Mixed Ligand Metal Complexes Research Articles

Structural Characterization and Antimicrobial Studies of Some New Mixed Ligand Complexes of Lomefloxacin and 3‐(Bromoacetyl)coumarin with Some Metals

AbstractThe interaction of Mn(II) (1), Fe(II) (2), Co(II) (3), Ni(II) (4), Cu(II) (5), and Zn(II) (6) with lomefloxacin (LFX) in the existence of 3‐(bromoacetyl)coumarin (BAC) and NaOH in a 1 : 1 : 1 : 1 molar ratio resulted in the formation of unique mixed ligand metal complexes. The ability of two ligands to chelate metal ions was investigated by elemental analysis, molar conductance, effective magnetic moments FT‐IR, ultraviolet‐visible (UV‐Vis), 1H NMR spectra and thermogravimetric analyses (TG‐DTG). FT‐IR spectra of the complexes suggest that LFX reacted with metal ions as bi‐dentate through pyridone oxygen and carboxylate oxygen. BAC also interacts as bi‐dentate through oxygen of α,β‐unsaturated ketone and oxygen of lactone carbonyl of coumarin. These chelates are electrolytes, according to conductivity experiments, with a 1 : 1 ratio for Mn(II), Fe(II), and Zn(II) and a 1 : 2 ratio for Co(II), Ni(II), and Cu(II). Electronic and magnetic data revealed an octahedral shape for all compounds. The thermodynamic parameters of thermal breakdown processes such as Ea, ΔH*, ΔS* and ΔG* were determined from TG and DTG curves using Coats‐Redfern (CR) and Horowitz‐Metzeger (HM) techniques for LFX, BAC and their metal complexes. The structural geometry of the complexes is confirmed by molecular modeling studies. The findings show that the complexes are soft with regard to ligands, with values ranging from 0.058 eV for Fe(II) complex to 0.090 eV for Zn(II) complex and 11.11 to 17.24 eV for LFX and BAC, respectively, and 0.121, 8.26 eV and 0.111, 9.009 eV for LFX and BAC. The ligands and their complexes were tested in vitro for antibacterial activity against a variety of bacterial and fungal strains, and the results revealed that the complexes had significantly higher potency than the parent drug.

Robust corrosion guard, mechanical and UV aging properties of metal complex/epoxy hybrid composite coating for C-steel applications

Incorporation of novel-prepared metal–organic complexes as crosslinking accelerators for multifunctional epoxy was on top of interest by coating formulators. The present work investigated the loading of mixed ligand metal complexes (Zr(IV) and Cu(II)) of metformin (MF) and 2.2′bipyridine (Bipy) against the free ligands as crosslinking modifiers via some epoxy coating formulations to assess their superb performances on the C-steel surface. Zr(IV) and Cu(II) demonstrated the minor energy gap (∆E) values at 0.190 au compared to free MF and Bipy according to the calculated energy values, and this behavior reflected their enhanced properties via epoxy coating applications. EIS measurements using high saline formation water as a corrosive medium were performed and offered that PA-DGEBA/MC-Cu coated film showed the superior resistance values (Rct = 940 and Rc = 930 kΩ cm2). The accelerated corrosion salt spray experiment clarified that PA-DGEBA/MC-Cu coating achieved the least corrosion rate at 0.00049 mm/y and exhibited the highest protection efficiency of 99.84%. SEM/EDX combination survey affirmed the protective performance of the checked coatings. AFM microanalysis confirmed that surface-treated Cu(II) coating displayed the smoothest film surface with complete curing. Mechanical durability properties were evaluated and the obtained results illustrated that pull-off adhesion for PA-DGEBA/MC-Cu coated film fulfilled the highest adhesion strength at 6.3 MPa, the best bend character at 77, and the maximum impact resistance at 59.7 J. UV immovability trial was performed at 10 irradiance and 80 h duration. PA-DGEBA/MC-Cu coated film displayed the highest resistance to UV irradiance with blistering (#8 size and few frequencies) in addition to offering a minor gloss variation and matt properties.

