Antibacterial Activity Of Complexes Research Articles

Antioxidant and Antibacterial Screening and Hg(II) Sensing, Activities of Cu(II)pyridine-2,6-dicarboxylate Complexes.

In this study five different complexes of Cu(II) were synthesized for the purpose of environmentally notorious mercury sensing and preliminary biological screening. Pyridine-2,6-dicarboxylic acid (also known as dipicolinic acid, and abbreviated as H2DPA), 3-phenyl pyrazole (3-ppz), 4-iodo-1H-pyrazole (4-ipz), 4-nitropyrazole (4-npz), 4-bromopyrazole (4-bpz), and 4-chloropyrazole (4-cpz) were chosen as potential ligands. The synthesized complexes labelled as 1-5, namely [Cu(DPA)(3-ppz)], [Cu(DPA)(4-ipz)], [Cu(DPA)(4-npz)], [Cu(DPA)(4-bpz)], [Cu(DPA)(4-cpz)], were proposed based on spectroscopic data (FTIR, TGA, and UV-visible spectroscopy). These complexes feature C=O functionalities that are not involved in coordination and may be used for further applications. The isolated complexes were utilized for detecting Hg(II) ions in water samples. Various concentrations of Hg(II) ions were prepared for detection purposes, and changes in absorption concerning complexes 1-5 were determined using UV-Visible spectroscopy. It was found that complexes 3 and 4 exhibit efficient sensing abilities towards Hg(II) ions. The antibacterial activities of complexes 1-5 were assessed against S. typhi and E. coli. The complexes 1 and 3 displayed good antibacterial activities against S. typhi (13.67, and 13.56 mm, respectively) while complexes 1, 2 and 4 were found to be efficient against E. coli (11.6, 12.66, 11.31 mm, respectively). The absorption maxima of 2,2-diphenyl-1-picryhydrazyl (DPPH) at 517 nm, considerably shifted upon addition of complexes 1-5. The results reveal that the complexes possess potential free radical scavenging abilities.

Heterobimetallic Fe(II)–Cu(I) Complexes Supported with 1,1′-Bis(diphenylphosphino)ferrocene and Chelating Sulfur Donor Ligands: Structural Characterization, DFT Analysis, Anti-tyrosinase Assay and Biological Studies

Heterobimetallic complexes [(dppf)CuSP(S)(OiPr)2] (1), [(dppf)CuSP(S)(OEt)2] (2), [(dppf)CuSP(S)(OCy)2] (3) and [(dppf)CuS2H2B(mt)2] (4), supported with sulfur donors from the family of dialkyldithiophosphate, SP(S)(OR)2 (R = iPr, Et, Cy) and borate ligands, (S)2H2B(mt)2, were synthesized in one pot by the reaction of 1,1′-Bis(diphenylphosphino)ferrocene (dppf) with [Cu(CH3CN)4]BF4 and subsequent addition of the chelating sulfur donor ligands at room temperature in an overall moderate yield. 1-4 were characterized using a combination of 1H, 13C{1H}, 31P{1H} NMR, IR spectroscopy techniques, and single crystal X-ray diffraction. Crystal structure analysis revealed that Cu(I) centers in 1-4 adopt a distorted tetrahedral geometry. The borate ligand in 4 adopts a κ3-S,S,H mode in the solid state. A density functional theory geometry optimization calculation was used to extract further structural and electronic information about 1-4. To investigate the possible cytotoxicity of 1-4, in vitro cellular tests were carried out on the human cancerous breast cell line MCF-7. The antibacterial activities of complexes 1 and 4 were screened against gram-positive Staphylococcus aureus PTCC 1112 and gram-negative Escherichia coli PTCC 1330.

Heteroleptic Silver(I) and Gold(I) N-Heterocyclic Carbene Complexes: Structural Characterization, Computational Analysis, Tyrosinase Inhibitory, and Biological Effects.

