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A series of transition metal complexes having general formula [M(Lb)(L1)](NO3)2, (where, M = Cu(II), Ni(II), and Zn(II)) of mixed ligands, Lb = N-Isonicotinamido-Thiophene-2-Carbaldimine, L1 = 1, 10-phenanthroline, were synthesized. The obtained compounds were successfully characterized by different spectroscopic techniques. Conductivity measurements indicated that all complexes were 1:2 electrolytes in nature. IR spectra indicated that ligands coordinated to metals via the carbonyl oxygen atom and the azomethine nitrogen atom. Magnetic moment values and UV-Visible spectra confirmed square planar structure around the Cu(II), and Ni(II) ions, and a tetrahedral geometry around the Zn(II) ion. The metal complexes of Lb and L1 were tested against Escherichia coli and Pseudomonas sp. Among the tested compounds, Zn(II)complex showed higher antibacterial activity over both bacterial strains against reference drug Kanamycin. Moreover, synthesized metal complexes exhibited moderate antioxidant activity than the Schiff base. Cu(II) complexes were found to be most active whereas, Zn(II) complexes showed the lowest antioxidant activity comparable to the BHT.

A new Schiff base Co(II) complex and - peroxo complex were synthesized and characterized by thin layer chromatography (TLC), elemental analyses, magnetic moment, conductivity measurements, UV-Vis., IR and ESI-MS spectral studies. The cobalt ion was participated in direct complexation with the Schiff base (SB) ligand derived from o-aminobenzoic acid and cinnamaldehyde during the single pot reaction. IR spectral data showed that the Schiff base ligand coordinated to the metal ion through nitrogen of azomethine group and oxygen of carboxyl group (COO-). The molar conductance values indicated that both the complexes are non-electrolytic in nature. Antibacterial activity of the complexes was tested against four pathogenic bacteria namely Staphylococcus aureus, Bacillus cereus, Escherichia coli & Shigella dysenteriae with standard Kanamycin-30. The results showed that both type of complexes have moderate to strong antibacterial activity and the peroxo complex is relatively more potential towards all the tested organisms.

Zr (IV) and Sn (II) complexes were prepared with bidentate ligand, benzyl 2-(3-phenylallylidene) hydrazinecarbodithioate, derived from the condensation of S-benzyldithiocarbazate (SBDTC) with cinnamaldehyde and characterized by microanalysis, molar conductance and magnetic measurements, IR, electronic and ESI-MS studies. It was found that the ligand coordinated to the metal center through azomethine nitrogen and thiol sulfur atoms to form octahedral complexes with both the metal ions. The antimicrobial activities of the ligand and its complexes were investigated against the gram-positive and gram-negative bacteria and the fungus strain. The metal complexes showed strong activity than the free ligand.

Two new peroxo-complexes of Cd(II) and Zr(IV) ion containing Schiff base (SB) were synthesized and characterized by Thin Layer Chromatography (TLC), Elemental analyses, conductivity, magnetic moment measurements, UV-Vis. and FT-IR spectral studies. The Schiff base ligand derived from cinnamaldehyde and o-aminophenol participated in complexation through a single pot reaction. FT-IR spectra showed that the Schiff base ligand coordinated to the metal ion through nitrogen of azomethine group and oxygen of hydroxyl group & peroxo group (O-O). The molar conductance values indicated the non-electrolytic nature of both the complexes. Antibacterial activity of the complexes was tested against four pathogenic bacteria, two Gram-positive Staphylococcus aureus & Bacillus cereus and two Gram-negative Escherichia coli & Shigella dysenteriae with standard Kanamycin-30. The result showed that Cd(II) complex exhibited more potential antibacterial activity than the Zr(IV) complex against all the tested pathogens.

Two new peroxo complexes of Cu(II) and Ni(II) ion containing Schiff base (SB) were synthesized and characterized by TLC, Elemental analyses, conductivity, magnetic moment measurements, UV-Vis. and IR and ESI-MS spectral studies. The Schiff base ligand derived from cinnamaldehyde and o-aminophenol participated in complexation through a single pot reaction. IR spectra showed that the Schiff base ligand coordinated to the metal ion through nitrogen of azomethine group and oxygen of hydroxyl group & peroxo group (O-O). Magnetic moment value coupled with electronic spectral data suggested a square planar geometry for both the complexes. The molar conductance values indicated the non-electrolytic nature of the complexes. Antibacterial activity of the complexes was tested against four pathogenic bacteria, two Gram-positive Staphylococcus aureus & Bacillus cereus and two Gram-negative Escherichia coli & Shigella dysenteriae with Kanamycin (K-30) standard. The result shows that Cu(II) complex exhibited more potential antibacterial activity than the Ni(II) complex against all the tested organisms.

The metal (II) complexes, Na2[ML2] [M = Cu, Co, Ni, and Zn], of salicylaldehyde thiosemicarbazone (L) containing a trifunctional ONS-donor system have been synthesized and characterized on the basis of physicochemical data by elemental analysis, magnetic moment, molar conductance, and spectroscopic (electronic, IR and ESI-MS). The ligand functions as ONS tridentates producing octahedral complexes. All compounds showed significant antibacterial activity in different ranges against gram positive (Bacillus subtillus) and gram negative (Escherichia coli) bacteria.