Synthesis, Characterization and Antioxidant Activity of Mixed–Ligand Complexes of Mn(Ii), Co(Ii), Ni(Ii), Cu(Ii) And Zn(Ii) Ions with Nicotinic Acid and Phenylalanine

Mixed ligand metal complexes of nicotinic acid and phenylalanine with Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) have been synthesized and characterized using infrared spectroscopy, electronic spectra, conductivity, melting point, and solubility. Nicotinic acid and phenylalanine were reacted with some metal (II) chloride salts in the molar ratio of 1:2:1 (M: NA: Phe) which produced the complexes with various colours and a percentage yield range of 58 97%. The melting points of the compounds ranged from 320 to 348 oC, with conductivities ranging from 9.01-26.4 Scm-2mol-1. The infrared spectra of the ligands and metal complexes revealed that nicotinic acid is a monodentate ligand that coordinates to the metal via the nitrogen of the pyridine ring, whereas phenylalanine is a bidentate ligand that coordinates to the metal via the carbonyl oxygen v(C=O) and nitrogen of the amine v(N-H) groups. The electronic spectra of the compounds are compatible with an octahedral geometry, except for the zinc complex, which probably has a tetrahedral structure. All the complexes were slightly soluble in some of the organic solvents used, methanol, ethanol, dimethylformide (DMF), acetone, chloroform, ethyl acetate, and benzene. The ligands and complexes were evaluated for antioxidant activity in vitro using the DPPH and hydrogen peroxide methods. According to the findings, all the complexes have higher activity than the ligand (nicotinic acid) but were less active than the standard (ascorbic acid). This indicates, the complexes have strong antioxidant properties.

Synthesis, characterization and anti-microbial activities of mixed ligand complexes of sulphamethoxazole-urea with cobalt (II) and zinc (II) ions in water-methanol medium

Novel mixed ligand metal complexes of Zinc (II) and Cobalt (II) were respectively synthesized with sulphamethoxazole-urea in a water-methanol medium by refluxing method and characterized gravimetrically (using Mohr’s method for chloride and sulfur determination); the purity of the complexes through melting point determination; the functional groups present by infrared spectroscopy. The results predicted the coordination of the metals to the ligand through the amide group and oxygen atom of the sulphamethoxazole-urea bidentate. Solubility tests revealed that metal complexes were soluble in dimethyl sulphoxide acetone and ethanol. The metal complexes synthesized were also screened for their activities against some bacteria (Xanthomonas sp, E. coli, B. aureus, P. syrugiae, Staphylococcus sp., Bacillus aureus, and P. aureus) and some fungi (S. rolfsil, C. indimutiaum, C. capsicia) using Agar Disc diffusion principle. The metal complexes of sulphamethoxazole (SMX) and mixed ligands show little sign of bacteria inhibition but are more effective on fungi. The results indicate that the mixed ligand metal complexes were more biologically active than the free ligand. The better biological activity resulted in the MLC of Zn.

An in-vitro anti-inflammatory and anti-microbial essential on Ni(II), Cd(II) mixed ligand complexes by using 2,4-dinitrophenyl hydrazine and dimethylglyoxime

The objective of the present work deals among synthesis as well as characterization of Ni(II), Cd(II) mixed ligand complex were derived from 2,4 di-nitrophenyl hydrazine and dimethyl glyoxime. The mixed ligand metal complexes were prepared via 2,4-dinitrophenyl hydrazine as well as dimethylglyoxime among Ni(II) and Cd(II) in molar radio (M:L1:L1) 1:1:1. CHNO analysis, conductivity measurement, PXRD, SEM, UV–visible, infrared spectrum, and magnetic susceptibility, thermal analysis were used to characterizedthe synthesized compounds. According to the study of the results, all of the metal complexes have octahedral geometry. The molar conductance value indicate that non-electrolytic character of compounds Ni(II), Cd(II). According to the powder X-ray diffraction (PXRD) patterns, all of the compounds are crystalline character. Moreover the Ni(II), Cd(II) complexes were very stable in terms of thermal stability. Metal complexes have been tested against Gram-positive (S. aureus, B. subtilis and A. niger) and Gram-negative (P. aeruginosa, E. coli and C. albicans) pathogenic bacteria as well as fungus. As a result, the metal complexes have reported strong antimicrobial efficiency. ConclusionsFurthermore, applications of metal compounds were tested for anti-inflammatory efficiency utilize egg albumin. Result shows that the activities of metal complexes are good.

