Tetradentate N2O2 Donor Research Articles

Acid Mediated In‐Situ Catalytic Cleavage/Making of C=N Bonds in Bis‐Hydrazone Uranyl Complexes: Exploration of Photophysical, Electrochemical, Dye Sorption Properties and DFT Studies

AbstractTwo new uranium complexes [UO2L2(H2O)] (where L2=diacetyl bis‐isonicotinoyl hydrazone) complex 1, and [UO2(L1)2] (where L1=diacetylmonoxime isonicotinoylhydrazone) complex 2, have been synthesized by precisely adjusting the pH values of the reaction system. Complex 1 was formed in an acidic ethanolic solution (pH=3) through an in‐situ acid catalytic reaction of diacetylmonoxime isonicotinoylhydrazone and UO2(NO3)2.6H2O, while complex 2 was acquired in a neutral medium (pH=7) through self‐assembly of two ligands and one uranium (VI) metal centre. Both complexes were thoroughly characterized by elemental analysis, UV‐Visible spectroscopy, IR spectroscopy, NMR, TGA, cyclic voltammetry, and powder X‐ray diffraction. The studies indicate that the bis‐hydrazone in complex 1 is a dianionic tetradentate N2O2 donor, whereas in complex 2 it is a monoanionic tridendate N2O donor. The formation of complex 1 was further confirmed by a single‐crystal X‐ray diffraction study, which revealed the role of a water molecule in forming a pentagonal bipyramidal geometry of [UO2L2(H2O)]. Photophysical studies revealed that complexes 1 and 2 exhibited low band gap values of 2.07 and 2.12 eV, respectively, indicating their semiconducting nature. From the CV measurements, the higher negative potentials of the complexes 1 & 2 {1, −0.6 V and 2, −0.5 V vs. ferrocenium/ferrocene (Fc+/Fc)} in DMSO are assigned to the presence of {UO2}2+/{UO2}+ couple signifying their redox active nature. Dye adsorption studies show that both the complexes were able to remove 90 % of Methylene blue (MB) and Rhodamine B (RhB) from the solutions with the concentration of 10−5 M. The structural insights and electronic properties of Ligand HL1 and complex 1 were further explored by density functional theory (DFT) calculations.

An insight into the non-covalent Cl•••Cl interaction in the solid state structure of carboxylate bridged trinuclear mixed valence cobalt(III/II/III) complexes with tetradentate N2O2 donor reduced Schiff base ligands

Two mixed-valence trinuclear cobalt(III)-cobalt(II)-cobalt(III) complexes, [CoII{(μ-L1)(μ-OOCC6H5NO2)CoIII(N3)}2] (1) and [CoII{(μ-L2)(μ-OOCC6H4NO2CH3)CoIII(N3}2] (2) have been synthesized using two tetradentate N2O2 donor 'reduced Schiff base' ligands, H2L1 {2,2-dimethyl-1,3-propanediyl)bis(iminomethylene)bis(4-chlorophenol}, and H2L2{2-hydroxy-1,3-propanediyl)bis(iminomethylene)bis(4-chlorophenol}, and 3-nitrobenzoic benzoic acid or 4-methyl 3-nitrobenzoic benzoic acid as anionic co-ligands. The complexes have been characterized by spectroscopic measurements and their solid state structures have been determined by single crystal X-ray diffraction analysis. The trinuclear cobalt(III)-cobalt(II)-cobalt(III) skeleton of both the complexes are linear and centrosymmetric. Both the central cobalt(II) and terminal cobalt(III) of both the complexes are hexa-coordinated. DFT calculations have been used to analysed some supramolecular assemblies of the complex that have been observed in the solid state, specifically the Cl···Cl interactions that result in the creation of a stable 2D supramolecular assembly in the solid state. QTAIM and NCI Plot computational tools have been used to characterize the interactions. Thermo-gravimetric (TG) analysis was used to examine the thermal behaviour of both complexes. The redox behaviors of both the complexes were studied by using Cyclic Voltammetry (CV).

Formation of H-bonding networks in the solid state structure of a trinuclear cobalt(iii/ii/iii) complex with N2O2 donor Schiff base ligand and glutaric acid as bridging co-ligand: synthesis, structure and DFT study.