Derivatization of (NHC)M-Cl (M = Ag, Au) with selected sulfur donors from the family of dialkyldithiophosphates and bis(2-mercapto-1-methylimidazolyl)borate ligands gave a series of heteroleptic mononuclear complexes. In single-crystal X-ray diffraction analysis, Ag(I) complexes adopted a trigonal planar geometry, while Au(I) complexes are near-linear. TD-DFT and hole-electron analyses of the selected complexes gave insight into the electronic features of the metal complexes. In vitro cellular tests were conducted on the human cancerous breast cell line MCF-7 using 2 and 8. The antibacterial activities of complexes 1, 2, 3, 7, 8, and IPr-Ag-Cl were also screened against Gram-positive (Staphylococcus aureus PTCC 1112) and Gram-negative (Escherichia coli PTCC 1330) bacteria. Antityrosinase and hemolytic effects of the selected compounds were also determined.

Preparation, spectral characterization, crystal structure and antibacterial activity of two new supramolecular complexes [Ni(phen)2Cl(H2O)]2(PF6)2.2caf.H2O (I), [Ni(phen)2(H2O)2]2(PF6)4. 3caf.4H2O(II) constructed via hydrogen bond linking

Two new supramolecular complexes, [Ni(phen)2Cl(H2O)]2(PF6)2.2caf.H2O and [Ni(phen)2(H2O)2]2(PF6)4.3caf.4H2O, have been synthesized and characterized by X-Ray diffraction analysis, infrared, UV–visible and TGA/DTA. The complex (I) was crystallized in the monoclinic system with space group P 21/n. Another hand, the complex (II) was crystallized in the Triclinic system with space group P-1. The intermolecular hydrogen bonds OH…N, OH…O and π-π interactions are together playing a vital role in the stabilization of the crystal packing of the two complexes. In addition, the antibacterial activity of complexes was evaluated against two Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa) and Gram-positive bacteria (Enterococcus faecalis, Staphylococcus aureus).Therefore, two complexes displayed a bactericidal effect against all tested bacterial strains.

Novel Type of Tetranitrosyl Iron Salt: Synthesis, Structure and Antibacterial Activity of Complex [FeL'2(NO)2][FeL'L"(NO)2] with L'-thiobenzamide and L"-thiosulfate.

In this work a new donor of nitric oxide (NO) with antibacterial properties, namely nitrosyl iron complex of [Fe(C6H5C-SNH2)2(NO)2][Fe(C6H5C-SNH2)(S2O3)(NO)2] composition (complex I), has been synthesized and studied. Complex I was produced by the reduction of the aqueous solution of [Fe2(S2O3)2(NO)2]2− dianion by the thiosulfate, with the further treatment of the mixture by the acidified alcohol solution of thiobenzamide. Based on the structural study of I (X-ray analysis, quantum chemical calculations by NBO and QTAIM methods in the frame of DFT), the data were obtained on the presence of the NO…NO interactions, which stabilize the DNIC dimer in the solid phase. The conformation properties, electronic structure and free energies of complex I hydration were studied using B3LYP functional and the set of 6–31 + G(d,p) basis functions. The effect of an aquatic surrounding was taken into account in the frame of a polarized continuous model (PCM). The NO-donating activity of complex I was studied by the amperometry method using an “amiNO-700” sensor electrode of the “inNO Nitric Oxide Measuring System”. The antibacterial activity of I was studied on gram-negative (Escherichia coli) and gram-positive (Micrococcus luteus) bacteria. Cytotoxicity was studied using Vero cells. Complex I was found to exhibit antibacterial activity comparable to that of antibiotics, and moderate toxicity to Vero cells.

Inhancment of meropenem potency by methotrexate nanoparticles

The MTX was converted to MTX nanoparticles by the modified method based on changing the pH gradually . For the first time MTX NPs+Meropenem complex were prepared and evaluated as a potential tool to overcome antimicrobial resistance and to improve pharmacokinetics of the drug, the results showed that the antibacterial activity of complex (MTX NPs plus MEM) has increased (from 1( µg/ml) to >0.5( µg/ml) for p1 , from 2( µg/ml) to 1( µg/ml) for p10 and from 8( µg/ml) to 4( µg/ml) for p48).

