Perturbation of proton transfer of 2-(2′-hydroxyphenyl)benzimidazole and its nitrogenous analogues by nanoparticles

The proton transfer of 2-(2′-hydroxyphenyl)benzimidazole and its nitrogenous analogues are investigated on the surface of silver nanoparticles. Surface plasmon resonance, transmission electron microscopic and field emission scanning electron microscopic images establish that the fluorophores assist the growth of the nanoparticles and also stabilize them. Silver nanoparticles interact with the fluorophore through ring nitrogen. The ratio of intensity of the normal to that of tautomer band is enhanced. The interaction of nanoparticle with the pyridyl nitrogen reduces the electron density on the azole nitrogen. This weakens the intramolecular hydrogen and the equilibrium shifts toward trans-enol. [Display omitted] •Fluorophores stabilize the nanoparticles without any other stabilizers.•Pyrido compounds are better stabilizers.•Nanoparticles disturb the intramolecular H-bond that affects the equilibrium.•Nanoparticles shift the equilibrium more towards trans-enol.