New penta-Coordinated Cadmium(II) Complexes: Synthesis, Characterization, Thermal, Antimicrobial, Antioxidant and Cytotoxicity Properties

In this paper, a new tridentate Schiff base ligand (L) with nitrogen donor atoms and its cadmium(II) complexes with the general formula of CdLX2 (X=Cl-, Br-, I-, SCN-, N3 -, NO3 -) have been synthesized and characterized by physical and spectral (FT/IR, UV-Vis, Mass, and 1H, 13C NMR spectroscopies) methods. Also nano-structured cadmium chloride and bromide complexes were synthesized by sonochemical method and then used to prepare nanostructured cadmium oxide confirmed by XRD and SEM techniques. Thermal behavior of the compounds was studied in the temperature range of 25 to 900 °C under N2 atmosphere at a heating rate of 20 °C/ min. Moreover, thermo-kinetic activation parameters of thermal decomposition steps were calculated according to the Coats-Redfern relationship. Antimicrobial activities of the synthesized compounds against two gram-positive and two gram-negative bacteria such as Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and two fungi of Candida albicans and Aspergillus niger were investigated by well diffusion method. SEM technique was used to monitor the morphological changes of the bacteria treated with the compounds. The 2,2-Diphenyl-1-picrylhydrazyl(DPPH) and the ferric reducing antioxidant power (FRAP) methods were used to evaluate the antioxidant ability of the ligand and its cadmium(II) complexes. In final, the cytotoxicity properties of the ligand and some cadmium(II) complexes against PC3 cancer cells were evaluated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) bioassay and nitric oxide (NO) level measurement. The morphological changes of prostate cancer (PC3) cells due to treatment with the ligand and its complexes confirmed their anticancer effectiveness.

2-methoxy-4-(((5-nitropyridin-2-yl)imino)methyl)phenol Schiff base ligand and its Cu(II) and Zn(II) complexes: synthesis, characterization and biological investigations

In this current work we have prepared a Schiff base ligand, (HL) derived from 5- nitropyridine-2-amine with 4-hydroxy-3-methoxybenzaldehyde and its Cu(II), and Zn(II) in 2:1 stoichiometric ratio (2HL:M). The formation of the ligand and the metal complexes were evaluated by means of MS, FT-IR, UV-Visible, 1H-NMR, 13C-NMR and thermogravimetric methods. The free radical scavenging activity of compounds was evaluated through a sequence of in vitro assays viz., DPPH, ABTS and Superoxide where BHA was used as a positive controller. In vitro α-glucosidase inhibitory activities showed that complexes had considerable inhibitory potential when compared to the ligand.

Synthesis, Characterization, Antibiofilm and Anticancer Activity of New Ruthenium Complexes with 2,2'-Bipyridine-4,4'-Dicarboxamide

Abstract:

New ruthenium complexes bearing bipyridine ligands with different substituents (propyl, hexyl, isobutyl, and benzyl) were synthesized and characterized by MS, NMR, FTIR, and UV/Visible spectroscopy. Moreover, their cytotoxic, anti-carcinogenic, and anti-biofilm activities were evaluated. The electrochemical properties of the complexes have been investigated by cyclic voltammetry. The HOMO and LUMO energy levels of RuL1-RuL4 were found as (-5.45 eV)-(-5.46 eV) and (-2.98 eV)-(-3.01 eV), respectively. Cytotoxic activities of ruthenium complexes were investigated in Caco-2, HepG2, and HEK293 cells. It was found that RuL3 showed a cytotoxic effect on cancer cells without affecting non-cancerous cells at applied doses. The presence of the benzyl group may increase the cytotoxic effect of RuL3 compared to other derivatives that contain the alkyl group. The apoptotic effect of the RuL3 derivative was determined by using Arthur image-based cytometer. It found that RuL3 was induced apoptosis in Caco-2 (5-fold) and HepG2 (2-fold) cancer cells, respectively. All ruthenium complexes inhibited Staphylococcus aureus ATCC 29213 biofilm, but RuL3 had a more pronounced effect. Moreover, RuL3 had biofilm inhibition and biofilm degradation effect while RuL1 and RuL4 demonstrated only biofilm inhibition. The fluorescent microscopy analysis confirmed the antibiofilm effect of ruthenium complexes. All of these results clearly showed that RuL3 showed cytotoxic and apoptotic effects on cancer cells.

