Molar Conductance Values Research Articles

Spectroscopic and chemical characterization of the novel Minocycline/Mn complex with evaluation of its invitro potent antioxidant activity and high antibacterial effect against Escherichia coli (ATCC 8739), Bacillus subtilis (ATCC6633), Staphylococcus aureus (ATCC 6538), and Klebsiella pneumonia (ATCC 13883)

Background and objectiveMinocycline (Mino) is a broad-spectrum antimicrobial that is quickly and fully absorbed. Mino is considered a unique tetracycline derivative. Recently, the number of commercially available antibacterial agents has declined, failing to keep pace with the number of challenges of treating pathogens resistant to multiple drugs. Therefore, it is necessary to develop new classes of antibiotics with different modes of action. Material and methodsThe Mino/manganese (Mino/Mn) complex was synthesized and characterized using elemental analysis, spectroscopic methods (infrared (IR), ultraviolet (UV), X-ray diffraction (XRD)), magnetic susceptibility, scanning electron microscopy SEM, and transmission electron microscopy (TEM). The non-electrolytic nature of the Mino/Mnnovel complex was confirmed based on the molar conductance value. The novel Mino/Mn complex was tested using the ORAC assay and evaluated for its antibacterial activity against the following strains: Escherichia coli (ATCC 8739), Bacillus subtilis (ATCC 6633), Staphylococcus aureus (ATCC 6538), and Klebsiella pneumonia (ATCC 13883). ResultsSpectral data showed that Mino is coordinated with Mn(II) through the oxygen atoms of ketonic (CO) and hydroxyl groups. The magnetic moment value confirms the octahedral configuration of the complex. Surface morphology observed via SEM confirmed that the Mino/Mn novel complex appeared as small rectangular projections. TEM showed the formation of black spots for Mn(II) chelate with particle sizes ranging from 9 to 23 nm. The current findings confirmed the high antibacterial activity of the Mino/Mn complex against the four mentioned strains of bacteria at extremely low concentrations: 0.625 mg/ml for E. coli, 0.009 for B. subtilis, and 0.625 for S. aureus. The Mino/Mn complex exhibited potent antioxidant activity by capturing and scavenging free radicals resulting from antibiotic misuse. ConclusionTherefore, it can be concluded that the novel formula of the Mino/Mn complex is an effective antioxidant and antibacterial agent with expected high potentially significant biological effects.

Synthesis and catalytic application to form cyclic carbonates of novel Pd(II) Cu(II), and Fe(II) benzoate-based Schiff base metal complexes

This work describes the synthesis and characterisation of six novel Schiff base complexes, Cu(II), Pd(II), and Fe(II), which, under the right circumstances, function as very efficient catalysts for the production of cyclic carbonates from CO2 and epoxides. FT-IR spectroscopy, elemental analysis, UV–Vis spectroscopy, molar conductivity, melting point, and magnetic susceptibility measurements are among the spectroscopic methods used to characterize newly synthesized complexes. The molar conductivity values, ranging from 2.58 to 4.03 µS/cm, suggest that the complexes exhibit no molar conductivity. Co-catalysts, such as 4-(dimethylamino)pyridine, pyridine, triethylamine, and triphenyl phosphine, were used in these processes, both with and without one. 4-(Dimethylamino)pyridine was used as the co-catalyst in the catalytic studies. Additionally, a number of variables that affect the cycloaddition process were examined, including the temperature, CO2 pressure, reaction time, and co-catalyst. All novel catalysts exhibited exceptional catalytic activity and selectivity in the catalytic assays. Regarding the coupling of CO2 and epichlorohydrin as epoxides, the L2-Cu catalyst outperformed other catalysts in terms of catalytic activity (90.7%) and selectivity (98.9%).

