Amidooxime‐Based Mononuclear Mn(II) Complexes: Synthesis, Characterization, and Studies on DNA Binding and Nuclease Activity

Abstract

A number of new amidooxime based manganese(II) complexes have been synthesized and characterized by single crystal X‐ray diffraction studies as well as by geometry optimization of complex 2 using DFT/B3LYP. All four complexes (1‐4) are mononuclear having octahedral geometry. DNA binding interaction and nuclease activity of these compounds were investigated for diverse biomedical applications. The results of photophysical studies indicated that the Mn(II) compounds bind with DNA by intercalation mode and the complex 1 containing pyrimidine moiety and chloro ligation showed highest binding affinity. The binding affinities of these compounds were of the order of 104‐105 M−1 and all of them were found to be capable of inducing DNA cleavage.

New DNA-Interactive Manganese(II) Complex of Amidooxime: Crystal Structure, DFT Calculation, Biophysical and Molecular Docking Studies

“…[Mn II (HL 1 ) 2 (Cl)­(CH 3 COO)]­( 1 ) was prepared by the following in situ preparation procedure (Scheme ). A mixture of 2-cyano pyrimidine (0.104 g, 1 mmol) and hydroxylamine hydrochloride (0.069 g, 1 mmol) in methanol (30 mL) was refluxed at 60 °C for 10 min to form pyrimidine 2-amidooxime (HL), and then, immediately MnCl 2 ·4H 2 O (0.199 g, 1 mmol) was added to the hazy white solution and stirred for additional 25 min whereupon, the solution turned bright yellow. The stirring was continued for further 1 h with addition of NaOAC (0.082 g, 1 mmol) as a base, and the resulting solution was filtered and kept undisturbed, allowing slow evaporation for few days.…”

“…DNA binding measurements were carried out following similar protocols elaborated previously. ,,, The DNA sample exhibited a characteristic ultraviolet absorption spectrum with an A 260 / A 280 ratio between 1.88 and 1.92 and an A 260 / A 230 ratio between 2.12 and 2.22. The DNA concentration in base pairs was estimated by recording absorbance at 260 nm employing a molar absorption coefficient (ε) value of 13,200 M –1 cm –1 .…”

“…The absorption and fluorescence spectral titrations were performed at 298.15 ± 0.5 K using quartz cuvettes of path length 1 cm, following the methods standardized in our laboratory and reported earlier. ,,, The electronic spectra of 1 were monitored as a function of the concentration of DNA. In each case, a fixed concentration of 1 (20 μM) was titrated with increasing concentration of DNA (0–30 μM).…”

“…On the other hand, studies on the bioactivity of the oxime-based manganese complexes are in their infant stage. Very few studies have been reported in recent years, − , and work on manganese complexes exhibiting bioactivity and DNA binding has attracted special attention recently.…”

The crystal structure of bis(acetato-κ1 O)-bis(N′-hydroxypyrimidine-2-carboximidamide-κ2 N,N′)manganese(II) — methanol (1/2), C14H18MnN8O6, 2(CH3OH)′

“…A limited number of coordination compounds based on N′-hydroxypyrimidine-2-carboximidamide have been structurally characterized and reported. So far, to the best of our knowledge, only ten examples of coordination compound containing N′-hydroxypyrimidine-2-carboximidamide have been reported [5][6][7][8][9]. The title structure is neutral discrete mononuclear manganese complex.…”