Ab initio study on the excited states of pyrene and its derivatives using multi-reference perturbation theory methods

Abstract

The excited states of phenyl-substituted pyrene derivatives were calculated using multi-reference perturbation theory methods.

Simulation of vibrationally resolved absorption spectra of neutral and cationic polyaromatic hydrocarbons

“…The analysis is now extended to the larger molecule pyrene. The excited states of pyrene have been studied in earlier work using multiconfigurational wave function-based methods and TDDFT [33,34,36,43] and the vibrational resolved spectra for the lowest allowed transition (1B 3u ) have been reported [42,43]. The computed vertical excitation energies along with a description of the transition in terms of the molecular orbitals, shown in Fig.…”

“…This highlights the challenge of predicting the vertical excitation energies with sufficient accuracy that allows direct comparison with experimental spectra that involve contributions from a range of electronic transitions. Multiconfigurational wave function-based methods have considered the lowest two energy states (1B 2u and 1B 3u ) [33,34], so while they predict accurate values for these states, their performance for the higher-energy states has not been established. Figure 7 shows a comparison between the experimental spectrum and the calculated spectrum using the FCHT approximation that incorporates the lowest two energy allowed transitions and the bond lengths for the different excited states are shown in Figure S4.…”

“…Second-order coupled cluster theory calculations of the excited states of neutral naphthalene have also been reported [32]. These types of approaches have also been applied to larger PAH molecules; for example, pyrene has been studied with multireference perturbation theory [33] and multireference configuration interaction methods [34]. Time-dependent density functional theory (TDDFT) lies at an intermediate computational cost, and the excited states of neutral and cationic forms of a wide range of PAH molecules have been studied using TDDFT [14,[35][36][37][38][39].…”

Probing the supramolecular featuresviaπ–π interaction of a di-iminopyrene-di-benzo-18-crown-6-ether compound: experimental and theoretical study

“…Moreover, they observed that the dyeing effect of the pyrene derivative is more sensitive and stronger than that of pyrene. Because of its characteristic photophysical behavior such as its prominent and typical absorption bands and uorescence emission, 25,26 pyrene was involved in numerous supramolecular studies. The rst two excited states of pyrene compounds, 1La and 1Lb, p / p*, corresponding to S 0 / S 1 and S 0 / S 2 excitations, proved to have the main role in the photophysical processes involving such molecular systems.…”

“…The rst two excited states of pyrene compounds, 1La and 1Lb, p / p*, corresponding to S 0 / S 1 and S 0 / S 2 excitations, proved to have the main role in the photophysical processes involving such molecular systems. 25,[27][28][29][30] The band's intensity variation (including their appearance or disappearance), together with the wavelength shis in UV-vis and uorescence spectra varies from one pyrene derivative to another. The studies indicate that pyrene compounds are able to form dimers (by the weak association in the ground state), excimers (by the strong association in the excited states), and/or p-p stacking aggregates.…”