Synthesis, characterization, and biological potential of 2-thiophene carbaldehyde o-phenylenediamine Schiff base and its Cr(II), Mn(II), and Fe(II) Complexes

A Schiff base was produced through the chemical reaction of 2-thiophene carbaldehyde with o-phenylenediamine. The corresponding metal (II) chlorides were refluxed with the Schiff base to produce the complexes of Cr (II), Mn (II), and Fe (II). These complexes were then characterized by elemental analysis, FT-IR, atomic absorption spectroscopy, solubility, melting/decomposition temperature, and magnetic susceptibility. The vibrational peak at 1622 cm̄1 in the FT-IR spectral data of the Schiff base was ascribed to the vibration frequencies of azomethine u(C=N). But in the complexes, it was discovered that the azomethine band shifted between 1614 and 1659 cm̄1 , suggesting that they were involved in the complexes’ creation. The complexes’ measured absorption bands in the range of 713–769 cm1 were attributed to the M–N bond, indicating the occurrence of metal–nitrogen bonds. The complexes exhibit non-electrolyte properties attributed to their low molar conductance values ranging from 8.00 to 29 Ohm̄1 cm̄ ²mol̄¹. The determination of the melting point of the Schiff base yielded 120 °C, while the decomposition temperature fell within the range of 149–160 °C for the complexes, indicating their thermal stability. Analysis of magnetic susceptibility indicated an octahedral geometry for all the complexes, with values ranging from 2.24 to 3.12 BM. The elemental should analysis of both the Schiff base and its metal (II) complexes for C, H, and N indicated a close agreement between observed and calculated percentages, suggesting a consistent 1:2 metal-Schiff base ratio across all complexes. The qualitative analysis of the compounds confirmed the presence of chloride, which was quantified and determined to range from 4.62% to 7.90%. The prepared Schiff base and its metal (II) complexes underwent evaluation for their antibacterial efficacy against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, and Pseudomonas aeruginosa, as well as their antifungal properties against Candida albicans and Aspergillus niger. The results of the experiments indicated that the metal complexes displayed notable antimicrobial effects.

Solvent assisted mechanochemical synthesis, antimicrobial and antioxidant studies of Ni2+, Mn2+, Cr<sup>2+</sup> , and Cu<sup>2+</sup> Metal complexes of some ligands derived from l-histidine and l-alanine

Mechanochemistry enables rapid, quantitative reactions to occur at or close to 27℃. It is a one-step process that allows for reactant homogenization, product nucleation, and particle growth. These processes use little or no solvent, making them less wasteful and more environmentally friendly than solvent-based reactions. Ni2+ , Mn2+, Cr2+and Cu2+ metal ions were synthesized by grinding in an agate mortar with pestle using ligands derived from amino acids (Histidine &Alanine) which were further synthesized to form complexes. The entire experiment was carried out by solvent solvent-assisted mechanochemical process and ethanol was used as liquid liquid-assisted solvent. The complexes were characterized by IR spectroscopy, U-V spectroscopy, X-ray analysis, melting point, solubility test, and conductivity measurement. The Solubility test showed that the complexes are soluble in DMSO, DMF, and ethanol and are insoluble in both hexane and tetrachloromethane. The molar conductivity values are in the range of (6.05-28.56) Ω-1cm2mol-1 ) indicating the complexes behave as non-electrolytes. IR analysis showed a vibrational frequency band observed at (1620-1625) cm-1 which is assigned to the ʋ(C=N) of the azomethine, also the new bands M=N, M=O indicate the coordination reaction between the metal and the ligands. The UV visible analysis shows various transitions, the metal complexes showed adsorption bands at λ of 420 and 575nm respectively because of the ligand-to-metal charge transfer (LMCT). The XRD analysis showed that there was a change in phase between the starting material and the product which indicate that a reaction occurred, also the nature of the spectra showed that the compounds are all crystalline. The Antimicrobial activity showed that both the complexes and the ligands have good activity against the bacterial isolates. Antioxidant activity was also tested and the compound appeared to have moderate scavenging activities compared to the reference used. The values indicated that the activities are more pronounced when coordinated with metal ions.

Synthesis, Structural Determination, DFT Calculation and Biological Evaluation Supported by Molecular Docking Approach of Some New Complexes Incorporating (E)‐N'‐(3,5‐di‐Tert‐Butyl‐2‐Hydroxybenzylidene) Isonicotino Hydrazide Ligand

