Tetranuclear Schiff base copper(II) complexes: Syntheses, crystal structure, DNA/protein binding and catecholase-like activity (original) (raw)
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ChemistrySelect, 2018
Copper(II) complexes {[Cu(HL)(ClO 4)(H 2 O)](ClO 4)⋅3H 2 O} (1), {[Cu (HL)(m-phth)]⋅5H 2 O} (2) and {[Cu(HL)(NCS)] 2 (ClO 4) 2 ⋅2H 2 O} (3) (HL = 2-{[2-(1-piperazinyl)ethylimino]methyl}phenol; m-phth = 1,3-benzenedicarboxylate] have been synthesized and characterized by structural determination and spectroscopic studies. The mononuclear square pyramidal complex 1 resulted from the reaction of HL with copper perchlorate hexahydrate. Then mononuclear square planar complex 2 and dinuclear thiocyanato bridged complex 3 were obtained by reacting 1 with disodium 1,3-benzenedicarboxylate (Na 2 (m-phth)) and potassium thiocyanate, respectively. The interactions of 1-3 with CT-DNA / serum albumins were investigated by UV-visible absorption and fluorescence spectroscopy. The intrinsic binding constants of 1, 2 and 3 with CT-DNA were calculated as 1.44 (� 0.13) × 10 5 , 4.86 (� 0.11) × 10 5 and 4.51 (� 0.16) × 10 5 L mol À 1 , respectively. Study of the interactions of 1-3 with human serum albumin (HSA) / bovine serum albumin (BSA) showed that all the complexes could quench intrinsic fluorescence of HSA and BSA through a static quenching process. Molecular docking technique was utilised to confirm the mode of interaction of complexes with CT-DNA / serum albumin. Anticancer activities of the complexes have been tested using human breast cancer cell lines MCF7 and MBA-MB-231. Among the complexes studied 3 shows the higher cytotoxic activity and growth inhibition of cancer cells via induction of apoptotic cell death.
Central European Journal of Chemistry, 2006
The new homodinuclear complexes 1–4 of the type [LMII 2Cl2], heterotrinuclear complexes 5 and 6 of the type [LMII 2SnIVCl6] where M = CuII, MnII, CoII, NiII and CuII and NiII, respectively have been synthesized and characterized by elemental analysis and various spectroscopic techniques. The homodinuclear complexes possess two different environments (N2 and N2O2donor sets) for holding the metal ions. The metal ion in N2 set exhibits square planar geometry with two chloride ions in the inner sphere but rhombic structure is found in tetradentate N2O2 Schiff base cavity while in heterotrinuclear complexes SnIV atom is in the octahedral environment. The interaction of complexes 1 and 5 with calf thymus DNA was carried out by absorption spectroscopy and cyclic voltammetry. The intrinsic binding constants (K b) of complex 1 and 5 were determined as 3.2 × 103 M−1 and 9.6 × 103 M−1, respectively suggesting that complex 5 binds more strongly to CT-DNA than complex 1. Fluorescence studies alo...
Journal of inorganic biochemistry, 2018
The reaction of the copper(II) diclofenac complex [Cu(dicl)(HO)] (1) (dicl = deprotonated diclofenac (Hdicl)) with the chelating N-donor ligands ethylenediamine (en), propan-1,3-diamine (pn), unsymmetrical dimethylethylene-diamine (unsym-dmen) and N,N,N',N'-tetramethylethylene-diamine (temed) in methanol-water (4:1 v/v) yielded the novel copper(II) complexes [Cu(en)(HO)](dicl)·2HO (2), [Cu(pn)(HO)](dicl)·2HO (3), [Cu(unsym-dmen)(HO)](dicl)·HO (4) and [Cu(temed)(dicl)] (5), respectively. All the synthesized complexes were characterized by spectroscopic (UV-vis, FT-IR) methods. The structures of complexes 2, 3 and 5 were unambiguously determined by single-crystal X-ray crystallography. X-ray structures of complexes clearly revealed the ionic structure of complexes 2, 3 and the covalent structure of complex 5. The geometry of complex 4 was optimized by Density Functional Theory (DFT) calculations. The ability of the complexes 1-5 to bind to calf-thymus DNA was monitored in vitr...
