Exploration of 6,8-diphenylthieno[3,4-f]pentathiepine derivatives via conceptual DFT and TD-DFT for optoelectronic applications.

contextThe present work is undertaken to design and theoretically investigate new sulphur-fused indole derivatives with enhanced optoelectronic properties by modifying the parent compound, 6,8-diphenylthieno[3,4-f][1,2,3,4,5]pentathiepine. Structural tuning was achieved through the introduction of various substituents (-OH, -OCH₃, -NH₂, etc.) at the para positions of the phenyl rings and by extending the π-conjugation using four- and six-carbon chromophoric systems with terminal auxochromes. These modifications were intended to alter the electronic structure, stability and light absorption/emission characteristics of the molecules. The study provides insight into structure-property relationships and helps identify potential candidates for applications in organic optoelectronic devices.

methodConceptual Density Functional Theory (CDFT) was employed for the initial screening to evaluate stability and predict spectral behaviour, while the most promising candidates were further studied using Time-Dependent Density Functional Theory (TD-DFT) to analyse their photophysical properties. All the DFT and TD-DFT calculations were performed using ORCA Quantum Chem. Program 6.0.1 by employing B3LYP functional and Def2-SVP basis set.