ABSTRACTThe synthesis and structural analysis of complexes derived from (E)‐N′‐(3,5‐di‐tert‐butyl‐2‐hydroxybenzylidene) isonicotino hydrazide (ITB ligand) were examined using multiple analytical techniques. These techniques included TGA, decomposition point determination, elemental analysis (CHN), spectroscopic (IR, NMR, mass spectrometry) analysis, magnetic susceptibility, conductivity, as well UV–Vis spectrum analysis, along with theoretical studies. Molar conductance values indicated that the Cd (II), Co (II), Cu (II), Ni (II), and Zn (II) complexes are non‐electrolytes in fresh DMSO solutions, with conductance values ranging from 8.5 to 14.35 Ω−1 cm2 mol−1. IR spectra suggested which the ligand coordinates through the metal ions in a tridentate fashion, utilizing the (N & O) donor sites from the (CN & CO & CO) groups in the hydroxybenzylidene moiety. Analytical data from solution complexation, job's method suggested a 1:1 (metal:ligand) molar ratio. The stability order of the complexes was determined as ITBCo > ITBCu > ITBNi > ITBZn > ITBCd, consistent with the stability constant (Kf) values. The pH profile indicated that the studied complexes exhibit stability upon a wide pH scale, typically between (pH = 4:10). Magnetic and electronic spectral analyses helped deduce the ligand coordination abilities and the geometric structures of the complexes. In vitro (antimicrobial & anticancer) performances of the studied complexes were tested versus various (microbial strains & cancer cell lines), revealing higher activity in the chelates assessed to the free (ITB) ligand. The antioxidant potential was also assessed using the DPPH assay. Finally, molecular docking was performed toward estimate the binding efficiency between various protein receptors and the compounds, with results aligning with the biological investigations.

Synthesis, structural characterization, thermal analysis and antimicrobial assay of Co (II) complexes derived from benzaldehyde N4-substituted thiosemicarbazone

Microwave assisted Co (II) complexes of N4 -Substituted thiosemicarbazone were synthesized (TSC-La-f) and characterized by UV-visible spectra, IR spectra, 1H and 13C NMR spectra, elemental analysis, TGA, magnetic measurements and molar conductance. On the basis of spectral data, magnetic moment and thermal analysis square planar geometry assigned to Co(II) complexes. The electrolytic nature of the complexes was confirmed by their moderately high molar conductance values. All the metal complexes were screened for antimicrobial assay. Among all the complexes (TSC-Le) showed more activity than other Co (II) complexes. From this study it was concluded that complexes are more potent bactericide and fungicide than their corresponding ligands. Keywords: Thiosemicarbazones, benzaldehyde, Co(II) complexes, antimicrobial activity.

Targeted synthesis, structural elucidation, density functional theory, and molecular docking studies of transition metal(II)/(III) complexes of levofloxacin‐based Schiff base for promising their antioxidant and antibacterial applications

Levofloxacin and 4‐aminoantipyrine undergo a condensation process to synthesize a novel Schiff base ligand (L). Metal complexes containing Co(II), Cu(II), Cd(II), Mn(II), Zn(II), Cr(III), Ni(II), and Fe(III) metal ions are prepared using this Schiff base ligand. The new ligand and its complexes are characterized by elemental analyses, Fourier transform infrared, mass spectrometry, ultraviolet–visible, magnetic moment, 1H‐NMR, molar conductivity, and powder X‐ray diffraction, and further thermogravimetric analysis (TG, DTA) verifies their thermal stability. The metal to ligand ratio is 1:1, according to the analytical results. Spectroscopic methods reveal that metal complexes are expected to have an octahedral geometry and demonstrate a neutral tridentate ligand behavior. It also becomes apparent from the molar conductivity values that all metal complexes are electrolytic in nature except zinc(II) and cadmium(II) complexes which are non‐electrolytes. Moreover, the bioactivity of the compounds are investigated. The antibacterial activity is investigated in relation to various Gram‐positive and Gram‐negative bacteria. The results give good indication for higher activity of the prepared compounds than the standard antibiotic drug. Also, the antioxidant activity of the newly prepared ligand and its complexes has been investigated via 2,2‐diphenyl‐1‐picrylhydrazyle (DPPH) free radical scavenging assay. The findings show that Schiff base complexes exhibit good antioxidant activity. Finally, theoretical density functional theory using density functional theory/B3LYP method and molecular docking studies with two receptors of 3T88 and 3Q8U are calculated for the investigated compounds.

