CHARACTERIZATION OF THIAZOLO-CHROMANDIONE BY MOLECULAR SPECTROSCOPY AND SPECTRAL BEHAVIOR IN A WIDE pH RANGE

In this study, the derivatives of coumarin with a complex organic structure were analyzed using spectroscopic methods through UV/Vis and IR spectroscopy. UV/Vis measurements were conducted using different pH conditions, varying from pH 1-12, to observe the impact of pH on the electronic behavior and structure of the substance. In the UV/Vis spectra, measurements were made recording the light absorbance in the region of (200-800 nm). Three main absorption bands have been identified. The first notable shift was observed in the band of (212 nm) in a highly acidic environment (pH = 1), suggesting the protonation of the substance. Second shift was observed in (190-210 nm) corresponding to π→π* and third shift to n→σ* (250 nm) electronic transitions, with the lone pairs of heteroatoms such as oxygen and nitrogen playing a key role in stabilizing these transitions. Structural changes and spectral shifts were observed through the changes in pH, especially in basic pH, where coumarin structure breakdown and regeneration occurred. Using IR spectroscopy, the characteristic vibrations of functional groups were analyzed. Benzene deformations and the presence of a diazo group (N=N) were observed in the infrared spectrum. Using a combination of these methods helped to identify the characteristic groups and determine the structure of the substance, displaying the connection between its structure and behavior under a wide pH range.