Spectral, thermal, biological and multi‐heating rate kinetic properties of Cu(II) complexes containing N₂O₂ donor ligands: 1,10‐phenanthroline and acyl coumarins

Abstract

A series of newly synthesized coumarin‐based mixed‐ligand copper complexes with 1,10‐phenanthroline (Ph) were investigated by means of thermogravimetry, differential thermogravimetry, differential scanning calorimetry (DSC), electronic spectra and magnetic measurements. Structural and spectroscopic properties of neutral bidentate ligands as well as all complexes were studied on the basis of mass spectra, NMR (1H and 13C) spectra, FT‐IR spectrophotometry and elemental analyses. IR spectral data suggest tetra‐coordinated N2O2 bonding of ligand toward metal ion. Dynamic scan of DSC experiments for copper complexes were obtained at different heating rates (2.5–20°C min−1). Isoconversion methods of Kissinger and Ozawa were used for the determination of the pre‐exponential factor (A), activation energy (Ea) and order of reaction (n). Kinetic parameters for second‐step degradation obtained by Kissinger's and Ozawa's methods are in good agreement. The results indicate that complexes are much stronger free radical scavenger and antioxidant compounds than ligands. Antimycobacterial screening of ligand and its copper compound against Mycobacterium tuberculosis shows clear enhancement in antitubercular activity upon copper complexation. Also good antimicrobial activities of the complexes against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Salmonella typhus, Aspergillus niger, Candida albicans and Aspergillus clavatus have been found compared to its free ligands. Copyright © 2012 John Wiley & Sons, Ltd.

Synthesis of Cu(II), Ni(II), Co(II), and Mn(II) Complexes with Ciprofloxacin and Their Evaluation of Antimicrobial, Antioxidant and Anti-Tubercular Activity

“…The IR spectra of the coumarin derivatives shows ≈1612 cm −1 and ≈1745 cm −1 bands corresponding to α, β-unsaturated ketone and lactone carbonyl ketone respectively, on complexation these peaks shifted to a lower frequency ≈1600 cm −1 and ≈1735 cm −1 due to complex formation. In all the complexes, a new band is seen in the ≈ 538 -546 cm −1 region, which is probably due to the formation of the weak band observed in the ≈ -455 cm -1 range can be attributed to ν (M-O) [26][27].…”

Inhibition behavior on alkaline phosphatase activity, antibacterial and antioxidant activities of ternary methimazole–phenanthroline–copper(II) complex

“…) there is an increase in the biocidal activity in terms of their minimum inhibitory concentration (MIC) values and several phenanthroline derived complexes have been demonstrated to have antimicrobial activity [18][19][20]. Related to the ability of this ligand as inhibitor of the alkaline phosphatase (ALP) activity, it is well documented that this chelating agent inhibits Escherichia coli alkaline phosphatase by removal of its zinc ion on complexation [21].…”

Unprecedented in Vitro Antitubercular Activitiy of Manganese(II) Complexes Containing 1,10-Phenanthroline and Dicarboxylate Ligands: Increased Activity, Superior Selectivity, and Lower Toxicity in Comparison to Their Copper(II) Analogs

“…Against M. tuberculosis H37Rv, only complexes incorporating hydroxylated (-3-OH) and chlorinated (-4-Cl) dicoumarols showed appreciable activity (MIC 90 = 4.05 and 64.8 μM, respectively). Patel et al ( 2012 ) tested an array of similar Cu(II) acyl coumarin/phen complexes which displayed only moderate anti -M. tuberculosis activity (MIC range 49.5->243 μM). Segura et al ( 2014 ) synthesized Ag(I) thiourea (tu)/phen complexes, [{Ag(phen)(μ-tu)} 2 ]X 2 (X = , CF 3 ), having MIC values of 11.0 and 14.2 μM (X = and CF 3 , respectively) against H37Rv.…”