Sulfanilamide and 2‐hydroxy acetophenone driven Schiff base metal complex synthesizing, identification, and promising bioactivity

It has been possible to create complexes of metals from the Schiff base ((E)‐4‐(2‐hydroxy‐1‐phenylethylideneamino) benzenesulfonamide) (Sn.HA), which is generated from sulfanilamide and 2‐hydroxy acetophenone. These substances have been identified using various physicochemical methods, featuring mass spectral analysis, melting point, (inductively coupled plasma mass spectrometry [ICP‐MS]), Proton nuclear magnetic resonance (1H NMR), Fourier transform infrared (FTIR) spectroscopy, ultraviolet (UV) spectroscopy, elemental analysis, conductance measurements, electron spin resonance (ESR), and magnetic susceptibility. Most complexes are non‐electrolytes, according to the determined molar conductance values. Spectroscopic analyses indicate coordination of the majority of complexes by 2 C=N groups and 2 (OH) phenolic groups of ligand in a 2 L:1 M molar ratio in a consistent octahedral configuration [L2‐M‐(H2O)2], (L) Schiff base ligand (Sn.HA) and (M) metal, bacteria Gram‐negative (Pseudomonas aeruginosa and Escherichia coli), bacteria Gram‐positive (Streptococcus pneumonia and Bacillus subtilis), and antifungal (Candida albicans and Aspergillus fumigatus) have all been tested on complexes to check the activity of antibacterial and antifungal, with the metal complexes showing promising activity, where the unbound ligand is less active than the metal complexes.

New Nanosized V(III), Fe(III), and Ni(II) Complexes Comprising Schiff Base and 2-Amino-4-Methyl Pyrimidine: Synthesis, Properties, and Biological Activity.

A new synthesis of mixed ligand complexes vanadium(III), iron(III), and nickel(II), [M : L1 : L2], where L1 = Schiff base 2-((E)-((4-(((E)-benzylidene)amino)phenyl)imino)methyl)-naphthalene-1-ol (C24H18N2O) as for L2 = AMPY 2-amino-4-methyl pyrimidine (C5H7N3) were prepared in powder and investigated. Element analysis, molar conductivity, FT-IR, UV-vis, and magnetic susceptibility values have been acquired to describe the generated complexes. The values of vanadium(III), iron(III), and nickel(II) compounds are, respectively, 2.88 BM, 5.96 BM, and 2.92 BM, demonstrating that all compounds conform to the recommended octahedral geometry. Thermal gravimetric analysis (TGA) is used to further assess the complexes and establish the temperature stability and degradation of the metal complexes. The calculations abstracted from XRD patterns propose nanosized complexes (average size 29-50 nm). The microstructures of the samples have also been investigated by scanning electron microscopy (SEM). The disc diffusion method was used to assess and analyze the inhibition of the growth of compounds against harmful bacterial and fungal strains. The prepared complexes were tested against three strains of bacteria, one gram-positive strain (Bacillus subtilis), two gram-negative strains (Escherichia coli and Pseudomonas aeruginosa), and one fungus (Aspergillus fumigatus). The complexes inferred antimicrobial activity against the studied organisms. Specifically, vanadium(III) and nickel(II) are more effective than iron(III), making them promising drugs.

Synthesis, Physicochemical and Antimicrobial Studies of Schiff base derived from 2, 4-dinitrophenyl hydrazine with Salicyldehyde and its Co (II) and Ni (II) Complexes

A Schiff base ligand derived from salicylaldehyde and 2, 4-dinitrophenylhydrazine was synthesized, along with its Co(II) and Ni(II) complexes (CoL2 and NiL2). These compounds were characterized by melting point/decomposition temperature, solubility, molar conductance, magnetic susceptibility, infrared analysis, and UV-visible spectrophotometry. The metal-ligand ratio in the complexes is 1:2. All complexes exhibited low molar conductance values (5.2-11.0), indicating their non-electrolytic nature. The synthesized ligand and its metal (II) complexes were evaluated for antibacterial activity against five bacterial isolates (Escherichia coli, Proteus mirabilis, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus) and three fungal isolates (Fusarium solani, Aspergillus fumigatus, and Candida albicans) using the well diffusion method. The results demonstrated that the metal complexes exhibited greater antimicrobial activity compared to the Schiff base ligand. Keywords: Isolates, Conductance value, Synthesis, Non-electrolytic, Fusarium solani