A trinuclear linear mixed-valence centrosymmetric cobalt(iii)-cobalt(ii)-cobalt(iii) complex, [CoII{(μ-L)(μ-Hglu)CoIII(OH2)}2](ClO4)2·6H2O has been synthesized during tetradentate N2O2 donor 'Schiff base' ligand, H2L {N,N'-bis(salicylidene)-1,3-diaminopropane} and glutaric acid (H2glu) as anionic co-ligand. The complex has been characterized by spectroscopic measurements and its solid state structure has been determined by single crystal X-ray diffraction analysis. The supra-molecular assembly formed by the hydrogen bonding interactions in the solid state of the complex has been analysed using DFT calculations.

Application of a distinctly bent, trinuclear, end-to-end azide bridged, mixed valence cobalt(iii/ii/iii) complex in the fabrication of photosensitive Schottky barrier diodes.

A mixed-valence trinuclear cobalt(iii)-cobalt(ii)-cobalt(iii) complex, [(μ-1,3-N3)Co3L(N3)3]·MeOH has been synthesized using a tetradentate N2O2 donor 'reduced Schiff base' ligand, H2L {1,3-bis(2-hydroxybenzylamino)2,2-dimethylpropane} and azide as anionic co-ligand. The complex has been characterised by elemental analysis, IR, UV-vis spectroscopy and single-crystal X-ray diffraction studies etc. The cobalt(iii)-cobalt(ii)-cobalt(iii) skeleton in the complex is non-linear and non-centrosymmetric. The redox behavior of the complex was studied by using Cyclic Voltammetry (CV). The complex is found to be a semiconductor material as confirmed by determining the band gap of this complex by experimental as well as theoretical studies. The band gap in the solid state has been determined experimentally. The conductivity of the synthesized complex based device improves considerably in illumination conditions from the non-illuminated conditions. The complex has also been used to fabricate Schottky barrier diodes.

Biphenol-based tetradentate N2O2 donor scaffold binuclear Zn(II) and trinuclear Cu(II) Complexes: Synthesis, Structure, Characterizations, and catalytic cyanosilylation of aldehydes at room temperature

In this work, two dinuclear Zn(II) complexes [Zn(H2L1)]2(complex 1), [Zn(H2L2)]2(complex 2), and a trinuclear Cu(II) complex [Cu(H2L2)]3 (complex 3) (H2L1 = 3,3′-bis-[(2,6-dimethyl-phenylimino)-methyl]-[1,1′]-biphenyl-2,2′-diol, H2L2 = 2,6-diethyl phenylimino)-ethyl]-[1,1′]-biphenyl-2,2′- diol) are reported. The complexes 1, 2 &3 have been produced and isolated for the first time in a well-defined and air-stable form by reacting biphenol-based tetradentate N2O2-type (H2L1 and H2L2) ligands with the respective metal acetate salts. The synthesised compounds were characterized by UV–Vis spectroscopy, elemental analysis, mass spectrometry and Fourier-transform infrared spectroscopy (FT-IR). Single crystal X-ray diffraction (SCXRD) study revealed distorted tetrahedral geometry surrounding the core Zn2+ cations (1–2) that were bridging the teradentate N2O2 ligands. In complex-3, the Cu(II) center is four-coordinated via tetradentate N2O2 donor ligand, forming slightly distorted square planar geometry with an angular C2-symmetric core and exhibits weak antiferromagnetic (AF) interactions. Hirshfeld surface analysis and fingerprint plots were used to investigate the intermolecular interactions in the crystalline state. Strong H…H and H… C/C…H intermolecular interactions were seen on the Hirshfeld surface when it was mapped over dnorm, shape index, and curvature. These interactions were found to be the main contributors to crystal packing. Excellent catalytic activity was demonstrated for the dinuclear zinc(II) complexes [Zn(H2L1)]2 (1)and [Zn(H2L2)]2 (2) in the cyanosilylation reaction of various aryl aldehydes into value-added cyanohydrins at room temperature and under solvent free conditions.

