),26-ene (L) was synthesized by condensation of diethyltriamine with pyridine-1-oxide-2,6-dicarboxaldehyde. A porous three-dimensional layer structure in its crystal was formed by self-assembly through hydrogen bonds and π-π interaction. Its dinuclear copper(I) complex [Cu2L(MeOH)2]-(BF4)2*2H2O and dinuclear-copper(II) complex [Cu2L(MeOH)2](ClO4)4*2H2O were obtained and could oxidize catalytically four phenolic substrates hydroquinone, 2-methyl-hydroquinone, 2,6-di-tert-butylphenol and 2,6-dimethylphenol, in a mixture of methanol and acetonitrile (V : V, 4 : 1). The copper(I) complex reacted with dioxygen to form an oxygenated species as an initial active intermediate for oxidation of the phenols. Oxidation of the substrates by the copper(II) complex produced a copper(I) complex and the oxidation products of the substrates.