Copper(II) perchlorate complexes with antipyrine: synthesis,structure, cytotoxicity and DFT calculations

The synthesis, structure and properties of copper(II) perchlorate complexes with antipyrine (AP), [Cu(AP)₄(H₂O)](ClO₄)₂ and [Cu(AP)₅](ClO₄)₂, are described and compared with those of alternative compounds containing different AP ligands.     

Metal complexes in molecular electronics: progress and possibilities

A selective summary of some of the issues surrounding the development of a molecular-based electronics technology is presented, highlighting the characteristics of metal complexes that make these species particularly attractive for the construction of highly integrated, functional molecular components.     

Copper oxalate complexes: synthesis and structural characterisation

Six copper(II) oxalate complexes, namely {K₂[Cu(ox)₂]} _n (1), {(Hiz)₂[Cu(ox)₂]} _n (2), {[Cu(ox) (N-Bzliz)₂]} _n (3), (HMeiz)₂[Cu(ox)₂] (4), {[Cu(ox)(Meiz)₂]} _n (5), and [Cu(Hox)₂(H₂O)₂](N-Bzliz) (6) where ox = oxalate ion, iz = imidazole, N-Bzliz = N-benzylimidazole, Meiz = 2-methylimidazole, were synthesised and characterised by single crystal X-ray diffraction (complexes 1–5) or powder X-ray diffraction (compound 6). The three-dimensional crystal packing structures of 2, 4, and 5 are consolidated by intermolecular hydrogen bonds linking the oxygen atom of the oxalate group and the amine or imine group of the imidazole-based part into chains. The molecules of complex 6 are held together by intermolecular hydrogen bonds between the oxygen atoms of the oxalate group and coordinated water molecules.     

Copper complexes with N-aminotriazolethione azomethines: Structures and magnetochemical properties

Azomethine derivatives of 4-amino-1,2,4-triazole-3-thiones (H₂L) and their metal complexes were obtained. The stabilities of the ligand conformers were calculated using quantum-chemical techniques. Ab initio (B3LYP/LANL2DZ) calculations of the complexes in the lower singlet and triplet states were performed with full geometry optimization. The structures and magnetochemical properties of the chelate complexes obtained were examined over a wide temperature range.     

Copper complexes with polydentate hetarylformazanylcelluloses

Copper complexes with polydentate irregular 1-aryl-5-heterylformazan-6-celluloses were synthesized (aryl is phenyl, 2-hydroxy-4-nitrophenyl, 2-hydroxy-5-nitrophenyl, 2-hydroxy-4-chloro-5-nitrophenyl, 2-hydroxy-4-nitro-5-chlorophenyl, 2-carboxyphenyl, 4-sulfophenyl; heteryl is 4-methyl-6-methoxypyrimidin-2-yl, 4,6-dimethylpyrimidin-2-yl, 4-methyl-1,6-dihydro-1H-6-oxopyrimidin-2-yl, benzoxazol-2-yl, benzothiazol-2-yl). The structures of the complexes were determined by EPR. The relationship between the static exchange capacity in terms of Cu²⁺ and the number of formazan groups in the matrix, which is 0.1–0.3 mM/g for hetarylformazancelluloses, was established.     

Copper complexes as chemical nucleases

Redox active mononuclear and binuclear copper(II) complexes have been prepared and structurally characterized. The complexes have planar N-donor heterocyclic bases like 1,10-phenanthroline (phen), dipyridoquinoxaline (dpq) and dipyridophenazine (dppz) ligands that are suitable for intercalation to B-DNA. Complexes studied for nuclease activity have the formulations [Cu(dpq)₂(H₂O)] (ClO₄)₂.H₂O (1), [CuL(H₂O)₂(μ-ox)](ClO₄)₂ (L = bpy,2; phen,3; dpq,4; and dppz,5) and [Cu(L)(salgly)] (L = bpy,6; phen,7; dpq,8; and dppz,9), where salgly is a tridentate Schiff base obtained from the condensation of glycine and salicylaldehyde. The dpq complexes are efficient DNA binding and cleavage active species. The dppz complexes show good binding ability but poor nuclease activity. The cleavage activity of thebis-dpq complex is significantly higher than thebis-phen complex of copper(II). The nuclease activity is found to be dependent on the intercalating nature of the complex and on the redox potential of the copper(II)/copper(I) couple. The ancillary ligand plays a significant role in binding and cleavage activity.     

