2.5. UV-Vis Spectroscopy Studies

Electronic absorption spectra were recorded on a Jasco V-630 BIO UV-visible spectrometer equipped with a PAC-743 model temperature control accessory. Titrations were performed at 20°C, and the concentration of compound remained constant (50 μmol·L⁻¹), while the concentration of CT-DNA was gradually increased (0 to 50 μmol·L⁻¹). After each addition of titrant, an electronic absorption spectrum of the test solution was recorded from 230 nm to 500 nm. The solutions of the complexes contained deionized water and DMSO of approximately 0.1%. The CT-DNA absorbance was eliminated by adding an equal amount of CT-DNA to the sample and the standard solution. A solution of CT-DNA (2100 μmol·L⁻¹) in nucleotides was prepared using ε ₂₆₀ = 6600 cm⁻¹·mol⁻¹·L as the molar extinction coefficient, and the absorbance was measured at 260 nm. The stock solution was stored at −5°C.