Mononuclear Mn(III) complex with a terminal azide supported by phenol-based tetradentate N2O2 donor ligand: Synthesis, structure, properties, and catechol oxidase activity

Mixed ligand octahedral Mn(III) complex [Mn(L)(CH3OH)(N3)] (1) with sterically constrained phenol-based tetradentate N2O2 ligand, N,Nʹ-dimethyl-N,Nʹ-bis (2-hydroxy-3,5-dichlorobenzyl)-ethylenediamine (H2L) in association with azide ion and methanol as ancillary ligand has been synthesized. Synthesis, structure, properties, and catecholase activity of the mononuclear manganese complex (1) are described. Complex (1) crystallizes in triclinic space group P-1 with a = 10.5431(5) Å, b = 11.3731(6) Å and c = 22.9638(12) Å. The crystal structure reveals that complex (1) is an Mn (III) complex with flexible phenol-based ligand in association with azide as a terminal monodentate ligand. Electrochemical study of the mononuclear manganese complex (1) gives two quasi reversible oxidation peaks (E11/2≈ 0.18 V and E21/2≈ 0.23 V) in the positive potential range versus Ag/AgCl reference in acetonitrile due to ligand centered phenolate/phenoxyl couple. Complex (1) shows a strong emission band at 440 nm. The complex exhibits catechol oxidase activity in methanol. Oxidation of 3,5-di-tert-butylcatechol to 3,5-di-tert-butylquinone in methanol has been accelerated in presence of reported manganese complex (1) with a high Kcat value of 1.43 × 104h−1.

An insight to the role of perchlorate counter ions and different non-covalent interactions in the solid state structures of mono-anionic malonic acid bridged trinuclear mixed valence cationic complexes of cobalt with tetradentate N2O2 donor ligands

Two linear mixed-valence trinuclear centrosymmetric cobalt(III)-cobalt(II)-cobalt(III) complexes, [CoII{(μ-L1)(μ-OOCCH2COOH)CoIII(DMF)}2](ClO4)2⋅2DMSO (1) and [CoII{(μ-L2)(μ-OOCCH2COOH)CoIII(DMF)}2](ClO4)2⋅2DMSO (2) have been synthesized using tetradentate N2O2 donor ‘reduced Schiff base’ ligands, H2L1 (2,2-dimethyl-1,3-propanediyl)bis(iminomethylene)bis(phenol) and H2L2 (2,2-dimethyl-1,3-propanediyl)bis(iminomethylene)bis(4-chlorophenol), and malonic acid as anionic co-ligand. The complexes have been characterized by spectroscopic measurements and their solid state structures have been determined by single crystal X-ray diffraction analysis. Some supra-molecular assemblies observed in the solid state structures of both complexes have been analysed using DFT calculations, in particular CH3···π and Cl···Cl interactions. QTAIM and NCI Plot computational tools have been used to characterize the interactions.

Structural, theoretical and optical investigations of two lateral twisting trinuclear Co(II) and Ni(II) salamo type complexes

Two trinuclear Co(II) and Ni(II) complexes, [{Co3(L)2(μ-OAc)2}2]·3CH2Cl2 (1) and [Ni3(L)2(μ-OAc)2(EtOH)2]·2EtOH (2) have been successfully obtained by a new nonsymmetrical salamo type ligand H2L with Co(OAc)2·4H2O and Ni(OAc)2·6H2O, respectively. Single crystal X-ray diffraction analysis revealed that complex 1 is an unsymmetric trinuclear structure, two tetradentate N2O2-donor ligand (L)2- units are coordinated to three Co(II) atoms where two terminal Co(II) atoms are penta-coordinated lateral twisting trigonal bipyramidal geometries but central Co(II) atom is hexa-coordinated lateral twisting octahedral configuration. Complex 2 is a centrosymmetrical trinuclear structure, all of the three Ni(II) atoms are hexa-coordinated lateral twisting octahedral configurations. In addition, complexes 1 and 2 have been characterized by physicochemical and spectroscopic methods. Molecular electrostatic potential analysis revealed that the phenolic oxygen atoms in the ligand H2L have nucleophilic reactions with Co(II) and Ni(II) atoms to form chemical bonds. Hirshfeld surfaces analyses showed that H···H/H···H interactions are the predominant, indicating the presence of great amount hydrogen bonds in complexes 1 and 2. IRI analyses indicated the presence of weak hydrogen bonding interactions that made complexes 1 and 2 more stable.