Synthesis, structural elucidation, molecular modeling, and antimicrobial studies of some nanoparticles mixed ligands complexes of cetirizine in presence of 2,2′‐bipyridine

A four mixed ligand metal complexes derived from the interaction of Cu(II), Zn(II), Zr(IV), and Cd(II) with antihistamine cetirizine.2HCl (Cetz) in the presence of 2,2′‐bipyridine (Bipy) were synthesized and characterized by using elemental analyses, Fourier transform infrared (FT‐IR), UV–visible (UV–Vis), 1H NMR, thermal analysis (thermogravimetric–differential thermogravimetry [TG–DTG]), X‐ray diffraction (XRD) analysis, molar conductance, and magnetic moment. The infrared data confirmed that Cetz interacted with metal ion as monodentate ligand through carboxylate oxygen atom, and Bipy chelated through nitrogen atoms. The decomposition mechanism (TG and DTG) for Cetz, Bipy, and their complexes were accomplished, and thermodynamic parameters (Ea, ΔH*, ΔS*, and ΔG*) were determined using Horowitz–Metzger (HM) and Coats–Redfern (CR) methods. The powder XRD analysis of all compounds was carried out to determine the average crystalline size (d) and the nature of the compounds (crystalline or amorphous). The density functional theory (DFT) was achieved to comprehend the optimized geometry for the compounds. All complexes regarded as soft in relation to Cetz, with values ranging from 12.987 to 22.727 eV and equal to 12.658 eV for Cetz. The compounds biological activity was examined against number of bacterial and fungal strains. The data revealed that the investigated complexes have a significant efficiency and may be used as better bactericides.

2,2′-Bipyridine based biologically active mixed ligand metal(II) complexes: Synthesis, characterization, DFT and antioxidant studies

Mixed ligand [CoL(bpy)], [NiL(bpy)], [CuL(bpy)] and [ZnL(bpy)] complexes were synthesized from Schiff base ligand L, metal(II) acetates of Co, Ni, Cu and Zn with 2,2′-bipyridine (bpy). The synthesized compounds were characterized using molar conductance, elemental analyses, 1H-NMR, FTIR and mass spectral studies. The geometry of metal complexes has been assigned by magnetic moment analysis and UV-vis spectral techniques. The X-band ESR spectra of [CuL(bpy)] complex in DMSO were recorded at room temperature and liquid nitrogen temperature. Grain size of metal complexes was predicted using Powder XRD. Computational DFT studies were performed using Gaussian 6.0 program package. HOMO-LUMO of L, optimized geometry, bond angle and bond length calculations were preceded at B3LYP/GENECP level with 6-31G (d,p) basis sets. Antimicrobial and antioxidant activities of complexes were evaluated.

Bis(indolyl)methane and 8-Hydroxyquinoline Derivative based Mixed Ligand Metal Complexes: Synthesis, Characterization, Antimicrobial Screening and Molecular Docking Study

Present study described the synthesis of mixed ligand metal complexes of Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II). Metal complexes were synthesized by two ligands such as 8-hydroxyquinoline derivative (primary ligand) and bis(indolyl)methane derivative (secondary ligand). The ligands and their transition metal complexes were characterized by IR, 1H NMR, mass spectrum, elemental analysis, TGA, electronic spectra (UV) and molar conductance. The results of analysis predicted that both ligands are bidentate and resulting complexes are ML1L2 type with molar ratio 1:1:1. To screen their biological potential, the antibacterial and antifungal activity of synthesized compounds have also been investigated. Results of antimicrobial activity were expressed as minimum inhibitory concentration (MIC). Synthesized complexes showed moderate to excellent antimicrobial activity against pathogens. Further, the more potent antimicrobial complexes of Fe(II) and Co(II) were docked with topoisomerase II as a receptor protein, Fe-complex bound to Met1113 (2.53 Å), Asn1296 (2.86 Å) and with nucleotide DC12 (3.28 Å). Similarly, Co-complex bound to Lys1276 (2.27 Å), Leu1280 (2.40 Å), Thr1325 (2.37 Å) and Gly1332 (2.42 Å) via intermolecular hydrogen bonding.