Synthesis and Biological Evaluation of Novel Zn(II) and Cd(II) Schiff Base Complexes as Antimicrobial, Antifungal, and Antioxidant Agents

(E)-N,N-Dimethyl-2-((E-1-(2-(p-tolyl)hydrazono)propan-2-ylidene)hydrazine-1-carbothioamide (DMPTHP) and their Zn(II) and Cd(II) complexes have been synthesized and characterized. Different tools of analysis such as elemental analyses, IR, mass spectra, and 1H-NMR measurements were used to elucidate the structure of the synthesized compounds. According to these spectral results, the DMPTHP ligand behaved as a mononegatively charged tridentate anion. Modeling and docking studies were investigated and discussed. Novel Schiff base (DMPTHP) ligand protonation constants and their formation constants with Cd(II) and Zn(II) ions were measured in 50% DMSO solution at 15°C, 25°C, and 35°C at I = 0.1 mol·dm−3 NaNO3. The solution speciation of different species was measured in accordance with pH. Calculation and discussion of the thermodynamic parameters were achieved. Both log K1 and –ΔH1, for M(II)-thiosemicarbazone complexes were found to be somewhat larger than log K2 and –ΔH2, demonstrating a shift in the dentate character of DMPTHP from tridentate in 1 : 1 chelates to bidentate in 1 : 2; M : L chelates and steric hindrance were generated by addition of the 2nd molecule. The compounds prepared have significant activity as antioxidants, similar to ascorbic acid. It is hoped that the results will be beneficial to antimicrobial agent chemistry. The formed compounds acted as a potent antibacterial agent. Molecular docking studies were investigated and have proved that DMPTHP as antibacterial agents act on highly resistant strains of E. coli and also as an anticancer agent.

Anticancer Activities of Cu(II) Complex-Schiff Base and Low-Frequency Electromagnetic Fields and the Interaction Between Cu(II) Complex-Schiff Base with Bovine Serum Albumin by Spectroscopy

Cancer is the consequence of abnormal cell proliferation, which leads to the formation of abnormal mass. In this study, we aimed to determine the anticancer properties of Cu(II)-Schiff base complex and low-frequency electromagnetic field, and the interaction between BSA and Cu(II) complex. Firstly, Schiff base of the Cu(II) complex in the N,N'-dipyridoxyl(1,2 diaminobenzene) was originally synthesized. Following, the breast cancer was transplanted with the TUBO cells in vivo. Then, treatment of the cancerous mice was done by low-frequency electromagnetic field and the Cu(II)-Schiff base complex. In this project, antiproliferative activity on breast cancer cells was tested by TUBO cells using MTT assay and apoptosis properties were studied by flow cytometry. The interaction between the Cu(II)-Schiff base complex and bovine serum albumin (BSA) was checked by fluorescence and UV-vis absorbance spectroscopy. Tumor tissue investigation demonstrated that the low-frequency electromagnetic field and Cu(II)-Schiff base complex induce apoptosis and inhibit tumor growth. MTT results unveiled a cytotoxic impact on breast cancer cells. Flow cytometry analysis demonstrates that the anticancer effect of Cu(II)-Schiff base complex on breast cancer cells (MCF7) was associated with the cell cycle arrest. The results of fluorescence spectra and UV-vis absorption spectra showed that the conformation of bovine serum albumin has been changed in the presence of Cu(II)-Schiff base complex. Cu(II)-Schiff base complex and low-frequency electromagnetic field have anticancer properties. The spectroscopy method indicates the binding between Cu(II)-Schiff base complex and BSA.

Synthesis and Biological Evaluation of New Hydrazone Derivatives of Quinoline and Their Cu(II) and Zn(II) Complexes against Mycobacterium tuberculosis

A new series of quinoline hydrazone derivatives and their metal complexes have been synthesized and their biological properties have been evaluated against Mycobacterium tuberculosis (H37 RV strain). Most of the newly synthesized compounds displayed 100% inhibitory activity at a concentration of 6.25–25 μg/mL, against Mycobacterium tuberculosis. Fluorescence properties of all the synthesized compounds have been studied.

