Heterocyclic compounds with effective solid-state luminescence
offer a wide range of uses. It has been observed that combining
pyrimidine and indole moieties in a single molecule can enhance material
behavior dramatically. Here, different heterocyclic compounds with
indole and pyrimidine moieties have been synthesized effectively, and
their structures have been validated using NMR, IR, and mass
spectroscopy. The photoluminescence behavior of two substances was
investigated in powder form and solutions of varying concentrations.
After aggregation, one molecule displayed a redshifted luminescence
spectrum, whereas another homolog showed a blueshift. Thus, density
functional theory calculations were carried out to establish that
introducing a terminal group allows modifying of the luminescence
behavior by altering the molecular packing. Because of the non-planarity,
intermolecular interactions, and tiny intermolecular distances within the
dimers, the materials demonstrated a good emission quantum yield (Φem) in the solid state (ex. 25.6%). At high temperatures, the
compounds also demonstrated a stable emission characteristic.