Applied Organometallic Chemistry, 2017
Three mixed ligand copper(II) complexes [Cu(o-vanillin-L-tryptophan Schiff base) (diimine)] (diimine =2,2′-bipyridine (1), 1,10-phenanthroline (2) and 5,6dimethyl-1,10-phenanthroline(3)) were synthesized and characterized using analytical and spectral methods. The molecular structures of 1-3 were optimized using density functional theory (DFT) at B3LYP/LanL2DZ levels in the gas phase. Spectral and DFT studies suggest a distorted square pyramidal geometry around the copper ion. Binding interactions of 1-3 with calf thymus DNA and bovine serum albumin protein were studied using UV-visible and fluorescence spectroscopies, viscometric titrations and cyclic voltammetry and also using molecular docking analysis. Studies of the binding of the complexes with calf thymus DNA reveal intercalation, which is supported by molecular docking simulation. The DNA cleavage nature of 1-3 with pUC19 DNA shows that the complexes can cleave DNA without any external agents, and the efficiency follows the order 1 > 3 > 2. Synchronous and three-dimensional fluorescence spectral studies suggest that the secondary structures of the protein are altered by the complexes. Antioxidant studies reveal that the complexes have significant radical scavenging activity against DPPH. In vitro cytotoxic activity of the complexes was evaluated against breast cancer cells (MCF-7), revealing that complex 2 exhibits higher cytotoxicity than the other complexes. Nuclear chromatin condensation and fragmentation were observed with DAPI staining assay. The mitochondrial membrane potential damage was studied by FITC staining assay. Flow cytometric analysis suggests that all the metal complexes induce cell apoptosis.
Inorganic Chemistry, 2011
Two mononuclear fluorophore-labeled copper(II) complexes [Cu(nip)(acac)] þ (2) and [Cu(nip) 2 ] 2þ (3), where fluorophore is 2-(naphthalen-1-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (nip) (1) and acac is acetylacetone, have been synthesized and characterized by various techniques. The ligand 1 and complex 2 are structurally characterized by single-crystal X-ray diffraction. The coordination geometries around the copper are square planar in solid as well as solution state as evidenced by electron paramagnetic resonance (EPR) spectroscopy. The density functional calculations carried out on 1-3 have shown that electron-rich regions in the highest occupied orbital are localized on the naphthalene and partly on the phenanthroline moiety. Both complexes 2 and 3 in dimethyl sulfoxide (DMSO) exhibit near square planar structure around the metal ion in their ground state. Time-dependent density functional theory (TD-DFT) calculations reveal that Cu(II) ion in complex 2 shows tetrahedral coordination around the metal while 3 retains its square planar geometry in the lowest excited state. The interaction of complexes with calf-thymus DNA (CT DNA) has been explored by using absorption, emission, thermal denaturation, and viscosity studies, and the intercalating mode of DNA binding has been proposed. The complexes cleave DNA oxidatively without any exogenous additives. The protein binding ability has been monitored by quenching of tryptophan emission in the presence of complexes using bovine serum albumin (BSA) as model protein. The compounds showed dynamic quenching behavior. Further, the anticancer activity of the complexes on MCF-7 (human breast cancer), HeLa (human cervical cancer), HL-60 (human promyelocytic leukemia), and MCF-12A (normal epithelial) cell lines has been studied. It has been observed that 3 exhibits higher cytotoxicity than 2, and the cells undergo apoptotic cell death.
Journal of Molecular Structure, 2010
Two terdentate NNO donor Schiff base ligands CH 3 C(OH)@CHC(CH 3)@NCH 2 C 5 H 4 N [HL 1 ] and C 6 H 5 C(OH)@CHC(CH 3)@NCH 2 C 5 H 4 N [HL 2 ] were used to synthesize two mononuclear square planar copper(II) complexes, [CuL 1 (CF 3 COO)] (1) and [CuL 2 (CF 3 COO)] (2). The complexes were characterized by elemental analyses, FT-IR, UV-vis spectral methods and their structures were established by single crystal X-ray diffraction study. The biochemical activity of the complexes towards DNA binding were performed using absorbance and fluorescence titration methods and their mode of binding with calf thymus DNA has been established by viscosity measurement technique.