Triarylazoimidazole-ZnII, CdII, and HgII Complexes: Structures, Photophysics, and Antibacterial Properties

Novel triarylazoimidazoles containing strong electron donors (p-NEt2) or acceptors (p-NO2) by the azoaryl group, and their group 12 metal complexes were synthesized and fully characterized, including X-ray analysis for several complexes. Novel complexes exhibit red photo-luminescence emission (Φ up to 0.21) in a solution. Moreover, the antibacterial activity of complexes was tested against Gram-positive microorganism S. aureus and Gram-negative microorganism E. coli.

Synthesis, Characterization, Biological Activity and Molecular Docking Studies of Novel Organotin(IV) Carboxylates.

Four new carboxylates complexes with general formula R2SnL2 and R3SnL, where R = n-butyl (1, 3), methyl (2, 4) and L = 4-Chlorophenoxyacetate, were synthesized in significant yields. FT-IR analysis revealed a chelating (1 and 2) and a bridging bidentate (3 and 4) coordination modes for the carboxylate ligand in solid state which was further confirmed by the single crystal X-ray analysis of complex 4. The NMR data (1H, 13C and 119Sn) revealed a higher coordination number around the tin center in R2SnL2 (1 and 2) compared to R3SnL (3 and 4). A close matching was observed between the experimental and calculated structures (obtained at B3LYP/6-31G* + LANL2DZ basis set). Quantum chemical analysis indicates that the carboxylate moiety has the major contribution in the formation of filled and unfilled orbitals as well as in ligand to ligand intramolecular charge transfer during the electronic transitions. The cytotoxicity data of the screened compounds evaluated against lung cancer cell line (A549) and normal lung fibroblast cell line (MRC-5) revealed that 1, 3 and 4 have shown dose dependent cytotoxic effects while HL and 2 have shown steady and low cytotoxic activities. The antibacterial activity of complexes 1–4 is higher than that of HL. Molecular docking study showed an intercalation binding mode for complex 3 with DNA (docking score = −3.6005) involving four polar interactions. Complex 3 docking with tubulin (PDB ID 1SA0) with colchicine as a target protein resulted in three polar interactions (docking score −5.2957). Further, the docking analysis of the HL and 1–4 has shown an adequate interactions with the coronavirus SARS-CoV-2 spike protein, nucleocapsid protein and human angiotensin converting enzyme (ACE2).

Synthesis, spectroscopic characterization, computational studies, theoretical investigation of NLO properties and antibacterial activities of mixed ligand complexes of Co(II) and Cu(II)

The reaction of Schiff base 2-(4-(dimethylamino)benzylideneamino)phenol (DBAP) and diethylenetriamine/ethylenediamine with cobalt(II) and copper(II) metal ion in equimolar ratio afforded mixed ligand complexes [M(DBAP)(L)Cl(H2O)n] (1–4), where M = Co(II) 1, 2; Cu(II) 3, 4; L = diethylenetriamine (1, 3); n = 0 and ethylenediamine (2, 4); n = 1. All the newly synthesized complexes were characterized by elemental analysis, spectroscopic techniques viz., UV-vis, FT-IR, ESR, PXRD and mass spectrometry. The influence of chelation of cobalt(II) and copper(II) ion on nonlinear optical properties of Schiff base (DBAP) were examined with DFT study. The polarizability (α0) and first-order hyperpolarizability (β) of ligand and their metal complexes were calculated and compared with reference molecule p-nitroaniline. The hyperpolarizability of Schiff base and their metal complexes show a good nonlinear optical behavior. Theoretical investigation of the complexes was performed by DFT using B3LYP level of theory on the basis set 6-31 G (d, p)/LanL2DZ. On the basis of spectroscopic data and DFT computation, a six-coordinate geometry is tentatively proposed around the metal ion. In vitro antibacterial activities of these complexes were also screened against V. cholerae and E. coli, and found to have good antibacterial activity.

