Blue luminescent cyanopyridone based molecular architectures: A structure-property study

A new class of molecular architecture made of five conjugated rings carrying terminal methyl or variable alkoxy (chain lengths of 4, 6, 8, or 16) substituted at para positions has been synthesized. Among the five rings, two rings are of cyanopyridones utilized as an electron deficient N-heterocycle along with blue luminescent motif, and the rest of them are phenylene motifs. All the compounds produced good yield and ATR-IR, NMR and Mass spectroscopy confirmed their structures. Further, the compounds were stable up to ≈200 °C and the degradation occurs at higher temperature as evident from the TGA analysis. The mesomorphic study reveals that compound is only having very long terminal n-hexadecyloxy substituents appeared in-layers liquid crystalline organization as confirmed by POM and variable temperature XRD analysis. Further, the compounds showed intense blue fluorescence in both solution as well as solid state and their fluorescence quantum yields are dependent on the length of alkoxy chains. Calculated HOMO/LUMO levels by cyclic voltammetry measurements revealed that the compounds are ambipolar in nature and cited as an ideal candidates for electroluminescent applications.