Synthesis, characterization and electrochemical studies of heterometallic manganese(IV)–zinc(II) and manganese(IV)–copper(II) complexes derived from bis(2-hydroxy-1-naphthaldehyde)oxaloyldihydrazone

Structural-Dependent N,O-Donor Imine-Appended Cu(II)/Zn(II) Complexes: Synthesis, Spectral, and in Vitro Pharmacological Assessment

Four mononuclear bioefficient imine-based coordination complexes, [(L ¹ ) ₂ Cu], [(L ¹ ) ₂ Zn], [(L ² )Cu(H ₂ O)], and [(L ² )Zn(H ₂ O)], were synthesized using ligands [L ¹ = 2-(((3-hydroxynaphthalen-2-yl)methylene)amino)-2-methylpropane-1,3-diol and L ² = 4-(1-((1,3-dihydroxy-2-methylpropan-2-yl)imino)ethyl)benzene-1,3-diol]. The formation of the complexes was ascertained by elemental analysis, Fourier transform infrared, ¹H NMR, ¹³C NMR, electrospray ionization-mass spectroscopy, electron paramagnetic resonance, and thermogravimetric analysis. The comparative binding propensity profiles of the above-synthesized complexes with the DNA/human serum albumin (HSA) were investigated via UV absorption, fluorescence, and Förster resonance energy-transfer studies. On the basis of extended conjugation and planarity, L ¹ complexes exhibited superior bioactivity with greater calculated DNA binding constant values, (K _b) 2.9444 × 10³ [(L ¹ ) ₂ Cu] and 2.2693 × 10³ [(L ¹ ) ₂ Zn], as compared to L ² complexes, 1.793 × 10³ [(L ² )Cu(H ₂ O)] and 9.801 × 10² [(L ² )Zn(H ₂ O)]. The competitive displacement assay of complexes was performed by means of fluorogenic dyes (EtBr and Hoechst), which corroborates the occurrence of minor groove binding because of the enhanced displacement activity with Hoechst 33258. The minor groove binding of the [(L ¹ ) ₂ Cu] complex is further confirmed by the molecular docking study. Moreover, the HSA study demonstrated effective static quenching of complexes with substantial K _sv values. The [(L ¹ ) ₂ Cu] complex was found to have pronounced cleavage efficiency as evaluated from sodium dodecyl sulfate polyacrylamide gel electrophoresis electrophoresis. Furthermore, in vitro antioxidant activity against 2,2-diphenyl-1-picrylhydrazyl and superoxide radicals further proclaimed the remarkable bioefficiency of compounds, which make them promising as active chemotherapeutic agents.

Hybrid pharmacophore approach for bio-relevant di-imines based homobimetallic complexes incorporating functionalized dicarboxylates as co-ligands: Synthesis, spectral and structural activity dependent biological insights (in-vitro DNA and HSA binding, antioxidant and cytotoxicity)

Synthesis of bio-efficient homobimetallic complexes, [Cu₂(L¹)₂(dipic)](NO₃)₂.3H₂O (1), [Zn₂(L¹)₂(dipic)](NO₃)₂.4H₂O (2), [Cu₂(L²)₂(oxa)](NO₃)₂.4H₂O (3) and [Zn₂(L²)₂(oxa)] (NO₃)₂.5H₂O (4) was carried out using Schiff bases [(N¹E,N²E)-N¹,N²-bis(5-chlorothiophen-2-ylmethylene)-4-chlorobenzene-1,2-diamine; L¹] and [(N¹E,N²E)-N¹,N²-bis(5-chlorofuran-2-ylmethylene)-4-chlorobenzene-1,2-diamine; L²] as main ligands and dicarboxylate moieties of 2,6-pyridine dicarboxylic acid (H₂-dipic) and oxalic acid (H₂-oxa) as co-ligands, respectively in order to apprehend their structure activity relationships on the basis of pharmacophore hybrid approach. The stoichiometry, geometry, thermal stability, morphology and crystallite size of the compounds were inferred by analytical, spectral (FT-IR, ¹H NMR and ¹³C NMR and Mass), thermal (TGA/DTA), SEM and XRD studies. In-vitro DNA and HSA binding profiles of complexes were analysed by different biophysical measurements. The absorption study divulged that the observed alterations in the physico-chemical properties of complexes upon binding with DNA connoted their intercalative binding mode while fluorescence quenching mechanism was quantified by using Stern Volmer constant (K_SV)_; 1.73×10⁴ (1), 1.47×10⁴ (2), 5.65×10³ (3) and 3.60×10³M^-1 (4) which discerned that hybrid pharmacophore active metal complexes (1 and 2) exhibited efficient quenching effect with Ct-DNA in comparison to complexes (3 and 4) due to greater planarity and extent of conjugation (π-π interactions). The intercalative binding mode of complexes is further supported by competitive displacement assay by using fluorogenic dyes (EtBr and Hoechst 33258). The results of HSA fluorescence study divulged static quenching of the complexes (1-4) with K_SV values of 7.24×10⁴ (1), 6.03×10⁴ (2), 5.06×10⁴ (3) and 2.85×10⁴ (4) while K_b values; 1.16×10⁵ (1), 2.01×10⁴ (2), 5.84×10³ (3) and 8.60×10² (4) suggested them potent avid binder of HSA. Additionally, comparative estimation of scavenging properties using DPPH, superoxide(O₂^.-), hydroxyl (OH^-) and ABTS method and in-vitro cytotoxicity against different cell lines (MCF-7, HeLa and Hep G2) brought out distinct biopotency of complexes due to diverse structural features and chelation effect.

