Synthesis, characterization and antimicrobial activity of mixed transition metal complexes of salicylic acid with 1, 10-phenanthroline

A new series of Mn(II), Fe(II), Co(II), Cu(II) and Zn(II) mixed ligands-metal complexes derived from salicylic acid (SA) and 1,10-phenanthroline (PHEN) have been synthesized and characterized by spectroscopic studies. The coordination of the two ligands towards central metal ions has been proposed in the light of elemental analysis, IR, UV–vis spectroscopic studies. The results of the physical and spectroscopic data confirmed that the ligands are chelating agents. In 1, 10-phenanthroline, coordination occurred through the two pyridinic nitrogen groups, while in the salicylic acid coordination occurred through the oxygen of the hydroxyl and the carboxylic groups. All the complexes synthesized were of octahedral geometry. Antimicrobial activity of the mixed ligands metal complexes and the free ligands were carried out against the bacterial Escherichia coli, staphylococcus aureus, klebsiella pneumonia, pseudomonas aeruginosa and the fungi candida spp. The mixed ligands metal complexes showed higher activities when compared to the free ligands of salicylic acid but were less active than the free 1,10-phenanthroline ligand. The complexes of Cu (II) showed the highest antimicrobial activity while the Fe(II ) complex showed the least activity against the bacterial and fungi organisms.Keywords: 1,10-phenanthroline, Salicylic acid, Mixed ligands-metal complexes, Transition metal, Spectroscopy, Antimicrobia

Synthesis, Characterization and in vitro Antibacterial Studies of Novel Transition Metal (II) Complexes of 2,5-Diamino-2-(difluoromethyl)pentanoic Acid Hydrochloride Hydrate

The synthesis and characterization of novel transition Metal (Cu(II), Co(II), Ni(II) and Zn (II)) complexes of  2,5-diamino-2-(difluoromethyl) pentanoic acid hydrochloride hydrate (DPH) have been described. The ligand and metal complexes were characterized by Melting point, Conductivity measurement, Elemental analysis, Fourier Transform infrared (FTIR) spectroscopy, Electronic spectroscopy, Magnetic susceptibility measurement and Electrospray Ionization Mass Spectrometry (ESI-MS). The FTIR spectral data suggests that the ligand behaves as a bidentate ligand coordinates to the metal ions through an oxygen atom of the carboxylate and a nitrogen atom of amino group. The terminal amino group of the ligand is protonated to form NH3+ while the carboxylic moiety is deprotonated forming zwitterionic complexes. Electronic spectral and magnetic studies data suggest that the complexes of Cu(II), Co(II) and Ni(II) have octahedral geometry around metal ions while tetrahedral geometry was proposed Zn (II) ion. In vitro anti-bacterial activities of the ligand and metal complexes were carried out using agar diffusion method against two gram-positive bacteria (Staphylococcus aureus, Bacillus substilis) and two gram-negative bacteria (Escherichia coli, Klebsiella pneumonia). The results obtained revealed that the metal complexes showed enhanced antibacterial activities against the four micro-organisms with lowest minimum inhibitory concentration (MIC) when compared to parent compound. DOI: http://dx.doi.org/10.17807/orbital.v10i5.962</p

A focus on biometal systems of some phyto-antibiotic drug complexes

Biometal coordination bearing active donor atoms of medicinal plant extracts or herbal isolates (phytochemicals) in the recent approach of biomedical sciences is a new and advanced chemotherapeutics for combating antibiotics resistance. Stereochemistry of central metal ions around active plant molecules can give rise to robust solid state 3D metal complexes of antibiotics aiding better biological performance/affinity without any side effect compared with the parent biomolecules (organic ligands). This review therefore focuses on the applications of medicinal plant extracts as antibiotics. Structural systems of metal complexes of flavonoids, curcumins, alkaloids, carotenoids and coumarins from aloe vera, acalypha and henna leaf (AAH) are also described with a view to achieving the rationale for functional bioactive antibiotic drug

Iron(III) and copper(II) complexes bearing 8-quinolinol with amino-acids mixed ligands: Synthesis, characterization and antibacterial investigation

AbstractFour d-orbital metal complexes with mixed ligands derived from 8-hydroxyquinoline (HQ) and amino acids (AA): l-alanine and methionine have been synthesized through a mild reflux in alkaline solution and characterized by elemental analyses, infrared, electronic transition, and temperature dependant magnetic susceptibility. The IR spectroscopy revealed that iron and copper ions coordinated through carbonyl (CO), hydroxyl group (OH) of the amino acids, N-pyridine ring of hydroxyquinoline. The elemental analysis measurement with other obtained data suggested an octahedral geometry for the iron(III) complexes and tetrahedral geometry for the copper(II) complexes. From the molar magnetic susceptibility measurement, the iron(III) system (S=5/2) d5 (non-degenerate 6A1) with χmT=0.38cm3Kmol−1 showed an antiferromagnetic while Cu2+ ions system (S=½) (2T2g) has χmT=4.77cm3Kmol−1 described as paramagnetic behaviour. In vitro antimicrobial investigations of the metal complexes against standard bacteria species gave significant inhibition with, copper complex showing highest inhibitions against Pseudomonas aeruginosa (ATCC27853) of 43mm at 10μg/ml signalling its potential as pharmaceutical or chemotherapeutic agents