Copper carbene complexes: advanced catalysts,new insights

Controlling the selectivity of reactive intermediates is a major goal of organic chemists. Carbenes generated by thermal or photochemical extrusion of nitrogen from diazo compounds defy external control and tend to give complex product mixtures. However, the catalyzed decomposition of diazo compounds gives rise to highly selective "carbenoids" which have found extensive application in synthesis although little is known of their precise nature. On the other hand, a large variety of carbene metal complexes have been prepared and characterized which more or less lack carbenoid reactivity. Structural evidence for the transients of catalyzed diazo decomposition is becoming available through experiment and computation. Although the present report focuses on copper complexes, outstanding results with other metals are also covered.     

Copper(II) oxalate and oxamate complexes

Reaction of Cu^II salts with phenanthroline and oxalate (ox) or oxamate (oxm) gives [Cu(phen)(ox)(H₂O)] · H₂O or [Cu(phen)(oxm)(H₂O)] · H₂O complexes while direct treatment of Cu^II salts with oxalate or oxamate gives [NH₄]₂[Cu(ox)₂] and [Cu(oxm)₂(H₂O)₂] respectively. The X-ray structures of one example of each system, aquo-oxamato-phenanthroline-copper(II)-dihydrate and the polymeric ammonium-bis(aquo)-tetraoxalato-dicopper(II)-dihydrate, are reported.     

Copper(II), palladium(II) and platinum(II) chloride complexes with 5-amino-2-tert-butyltetrazole: Synthesis, characterization and cytotoxicity

Complexes CuL₃Cl₂, PdL₂Cl₂ and PtL₂Cl₂, where L is a novel ligand from the series of 2-substituted 5-aminotetrazoles, namely 5-amino-2-tert-butyltetrazole (1), have been synthesized by the reaction of metal(II) chlorides with 1 and characterized by IR spectroscopy, thermal and X-ray analyses. The crystallographic structural analysis of these complexes revealed that 1 acts as a monodentate ligand coordinated to the metal via endocyclic N4 atom. Platinum complex demonstrates promising cytotoxicity against human cervical carcinoma cells with IC₅₀ value average between those of cisplatin and carboplatin.     

Copper(I) complexes of rhodanine

Summary Some new crystalline copper(I) complexes of rhodanine (HL) have been prepared and studied by i.r. and conductometric methods. The neutral ligand is bonded to the metal atom through the thiocarbonylic sulphur atom. The Cu(HL)₂OH · 0.5 H₂O complex has a dimeric tetrahedral hydroxyl-bridged structure as have the isostructural halides Cu(HL)₂X (X = Cl, Br and I) for which the halide-bridged stretching bands have been identified. The Cu(HL)₃A (A = ClO₄, BF₄, 0.5 SO₄ and CF₃CO₂) complexes have monomeric distorted tetrahedral structures with the anion bonded to the metal.     

Copper(II) complexes with aroylhydrazones

The coordination chemistry of copper(II) with tridentate aroylhydrazones is briefly discussed in this article. Two types of aroylhydrazones derived from aroylhydrazines and ortho-hydroxy aldehydes or 2-pyridine-carboxaldehyde have been used. The characterization of the complexes has been performed with the help of various physico-chemical techniques. Solid state structural patterns have been established by X-ray crystallography. In the solid state, structural varieties of these complexes are seen to range from monomeric, dimeric, polymeric and one-dimensional self-assembly via hydrogen bonds and π-π interactions. EPR spectroscopy and variable temperature magnetic susceptibility measurements have been used to reveal the nature of the coordination geometry and magnetic characteristics of these complexes.     