Synthesis, characterization and electrochemical studies of some Ni(II)Cu(II) heterobimetallic complexes derived from succinoyldihydrazones

Synthesis, structural characterization and redox properties of three heterobimetallic complexes with formule {[NiCu(L(n))(CH3OH)3]·CH3OH} using [Cu(H2L(n))(H2O)] as metalloligand have been demonstrated in the present paper. Electronic spectroscopy suggests that the copper center has a pseudo square pyramidal stereochemistry in all the complexes while the nickel center has a distorted octahedral stereochemistry. The electron transfer reactions of the complexes have been investigated by cyclic voltammetry.

Structural, spectral, NLO and MEP analysis of the [MgO₂Ti₂(OPr(i)ⁱⁱ)₆], [MgO₂Ti₂(OPr(i)ⁱ)₂(acac)₄] and [MgO₂Ti₂(OPr(i)ⁱ)2(bzac)₄] by DFT method

Quantum chemical calculations are performed on [MgO2Ti2(OPr(i))6] and [MgO2Ti2(OPr(i))2(L)4] complexes. L is acetylacetonate (acac) and benzoylacetonate (bzac) anion. The crystal structures of these complexes have not been obtained as experimentally but optimized structures of these complexes are obtained as theoretically in this study. Universal force field (UFF) and DFT/B3LYP method are used to obtain optimized structures. Theoretical spectral analysis (IR, (1)H and (13)C NMR) is compared with their experimental values. A good agreement is found between experimental and theoretical spectral analysis. These results mean that the optimized structures of mentioned complexes are appropriate. Additionally, the active sites of mentioned complexes are determined by molecular electrostatic potential (MEP) diagrams and non-linear optical (NLO) properties are investigated.

Synthesis, characterization and reactivity of trinuclear Cu(II) complexes derived from disalicylaldehyde malonoyldihydrazone

Three new homotrinuclear copper(II) complexes [Cu3(slmh)(μ-Cl)2(CH3OH)3]⋅0.5CH3OH (1), [Cu3(slmh)(NO3)2(CH3OH)5]⋅1.5CH3OH (2) and [Cu3(slmh)(μ-ClO4)2(CH3OH)3]⋅2CH3OH (3) from disalicylaldehyde malonoyldihydrazone have been synthesized and characterized. The composition of the complexes has been established on the basis of data obtained from analytical and thermoanalytical data. The structure of the complexes has been discussed in the light of molar conductance, electronic, FT-IR and far-IR spectral data, magnetic moment and EPR spectral studies. The molar conductance values for the complexes in DMSO solution indicate that all of them are non-electrolyte. The magnetic moment values for the complexes suggest considerable metal-metal intramolecular interaction between metal ions in the structural unit of the complexes. The EPR spectral features reveal that at RT, the ground state for the complexes is a mixture of the quartet state (S=3/2) and doublet state (S=1/2). At lower temperature, the ground state for the complexes is dx(2)-y(2) with considerable contribution from dz(2) orbital. Dihydrazone ligand is present in enol form in all of the complexes. The complexes have distorted square pyramidal stereochemistry. The electron transfer reactions of the complexes have been investigated by cyclic voltammetry. Hydrogen peroxide mediated oxidation of benzyl alcohol catalyzed by complex 1 has been studied.