Synthesis and spectroscopic characterizations of nanostructured charge transfer complexes associated between moxifloxacin drug donor and metal chloride acceptors as a catalytic agent in a recycling of wastewater

Moxifloxacin Histidine mixed ligand (MHL) metal complexes of the M.Mof.His·nH2O type, where M are (Mg(II), Ca(II), Fe(III), and Zn(II)), Mof is moxifloxacin and His is a histidine amino acid, have been prepared. The MHL metal complexes could be synthesized using M(II/III): moxifloxacin: histidine amino acids in proportion of 1:1:1 in situ stereoselective chelation. The characterization of MHL complexes obtained have been done using elemental analyses, thermal analysis, spectroscopic and various techniques of physicochemical methods such as conductivity measurements, magnetic susceptibility, Electronic UV–Vis. absorption, infrared and 1HNMR spectral studies. The magnetic susceptibility measurements at room temperature for these complexes are indicative of an octahedral geometrical structure except for zinc(II) complex has four coordination. Moxifloxacin and histidine ligands have a bidentate fashion through the oxygen atoms of carbonyl (quinolone) and carboxylic groups regarding Mof ligand and through the nitrogen and oxygen atoms of NH2 group and deprotonated carboxylic group regarding His secondary ligand. The catalytic degradation properties of metal complexes have been determined under UV light against methylene blue (MB) in aqueous solution. The results proposed that catalytic degradation toward MB in the presence of complexes of Mg(II), Ca(II), Fe(III) and Zn(II) are 33, 30, 81 and 51%, respectively, in 240 min. DFT studies using B3LYP/6-311G and lanL2DZ level of theory were used to obtain optimized geometry of synthesized metal complexes along with their electronic energy gap and MEP map. Also, the plausible mechanistic pathways by which metal complexes executed photodegradation have been explained with the aid of band gap calculations implementing density of states and partial density of states.

Study molecular modeling and the effect of some biological metals on the efficiency of norfloxacin in presence of 3‐(bromoacetyl)coumarin

AbstractA series of new mixed ligand metal complexes of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Zn(II) have been synthesized by the reaction of norfloxacin (NOR) with 3‐(bromoacetyl)coumarin (BAC) in 1:1:1 (Mn+:NOR:BAC) molar ratio, which characterized by elemental analysis, spectroscopic measurements (FT‐IR, UV–Vis) molar conductance, effective magnetic moments, and thermogravimetric analysis (TG) and (DTG). All the complexes soluble in DMSO and the conductivity measurement indicate that the complexes are electrolyte with ratio 1:1 for Mn(II), Fe(II), and Zn(II) and 1:2 for Co(II), Ni(II), and Cu(II). Electronic and magnetic data elucidated the octahedral structure for all complexes. Assorted thermodynamic factors are calculated, and the results are explicated. Molecular modeling calculations (bond angles, dihedral angles, total energy, heat of formation, and dipole moment) confirm the structural geometry of the complexes and indicate the very good agreement between the computed and experimental geometrical parameters. The calculated data for the hardness (η) and absolute softness (σ) showed that all complexes are soft with respect to ligands. The two ligands and their metal complexes have also been screened for their antibacterial and antifungal activity against some selected species; the data showed that the complexes have remarkable potency as compared with the parent ligands.

Synthesis, DFT Calculations, Antiproliferative, Bactericidal Activity and Molecular Docking of Novel Mixed-Ligand Salen/8-Hydroxyquinoline Metal Complexes.

Despite the common use of salens and hydroxyquinolines as therapeutic and bioactive agents, their metal complexes are still under development. Here, we report the synthesis of novel mixed-ligand metal complexes (MSQ) comprising salen (S), derived from (2,2′-{1,2-ethanediylbis[nitrilo(E) methylylidene]}diphenol, and 8-hydroxyquinoline (Q) with Co(II), Ni(II), Cd(II), Al(III), and La(III). The structures and properties of these MSQ metal complexes were investigated using molar conductivity, melting point, FTIR, 1H NMR, 13C NMR, UV–VIS, mass spectra, and thermal analysis. Quantum calculation, analytical, and experimental measurements seem to suggest the proposed structure of the compounds and its uncommon monobasic tridentate binding mode of salen via phenolic oxygen, azomethine group, and the NH group. The general molecular formula of MSQ metal complexes is [M(S)(Q)(H2O)] for M (II) = Co, Ni, and Cd or [M(S)(Q)(Cl)] and [M(S)(Q)(H2O)]Cl for M(III) = La and Al, respectively. Importantly, all prepared metal complexes were evaluated for their antimicrobial and anticancer activities. The metal complexes exhibited high cytotoxic potency against human breast cancer (MDA-MB231) and liver cancer (Hep-G2) cell lines. Among all MSQ metal complexes, CoSQ and LaSQ produced IC50 values (1.49 and 1.95 µM, respectively) that were comparable to that of cisplatin (1.55 µM) against Hep-G2 cells, whereas CdSQ and LaSQ had best potency against MDA-MB231 with IC50 values of 1.95 and 1.43 µM, respectively. Furthermore, the metal complexes exhibited significant antimicrobial activities against a wide spectrum of both Gram-positive and -negative bacterial and fungal strains. The antibacterial and antifungal efficacies for the MSQ metal complexes, the free S and Q ligands, and the standard drugs gentamycin and ketoconazole decreased in the order AlSQ > LaSQ > CdSQ > gentamycin > NiSQ > CoSQ > Q > S for antibacterial activity, and for antifungal activity followed the trend of LaSQ > AlSQ > CdSQ > ketoconazole > NiSQ > CoSQ > Q > S. Molecular docking studies were performed to investigate the binding of the synthesized compounds with breast cancer oxidoreductase (PDB ID: 3HB5). According to the data obtained, the most probable coordination geometry is octahedral for all the metal complexes. The molecular and electronic structures of the metal complexes were optimized theoretically, and their quantum chemical parameters were calculated. PXRD results for the Cd(II) and La(III) metal complexes indicated that they were crystalline in nature.