Counteranion-driven self-assembly of di- and tetra-nuclear Zn(II) single‐armed salamo‐type complexes

Di- and tetra-nuclear Zn(II) complexes, [Zn2(L)(µ-OAc)(CH3OH)]·CH3OH (1) and [Zn4(L)2(OMe)2]·2CH3COCH3·CH3OH (2) have been successfully self-assembled by the reaction of a single‐armed salamo‐type ligand (H3L), Zn(OAc)2·2H2O and Zn(NO3)2·6H2O, respectively. In the ligand H3L, tetradentate N2O2 donor part of pocket I and NO2 donor part of pocket II are designed to bond Zn(II) atoms, then unusually structural complexes were obtained by counteranion-driven self-assembled. Both complexes 1 and 2 are characterized by elemental analyses, IR spectra, UV-Vis spectra and single crystal X-ray diffraction. All of the Zn(II) atoms in complexes 1 and 2 are penta-coordinated, but highly distinct configurations are obtained because of the introduction of two kinds of counter-anions. In complex 1, μ-OAc− counter-anion connects the two Zn(II) atoms in one ligand. In complex 2, μ-OMe− counter-anions link the Zn(II) atoms within two ligand molecules and the structure of complex 2 is more complicated. What's more, in complex 1, all Zn(II) atoms have the geometries of distorted trigonal bipyramid, while in complex 2, all Zn(II) atoms have the geometries of distorted square pyramid. There are obvious π···π stacking interactions existing in complexes 1 and 2, which are quantitatively valued by Hirshfeld surfaces analyses. Fluorescence properties are also investigated.

Synthesis, Spectral Characterisation and Pharmacological Studies on Co(II), Ni(II), Cu(II) and Zn(II) Bis-Schiff Base Complexes Derived From 4-hydroxybenzohydrazide

The transition metal(II) chelates were prepared by the reactions of bis-Schiff base ligands derived from 4-hydroxy benzohydrazide and isophthalaldehyde / o-phthaldehyde in 1:1 metal to ligand ratio. The formed ligands and their metal complexes have been investigated by the following spectroscopic tools i.e, elemental analysis, FT-IR spectra, molar conductance, 1H NMR, ESI-mass, electronic spectra, magnetic moments, ESR and thermal analyses. The low molar conductance values give the non- electrolytic nature of the metal(II) chelates. From that the spectroscopic observations of complexes having the molecular formula [M(Ln)2Cl2] (where M= Co(II), Ni(II), Cu(II) and Zn(II), n=1and 2) and act as tetradentate N2O2 donor sites of ligands. The docking results predicts that the protein with ligands having good interaction energy. All formed complexes have efficient antibacterial activity than ligand of tested pathogens. The mode of binding interaction of ct-DNA and Cu(II) complexes gives the intercalative binding with hypochromism shifts using electronic titrations method. In electrophoresis, cleavages of PUC18DNA to cleave effectively with Cu(II) complexes in the presence of hydroxyl radicals. The antioxidant assay of DPPH radical scavenging activity of tested compounds shows good results, when compared to ascorbic acid as standard. The anticancer MTT assay of Cu(II) complexes tested against MCF-7 cancerous cells gives the promising therapeutic activity.

On the importance of RH3C⋯N tetrel bonding interactions in the solid state of a dinuclear zinc complex with a tetradentate Schiff base ligand

The tetrel bonding and π-stacking interactions in a new dinuclear zinc complex using a tetradentate N2O2 donor Schiff base have been analysed energetically using DFT calculations and several computational tools.

Non-Linear Optical Property and Biological Assays of Therapeutic Potentials Under In Vitro Conditions of Pd(II), Ag(I) and Cu(II) Complexes of 5-Diethyl amino-2-({2-[(2-hydroxy-Benzylidene)-amino]-phenylimino}-methyl)-phenol.

Herein, we report facile procedures for synthesis of a new Schiff base ligand (H2L,5-Diethylamino-2-({2-[(2-hydroxy-benzylidene)-amino]-phenylimino}-methyl)-phenol) and its Ag(I), Pd(II) and Cu(II) complexes. The structure of the H2L ligand as well as its metal complexes was deduced based on wide range of analytical, structural and spectroscopic tools, along with theoretical evidence via density functional theory (DFT) calculations. The obtained results indicated that the Schiff base (H2L) ligand acts as a tetradentate N2O2 donor with two azomethine nitrogen’s (N1, N2) and two deprotonated phenolic oxygens (O1, O2) atoms. A distorted octahedral structure is assigned to [CuL(OH2)2]·3/2H2O complex and square planar structure for PdL and AgL complexes. The electronic structure and non-linear optical (NLO) property of the prepared compounds were discussed theoretically by the B3LYP/GENECP program. Results revealed that all complexes have non-planner geometries as indicated from the dihedral angles. The charge transfer occurs within the synthesized complexes as indicated from the calculated energy gap between HOMO and LUMO energies. The H2L ligand and its complexes are excellent candidates for NLO materials as implied from their hyperpolarizabilities and polarizabilities values. The biological activities of the prepared complexes against selected microorganisms and cancer cell lines gave good growth inhibitory effect. The biocidal potencies of the ligand and its complexes can be arranged as follows: AgL > CuL > PdL > H2L, as compared to the used standard drugs. The antiproliferative activity of the studied complexes against different carcinoma cell lines such as liver (Hep-G2), breast (MCF-7) and colon (HCT-116) followed the order H2L < AgL< PdL < CuL < vinblastine. Probing the binding interactions of prepared complexes with calf thymus (CT)-DNA using electronic absorption, gel electrophoresis and viscosity measurements revealed strong interaction via intercalation modes, as also evidenced by their molecular docking study.