New complexes of Cu (II) and Ni (II) of the Schiff Base, 2-(((2-((4-hydroxybenzylidene) amino)ethyl)imino)methyl) phenol were synthesized and characterized by analytical and physico-chemical techniques including magnetic susceptibility, conductivity measurements, electronic and IR spectral studies. The infrared spectral studies revealed the tetra-dentate nature of the Schiff base in the complexes. On the basis of all characterizations, square- planar geometry has proposed for all the obtained complexes. The complexes showed moderate antimicrobial activity against Escherichia coli and Staphylococcus aureus.

Two complexes of Cu(II) and Ni(II) with the ligand N- (4-methoxybenzylidene) isonicotinohydrazide, having the formula [M(La)2]2+ (M = Cu(II) and Ni(II)) were synthesized. The ligand was synthesized by the condensation of isonicotinic acid hydrazide (isoniazid) with 4- methoxybenzaldehyde (p- anisaldehyde). The complexes were characterized by FTIR, UV-Vis spectroscopy, molar conductivity, magnetic susceptibility and evaluated for their in vitro antibacterial activity against human pathogens like gram negative Escherichia coli (E. coli) and gram positive Bacillus cereus (B. cereus)strains. The results indicate that all complexes consist of N and O coordination with metals has better antimicrobial activity.

Schiff base, S-methyl-2-(4-methoxybenzylidine) dithiocarbazate as a primary ligand (HL1), quinoline (L2) as a co-ligand, and hydrated metal salts have been reacted in ethanol in 1:2:1 molar ratio to produce mixed-ligand complexes of the type, [M(L1)(L2)].NO3 [M = Uranyl(VI), Th(VI), Zr(IV)], The isolated products have been structurally investigated by elemental analyses, 1H NMR, IR and UV-Vis studies. The electronic studies shows octahedral geometry for all the studied complexes, whereas the molar conductance data suggest an ionic nature. Density functional computation (DFT) studies are also carried out in order to determine the bonding inside the structure of the complexes. The studied mixed-ligand complexes showed moderate antibacterial activity when evaluated against four pathogenic bacteria: Shigella dysenteriae, Bacillus subtilis, Agrobacterium tumefaciens, and Escherichia coli. In addition, molecular docking analysis for all the complexes, using the CLC Drug Discovery Workbench software, showed that they virtually docked on S. dysenteriae, B. subtilis, A. tumefaciens, and E. coli.

A new series of [Ni(II)L2](1), [Cu(II)L2](2) and [Co(II)L2](3)(L = benzyl-2-((1E,4E)-1,5-diphenylpenta-1,4-dien-3-ylidene) hydrazine carbodithioate) Schiff base metal complexes have been synthesized. The ligand and its metal complexes were characterized by elemental analysis, 1H NMR, UV-Vis, FT-IR and magnetic moment, molar conductance and thermal analysis. The electrochemical behaviors of these complexes were investigated by cyclic voltammetry in DMF. The spectroscopic analyses and magnetic moment value suggested four coordinated geometry for three metal complexes, tetrahedral structure of complex 1 and square planer structure of complex 2 and 3. The ligand and its metal complexes were evaluated for their antibacterial (Bacillus cereus, Bacillus subtilis, Escherichia coli) activities. The complex 1 and Complex 2 revealed moderate activity against both gram positive bacteria (B. cereus and B. subtilis) with the minimum inhibitory concentration (MIC) value of 256 microg/mL.

Five oxovanadium(IV) complexes of the type [VO(L)(DPhen)], containing Schiff base derived from α-amino acid, [where L = 3-hydroxybenzaldehyde-α-alanine (hb-Ala), 3-hydroxybenzaldehyde-DL-phenylalanine (hb-Phe), 3-hydroxybenzaldehyde-leucine (hb-Leu), 3-hydroxybenzaldehyde-glycine (hb-Gly) and 3-hydroxybenzaldehyde-DL-methionine (hb-Met) & DPhen = 5,6-Dimethyl-1,10-phenanthroline] have been synthesized and characterized by some physicochemical properties, molar conductance, magnetic susceptibilities measurements, elemental analysis, UV-Visible, FT-IR and EIS-MS spectral studies. The molar conductance values evidenced the non-electrolytic nature of the complexes. The magnetic moment values of the complexes are in accordance with the d1 electronic configuration of the VIVO2+ moiety and indicates the paramagnetic behavior of the complexes. IR spectral data indicates the coordination of tridentate amino acid Schiff base ligands to the vanadyl (VO2+) ion through O, N, O-donor. ESI-MS spectral study confirmed the proposed structure of the complexes. All the analytical data suggested that all the complexes possess to have distorted octahedral geometry. The complexes were screened for their antibacterial activity against four human pathogenic bacteria; two Gram positive Escherichia coli & Pseudomonas aeruginosa and two Gram negative Staphylococcus aureus & Bacillus cereus with Kanamycin (K-30) standard. The result shows that all the complexes have moderate to strong potential antibacterial activity against all the pathogenic bacteria. This work is licensed under a Creative Commons Attribution 4.0 International License.