Pyrazole-based trinuclear and mononuclear complexes: synthesis,characterization, DNA interactions and cytotoxicity studies

Transition Metal Chemistry - A new trinuclear Cu(II) complex [Cu3(μ3-OH)(μ-pz)3(Hpz)2(HCOO)(BTAO)Cl] (1) (Hpz = pyrazole, BTAO = 4,6-bis(dimethylamino)-1,3,5-triazin-2(1H)-one) and four...     

Copper(II) complexes bearing cyclobutanecarboxylate and pyridine ligands: a new series of dinuclear paddle-wheel complexes

Monatshefte für Chemie - Chemical Monthly - Four members of a new series of paddle-wheel copper(II) complexes bearing cyclobutanecarboxylate as bridging ligand with pyridine derived ligands in...     

New dimeric Schiff base quinoline complexes: Synthesis,spectral characterization,electrochemistry and cytotoxicity

A novel Schiff base ligand (H‐DPPMHQ) derived from 2‐hydrazineylquinoline and 1,3‐diphenyl‐1H‐pyrazole‐5‐carbaldehyde and its dimeric complexes with compositions [Cr(DPPMHQ)Cl]₂?2Cl and [M(DPPMHQ)Cl]₂ (where M = Cu(II), Co(II), Ni(II) and Zn(II)) have been synthesized and characterized using physicochemical methods like elemental analysis, magnetic susceptibility and molar conductivity measurements, multispectral techniques and electrochemical studies. The molar conductance data reveal that all metal chelates are non‐electrolytes, except the Cr(III) complex which shows a Λ_M value of 146.82 Ω^?1 cm² mol^?1, indicating that it is a 1:2 electrolyte. Infrared spectral results show that the metal is organized through four nitrogen atoms (azomethine and deprotonated imine groups, pyrazole and quinoline rings) besides chlorine atoms. The NH proton is also displaced during complexation, as indicated by ¹H NMR spectral data. Based on the electron spin resonance and ligand field parameter data, the bonding parameters of these complexes have been calculated. Using Coats–Redfern and Horowitz–Metzger equations, thermodynamic parameters were determined. The spectral data indicate that the dimeric complexes have octahedral geometry around the central metal ions. The cytotoxic activities of all compounds were evaluated towards human breast cancer (MCF‐7) and lung cancer (A549) cell lines.     

Insulated conducting polymers: manipulating charge transport using supramolecular complexes

Rotaxane structures which provide functional insulation to conducting polymers can provide over a 4000-fold reduction in conductivity over non-rotaxane structures and with electronically active copper ions in the rotaxane units the conductivity increases by more than 80 times relative to the metal-free analog.     

Copper(II) cyclam-based complexes for radiopharmaceutical applications: synthesis and structural analysis

Two molecular structures of the copper(II) complex, Cu(H(2)TETA), have been determined by X-ray crystallography. The Jahn-Teller distortion differs between the two structures; occurring either along the axis of the pendant acetate arms or across the macrocyclic ring. An analysis of deposited data from over one hundred copper(II) cyclam X-ray structures in the Cambridge Structural Database (CSD) reveals that Jahn-Teller distortion across the ring is highly unusual for such compounds in the solid state. Novel chelators based on the piperazino/side-bridged cyclam have been prepared and copper(II) complexes formed. The single crystal X-ray structures of two copper(II) complexes, with either an ester or acid N-pendant arm, have been determined and in both cases the pendant arm is bound to the metal centre.     

Copper(II) complexes of pyrrolidine dithiocarbamate

Copper(II)-pyrrolidine dithiocarbamate (PDTC) complexes having the general formula, [Cu(PDTC)₂], [Cu(PDTC)X₂]⁻ (where X = Cl⁻, I⁻, CN⁻, SCN⁻) and [Cu(PDTC)(en)]⁺ (en = ethylenediamine) have been prepared and characterized by IR spectroscopy and by thermogravimetric analysis (TGA and DTA). The IR data suggests that coordination of pyrrolidine dithiocarbamate (PDTC) takes place through the two sulphur atoms in a symmetrical bidentate fashion. The results of thermal analysis are consistent with the proposed composition of the complexes.