Comprehensive investigation on fabrication, spectral characterization and biological importance of Co(II) and Ni(II) heteroleptic complexes

Using the microwave irradiation approach, novel metallic complexes of Cobalt [Co(II)] and Nickel [Ni(II)] complexes of 2-aminothiazole (ATZ) and thiocyanate ligands [IUPAC Name: Di(2-aminothiazole) thiocyanato cobalt(II), Di(2-aminothiazole) thiocyanato nickel(II)] were created. The molecular formulas and the geometry of the complexes have been deduced by elemental analysis, molar conductance, magnetic moment, UV–visible, FT-IR, thermogravimetric analysis, cyclic voltammetry, and powder-XRD techniques. Molar conductance values indicate that the complexes are non-electrolyte (1:0) type. The complexes have octahedral structure is revealed by the magnetic moment and UV–visible spectra. The FT-IR spectra reveal that the 2-aminothiazole and thiocyanate ions are coordinated to the metal ion in a monodentate manner. The antibacterial capabilities of ligands and their Co(II) and Ni(II) compounds were studied against a restricted set of microorganisms utilizing the agar-well diffusion method and varying concentrations.When compared to free 2-aminothiazole ligand, the complexes exhibit possible activity against the fungus than bacteria. By assessing how well the complexes and ligands interact with the stable free radical DPPH, their ability to scavenge free radicals has been established. Comparing the complexes to the free ligand, the complexes exhibit greater antioxidant activity due to the fact that metal complexes are widely recognized for their capacity to accelerate medication action and boost therapeutic agent potency when they coordinate with a metal ion. The primary goal of this research is to develop multimodal medicinal drugs, which include studying the roles of 2-aminothiazole and its transition metal complexes.

Ciprofloxacin Metal Complexes–Silica Nanoparticles: Characterization, Spectroscopic Study, DNA Interaction and Biological Activity

Ciprofloxacin (CIPH) was classified as one of the most effective quinolone antibiotics, which is commonly used to cure a wide range of infections resulting from Gram-negative and Gram-positive microorganisms. The complexes which formed due to the interaction of Ni(II), Zn(II), Cu(II), Gd(III) and Sm(III) with ciprofloxacin were characterized by CHN% analysis, conductivity, FTIR, electronic spectra, fluorescence measurements, and magnetic susceptibility, besides studying the complex–DNA interaction. Meanwhile, the molar conductance values (0.001 mol·L−1 in DMSO) revealed the electrolytic behavior of the complexes and could be designated with the A−B+ formula. In addition, the geometry of the compounds was confirmed from the electronic transitions as well as the μeff values as octahedral for all complexes. The postulated formula could be generally assigned as [M(CIP)a(CIPH)b(H2O)c](NO3)(H2O)n(C2H5OH)m. Moreover, the interaction between metal complexes and DNA revealed that the Cu complex had the highest binding constant. Nanotechnology was applied to synthesized compounds using silica nanoparticles (SiNPs), which were prepared using a sol–gel process. The silica nanoparticles were chemically functionalized for binding the ligand and its metal complexes; this enables the as-prepared compounds to enhance their features as a drug delivery platform. Meanwhile, the antimicrobial activity was tested for the free complexes and SiNPs composites. Collectively, Sm complex gave the largest zone of inhibition, while the Cu(II)–SiNPs composite showed the strongest potential to reduce the bacterial activity. Furthermore, the fluorescence data of CIPH, ligand–metal mixture and the effect of silica nanoparticles on them were studied.

Oxovanadium (IV) Complexes of α-Amino Acid Schiff Bases and 2,2'-Bipyridine Ligands: Synthesis, Characterization and Investigation of their Biological Potency