Dinuclear silver(I)- and gold(I)-N-heterocyclic carbene complexes of N-alkyl substituted bis-benzimidazol-2-ylidenes with aliphatic spacer: Synthesis, characterizations and antibacterial studies

New series of dinuclear Ag(I)-NHC and Au(I)-NHC complexes (NHC = N-heterocyclic carbene) bearing n-alkyl homologous series with propylene spacers were synthesized. Initially, bis-benzimidazolium salts, 1-5 were synthesized via two steps n-alkylation reaction. The salts were then subsequently deprotonated with basic metal source (Ag2O) using in-situ deprotonation method to obtain the Ag(I)-NHC complexes 6-10, respectively. The Au(I)-NHC complexes,11-15were synthesized via transmetalation reaction from their respective Ag(I)-NHC complexes. All compounds were fully characterized by elemental analyses, FT-IR, 1H and 13CNMR spectroscopy. The antibacterial studies of these compounds were evaluated against E. coli and S. aureus using disc diffusion method. The Ag(I)-NHC complexes exhibit better activities with inhibition zone of11 ± 1-20 ± 1mm and 9 ± 0-16 ± 1mm against E. coli and S. aureus respectively, while Au(I)-NHC complexes show inhibition zone of 7 ± 0-14 ± 1mmfor both E. coli and S. aureus bacteria. All the respective benzimidazolium salts were found to be inactive against the bacterial strains. Herein, we found that the antibacterial activity is enhanced by the degree of bond strength due to the match between the hardness and softness of the metal centre (Lewis acid) and NHC moiety (Lewis base). In this point of view, the Ag(I)-C bond was found to be stronger bond to NHC ligand (hard acid-hard base combination) than that of Au(I)-C (soft acid-hard base combination) which resulted the slow release of silver ions for better activity. This is due to the fact that the antibacterial activities of complexes are related with delaying in releasing the metal ions (Ag+ and Au+) into the cell membrane.

New mono- and polynuclear copper(II) complexes: Structural characterization, quantum chemical calculations and antioxidant superoxide dismutase studies

Two copper(II) complexes have been synthesized and characterized using elemental and spectral analysis. The molecular structures of both complexes have been confirmed by single crystal X-ray analysis. The stability of the metal centre was examined using cyclic and differential pulse voltammetry in DMSO solution. X-band electron paramagnetic spectra were recorded both in solid and frozen solution to confirm the d 9 configuration. Frozen solution spectra of complexes have the trend in the spin Hamiltonian parameters and cm -1 revealing a ground state with tetragonal symmetry for copper(II) ion. Density functional calculations have been performed and results are found to agree with the experimental results. Antibacterial activities of complexes were screened by taking gram-positive and gram-negative bacteria. Further, in vitro antioxidant (superoxide dismutase) properties of 1 and 2 showed considerable activity compared to other SOD mimics.

Cobalt(III) complex of substituted nalidixic acid: Synthesis, characterization (IR, UV, EPR), single crystal X-ray, antimicrobial activity, Hirshfeld surface analysis and molecular docking

