Biological evaluation, molecular docking, DNA interaction and thermal studies of new bioactive metal complexes of 2‐hydroxybenzaldehyde and fluorobenzamine Schiff base ligand

Abstract

Funding information DST-FIST Program of India Schiff base ligand named 2-((E)-(2-fluorophenylimino)methyl)phenol (HL) was prepared by the condensation of 2-hydroxybenzaldehyde and 2-fluorobenzamine in 1:1 molar ratio. The coordination behaviour of a series of transition metal ions with the synthesized HL ligand, [Cr(HL) 2 ] (1), [Fe (HL) 2 ] (2), [Co(HL) 2 ] (3) and [Cu(HL) 2 ] (4) is reported. The structure and bonding of the metal complexes have been deduced by analytical and spectral studies. Based on the above studies, the metal centres were found to be octahedral for all the complexes. The activation thermodynamic properties were calculated using the Coats-Redfern method. Thermal decomposition processes of complexes 1, 2, 3 and 4 are non-spontaneous; that is, the complexes are thermally stable. The positive value of Gibbs free energy of decomposition (ΔG*) for all the complexes is non-spontaneous processes. DNA binding properties of these metal complexes, investigated using UV-visible absorption, fluorescence and viscosity measurement studies, imply that the complexes bind to DNA by intercalation. The intrinsic binding constant K b from the electronic absorption studies are 3.12 × 10 4 M −1 , 1.86 × 10 4 M −1 , 3.96 × 10 4 M −1 and 5.89 × 10 4 M −1 , and the Stern-Volmer quenching constant K sv values from fluorescence studies are 2.29 × 10 4 M −1 , 1.92 × 10 4 M −1 , 5.62 × 10 4 M −1 and 8.91 × 10 4 M −1 , for the complexes 1, 2, 3 and 4, respectively. DNA photo cleavage activities of these complexes were studied with supercoiled pUC19 DNA, in the presence of H 2 O 2. GOLD 3.1 program was used to evaluate binding affinities of complexes with human DNA topoisomerase I protein. in vitro cytotoxic and antimicrobial studies revealed higher activity of metal complexes, compared with the ligand.

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

“…Electronic transition 4 T 1g (F) → 4 T 1g (P) and 4 T 1g (F) → 4 T 2g (F) appeared at 562 and 519 nm, respectively, in the spectrum of complex 2 due to octahedral arrangement of ligands around Co(II) metal 46 . Bands appeared at 458, 511, and 546 nm for complex 4 can be attributed to the 2 B 1g → 2 E g , 2 B 1g → 2 B 2g , and 2 B 1g → 2 A 1g transitions, respectively, suggesting square planar geometry 47 …”

DNA interaction, molecular dynamics simulation, molecular docking, biological, in vivo anti‐inflammatory and thermal studies of o‐hydroxyacetophenone and 2‐fluoroaniline Schiff base complexes

“…The reaction progresses by adding calf‐thymus (CT) DNA to the metal complex and the solution obtained was equilibrated for 5 min at 27°C, for recording the absorption intensities of the ligand‐to‐metal charge transfer (LMCT) band. [ 10 ] The K b intrinsic binding constant was derived from the spectrum using Wolfe–Shimmer formula: where [DNA] = deoxyribonucleic acid concentration, ɛ b = extinction coefficient for fully bound metal complex, ɛ a = apparent extinction coefficient (=A obsd /[complex]) and ɛ f = extinction coefficient of free metal ion complex. K b values were derived on substituting experimental data in the above equation.…”

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) .…”

“…As a rule, for decomposition the activation energy values markedly smaller than 100 kJ mol À1 should raise suspicion. Yet, the majority of the aforementioned publications report the values less than 50 kJ mol À1 and some of them less than 10 [3,6,11,14,21,22] and even less than 1 [6] kJ mol À1 . If such energy barriers were real, the respective compounds would unlikely be stable at ambient temperature.…”