Chemical shift assignment of mono- and di-bromo triimidazo[1,2-a:1',2'-c:1'',2''-e][1,3,5]triazine derivatives by DFT/NMR integrated approach

Solid state organic compounds, endowed with enhanced emission, have been gaining great attention in the scientific community for their potential application in different areas, such as lighting technologies or bioimaging. In this field, mono- and di-bromo derivatives of triimidazo[1,2-a:1?,2?-c:1?,2?-e][1,3,5] triazine have been proposed as new organic molecules presenting a very rich and complex photophysical behavior. Their structures were investigated by standard 1D and 2D nuclear magnetic resonance (NMR) experiments, but the correct structural assignment of all proton and carbon resonances was made difficult because of the lack of crucial and diagnostic long-range correlations between quaternary carbon and proton signals. Thus, we afforded the correct chemical shift assignment by integrating the experimental data with density functional theory calculation of NMR parameters. Our findings lay foundation for a structural reference in the organic synthesis and characterization of new congeners of this intriguing class of molecules.