Spectroscopic Studies and Antimicrobial Evaluation of New Mixed Ligand Mn(II), Ni(II), Cu(II) Complexes Synthesized from an Ionic Liquid-Supported Schiff Base and 1-Methyl Imidazole

Mn(II), Ni(II), Cu(II) complexes with the ionic liquid-supported Schiff base 1-{2-(2-hydroxy-5-chlorobenzylamine)ethyl}-3-methylimidazolium tetrafluoroborate (primary ligand) and 1-methyl imidazole (secondary ligand) and were synthesized and characterized by PXRD, SEM, ESI-MS, UV-Visible, FT-IR, 1H NMR, 13CNMR spectroscopic and various analytical (elemental analysis and magnetic susceptibility measurements) methods. Based on these spectra and spectral data hexa coordinated geometries were assigned for the synthesized mixed ligand metal (II) complexes. Antimicrobial activity of the mixed ligand Mn(II), Ni(II), Cu(II) complexes with respect to the Schiff base against two gram positive (Staphylococcus aureus and Bacillus cereus) and two were gram negative (Escherichia coli and Klebsiella pneumoniae) were conducted to assess their antibacterial activities. The Schiff base along with the mixed ligand complexes exhibited very significant responses for gram positive and negative bacterial samples though maximum inhibition zone was produced by Ni(II) complex while the minimum inhibition zone was produced by Cu(II) complex in plates of Staphylococcus aureus.

A new class of mixed ligand complexes bearing bisphenol and 1,10-Phenanthroline for antimicrobial and antioxidant activities: synthesis, spectral and electrochemical studies

A new class of mixed ligand complexes, [M(L)(phen)2], using a bidentate bischlorophenol ligand H2L (2,2′-methylenebis(4-chlorophenol)) and phenanthroline has been synthesized. All the compounds were characterized by spectral (IR, UV, NMR and mass), magnetic, molar conductivity and cyclic voltammetry studies. The IR spectral data revealed that the bisphenol and phenanthroline ligands coordinate to the metal ions through the formation of M–O and M–N bonds. The electronic and magnetic data indicate the octahedral geometry of the complexes. The ESR spectrum of mononuclear copper complex shows four lines due to hyperfine splitting and the copper + 2 ion is present in octahedral environment. Cyclic voltammograms show two reduction potentials in cathodic direction. The first one at higher potential, − 1.05 to − 1.58 V, is due to the phenanthroline moiety and the second one at − 0.58 to − 0.65 V is due to the metal centered reduction potential. The antimicrobial activity of all the compounds was studied on some human pathogenic bacteria (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Enterococci species) and fungi (Candida species, Aspergillus species). Copper complex 3 and cobalt complex 1 show higher antibacterial and antifungal activities, respectively, than the ligand and other complexes. The in-vitro antioxidant activity was spectrophotometrically studied by radical scavenging and reducing power activities. The biological activities of mixed ligand metal complexes are improved through synergistic effect of ligand, co-ligand and metal center.