Luminescent properties of Zn complexes based on tetradentate N2O2-donor pyrazolone schiff bases

A nine new Zn(II) complex were synthesized based on a new Salen-type tetradentate N2O2 ligands derived from 1-phenyl-3-methyl-4-formyl-5-pyrazolone. Complexes have been characterized by single-crystal X-ray diffraction, ESI-mass spectroscopy, elemental analysis, IR spectroscopy and thermal gravimetric analysis. UV–vis, emission and electrochemical studies indicated that changes of the electronic states of the diamine moieties are main parameter that influences the absorption and the emission color of the investigated zinc(II) complexes.

A Semiconducting Copper(II) Coordination Polymer with (4,4) Square Grid Topology: Synthesis, Characterization, and Application in the Formation of a Photoswitch

A phenoxo and end-to-end thiocyanate bridged copper(II) coordination polymer (CP), [Cu2L2(μ-1,3-SCN)2]n, where HL is an potential tetradentate N2O2 donor Schiff base ligand, 2-(2-(ethylamino)ethylimino)methyl)-6-ethoxyphenol, has been synthesized and characterized. The band gap, bulk capacitance, electron lifetime, relaxation time, dielectric constant, and DC conductivity of the complex in the solid state have been studied. Variable temperature magnetic susceptibility measurement indicates the presence of weak antiferromagnetic interactions among the copper(II) centers with J = −0.97 cm–1. The complex shows increase in conductivity when illuminated with visible light (photosensitivity ∼2.833).

Synthesis and structural characterization of a hemiacetal and aldehyde bound diiron(III) complex with two different coordination numbers: A product by oxidative cleavage of carbon[sbnd]nitrogen single bond

The work in this report presents the synthesis, structural and spectroscopic characterization of a hemiacetal and aldehyde bound diiron(III) complex 1 with two different coordination numbers supported by a tetradentate N2O2 donor H2L ligand, despite the fact that no aldehyde molecules have been added to the solution. The complex 1 is a phenoxo and alkoxo bridged complex and it was generated when oxo-transfer reagent iodosylbenzene was treated to a methanolic solution containing Fe(BF4)2·6H2O and deprotonated H2L ligand. The Fe⋯Fe separation of this complex is 3.158Å.

Crystal Structure, Spectral Characterization and Biologically Studies of Mononuclear Transition Metal Complexes Derived from New N2O2 Type Ligand

The new mononuclear metal complexes viz Mn(III), Co(II), Ni(II) and Cu(II) have been synthesized by using tetradentate N2O2 donor symmetric schiff base 6,6’-((1E,1’E)-(1,2-phenylenebis(azanylylidene))bis(methanylylidene)) bis(5-isopropyl-2-methylphenol) HL and employing with corresponding metal chloride or acetate salts. After successful synthesis of compounds were thoroughly characterized by Elemental analysis, FT-IR, Uv-visible, NMR spectroscopy, LC-MS spectrometry, SEM analysis, Magnetic susceptibility measurement, Molar conductance, ESR spectroscopy. X-ray single crystal structure of HL schiff base has been determined. The synthesized compounds have been screened for their antimicrobial and antioxidant activities, which show significant results.