The mixed–ligand title complex, [Co(nal)2(py)2].4H2O (Hnal=nalidixic acid, py=pyridine), was synthesized. Its structural properties were characterized by X–ray diffraction technique (XRD) and elemental analysis. The spectroscopic properties are investigated by Fourier transform infrared spectroscopy (FT–IR), UV–Vis spectroscopy and EPR spectroscopy. The Co(II) ion has slightly distorted octahedral geometry surrounded by two oxygen atoms of keto and carboxyl groups bonded as chelate from nalidixate, two nitrogen atoms from two pyridine ligands. The monomer are connected by C–H···O and C–H···C interactions to form sheet structures. The FT-IR studies of the complex were commented, focusing on the shifts in the vibrational peaks between the complex form and free nalidixic acid. The powder EPR spectra of Cu(II)-doped complex were investigated at room and at liquid nitrogen temperature. The EPR and UV–Vis spectroscopy studies showed that the unpaired electrons were found in the dx2−y2 orbitals by calculating the spin-Hamiltonian and bond parameters. 2D and 3D Hirshfeld analyses were performed in order to quantify the order and nature of intermolecular interactions in crystal network. Antibacterial activity of complex was studied against S. aureus, B. subtilis, P. aeruginosa, E. coli, C. albicans and A. flavus by using the micro dilution. The optimized complex is docked to 5J9B (S. aerous), 5BMM (E. Coli), 5HTG (C. Albicans), 1ZUV (B. Subtilis), 4F0V (P. aeruginosa) and 4YNU (A. flavus).

The photodynamic antimicrobial chemotherapy of Stapphylococcus aureus using an asymmetrical zinc phthalocyanine conjugated to silver and iron oxide based nanoparticles

The synthesis and characterisation of asymmetrical zinc(II) 2(3)-mono-isophthalic acid-9(10),16(17),23 (24)-tri (tert-butylphenoxy) phthalocyanine (complex 4) are reported. The phthalocyanine is conjugated to cysteamine capped silver nanoparticles (Cys-Ag NPs), amine functionalised iron oxide magnetic nanoparticles (NH2-Fe3O4 NPs) and a core-shell composite of the two (Cys-Fe3O4@Ag) via amide bonds. The photo-physico-chemical properties of complex 4 and its respective nanoconjugates (4-Ag, 4-Fe3O4 NPs and 4-Fe3O4@Ag NPs) are also reported. The nanoconjugates showed improved triplet and singlet oxygen quantum yields compared to complex 4. The antibacterial activity of complex 4 and its nanoconjugates were also evaluated on S. aureus wherein their activity was found to be mainly visible light driven with the best catalyst being 4-Fe3O4@Ag. The work therefore demonstrates the feasibility of phthalocyanine-nanoparticle based compounds as potential agents in real life antibacterial treatment.

Synthesis and Characterization of Schiff Base Complexes of Cu(II), Co(II) and Cd(II) Derived from Ethylenediamine and Benzaldehyde Derivatives

Metal complexes of Cu(II), Co(II) and Cd(II) have been synthesized using two new Schiff base ligands, N,N'-bis(4-chlorobenzylidene)ethane-1,2-diamine (L1) and N,N'-bis(3-nitrobenzylidene) ethane-1,2-diamine (L2). The Schiff bases were prepared from the condensation reaction of ethylenediamine with benzaldehyde derivatives (4-chlorobenzaldehyde and 3-nitrobenzaldehyde). The complexes have been characterized by elemental analysis, conductivity measurements, UV-visible, FT-IR and magnetic susceptibility measurements. The magnetic susceptibility measurements and UV-visible spectral data revealed that the geometry of Cu(II) and Co(II) complexes are square planar, whereas the geometry of Cd(II) complex is tetrahedral. The molar conductance data showed that the complexes are non-electrolytic in nature. The complexes were screened for antibacterial activities against four human pathogenic bacteria viz. Escherichia coli, Shigella boydii, Bacillus cereus and Staphylococcus aureus. The results indicate that Cd(II) complex of ligand (L1) has higher antibacterial activity compared to the free ligands, but less than the standard drug, kanamycine. This suggests that the metal ion plays an important role in the antibacterial activities of complexes.

