Synthesis, structure and photophysical properties of novel thiazolo[2,3-b]pteridines

A one-pot synthesis of a series of thiazolo[2,3-b]pteridines, along with an alternative step-by-step procedure, has been developed. The regioselectivity of the heterocyclization was determined using a combination of physicochemical methods, including X-ray crystallography. The photophysical properties of the synthesized compounds, such as their absorption and emission spectra, were systematically investigated. The absorption spectra were found to depend on the electronic effects of the substituents and the length of the conjugated system. In acetonitrile solutions, the compounds exhibited luminescence with emission maxima in the range of 452-570 nm, quantum yields of up to 6.8%, and negligible Stokes shifts. These results were further supported by DFT calculations, which showed good agreement with the experimental data. Overall, the findings highlight the potential of thiazolo[2,3-b]pteridines as promising candidates for the development of efficient luminescent materials.