Application of Novel Ruthenium (II) Polypyridyl Complexes as Robust DNA Probes, Optical Material and Antimicrobials—An Experimental and DFT Approach

The nature of the interaction of DNA with heteroleptic Ruthenium (II) Polypyridyl complexes of the type [Ru (A)TPIP], where TPIP = 2—(1-p-tolyl—1H pyrazol—4 -yl)—1H—imidazo [4, 5—f[1. 10] phenanthroline and A = 1,10 phenanthroline (1),4,4’-dimethyl-1,10—ortho Phenanthroline (2), 2,2' - bipyridine (3) and 4, 4' dimethyl 2, 2'- bipyridine (4), has been investigated by experimentaland molecular docking approaches. The order of the DNA binding affinities of the synthesised complexes is 1 > 2 > 3 > 4. The findings imply that the unsubstituted complex has a better affinity to bind with DNA than the substituted (dmp and dmb) emphasizing the significance of the auxiliary ligand. Additionally, as the medium's ionic strength drops, the DNA/Ru ratio rises, or when water is displaced by glycerol, the intercalation of complexes into DNA increases. DFT calculations at the B3LYP/LANL2MB level was used for molecular geometry (Ground State) and electronic characteristic calculations. The HOMO—LUMO gap of the Ru [II] complex is less than the intercalator and hence kinetically labile. Among the complexes, the bpy complex has shown utmost non-linear optical properties (α = -153.9099 10esu and β = 3.8498 10esu). The docking study shows the significance of the Metal-intercalator's shorter length may increase DNA binding affinity. This study divulges that the Ruthenium (II) polypyridyl complexes bind to DNA preponderantly by intercalation supporting Viscosity studies. All the complexes have a considerable attraction for guanine. The standard disk diffusion method reveals that complexes (1, 2, 3 and 4) have good antibacterial activity.