An estimation of the binding mode of Ru(II) polypyridyl complexes with DNA using analytical techniques Navaneetha Nambigari 1,2 *
University College of Science, Osmania University, India. Email - navaneeta@osmania.ac.in , nitha379@gmail.com
Recent literature on the metal complex interaction with biomolecules (DNA) shows a significant role in medicine, pharmacy, and diagnostics [1]. The design, synthesis, and choice of ligands result in interesting spectral profiles, DNA-binding, cleavage, and biological activities [2]. In view of the above attention, the present study emphasis on synthesis and spectroscopic studies (CHN Analysis, electronic absorption, FT-IR, NMR, and ESI-MS techniques) of the [Ru(A) 2 L](ClO 4 ) 2 .2H 2 O complexes, where A = Ancillary ligand; phen (1), dmp (2), bpy (3) & dmb (4), L is a novel intercalator ligand TPIP = [2-(-1-p-tolyl -1H-pyrazol-4-yl)-1H-imidazo [4,5-f][1,10]Phenanthroline]. The IR spectral data for the Ru(II) complexes exhibit bands around 624 - 628cm -1 corresponding to the Ru-N bond. UV- VISIBLE spectra of complexes display broadband at 430 - 480 region corresponding to LMCT transitions [3]. Binding mode analysis of interaction Ru (II) complexes with DNA was studied via analytical techniques (Absorption, emission methods, and viscosity) to show binding via intercalation [4]. The intrinsic binding constant, K b values are 4×10 5 M -1 , 3.8×10 5 M -1 , 3.3×10 5 M -1 , and 2.5×10 5 M -1 , respectively indicative of the intercalation wherein the simple ancillary ligands (phen and bpy) are more robust binding due to hydrophobic effects. The interaction of plasmid pBR322 DNA with the complexes determines the cleavage of supercoiled DNA (form I) to the nicked circular DNA (form II) 65 and linear DNA (form III) for all the complexes. The increased degree of viscosity also supports the order of binding of the complexes to DNA as determined by other methods, which follow the order EB > (1)> (2)> (3)> (4). Furthermore, the molecular docking studies of the Ru(II) complexes indicate an inclination towards Guanine-rich sites of DNA by the intercalator. This study has widened the scope of developing these imidazole derivatives as promising antibacterial agents. References 1. Jeylakshmi et al., Inorg.Chem.Front . 2015 , 2, 780-798. 2. W.Liu et al ., J.Inorg.Biochem. 2005 , 99, 2372. 3. K. Gupta et al., Inorg. Chem. 2013 , 52, 3687–3869. 4. Navaneetha et al., Anal.Chem.Letts. 2022, 12 (1), DOI:10.1080/22297928.2021.2021110.
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© The Author(s), 2022
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