New pyrazolao pyridine carbonitrile derivative: Structural and optical properties induced by ultraviolet radiation

A novel pyrazolo derivative powder is synthetized by reacting nitro phenyl- methylene malono nitriles with 1,5-dimethyl-4-nitroso-2-penyl-1H-pyrazol-(3(2H)-one in ethanol. The derivative thin films are deposited using thermal evaporation technique. Powder and thin films structural properties of the pyrazolo material are investigated by means of FTIR, XRD, and AFM. FTIR analysis prove the chemical stability of the derivative under thermal evaporation and UV irradiation. Spectrophotometric technique is applied in order to study the optical properties of the Pyrazolo thin films. Thin films are irradiated using ultraviolet radiation source. The surface topography images show that UV irradiation modify the surface morphology of thin films. Absorption analysis reveal that the material has two absorption peaks due to π to π* transitions. UV irradiation changes the refractive index and dielectric constants of the material. Also, it decreases the band gap's value and introduces more disorder in the films creating additional localized states. UV irradiation could tune the optical constants of the pyrazolo derivative.