Tuning the Photophysical Properties of Pyrene-Based Systems: A Theoretical Study

Abstract

Recently new molecular systems based on the pyrene moiety were developed for photovoltaic applications. Here we present the results of a quantum chemical study focused on the effects induced by some different substituents on the electronic properties of pyrene, to obtain general hints for the molecular design of new pyrene-based systems. In particular, a series of electron-donating (hydroxy, amino, acetylamino) and electron-withdrawing (cyano, carbamoyl, formyl, ethynyl, ethenyl) groups were considered. Furthermore, in addition to the single pyrene molecule, two pyrene units linked by ethenylene, ethynylene, 2,5-thienylene, and ethynylene-p-phenylene containing chains of different lengths were taken into account. For all of the model structures presented, the ground state geometries have been optimized using the density functional approach, while the vertical transition energies were calculated using the time-dependent density functional theory. We will show that the tuning of the lowest electronic excitation energy (i.e., the HOMO-LUMO energy gap) as well as the localization of the spatial distributions of the frontier molecular orbitals (i.e., the nature of the electron-hole pair, generated by photon absorption) can be obtained through the analysis of the pyrene frontier molecular orbitals. This approach allows to evaluate the most suitable position of the substituents on the pyrene moiety giving rise to enhanced electronic effects also in function of their electronic nature. In this way, pyrene-structures with tailored electronic properties could be modeled. Our screening shows that promising candidates for photovoltaic applications could be molecular structures formed by two pyrene units joined/linked by a short conjugated bridge containing double or triple bonds (henceforth pyrene-linked dimers). As far as the single pyrene units are considered, the most significant reduction of the transition energy of the lowest optical electronic excitation is obtained with disubstituted pyrenes with push-pull character.

Efficient synthesis of pyrene-1-carbothioamides and carboxamides. Tunable solid-state fluorescence of pyrene-1-carboxamides

“…3,[7][8][9] Considerable attention has been paid to the development of synthetic routes to pyrenes bearing various substituents 1,10,11 and to studies on their uorescence properties. [11][12][13] Several recent works have focused on environmentallyresponsive emission of pyrene-1-carboxamides which is strongly dependent on the substituents at the nitrogen atom. 12,[14][15][16] Moreover, these compounds were used in the synthesis of polymers with tunable luminescent properties 17 and in the labelling of nucleosides.…”

Fabrication of a Poly(3-octylthiophene-2,5-diyl) Electrochemiluminescence Device Assisted by Perylene

“…Figure 5 shows the cyclic voltammograms of P3OT (Figure 5a) and perylene (Figure 5b) from the oxidation side, and Table 2 shows the summary of CV and UV-Vis absorption spectra measurement results. The measurement results of 9,10-diphenylanthracene (DPA) [15], pyrene [16], and naphthacene [17] are also summarized in Table 2 for comparison. …”

A DFT and TDDFT investigation of interactions between 1-hydroxypyrene and aromatic amino acids

“…The design of these new structures needs accurate knowledge of the effects induced by the substituents on the electronic properties of the Pyrene moiety. Quantum chemical studies can give useful information about the correlation between the structural and electronic properties [17,42].…”