Synthesis, Structures, and Antibacterial Activities of Four Similar 1D Metal‐organic Polymers with Different Metal Ions

Four similar 1D metal‐organic polymers [Cd(impc)2(H2O)2]n (1), [Co(impc)2(H2O)2]n (2), [Mn(impc)2(H2O)2]n (3), and {[Cu(impc)2]·[jy2H2O}n (4) based on an asymmetric 5‐(1H‐imidazole‐l‐yl)‐3‐pyridinecarboxylic acid (Himpc) were prepared hydrothermally and structurally characterized. According to the frontier molecular orbital (FMOs) calculations, the photoluminescence of 1 should be assigned as the n→π* transition. The antibacterial properties of 1–4 were studied. 1 exhibited good antibacterial activities towards B. subtilis and S. aureus with the smallest MIC value of 2 μg·mL–1. Compared with CoII, MnII and CuII ions, the polymer with CdII ion has the better antibacterial activity. Our work preliminarily reveals that the metal ions also have different influences on antibacterial activities of complexes.

Synthesis, characterization, density functional theory calculations, and in vitro antibacterial activity of novel transition metal complexes containing an O3‐tridentate amoxicillin‐based Schiff base: A silver(II) complex as alternative against Pseudomonas aeruginosa resistant to amoxicillin

Transition metal complexes containing an amoxicillin‐based Schiff base (H2L, 3) obtained from the condensation of amoxicillin 1 with salicylaldehyde 2 were prepared. Spectroscopic and physicochemical techniques, namely, UV–visible, Fourier‐transform infrared spectroscopy, 1H NMR, electron paramagnetic resonance, transmission electron microscopy, mass spectrometry, magnetic susceptibility, molar conductance, density functional theory (DFT) calculations, together with elemental and thermal analyses were used to characterize the synthesized complexes. Based on these studies, the general formulae [ML(H2O)3], where M = Mn 4, Ni 5, Zn 6, and [ML(H2O)], where M = Cu 7, Ag 8, were proposed for the complexes. The amoxicillin‐based Schiff base ligand behaved as a dianionic O3‐tridentate chelating agent. DFT studies and magnetic and spectral data revealed octahedral geometries for Mn, Ni, and Zn atoms and distorted tetrahedral geometries for Cu(II) and Ag(II) complexes. Synthesized compounds were tested for antibacterial activity by both agar disk diffusion method and the minimum inhibitory concentration. in vitro bacterial viability revealed that complex 5 had similar antibacterial activity as 1 against Staphylococcus aureus and Staphylococcus epidermidis, whereas Pseudomonas aeruginosa, resistant to amoxicillin, was sensitive to complex 8. The antibacterial activity of complex 8 could be attributed to its greater catalytic activity as shown by DFT calculations. Toxicity bioassay of the tested compounds showed LC50 values > 1000 ppm, indicating their nontoxicity against brine shrimp nauplii (Artemia salina).

PH-dependent synthesis of two three-dimensional cobalt-based metal organic frameworks with antibacterial activity and dye adsorption

Two Co-based metal organic frameworks (MOFs), namely, {Co(Hin)2}n·DMF (1) and {Co2(Hin)4}n (2) (Hin = isonicotinic acid), are solvothermally synthesized from the reaction of isonicotinic acid and cobalt chloride under different pH conditions. Interestingly, both complexes are constructed under acidic conditions, and complex 2 can be fabricated at a lower pH value. Both complexes are characterized by IR spectroscopy, elemental analyses, powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA). The single crystal X-ray diffraction studies indicate that complex 1 and complex 2 are three-dimensional frameworks. The antibacterial activities of complex 1 and complex 2 are investigated by determining their minimal inhibitory concentration (MIC) values against gram-positive bacteria (Staphylococcus. aureus) and gram-negative bacteria (Escherichia. coli), which are bacteria commonly encountered in our daily environments. The results reveal that both complexes are more sensitive to S. aureus than to E. coli. Furthermore, the dye adsorption capacities of complex 1 and complex 2 are investigated. The common organic dyes Congo red and Orange IV are chosen to be absorbed by the title complexes. The results show that both complex 1 and complex 2 have strong absorption capacities toward Orange IV within a short time.