A novel bidentate Schiff base containing NS donor sequences was synthesized by condensing S-methyldithiocarbazate (SMDTC) with p-anisaldehyde. A series of complexes of the ligand with Cu(II), Ni(II), Zn(II), Pb(II), Co(II), Mn(II) and U(VI) were studied and characterized by various physico-chemical methods. Cu(II), Ni(II) and Zn(II), Pb(II) complexes were four-coordinate with square plannar and tetrahedral geometry respectively. Co(II), Mn(II), and U(VI) complexes were six-coordinate with octahedral geometry. Antimicrobial activity of the prepared complexes was tested as resistance to antimicrobial agents in a wide variety of nosocomial and community-acquired pathogens. The highest antimicrobial activity was detected for the complex Co(II) against candida species.

A novel series of transition metal complexes of Mn(II), Fe(III) Co(II), Ni(II), Cu(II), and Sb(III) containing the bidentate Schiff base derived from condensation of S-methyldithiocarbazate and cinnamaldehyde were synthesized and characterized by IR, 1H NMR, UV-Vis, and some physical measurements. IR spectral studies indicated the binding sites of the Schiff base ligand with the metal ions. Molar conductance data and magnetic susceptibility measurements indicated monomeric and neutral nature of the complexes. The complexes demonstrated moderate to strong antimicrobial activity.

Copper(II) complexes containing two Schiff base ligands derived from 2-hydroxybenzaldehyde with 2-aminophenol and 3-aminophenol have been synthesized and characterized by means of analytical, magnetic, and spectroscopic methods. Bacteria, fungus,Entamoeba histolytica, and antineoplastic activities of the synthesized complexes have been determined by monitoring the parameters cell growth inhibition, survival time of tumour mice, time-body relation, causing of intraperitoneal cells and macrophages, alkaline phosphatase activity, hematological effect, and biopsy of tumour.

Metals contribute important roles in biological system. It is recognized that metals are highly linked in cellular and subcellular functions. With the application of novel and experienced tools to study biological and biochemical systems the true role of inorganic salts in biological systems can be studied. Schiff base metal complexes show a broad range of biological activity. The activity of Schiff base ligand is usually increased by complexation with the metal ion. The copper complexes of Schiff bases have striking properties such as antibacterial, antifungal, antiviral, anti-inflammatory, anti-tumor and cytotoxic activities, plant development controller, enzymatic activity and applications in pharmaceutical fields. The divalent cations Zn2+, Ca2+ and Mg2+ prevent cytotoxicity and in vivo antagonize Cd- induced carcinogenesis. Lack of body iron is common in cancer patients and it is associated with complications in surgery and in animal experiments. The transport of iron and other metal ions by the blood plasma is achieved through the formation of protein complexes. Copper is placed as a vital metalloelement and is primarily connected with copper-dependent cellular enzymes. Metals are also used as inorganic drugs for many diseases. In this review our main focused on research undertaken for biological activity study of Cu(II) metal complexes containing Schiff bases over the past few decades.

Schiff base ligand and its Cu(II) complex had been synthesized by the condensation reaction of isatin with amino acids (cysteine / glycine / leucine / alanine ). The Structure and spectral properties of ligand and complex were confirmed by UV, FT-IR and some physiochemical measurements. The spectral properties showed that it was a distorted tetrahedral geometry with a tridentate ligand and chloride ion. IR spectral studies show the binding sites of the Schiff base ligand with the metal ion. Molar conductance data and magnetic susceptibility measurements give evidence for monomeric and non-electrolytic nature of the complexes. The Schiff base Cu(II) complex was subjected to antimicrobial studies screened by employing the Disc Diffusion method. All the synthesized complexes showed strong antibacterial activity.

A series of transition metal complexes of Cu(II), Ni(III) Zn(II), Cd(II), Co(II), Sb(III) and Fe(III)Containing Bidentate Schiff base, [NI-(4-chloro-benzylidene)-hydrazecarbodithioicacid methyl ester] derived from the condensation of S- methyldithiocarbazate and P-chlorobenzaldehyde were synthesized and characterized by IR, UV- Vis., and some physical measurements. IR spectral studies show the binding sites of the Schiff base ligand with the metal ion. Molar conductance data and magnetic susceptibility measurements give evidence for monomeric and neutral nature of the complexes.

Transition metal complexes of Cu(II), Ni(II), Co(II) and Fe(III) Containing Bidentate Schiff base, derived from the condensation of salicyladehyde and 2-aminophenol were synthesized and characterized by IR, UV- Vis., and some physical measurements. IR spectral studies show the binding sites of the Schiff base ligand with the metal ion. Molar conductance data and magnetic susceptibility measurements give evidence for monomeric and electrolytic nature of the complexes. Structural studies showed that Cu(II), Ni(II) and Co(II) ion complexes are tetrahedral and Fe(III) ion complex is octahedral.