Assessing One- and Two-Photon Optical Properties of Boron Containing Arenes

Abstract

Linear and nonlinear optical properties of a series of bis(E-dimesitylborylethenyl)-substituted arenes have been modeled by high-level computational protocols. The former compounds show a remarkable interest as infrared two-photon absorbers and hence may be used in the field of optical active and smart materials or for energy storage purposes. Excited state topologies, absorption and emission spectra, excited state metrics, natural transition orbitals and two-photon absorption cross-section of a series of chromophores have been computed by means of density functional theory (DFT) and timedependent DFT (TD-DFT). An extended benchmark test on the performance of different functionals had been performed. Dynamic and vibronic effects on absorption and emission spectra have been taken into account by sampling the conformational space by means of Wigner distribution and the former have been evidenced as rather important in order to recover absorption maxima and spectral band shape. Important infrared two photon absorption cross sections involving transitions to the second excited state have been observed. In particular, thiophene bridges have been evidenced as the most beneficial to increase TPA efficiency leading to cross-section exceeding 1000 GM.

Photophysics of chlorin e6: from one- and two-photon absorption to fluorescence and phosphorescence

“…The absorption maximum for the Q-band is now around 1100 nm while the Soret band appears at more than 700 nm. Although not as high as the ones of thiophene 46,66,67 systems, TPA crosssections are still reasonable and account for about 20 (Qband) and 60 GM (Soret band). The available experimental TPA value at 800 nm is 33.9 GM, 68 in remarkable agreement with the simulated value (33.2 GM).…”

“…Once again two different strategies can be used, one can perform classical molecular dynamics [38][39][40] (MD), or explore the vibrational normal modes performing a Wigner distribution based on the calculation of the harmonic vibrational frequencies at the ground-state equilibrium geometry. 46 Both methods have advantages and drawbacks, the MD based allows to explore simultaneously different conformers; furthermore it can be straightforwardly used in the case of interaction of chromophore with complex extended systems, such as biological polymers or membranes. However, the description of the normal modes is restricted at the force eld level.…”

Level of Theory and Solvent Effects on DASA Absorption Properties Prediction: Comparing TD-DFT, CASPT2 and NEVPT2

“…The absorption in the red or infrared region of the spectrum is especially required for biological applications. Apart from chemical modification, over the last few years the use of two-photon absorption (TPA) active compounds has emerged as a quite efficient and useful way to irradiate in the red and infrared windows [ 30 , 31 , 32 , 33 , 34 ]. In more detail, the molecule under irradiation simultaneously absorbs two photons, each one corresponding to half of the energy required by one-photon absorption (so called degenerate TPA).…”

Ultrafast dynamics in polycyclic aromatic hydrocarbons: the key case of conical intersections at higher excited states and their role in the photophysics of phenanthrene monomer

“…30 Absorption spectra at the FC region are obtained either as vertical transitions from the equilibrium geometry, only or taking into account the effects of thermal motions and vibrations by a sampling of the accessible conformational space via a Wigner distribution based on the harmonic vibrational frequencies, following a successful protocol widely used by some of the authors. [31][32][33][34][35][36] The geometries of the first (S A , dark) and the second (S B , bright) excited states have been optimized using TD-DFT at the same level of theory as described above. In addition, the PESs have been explored by means of a bi-dimensional linear interpolation via two generalized coordinates linking the FC region (R FC ) and the two excited states minima R S A and R S B , respectively as reported in eqn (3).…”