Theoretical spectroscopic study of seven zinc(II) complex with macrocyclic Schiff-base ligand

Seven zinc complexes, which are [ZnL(1)](2+), [ZnL(2)](2+), [ZnL(3)](2+), [ZnL(4)](2+), [ZnL(5)](2+), [ZnL(6)](2+) and [ZnL(7)](2+), are studied as theoretically. Structural parameters, vibration frequencies, electronic absorption spectra and (1)H and (13)C NMR spectra are obtained for Zn(II) complexes of macrocyclic penta and heptaaza Schiff-base ligand. Vibration spectra of Zn(II) complexes are studied by using Density Functional Theory (DFT) calculations at the B3LYP/LANL2DZ. The UV-VIS and NMR spectra of the zinc complexes are obtained by using Time Dependent-Density Functional Theory (TD-DFT) method and Giao method, respectively. The agreements are found between experimental data of [ZnL(5)](2+), [ZnL(6)](2+) and [ZnL(7)](2+) complex ions and their calculated results. The geometries of complexes are found as distorted pentagonal planar for [ZnL(1)](2+), [ZnL(2)](2+) and [ZnL(3)](2+) complex ions, distorted tetrahedral for [ZnL(4)](2+) complex ion and distorted pentagonal bipyramidal for [ZnL(5)](2+), [ZnL(6)](2+) and [ZnL(7)](2+) complex ions. Ranking of biological activity is determined by using quantum chemical parameters and this ranking is found as: [ZnL(7)](2+)>[ZnL(6)](2+)>[ZnL(5)](2+)>[ZnL(3)](2+)>[ZnL(2)](2+)>[ZnL(1)](2+).

Microwave assisted synthesis, characterization and biocidal activities of some new chelates of carbazole derived Schiff bases of cadmium and tin metals

This study is planned to report the advancement of green microwave approach in the fabrication of a new series of biologically potent (N^X, where X=O/S) donor Schiff bases and their cadmium(II) and tin(II) complexes. The ligands and their metal complexes have been characterized in terms of elemental analysis, molar ionic conductance, magnetic moment and spectral (IR, UV-Vis, NMR ((1)H, (119)Sn), FAB-mass, thermal and XRD) data. The data revealed that the ligands coordinated to the metal center via nitrogen and oxygen/sulfur atoms and form an octahedral arrangement of the ligands around central metal atom. All compounds were evaluated for their in vitro antimicrobial activities against two pathogenic bacteria Bacillus subtilis and Escherichia coli and two fungi Aspergillus niger and Aspergillus flavus by standard disc diffusion method. The discs were stored in an incubator at 37°C. The compounds were dissolved in DMF at 500 and 1000 ppm concentrations for screening biocidal activity. The compounds were dissolved in DMF to get the 100 and 200 ppm concentration of test solutions for screening fungicidal activity. The inhibition zone around each disc was measured (in mm) after 24 h and 96 h for biocidal and fungicidal activities respectively.

Spectroscopic and biological studies of new binuclear metal complexes of a tridentate ONS hydrazone ligand derived from 4-amino-6-methyl-3-thioxo-3,4-dihydro-1,2,4-triazin-5(2H)-one and 4,6-diacetylresorcinol

The binuclear hydrazone, H2L, ligand derived from 4-amino-6-methyl-3-thioxo-3,4-dihydro-1,2,4-triazin-5(2H)-one and 4,6-diacetylresorcinol, in the molar ratio 2:1, and its copper(II), nickel(II), cobalt(II), zinc(II), cadmium(II), cerium(III), iron(III), oxovanadium(IV) and dioxouranium(VI) complexes have been synthesized. Structures of the ligand and its metal complexes were characterized by elemental analyses, spectral (infrared, electronic, mass, 1H NMR and ESR) data, magnetic susceptibility, molar conductivity measurements and thermal gravimetric analysis (TGA). The ligand acts as dibasic with two ONS tridentate sites. The bonding sites are the azomethine nitrogen, phenolate oxygen and sulfur atoms. The metal complexes exhibit different geometrical arrangements such as square planer, tetrahedral and octahedral. The Coats-Redfern equation was used to calculate the kinetic and thermodynamic parameters for the different thermal decomposition steps of some complexes. The ligand and its metal complexes showed antimicrobial activity towards Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), Gram-negative bacteria (Salmonella typhimurium and Escherichia coli), yeast (Candida albicans) and fungus (Aspergillus fumigatus). Structural parameters of the ligand and its metal complexes were theoretically computed on the basis of semiempirical PM3 level, and the results were correlated with their experimental data.

