Theoretical predictions of red and near-infrared strongly emitting X-annulated rylenes

Abstract

The optical properties of rylenes are extremely interesting because their emission colors can be tuned from blue to near-infrared by simply elongating the chain length. However, for conjugated chains, the dipole-allowed odd-parity 1B u excited state often lies above the dipole-forbidden evenparity 2A g state as the chain length increases, thus preventing any significant luminescence according to Kasha's rule. We systemically investigated the 1B u /2A g crossover behaviors with respect to the elongating rylene chain length with various quantum chemistry approaches, such as timedepended density functional theory (TDDFT), complete active space self-consistent field theory (CASSCF/CASPT2), multireference configuration interaction (MRCI)/Zerner's intermediate neglect of diatomic overlap (ZINDO), and MRCI/modified neglect of differential overlap. The calculated results by CASSCF/CASPT2 and MRCI/ZINDO are completely coherent: the optical active 1B u state lies below the dark B 3g or 2A g state for perylene and terrylene, which results in strong fluorescence; while a crossover to S 1 = 2A g occurs and leads to much weaker fluorescence for quaterrylene. Then we put forward a molecular design rule on how to recover fluorescence for the longer rylenes by introducing heteroatom bridges. Several heteroatom-annulated rylenes are designed theoretically, which are predicted to be strongly emissive in the red and near-infrared ranges. These are further confirmed by theoretical emission spectra as well as radiative and nonradiative decay rate calculations by using the vibration correlation function formalisms we developed earlier coupled with TDDFT.

A Twisted Bay‐Substituted Quaterrylene Phosphorescing in the NIR Spectral Region

“…As previously observed for other molecules, these results suggest that the population of the triplet excited state recorded could be induced by the non‐planar geometry of molecule 1 as proposed for similar core‐twisted PAHs. [ ][ ][ ] The corresponding lifetime of 1 at 1720 nm at 77 K appeared to be < 10 ns ( i.e . beyond the limit of the detector response of our detector).…”

On the possibility of singlet fission in crystalline quaterrylene

“…Errors in the G 0 W 0 step may stem from the G 0 W 0 approximation itself (i.e., neglecting the vertex, lack of selfconsistency, and the diagonal approximation), [123][124][125][126][127][128] numerical settings, pseudopotentials, 129,130 the mean-field starting point (e.g., self-interaction errors in DFT functionals), 111,[131][132][133] and approximations used in the self-energy evaluation, such as the Hybertsen-Louie generalized plasmon-pole model. 89 GW+BSE only considers particlehole interactions and cannot describe states with multi-exciton character 134,135 (it has been postulated based on multi-reference calculations that one of the low-lying excitons of the quaterrylene molecule in the gas phase may have a fraction of double-excitation character, 136,137 however such calculations cannot be performed for molecular crystals with periodic boundary conditions). Furthermore, only direct transitions are considered in the BSE calculation.…”

Theoretical investigation of the two-photon absorption properties of 3,6-bis(4-vinylpyridinium) carbazole derivatives—new biological fluorescent probes

“…For all molecules, the CI-active spaces were restricted to the 30 highest occupied and 30 lowest unoccupied molecular orbitals for the singly excited configuration and the two highest occupied and two lowest unoccupied orbitals for the doubly excited configuration. The ZINDO method is often employed to investigate one-or two-photon properties as it provides a better description of the lowest-lying excited states for large organic molecules or practical organic molecules than ab initio methods and first-principles DFT [25,26]. We set up the FTRNLO program to calculate the third-order polarizability γ and the TPA cross-section δ, based on to Eqs.…”

“…In this subsection, the TPA properties of all of the molecules were studied using the ZINDO program in combination with the SOS formulae [21,[24][25][26][27][28][29][30] and Eqs. 1 and 2; the accuracy of this approach has already been validated in multiple studies [28,[33][34][35].…”