Five new oxovanadium(IV) complexes of the type [VO(L)(bpy)], [where L= 3-hydroxybenzaldehyde-α-alanine (hb-ala), 3-hydroxybenzaldehyde-DL-phenylalanine (hb-pheala), 3-hydroxybenzaldehyde-leucine (hb-leu), 3-hydroxybenzaldehyde-glycine (hb-gly) and 3-hydroxybenzaldehyde-DL-methionine (hb-met) and bpy = 2,2´-bipyridine] have been synthesized and characterized by some physicochemical properties, molar conductance, magnetic susceptibilities measurements, elemental analysis, UV-Visible and FTIR and ESI-MS spectral studies. The molar conductance values showed that the complexes are non-electrolytic in nature. The magnetic moment values of the complexes are in accordance with the d1 electronic configuration of the VIVO2+ moiety and indicates the paramagnetic nature 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 studies supports the proposed structure of the complexes. The magnetic moment value coupled with electronic spectral data suggested the distorted octahedral geometry of the complexes. All the complexes were screened for their antibacterial activity against three human pathogenic bacteria- Escherichia coli, Staphylococcus aureus and Bacillus cereus with Kanamycin (K-30) standard. The result shows that all the complexes possess to have moderate to strong potential antibacterial activity against all the tested pathogens.

Synthesis, characterization, and antibacterial studies of some of first transition series metals and zinc complexes with mixed ligands of trimethoprim-isatin and nitrogen base

Complexes of mixed-ligand Schiff bases [trimetho-prim (TMP) with isatin] (L1) and nitrogen bases [2,2′-bipyridine (bipy)] (L2), [1,10-phenanthroline (phen) (L3)] with metal chlorides: M = Cr3+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+ were prepared and characterized by metal content determination (%), FT-IR, electronic, nuclear magnetic resonance, mass spectroscopy, magnetic susceptibility, conductance measurements and elemental analysis (CHN). The bacterial activity of the ligands and their metal compounds was evaluated via various microorganisms. Infrared spectra of Schiff base showed an azomethine peak shifted in complexes that coincide synthesis and coordination of Schiff base through the nitrogen atom of azomethine C=N) and the oxygen atom of the carbonyl group of L1 with metal ions. L2, L3 (bipy, phen) coordinated through the di imine nitrogen atoms. Conductance dimensions suggested the non-conductance nature of all the compounds except Cr(III) complexes, this outcome fits in with the molar conductance value estimated for 1:1 electrolyte in DMF. Magnetic susceptibility analysis and electronic spectra indicated an octahedral geometry for all complexes. Biological study for prepared compounds have been evaluated towards pathogenic microbes Staphylococcus aureus and Bacillus subtilis. Some compounds have stronger antibacterial action than Schiff base towards tested microbes. KEY WORDS: Antimicrobial, Heterocyclic compounds, Schiff base, Trimethoprim drug, 2,2-Bipyridyl, 1,10-Phenanthroline Bull. Chem. Soc. Ethiop. 2024, 38(4), 1013-1025. DOI: https://dx.doi.org/10.4314/bcse.v38i4.16

Structural investigation, molecular docking, X‐ray studies, and in vitro biological activities of new transition metal complexes based isoleucine‐pyridyl hybrid Schiff base

One significant class of chemotherapeutic medicines with the ability to overcome drug resistance is metal‐based medications. The creation of novel therapeutic medications with distinct modes of action is required due to the rise in drug resistance, treatment failures, and the scarcity of available treatments. The amino acid isoleucine interacts with the arylidene (synthesized from isatin and 2,6‐diamino‐pyridine) forming the HL Schiff base ligand, which then interacts with some transition metal ions to form the metal complexes. Thermal analysis, spectroscopy (1H‐NMR, IR, mass, and ultraviolet–visible), solid reflectance, magnetic moment, molar conductivity, and elemental analyses were employed for examining the synthesized HL and resultant complexes. Mass spectra besides elemental analyses studies verified the formulae of the Schiff base ligand and metal complexes. All the complexes, except for the Fe(III) complex which is non‐electrolyte, exhibited electrolytic behavior as indicated by their molar conductivity values. The obtained complexes exhibited octahedral geometrical shapes, except for the complexes of Co(II), Ni(II), and Zn(II), which displayed tetrahedral geometry. Thermal analysis showed that the complexes consistently release organic ligands and anionic components following the initial loss of water molecules of hydration. The conducted X‐ray diffraction patterns elucidated their lattice dynamics and not only confirmed the purity of the samples, but also demonstrated that the ligand and complexes of Cr(III), Fe(III), Mn(II), Cu(II), Zn(II), and Cd(II) have a crystalline structure in addition to determination of average size of the crystallites. Scanning electron microscope (SEM) was investigated for Schiff base ligand and Co(II) complex. The complexes demonstrated superior efficacy than HL towards fungal and bacteria organisms against Aspergillus fumigatus and Candida albicans, Salmonella Sp., Bacillus subtilis, Staphylococcus aureus, and Escherichia coli. The MCF‐7 cancer cell was subjected to investigation by synthesized complexes and IC50 values ranged from 12 to 23.1 μg/ml. Molecular docking studies define and anticipate the inhibitory potential and binding mode of the generated ligand with the 1GS4, 2HQ6, 3DJD, and 5JPE receptors.