Theoretical Studies of Structure, Spectroscopy, and Properties of a New Hydrazine Derivative

We will report a combined experimental and theoretical study on molecular structure, vibrational spectra, and energies of (E)-1-(2,4-dinitrophenyl)-2-[(4-methylphenyl)methylidene]hydrazine (1). The molecular geometry and vibrational frequencies and energies in the ground state are calculated by using HF and DFT levels of theory with 6-311G basis sets. The calculated HOMO and LUMO energies also confirm that charge transfer occurs within the molecule. The harmonic vibrational frequencies were calculated, and the scaled values have been compared with experimental FTIR and FT-Raman spectra. The observed and the calculated frequencies are found to be in good agreement. The experimental spectra also coincide satisfactorily with those of theoretically constructed bar-type spectrograms.

Spectroscopic, thermal and toxicity studies of some 2-amino — 3- cyano — 1, 5 -diphenylpyrrole containing Schiff bases copper (II) complexes

Two novel Schiff base ligands of 2-amino-3-cyano-1,5-diphenylpyrrole and salicylaldehyde (HL1) or 2- hydroxy1-naphthylaldehyde (HL2) and their copper(II) complexes have been synthesized and characterized by elemental analyses, spectral (UV-Vis, IR, EPR, Mass (for ligands)), thermal (DTA-TGA) methods, magnetic and conductance measurements. IR results demonstrate the bidentate binding of the Schiff base ligands involving azomethine nitrogen, phenolic or naphtholic oxygen and suggest the presence of HL2 and complexes (1, 2, 4 and 8) in enolimine-ketonamine tautomeric forms in the solid state. The EPR spectral data of complexes (2, 5, 6) show that the metal — ligand bonds have considerable covalent character. The thermal studies show that complexes (1, 2, 4 and 8) that are present in enolimine-ketonamine tautomeric forms exhibit lower thermal stability. The effect of synthesized ligands (HL1, HL2) and complexes (1, 5) were tested on the mortality of entomopathogenic nematodes (EPN) (Heterorhabditis bacteriophora and Steinernema carpocapsae). The study shows that the mortality of the nematodes increased with increasing concentrations of copper(II) ion, ligands and complexes. Copper(II) ion was the most toxic for EPN.

Transition metal complexes of isonicotinic acid (2-hydroxybenzylidene)hydrazide

A new series of transition metal complexes of Schiff base isonicotinic acid (2-hydroxybenzylidene)hydrazide, HL, have been synthesized. The Schiff base reacted with Cu(II), Ni(II), Co(II), Mn(II), Fe(III) and UO2(II) ions as monobasic tridentate ligand to yield mononuclear complexes of 1:2 (metal:ligand) except that of Cu(II) which form complex of 1:1 (metal:ligand). The ligand and its metal complexes were characterized by elemental analyses, IR, UV-vis, mass and 1H NMR spectra, as well as magnetic moment, conductance measurements, and thermal analyses. All complexes have octahedral configurations except Cu(II) complex which has an extra square planar geometry distorted towards tetrahedral. While, the UO2(II) complex has its favour hepta-coordination. The ligand and its metal complexes were tested against one strain Gram +ve bacteria (Staphylococcus aureus), Gram -ve bacteria (Escherichia coli), and Fungi (Candida albicans). The tested compounds exhibited higher antibacterial activities.