Synthesis, Characterization, Antibacterial, Antifungal and Antimalarial Study of Mixed Ligand Metal Complexes Derived from Azo Quinoline with Thiosemicarbazone

Mixed ligand metal complexes of azo quinoline and thiosemicarbazone with Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) metal ions were synthesized. The structure and possible geometry of all the metal(II) complexes were analyzed and supported by IR, mass spectrum, elemental analysis, TG-DTA, electronic spectra (UV), magnetic susceptibility and molar conductance. The synthesized compounds were studied for their antibacterial, antifungal and antimalarial activities. The antimicrobial activity was carried out against bacteria (two Gram-positive bacteria and two Gram-negative bacteria), three fungal strain and one malarial pathogen

Mixed isatin with 3-(2-(aryl)hydrazono)acetylacetone Mn(II), Co(II) and Ni(II) complexes: antibacterial evaluation and molecular properties prediction

The metal complexes {Ni (II), Co (II) and Mn (II)} of 3-(2-(aryl)hydrazono)acetylacetone with isatin were synthesized and screened for their in vitro antibacterial activity against four pathogenic microorganisms {two Gram‐positive and two Gram negative}. The results of antibacterial activities revealed that all the metal complexes 1-9 exhibited moderate activities. Also, Lipinski's rule of five (RO5) of the mixed ligand metal complexes were calculated by SwissADME website.
 
 KEY WORDS: Isatin, 3-(2-(Aryl)hydrazono)acetylacetone, Metal complexes, Antibacterial activities, Lipinski rules
 
 Bull. Chem. Soc. Ethiop. 2020, 34(3), 533-541. 
 DOI: https://dx.doi.org/10.4314/bcse.v34i3.9

Synthesis, characterization, ADMET, in vitro and in vivo studies of mixed ligand metal complexes from a curcumin Schiff base and lawsone

Complexes are currently synthesized from plant origin because of their therapeutic effect against certain diseases with toxicity. Hence, in this work, four new transition metal(II) mixed ligand complexes have been synthesized using a curcumin Schiff base (primary ligand) and lawsone (as co-ligand). The geometry of these complexes was explored by elemental analyses, molar conductance, thermal analysis, magnetic moment values, IR, NMR, Mass, electronic and EPR spectral studies. Electronic absorption titrations, viscosity measurements and molecular docking studies reveal that all the metal complexes interact with the CT DNA by groove binding. Among all the complexes, the copper(II) complex (complex 1) exhibits a higher Kb value (3.5 × 10−4 M) which reveals that it has a strong binding efficiency toward the CT DNA. The complexes also possess strong DNA cleavage efficiency. Cytotoxicity investigations on Artemia salina show that all the complexes possess higher cytotoxic effect than the ligand. Moreover, all the metal complexes have better antimicrobial efficacy than the ligand. Swiss ADME, PASS and pkCSM online softwares are helpful to predict the pharmacokinetic and biological actions of the curcumin Schiff base. Theoretical results obtained from the in silico study are experimentally corroborated by in vivo anti-inflammatory screening study. All the above studies demonstrate that the copper complex possesses biological activity similar to that of the drug like molecules. Research Highlights Synthesis and characterization of four novel transition mixed ligand complexes using plant moieties Promising in vivo anti-inflammatory agents and in vitro DNA metallonucleases Cytotoxicity investigation on Artemia salina Higher cytotoxic effect for the complexes than the ligand Identification of copper(II) complex as lead like molecule among all

Synthesis, characterization, antimicrobial activity, DFT and molecular docking studies of the N-salicylidene-glycinato and their metal mixed ligand complexes with caffeine

Schiff base glycinate derived from the condensation of salicylaldehyde and glycine in basic media have been synthesized the N-salicylidene-glycinato (LH) and characterized by infrared, UV-Visible, NMR and DFT. The mixed Schiff base and caffeine complexes [M (LH)2 (caf)2]; M= Cu(II), Ni(II), Cd(II) and Zn(II) with LH= N-salicylidene-glycinato and caf= caffeine, were prepared and characterized by the molar conductance, FTIR, UV-Visible 1H & 13C NMR and TGA/DTA. The ligand (LH) acts in a chelate manner (NO) donor and coordination of caffeine by N9 through metal ions. The molar conductance reveals that the metal complexes are non-electrolytes. The postulated octahedral structure of the obtained complexes is also confirmed by the spectroscopic data and thermal analysis. The antimicrobial activity of the complexes was evaluated against eight bacteria species and four fungal strains. The results of their tests show that the metal (II) complexes are more effective against several bacterial and fungal strains. The results of the molecular docking show that the mixed Schiff glycine caffeine complexes have good affinity with the protein kinase (CK2).

