We present here the FT-IR, DFT computation, XRD, optical, and photophysical characterization of a heterocyclic compound with thienopyrimidine and pyran moieties. TD-DFT/DMOl3 and TD-DFT/CASTEP computations were used to study the geometry of isolated and dimer molecules and their optical behavior. The indirect (3.93 eV) and direct (3.29 eV) optical energy bandgaps, HOMO–LUMO energy gap (3.02 eV), and wavelength of maximum absorption (353 nm) were determined in the gas phase with M062X/6-31+G (d, p). A thin film of the studied molecule was studied using XRD, FT-IR, and UV–Vis spectroscopy. The average crystallite size was found as 74.95 nm. Also, the photoluminescence spectroscopy revealed that the compound exhibited different emission bands at the visible range with different intensities depending on the degree of molecular aggregation. For instance, solutions with different concentrations emitted blue, cyan, and green light. On the other hand, the solid-state material produced a dual emission with comparable intensities at λmax = 455, 505, and 621 nm to cover the entire visible range and produce white emission from a single material with CIE coordinates of (0.34, 0.32) that are very similar to the ideal pure white light. Consequently, these findings could lead to the development of more attractive new luminous materials.

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A thin film of 7-oxo-thiazolopyrimidine-3,8-dicarbonitrile derivative [7-ThPyDi]TF was prepared using a spin coating technique. The surface morphology and molecular structure are studied using various techniques such as XRD, FTIR, and scanning electron microscope (SEM). Moreover, the quantum chemical calculations were carried out through time-dependent density functional theory (TD-DFT) to investigate some reactivity descriptors such as softness and electronegativity. Also, Au/[7-ThPyDi]TF/p-Si/Al heterojunction diodes were fabricated. It was revealed that the energy bandgap value of [7-ThPyDi] as an organic thin film is 3.58 eV for direct transitions and 3.94 eV for indirect transitions, respectively, and this value falls within the semiconductor material range. The atomic force microscope demonstrated that the surface roughness of the thin film is approximately 32.2 nm. Because of its high refractive index, this material has the potential application as an antireflection coating for solar cells and as lenses with a wide focal range. We investigated a blue luminescent thiazolopyrimidine compound; the maximum emission in the more aggregated state (higher solution concentration) exhibits a notable blue shift compared to the more diluted solution. This uncommon phenomenon has been understood by structural analyses using density functional theory. The chemical structure of the molecule [planar conjugated cores and strong polar groups (–CO and –CN)] enables it to interact with both itself and the polar solvent. The intermolecular interactions result in the bending of the conjugated plane. As a result, the blue shift happens upon aggregation when the conjugated effect becomes weaker. The studied molecule gave different emission colors (blue, yellow, and reddish green) depending on the molecular packing.

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