The organic molecules of a chain structure containing phenyl, oxazole and oxadiazole rings are used in different combinations as active media for tunable lasers. From this viewpoint, we focused in the theoretical study of organic compounds of three rings, which have similar optical properties (fluorescence and laser properties). The main goal of this study is to compare the electronic structure through the analysis of molecular global descriptors defined in the DFT framework of2‐[2‐X‐phenyl]‐5‐phenyl‐1,3‐Oxazole, 2‐[2‐X‐phenyl]‐5‐phenyl‐1,3,4‐Oxadiazole, and 2‐[2‐X‐phenyl]‐5‐phenyl‐furane with X = H, F and Cl. The basis set used was 6−31G+(d).