Effects of substituent groups and solvent media on Pyrene in ground and excited states: A DFT and TDDFT study

This study presents a computational investigation of Pyrene and its –OH, –NH2, –CN, –CH2NH2, and –C6H5NH2 substituted derivatives in gas phase and different solvents. The calculations were performed using density functional theory (DFT) at rB3LYP/6-31G(d,p) level of theory for 1-substituted Pyrene derivatives. Excited state properties of molecules were obtained by time-dependent density functional theory (TDDFT). Molecular structure of the compounds, electronic and solvation energies, electronic transitions and HOMO–LUMO energy gaps were analyzed and compared using electron donor and electron acceptor substituents in gas phase and in solution. The results showed that the stability of the investigated systems increased with increasing solvent polarity. Analyses of the first excited singlet states revealed that there were slight charge transfers between substituent and Pyrene except for 1-Hydroxypyrene and 1-Aminopyrene. Among all the studied molecules, 1-Pyreneaniline is determined to be the best candidate for investigating and designing organic photosensitive materials with its high absorption intensity and charge transfer character.