Mixed ligand complexes of Cu(II)-2-(2-pyridyl)-benzimidazole and aliphatic or aromatic dicarboxylic acids: Synthesis, characterization and biological activity

The synthesis and structural characterization of mixed ligand complexes derived from 2-(2-pyridyl)-benzimidazole (PBI) (1ry ligand) and aliphatic or aromatic dicarboxylic acids (2ry ligand) are reported. Cu(II) complexes were characterized on the bases of their elemental analyses, IR, ESR and thermal analyses. The elemental analysis indicated the formation of mixed ligand complexes in a mole ratio 1:1:1 (Cu:L(1):L(2)), L(1)=PBI and L(2)=oxalic acid, phthalic acid or malonic acid. IR spectra showed that PBI acts as a neutral bidentate coordinated to the Cu(II) via the pyridyl and imidazolyl nitrogen atoms. The dicarboxylic acids are bidentate with monodentate carboxylate groups. Thermal decomposition study of complexes was monitored by thermogravimetric (TG) and derivative thermogravimetric (DTG) analysis in N(2) atmosphere. The decomposition course and steps were analysed and the activation parameters of the nonisothermal decomposition were calculated from the TG curves and discussed. The isolated metal chelates were screened for their antimicrobial activities and the results are reported, discussed and compared with some known antibiotics.

Antimicrobial activity and spectral, magnetic and thermal studies of some transition metal complexes of a Schiff base hydrazone containing a quinoline moiety

A series of new copper(II), cobalt(II), nickel(II), manganese(II), iron(III), and uranyl(VI) complexes of the Schiff base hydrazone 7-chloro-4-(benzylidene-hydrazo)quinoline (HL) were prepared and characterized. The Schiff base behaves as a monobasic bidentate ligand. Mononuclear complexes with the general composition [ML2(Cl)m(H2O)2(OEt)n] x xEtOH (M = Cu(II), Co(II), Ni(II), Mn(II), Fe(III) or UO2(VI); m and n = 0-1; x = 1-3) were obtained in the presence of Li(OH) as a deprotonating agent. The nature of bonding and the stereochemistry of the complexes have been deduced from elemental analyses, infrared, electronic spectra, magnetic susceptibility and conductivity measurements. An octahedral geometry was suggested for all the complexes except the Cu(II) and UO2(VI) ones. The Cu(II) complex has a square-planar geometry distorted towards tetrahedral, while the UO2(VI) complex displays its favored heptacoordination. The Schiff base ligand, HL, and its complexes were tested against one strain gram +ve bacteria (Staphylococcus aureus), gram -ve bacteria (Escherichia coli), and Fungi (Candida albicans). The prepared metal complexes exhibited higher antibacterial activities than the parent ligand and their biopotency is discussed.

Synthesis, magnetic, spectral, and antimicrobial studies of Cu(II), Ni(II) Co(II), Fe(III), and UO2(II) complexes of a new Schiff base hydrazone derived from 7-chloro-4-hydrazinoquinoline

A new hydrazone ligand, HL, was prepared by the reaction of 7-chloro-4-hydrazinoquinoline with o-hydroxybenzaldehyde. The ligand behaves as monoprotic bidentate. This was accounted for as the ligand contains a phenolic group and its hydrogen atom is reluctant to be replaced by a metal ion. The ligand reacted with Cu(II), Ni(II), Co(II), Fe(III), and UO2(II) ions to yield mononuclear complexes. In the case of Fe(III) ion two complexes, mono- and binuclear complexes, were obtained in the absence and presence of LiOH, respectively. Also, mixed ligand complexes were obtained from the reaction of the metal cations Cu(II), Ni(II) and Fe(III) with the ligand (HL) and 8-hydroxyquinoline (8-OHqu) in the presence of LiOH, in the molar ratio 1:1:1:1. It is clear that 8-OHqu behaves as monoprotic bidentate ligand in such mixed ligand complexes. The ligand, HL, and its metal complexes were characterized by elemental analyses, IR, UV-vis, mass, and 1H NMR spectra, as well as magnetic moment, conductance measurements, and thermal analyses. All complexes have octahedral configurations except Cu(II) complex which has an extra square-planar geometry, while Ni(II) mixed complex has also formed a tetrahedral configuration and UO2(II) complex which formed a favorable pentagonal biprymidial geometry. Magnetic moment of the binuclear Fe(III) complex is quite low compared to calculated value for two iron ions complex and thus shows antiferromagnetic interactions between the two adjacent ferric ions. The HL and metal complexes were tested against one stain Gram positive bacteria (Staphylococcus aureus), Gram negative bacteria (Escherichia coli), and fungi (Candida albicans). The tested compounds exhibited higher antibacterial acivities.