Selenylated-oxadiazoles as promising DNA intercalators: Synthesis, electronic structure, DNA interaction and cleavage.

A series of selenylated-oxadiazoles were prepared and their interaction with DNA was investigated. The photophysical studies showed that all the selenylated compounds presented absorption between 270 and 329 nm, assigned to combined n→π* and π→π* transitions, and an intense blue emission (325-380 nm) with quantum yield in the range of Φ F = 0.1-0.4. DFT and TD-DFT calculations were also performed to study the likely geometry and the excited state of these compounds. Electrochemical studies revealed the ionization potential energies (-5.13 to -6.01 eV) and electron affinity energies (-2.25 to -2.83 eV), depending directly on the electronic effect (electron-donating or electron-withdrawing) of the substituent attached to the product. Finally, the UV-Vis DNA interaction experiments indicated that the compounds can interact with the DNA molecule due to intercalation, except for 3g (which interacted via electrostatic interaction). Plasmid cleavage assay presented positive results only for 3f that presented the strongest interaction results. These results made the tested selenylated-oxadiazoles as suitable structures for the development of drugs and the design of structurally-related therapeutics.