Investigation on Biological Activities of Thiosemicarbazide Derived Schiff Base-Metal Complexes

A Schiff base ligand was synthesized via the condensation reaction of thiosemicarbazide and salicylaldehyde. A series of transition metal complexes of VO(IV), Ni(II), Cu(II), and Zn(II) were obtained by the complexation reaction with the synthesized Schiff base ligand. The Schiff base ligand and its metal complexes were characterized by UV-Vis and FTIR spectroscopy, TGA-DTA, and some physical measurements. FTIR spectral studies showed that the NOS donor ligand coordinated to the metal ions through the N of azomethine group, S of thiolate, and O of deprotonated hydroxyl group. Molar conductance values indicated non electrolytic nature of the complexes. Magnetic moment values coupled with electronic spectral data exhibited the geometrical structure of the complexes. The Schiff base and its complexes were exposed to disinfectant studies tested by using the disc diffusion method. All the synthesized compounds exhibited moderate to strong antibacterial activity. The copper complexes showed more antibacterial activity than other complexes and Schiff bases. All the Synthesized complexes showed a good cytotoxic activity.

Antioxidant novel activities of curcumin complexes with Mg(II), Ca(II), Cu(II), Cr(III) and Se(IV) metal ions: synthesis and spectral studies

Curcumin (Cur) metal complexes of Mg(II), Ca(II), Cu(II), Cr(III), and Se(IV) were prepared and characterized using elemental analysis, molar conductance, IR, UV-spectra, 1H NMR, SEM, TEM, and X-ray diffraction. The very low values of molar conductance confirm that Cl- ions are absent inside or outside the chelation sphere confirming their non-electrolytic nature, while for Cr(III) Cur is high compared to other curcumin complexes, confirming that Cl- ions are inside the complexation sphere. Based on IR and electronic spectra, the Cur C=O group in enol form chelated to Mg(II), Ca(II), Cu(II), Cr(III), and tetravalent metal (Se). The surface morphology of the curcumin chelates showed an increase in particle size and irregular grains shaped with an elongated morphology. Transmission electron microscopy revealed that the Cur chelates have spherical black spots like shape with a particle size of 72.21-88.75 nm, 34.89-57.33 nm, and 80.71-100 nm for Cu(II), Zn(II), and Se(IV) Cur respectively. X–ray powder diffraction patterns for Cu(II) Cur complexes showed particle size within 70-90 nm; the antioxidant activities of Cur and its metal complexes were assessed. Results showed that the Cur complexes with Cr, Mg, Ca, Cu, or Se showed potent antioxidant activities. Further studies could evaluate the potency of these complexes to elevate the antioxidant defense system and enhance body functions against degenerative diseases, such as aging, Alzheimer's disease, and viral diseases.
 KEY WORDS: Curcumin, Mg/Cur, Cu/Cur, Se/Cur, Electronic spectra, Antioxidant, Oxidative stress
 Bull. Chem. Soc. Ethiop. 2024, 38(2), 347-363. 
 DOI: https://dx.doi.org/10.4314/bcse.v38i2.6

Trivalent Tetraazamacrocyclic Complexes of Cr(III) and Fe(III): Synthesis, Characterization and Antimicrobial Evaluation

A novel series of macrocyclic compounds, [M(C37H36N4)X]X2; where M = Cr(III) and Fe(III); X = Clˉ, NO3ˉ, CH3COOˉ, have been synthesized by using the template condensation between 3,4-diaminotoluene, dibenzoyl methane and dimedone in the presence of chromium(III) and iron(III). Various physio-chemical studies were used to characterize these complexes including PXRD, magnetic susceptibility, elemental analysis, electronic, IR and mass spectroscopy. These studies suggested that all the metal complexes have a five-coordinated square pyramidal geometry around the metal ion. The molar conductance values of these complexes in the range of 168-140 ohm-1cm2mol-1 indicated the electrolytic nature of these complexes. Furthermore, the antibacterial and antifungal behavior of these complexes was also examined by using different microbial strains i.e. Bacillus subtilis, Escherichia coli and Candida albicans. In addition to this, the results of antibacterial and antifungal of complexes were compared with commercially available antibacterial and antifungal drug i.e. ciprofloxacin and Amphotericin B, respectively.