New Bioactive Co(II) and Ni(II) Complexes with Ofloxacin Mixed-Ligand

Four mixed-ligand metal(II) complexes with the molecular formulae [M(ofl)(bipy)]NO3�H2O and [M(ofl)(phen)]NO3�H2O were synthesized by the reaction of Co(II) and Ni(II) with ofloxacin (Hofl) in the presence of 1,10-phenanthroline (phen) / 2,2`-bipyridine (bipy) (1:1:1 molar ratio). The data obtained from elemental analysis, molar conductance, spectral infrared, reflectance spectra and magnetic studies gave information about the coordination of the ligands and the geometry of the metallic ion. The results suggest that Hofl is deprotonated and bidentately bound to the metal ion through the pyridone oxygen and the carboxylato oxygen while phen and bipy act as neutral bidentate ligands coordinated through the nitrogen atoms. Tetrahedral geometry is proposed for all complexes. Thermal analysis data led to useful information concerning the composition, dehydration and thermal behaviour of the complexes. Ofloxacin and the metal complexes were tested for antibacterial activity and also for antioxidant activity. The variations of physicochemical parameters were monitored, which explain the antibacterial behaviour of these compounds. The interactions between metal complexes and bacterial receptors have lower energy values compared to the ofloxacin ligand. The molecular docking studies allow the identification of the biological target and the predictions of the bonds between the studied compounds and the receptors of E. coli (3t88), S. aureus (3q8u) and P. aeruginosa (4lkd).

Synthesis of the Three Mixed-ligand Metal Complexes and One Organic Salt of 3,5-Dinitrobenzoic Acid for Biopharmaceutical Optimization Through Monoethanolamine: Structures and DFT Studies of Complexes

The simplest derivatives of benzoic acid show a wide spectrum of the biological action mostly being poor water soluble. In order to demonstrate on example of 3,5-dinitrobenzoic acid (DNBA) a possibility of the simultaneous enhancement of water solubility and antimicrobial activity the complexation (salt formation and metal coordination) approach has been examined. Monoethanolamine (MEA) is selected as the complexing agent. Three isomorphic mixed-ligand complexes of Cu, Ni, Co with DNBA and MEA as well one organic salt in the polymorphic form have been synthesized and their structures are characterized by the element analysis, FTIR and X-ray crystallography. Measurements of water solubility and determination of the antimicrobial activity attest that a solubility of the copper mixed-ligand complex and organic salt is increased about four and eight times with simultaneous enhancement of the bioactivity. The DFT studies by B3LYP/def2-TZVP and B3LYP/6-311G (d,p) showed that Cu, Ni, and Co complexes with DNBA and MEA have high-spin ground electronic states as a doublet, triplet and quartet, respectively. Calculated bond lengths and bond angles of all metal complexes in higher-spin ground electronic states are in good agreement (about R2 = 0.97) with X-ray data. Additionally, the energies of the frontier MOs and frontier electron densities and also electrostatic potential of isostructural complexes have been analyzed by the DFT/6-311G(d,p) method. The water solubility and bioactivity of poorly soluble 3,5-dinitrobenzoic acid are enhanced by a preparation of three isostructural metal complexes and one polymorphic organic salt with participation of monoethanolamine and DFT study of metal complexes has been carried out.

Bis(3,5-di-nitro-benzoato-κO)bis-(ethane-1,2-di-amine-κ2 N,N')cadmium(II).

During systematic investigations of bioavailability and biological action enhancement of well known compounds with low bioactivity, a new mixed-ligand metal complex, [Cd(DNBA)2(en)2)] (DNBA = 3,5-di-nitro-benzoate, C7H3N2O6; en = ethyl-endi-amine, C2H8N2), has been synthesized. The complex mol-ecules are located on inversion centers. Two DNBA anions monodentately coordinate the CdII atom through an oxygen atom of the carboxyl-ate group while two en mol-ecules coordinate in a chelate fashion, resulting in a distorted O2N4 coordination set. There is a weak intra-molecular hydrogen bond of 3.099 (4) Å between the non-coordinating oxygen atom of the carboxyl-ate group and one of the en amine groups. Three relatively weak inter-molecular N-H⋯O hydrogen bonds associate complex mol-ecules into sheets extending parallel to (01), which are further stabilized by π-π inter-actions. A Hirshfeld surface analysis of the crystal structure indicates that the most important contributions to the crystal packing are from H⋯O/O⋯H (50.2%) and H⋯H (21.1%) inter-actions.