Characterization, theoretical investigation, and biological applications of Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) complexes of a triazene ligand containing a benzothiazole ring

Abstract

Herein, Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) complexes of a previously synthesized triazene ligand, namely, (E)-2-(3-(4-nitrophenyl)triaz-1-en-1-yl)benzo [d]thiazole (L), were prepared. The metal:ligand ratio of complexes was determined by molar ratio method, and complexes were synthesized based on the result ratio (1:2 for Co(II), Ni(II), and Zn(II) complexes, and (1:1) for Cu(II) and Mn(II)). The complexes were characterized by infrared (IR) and electron paramagnetic resonance (EPR) spectroscopies, magnetic moment, and/or molar conductance measurements. IR spectra suggested the existence of bidentate binding through the nitrogen atom of the thiazole ring and nitrogen atom of the triazene linkage. Molar conductivities indicated the nonelectrolytic nature of all the complexes. Magnetic moment and EPR of the complexes confirmed their octahedral geometries. Thermal studies were conducted to confirm the structures and analyze the thermal stabilities of the complexes. Activation thermodynamic parameters were determined using the Coats-Redfern and Horowitz-Metzger methods. The calf thymus DNA binding activity was investigated by absorption titration experiments and viscosity measurements, and intrinsic binding constants of complexes range from 4.00 Â 10 5 to 5.00 Â 10 5 M À1 . Cytotoxic activities were examined against MCF-7 and HCT-116 cell lines. Although all the complexes exhibited reasonable cytotoxic effects, their cytotoxic activities were in the following order: Zn(II) > Cu(II) > Mn(II) > Co(II) > Ni(II). Zn(II) complex showed the highest activity with IC 50 values are 2.87 and 1.94 μg ml À1 against MCF-7 and HCT-116, respectively. Molecular docking was used to assess the binding affinities of these complexes to colon cancer (3ig7) and breast cancer (1hk7) proteins.Zn(II) complex showed the best docking scores compared with the ligand and other tested complexes. Results of molecular docking well correlated with those of the cytotoxicity experiments.

Synthesis, structural elucidation, molecular modeling and antimicrobial studies of Mn(II), Co(II), Ni(II), and Cu(II) complexes containing NO donor bidentate Schiff base

“…Synthesized complex ( 1 ) having Mn(II) metal possess the value of magnetic susceptibility of 5.99 BM, and it is in well accordance with the values previously reported for octahedral Mn(II) chelates and permits us to assign a value of S = 5/2 of effective spin for this Mn(II) complex 36 . Magnetic moment of 4.37 BM for complex 2 having Co(II) metal suggests octahedral geometry for complex 2 , which is paramagnetic with an effective spin value S = 3/2 37,38 . Complex 3 having Ni(II) metal has no value of magnetic moment as it is diamagnetic (ligand is strong field).…”

“…36 Magnetic moment of 4.37 BM for complex 2 having Co(II) metal suggests octahedral geometry for complex 2, which is paramagnetic with an effective spin value S = 3/2. 37,38 Complex 3 having Ni(II) metal has no value of magnetic moment as it is diamagnetic (ligand is strong field).…”

Designing, Characterization, DFT, Biological Effectiveness, and Molecular Docking Analysis of Novel Fe(III), Co(II), and Cu(II) Complexes Based on 4-Hydroxy-2H-pyrano[3,2-c]quinoline-2,5(6H)-dione

“…The magnetic moment of 4.84 μ B observed in C3 in accordance with the magnetic moment that is expected to occur during the transition to the d 7 high spin (t 2g 5 e g 2 ) configuration. − Lastly, the C4 complex showcased two distinct bands at wavelengths of 535 and 630 nm, associated with the 2 B 1g → 2 E 2g and 2 B 1g → 2 A 1g configurations in the tetrahedral complex . The presented data in Table underscores that the C4 complex displays a moment of magnetic attraction of 1.75 μ B , aligning with a transition toward the d 9 (e g 4 t 2g 5) configuration. , …”

Comments on multiple publications reporting single heating rate kinetics

“…The purpose of this note is to alert the Applied Organometallic Chemistry community to an alarming number of publications that report the single heating rate kinetics for thermal decomposition of compounds. According to Scopus, [ 1 ] most recently (i.e., in the years 2021 and 2022) this journal published 21 papers [ 2–22 ] that study the thermal decomposition kinetics as measured by thermogravimetry at a single heating rate. The resulting measurements are treated by means of the Coats–Redfern [ 23 ] or Horowitz–Metzger [ 24 ] method in order to evaluate the kinetic parameters, that is, the activation energy, E, preexponential factor, A, and reaction model, g(α) .…”

“…Indeed, many of the reported values are either too big or too small to be realistic. For example, some of the reported activation energies exceed 400, [9,10] 600, [9,12] 800, [8] and even 3000 [12] kJ mol À1 . Generally, the activation energy of a chemical reaction should not exceed the bond energy.…”