2014
The new chiral trinuclear complex, [bis(aquodiaminotryptophanato)Cu II-Sn 2 IV ] chloride (1) was synthesized by employing a well-designed three-step pathway under anhydrous conditions. Interaction of the complex (1) with calf-thymus DNA was studied by spectrophotometry, cyclic voltammetry and viscosity measurements. The kinetic studies of calf-thymus DNA binding were carried out at 260 nm (k max of calf-thymus DNA) under pseudo-first order conditions. The rate constants, k obs , were evaluated by the linear least squares regression method. The absorption spectra of the complex with calf-thymus DNA shows 'hyperchromism' which is attributed to the electrostatic interaction with calf-thymus DNA. The electrochemical behavior of complex (1) was studied in DMSO/H 2 O (5:95) solution and showed a quasireversible Cu II /Cu I redox couple. The voltammetric studies of the complex in the absence and in the presence of DNA exhibit a shift in the formal potential E 0 and ratio of cathodic to anodic peak currents i pa /i pc indicating strong binding of the complex to calf-thymus DNA. The viscosity of DNA decreases with increasing concentration of the complex, suggesting that complex (1) binds to calf-thymus DNA by electrostatic association.
Copper(II) complexes with simple and mixed ligands, [Cu(L)(ClO 4)] (1) and [Cu(L)(diimine)]ClO 4 (2–4) [where L is 4-chloro-2-((2-(phenylthio)phenylimino)methyl)phenol and diimine is 1,10-phenanthroline (phen, 2), 2,2 0-bipyridine (bpy, 3) or 4,4 0-dimethyl-2,2 0-bipyridyl (dmbpy, 4)], were synthesized and characterized by elemental analysis, UV-vis, FT-IR, electrospray ionization-mass spectrometry (ESI-MS) and electrochemical studies. Notably, complex 4 was structurally characterized using single X-ray crystallography. It was observed that this complex has a slightly distorted square planar geometry. The varying interactions of these complexes with herring sperm DNA (HS-DNA) were explored in detail using various spectral and electrochemical methods to gain insight into their structure–activity relationships. The obtained results revealed that complexes 1, 3 and 4 could interact with HS-DNA via a partial intercalation mode, whereas complex 2 was found to deeply stack between base pairs with a binding constant of 10 4 M À1 due to its enhanced planarity; moreover, 4 underwent a hydrophobic interaction with DNA. These experimental observations were found to be close to the theoretical observations investigated by the molecular docking technique. The interaction of these synthesized Cu(II) complexes with bovine serum albumin (BSA) was also evaluated using absorption and fluorescence techniques, which revealed a static quenching mechanism between the complexes and BSA. In addition, DNA cleavage by the complexes was monitored by electrophoretic spectrometry; the results showed that these complexes exhibited significant cleavage in the presence of a reducing agent (ascorbic acid). The in vitro cytotoxicity of these Cu(II) complexes was carried out in two different human tumour cell lines, A549 and Huh7. Furthermore, molecular docking was also used to evaluate and understand the interaction modes of the complexes with the molecular target DNA. All the in vitro pharmacological evaluation observations clearly indicated the superior DNA binding/cleaving and protein binding properties of these complexes, although the S-donor atom did not coordinate with the central copper ion in the mixed complexes.
Polyhedron, 2007
Ternary copper(II) complexes [Cu(L-pro)(B)(H 2 O)](NO 3) (1, 2) where L-pro = L-proline, B is a N,N-donor heterocyclic base, viz. 2,2 0bipyridine (bpy, 1), 1,10-phenanthroline (phen, 2), are synthesized, characterized, and their DNA binding and cleavage activity studied. The bpy complex (1) is structurally characterized by single-crystal X-ray crystallography. The complexes show the presence of a distorted square-pyramidal (4 + 1) CuN 3 O 2 coordination geometry. Complex [Cu(L-pro)(bpy)(H 2 O)](NO 3) (1) crystallizes in the triclinic space group P1 with unit cell parameters: a = 7.082(3) Å , b = 10.483(5) Å , c = 11.581(5) Å , a = 89.700(7)°, b = 83.488(8)°, c = 84.109(8)°a nd V = 849.7(7) Å 3. The one-electron paramagnetic complexes display a d-d band near 600 nm in water and show a cyclic voltammetric response due to Cu(II)/Cu(I) couple near 0.1 V (versus SCE) in Tris-HCl buffer-0.1 M KCl. Binding interactions of the complexes with calf thymus (CT) DNA have been investigated by emission, absorption, viscosity and DNA thermal denaturation studies. The phen complex displays significant binding propensity to the CT DNA giving an order: 2 (phen)) 1 (bpy). The bpy complex does not show any apparent binding to the DNA and hence poor cleavage efficiency. Complex 2 shows efficient oxidative cleavage of SC-DNA in the presence of 3-mercaptopropionic acid (MPA) involving hydroxyl radical species as evidenced from the control data showing inhibition of DNA cleavage in the presence of DMSO and catalase.
Journal of Molecular Structure, 2020
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