Synthesis, crystal structures, electrochemically studies and antibacterial properties of three new mono-nuclear and one very rare bi-nuclear cobalt(III) Schiff base complexes

Three new mononuclear and one new binuclear cobalt(III) complexes of tetradentate N2O2 donor Schiff base ligands [CoIII(L1)(3-Mepy)2]PF6 (1), [CoIII(L2)(3-Mepy)2]PF6 (2), [CoIII(L2)(4-Mepy)2]PF6 (3) and [CoIII2(L1)2(4-Mepy)4(PF6)4(K)2] (4) were synthesized by reaction of the resp. tetradentate ligands (L1=bis(acetylacetone)ethylenediimine dianion, L2=bis(benzoylacetone)ethylenediimine dianion) with the corresponding cobalt(II) salts in the presence of 3-Mepy and 4-Mepy. These complexes were characterized by FT-IR, 1H NMR and UV–Vis spectroscopy. The crystal structures of the complexes were determined by X-ray crystallography on solvated crystals. In dimeric cobalt(III) complex, two Co-Schiff base units were connected to two K(+) and four PF6 molecules to form the centrosymmetric, dimeric bi-nuclear complex, in which the Co(3+) cations showed distorted octahedral coordinations, while K(+) cations had different coordination numbers in two symmetry-independent moieties: in one of them it is 9-coordinated (irregular tricapped trigonal prism) and in the other 8-coordinated (distorted square prism). Biological activities of the complexes were studied on Staphylococcus aureus, Salmonella typhi, Escherichia coli, and Bacillus subtilis by the well diffusion method. The electrochemical behavior of these complexes with the goal of evaluating the structural effects on the redox properties was also studied.

Metal-assisted desulfurization of 2-thioorotic acid: Structure, theoretical (DFT) investigations, in vitro antibacterial and cytotoxic activity and DNA degradation ability of a copper(II) complex containing in situ formed bis(4-carboxylato-6-oxo-pyrimidine-2-yl)sulfide

Treatment of a dimethylsulfoxide solution of 2-thioorotic acid (THO) with copper(I) halides unexpectedly results in the formation of the [Cu(L)(DMSO)2] complex, where L is the tetradentate N2O2-donor bis(4-carboxylato-6-oxo-pyrimidine-2-yl)sulfide dianion formed in situ by metal-assisted desulfurization of 2-thioorotic acid. The complex features a tetragonally distorted octahedral copper(II) center with two pyrimidine N atoms and two carboxylate O atoms of the ligand, forming a square plane, whereas two O atoms of DMSO solvate molecules occupy the axial positions. The molecular structure, electronic properties and the energetics of the metal–ligand interactions have been studied on the level of density functional calculations. The new compound was evaluated for its in vitro antibacterial activity, DNA degradation activity and for its efficacy as anticancer agent against different cancer and normal human and murine cell lines as well.

Mononuclear and tetranuclear Fe(III) complexes with two different types of N, O donor Schiff base ligands

A mononuclear Fe(III) complex of a tetradentate N2O2 donor Schiff base ligand derived from 3-ethoxysalicaldehyde and ethylenediamine has been reported. In addition two tetranuclear Fe(III) complexes with discrete Fe4III(μ4-O) cores have been synthesized and characterized using two Schiff base ligands (H2L1–2) derived from two different aromatic acid hydrazides and diacetyl monoxime. The mononuclear Fe(III) and one of the tetranuclear Fe(III) complexes have been structurally characterized by single-crystal X-ray crystallography. The mononuclear complex has a highly distorted octahedral geometry. The tetranuclear Fe(III) complexes are found to be rare examples with discrete neutral alkoxido–oxido clusters with Fe4III(μ4-O) cores.

DNA binding mode of novel tetradentate amino acid based 2-hydroxybenzylidene-4-aminoantipyrine complexes

Few transition metal complexes of tetradentate N2O2 donor Schiff base ligands containing 2-hydroxybenzylidene-4-aminoantipyrine and amino acids (alanine/valine) abbreviated to KHL1/KHL2 have been synthesized. All the metal complexes have been fully characterized with the help of elemental analyses, molecular weights, molar conductance values, magnetic moments and spectroscopic data. The Schiff bases KHL1/KHL2 are found to act as tetradentate ligands using N2O2 donor set of atoms leading to a square-planar geometry for the complexes around the metal ions. The binding behaviors of the complexes to calf thymus DNA have been investigated by absorption spectra, viscosity measurements and cyclic voltammetry. The DNA binding constants reveal that all these complexes interact with DNA through minor groove binding mode. The studies on mechanism of photocleavage reveal that singlet oxygen (1O2) and superoxide anion radical (O2-) may play an important role in the photocleavage. The Schiff bases and their metal complexes have been screened for their in vitro antibacterial activities against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus epidermidis, Klebsiella pneumoniae and antifungal activities against Aspergillus niger, Fusarium solani, Culvularia lunata, Rhizoctonia bataicola and Candida albicans by MIC method.