Novel azo metal chelates of 3-aminophthalhydrazide derivative: Structural investigation, evaluation of DNA cleavage, anticancer and molecular docking studies

Transition bivalent metal ion (Mn, Co, Ni, Cu, and Zn) complexes derived from an azo ligand (HLCU) having 1,3-diketone moiety with 3-aminophthalhydrazide were prepared and characterized by using elemental analyses, ultraviolet–visible, Fourier transform infrared, nuclear magnetic resonance (1H, 13C), electron spin resonance, molar conductivity and magnetic measurement studies. Molar conductivity value indicated the non-electrolytic nature of all complexes. The ligand coordinates with the metal ion as a tridentate pattern and the binding sites are carbonyl oxygen, hydrazo nitrogen and hydroxy oxygen of phthalhydrazide moiety. The fluorescence spectra of the compounds were recorded and the results revealed that ligand have higher emission intensity than metal complexes. The X-ray powder diffraction indicated that the ligand (HLCU) and nickel(II) complex have orthorhombic crystal lattices. The ligand and metal complexes were subjected to DNA cleavage activity on pUC18 plasmid DNA using the gel electrophoresis method. The cobalt(II) complex completely cleaved DNA and other compounds showing higher cleaving activity than the control. The antitumor activity of the compounds was screened using sulforhodamine B assay towards the breast cancer and leukaemia cancer cell lines. Manganese(II), cobalt(II) and nickel(II) complexes have more promising activity, and the IC50 value is < 10 μg/mL against the leukaemia carcinoma cell line, which is equally potent as the positive control (adriamycin). The molecular docking study was used to find the binding mode of ligand and complexes of cobalt(II) and nickel(II) towards the molecular target protein receptor. The binding affinity of these compounds is −9.8, −13.6 and −10.5 kcal/mol respectively. The cobalt(II) complex has a more effective binding nature than the ligand and nickel(II) complex. Drug-likeness character indicates moderate activity of HLCU, and [Co(HLCU)(H2O)3], [Ni(HLCU)H2O] complexes, in agreement with invitro results.

Exploring the antimalarial, antioxidant and antimicrobial properties of newly synthesized diorganotin(IV) complexes with ONO-donor hydrazone ligands

Inspired by the role of organotin(IV) compounds as potential pharmaceutical agents, we have synthesized a series of new diorganotin(IV) complexes (5–20) of hydrazone ligands (1–4) derived from 2-chlorophenoxyacetic hydrazide and salicylaldehyde derivatives. Numerous techniques such as FT-IR, UV–Vis, (1H, 13C, 119Sn) NMR, mass spectrometry, powder XRD, SEM, EDAX, TGA and molar conductance were used to elucidate the structure of the synthesized compounds. These techniques ascertain that the hydrazone ligands coupled with diorganotin(IV) in a tridentate manner via imine nitrogen, phenolic oxygen atom and deprotonated hydroxyl group generating pentacoordinated geometry of the complexes. The low molar conductance values of synthesized compounds indicated their non-electrolytic nature. SnO2 was the final product formed as a result of the thermal breakdown of complexes which suggested the thermal stability of the complexes up to about 176°C. In vitro antimalarial (P.falciparum) activity was performed using microassay protocol which advocated for the higher potency of complexes 16,20 (IC50 = 0.62–0.67 µM). The antioxidant activity also supported the results of antimalarial data suggesting 16,20 complexes as active compounds. In vitro, the antimicrobial potential of the compounds has been tested against six pathogens including four bacterial and two fungal strains by serial dilution assay taking ciprofloxacin and fluconazole as reference drugs. Among the synthesized compounds, complexes 8 and 12 (MIC value = 0.0048, 0.0045 µmol/mL) exhibited superior activity. Additionally, the compounds were subjected to in silico ADME analysis suggesting that the compounds can be employed as orally active drugs.