Structural, spectral and biological investigations on Cu(II) and Zn(II) complexes derived from NNO donor tridentate Schiff base: Crystal structure of a 1D Cu(II) coordination polymer

Copper(II) and zinc(II) complexes of an NNO donor tridentate Schiff base, 4-bromo-2-(((3-(methylamino)propyl)imino)methyl)phenol (HL), were synthesised and characterized by different physicochemical methods including single crystal XRD, elemental analysis, IR, electronic and EPR spectral analysis. Copper(II) complex is a 1D coordination polymer in which chlorine acts as a bridging ligand and zinc(II) complex is a bis-ligated one. Hirshfeld surface analysis of the complexes has been carried out which provided better understanding of intermolecular interactions. Effects of solvents on charge transfer bands and d-d bands were investigated and the former shows a negative solvatochromic behaviour and latter a positive behaviour upon increasing solvent polarity. Luminescent properties were analysed and found that copper(II) and zinc(II) complexes exhibit quenching and enhancement of fluorescence respectively which is backed by quantum yield values. Cytotoxic activity of both complexes has been screened in vitro against lymphoma ascites cell lines. In addition, antibacterial activity of complexes has been screened against bacterial species Bacillus cereus, Staphylococcus aureus, Klebsiella pneumonia and Escherichia coli.

Synthesis, crystal structure, thermal, luminescent property and antibacterial activity of lanthanide ternary complexes with p-chlorobenzoic acid and 5,5′-dimethyl-2,2′-bipyridine

Four novel lanthanide coordination complexes, [La(p-ClBA)3(5,5′-DM-2,2′-bipy)H2O]n (1), [Ln(p-ClBA)3(5,5′-DM-2,2′-bipy)H2O]2 (Ln = Sm 2, Eu 3, Gd 4) were obtained from the reaction between p-chlorobenzoic acid (p-ClHBA), 5,5′-dimethyl-2,2′-bipyridine (5,5′-DM-2,2′-bipy) and lanthanide nitrate under solvothermal conditions. Single crystal X-ray diffraction analysis showed that complex 1 is a 1D chain structure, crystallized in the monoclinic system, space group P2(1)/n, and formed a 2D sheet through the C–H⋯O hydrogen bond interactions. While complexes 2–4 were binuclear unit and crystallizes isomorphically in the triclinic system, space group Pī. The binuclear unit were assembled into 1D supramolecular structures through the O–H⋯O hydrogen bond interactions along the a-axis and formed a 2D supramolecular structures through the π-π stacking interactions along the b-axis. The thermal analysis of four complexes were studied by TG-DSC/FTIR. The solid state photoluminescent properties of complex 3 were investigated at room temperature. Moreover, the antibacterial activities of complexes 1–4 on Candida albicans were studied.

Synthesis and Evaluation the Activity of 1, 3, 4-Thiadiazole Derivatives as Antibacterial Agent Against Common Pathogenic Bacteria

Schiff base compound 5-(benzylideneamino)-1,3,4-thiadiazole-2-thiol was prepared from condensation reaction of 2-amino-5-mercapto-1,3,4-thiadiazole with benzaldehyde. Schiff bases react with Copper(ӀӀ), Ferric(ӀӀӀ), Cobalt(ӀӀ) and Zinc(ӀӀ) to form four complexes. The Schiff base complexes were identification by using FTIR and UV-VIS. The antibacterial activity of complexes (Copper(ӀӀ), Ferric(ӀӀӀ), Cobalt(ӀӀ) and Zinc(ӀӀ)) were studied against S. aureus and S . epidermidis as a model of Gram positive, E. coli, P. mirabilis, C. freundii and P. aeruginosa as a Gram negative model to determine activity of synthesized complexes, after subjected them to some tests to confirm the identity of the pathogenic bacteria. Ten antibiotics (Ampicillin and Amoxicillin) have been chosen to investigate the ability of bacterial isolates to resistant the conventional antibiotic. Imipenem have been selected to contrast its efficiency with those of the new compounds because of its high efficiency. The results exhibited higher activity of the new compounds proportional to the chosen antibiotics.