scholarly journals Benchmarking Density Functional Approximations for Excited-State Properties of Fluorescent Dyes

Molecules ◽  
2021 ◽  
Vol 26 (24) ◽  
pp. 7434
Author(s):  
Anna M. Grabarz ◽  
Borys Ośmiałowski
Keyword(s):  
Excited State ◽  
Density Functional ◽  
Fluorescent Dyes ◽  
Dipole Moments ◽  
Photophysical Properties ◽  
Excitation Energies ◽  
Data Set ◽  
Vertical Excitation ◽  
A Minor ◽  
Vertical Excitation Energies

This study presents an extensive analysis of the predictive power of time-dependent density functional theory in determining the excited-state properties of two groups of important fluorescent dyes, difluoroboranes and hydroxyphenylimidazo[1,2-a]pyridine derivatives. To ensure statistically meaningful results, the data set is comprised of 85 molecules manifesting diverse photophysical properties. The vertical excitation energies and dipole moments (in the electronic ground and excited states) of the aforementioned dyes were determined using the RI-CC2 method (reference) and with 18 density functional approximations (DFA). The set encompasses DFAs with varying amounts of exact exchange energy (EEX): from 0% (e.g., SVWN, BLYP), through a medium (e.g., TPSSh, B3LYP), up to a major contribution of EEX (e.g., BMK, MN15). It also includes range-separated hybrids (CAM-B3LYP, LC-BLYP). Similar error profiles of vertical energy were obtained for both dye groups, although the errors related to hydroxyphenylimidazopiridines are significantly larger. Overall, functionals including 40–55% of EEX (SOGGA11-X, BMK, M06-2X) ensure satisfactory agreement with the reference vertical excitation energies obtained using the RI-CC2 method; however, MN15 significantly outperforms them, providing a mean absolute error of merely 0.04 eV together with a very high correlation coefficient (R2 = 0.98). Within the investigated set of functionals, there is no single functional that would equally accurately determine ground- and excited-state dipole moments of difluoroboranes and hydroxyphenylimidazopiridine derivatives. Depending on the chosen set of dyes, the most accurate μGS predictions were delivered by MN15 incorporating a major EEX contribution (difluoroboranes) and by PBE0 containing a minor EEX fraction (hydroxyphenylimidazopiridines). Reverse trends are observed for μES, i.e., for difluoroboranes the best results were obtained with functionals including a minor fraction of EEX, specifically PBE0, while in the case of hydroxyphenylimidazopiridines, much more accurate predictions were provided by functionals incorporating a major EEX contribution (BMK, MN15).

scholarly journals Cross-conjugation controls the stabilities and photophysical properties of heteroazoarene photoswitches

2021 ◽  
Author(s):  
Daniel Adrion ◽  
Steven Lopez
Keyword(s):  
High Throughput Screening ◽  
Density Functional ◽  
Photophysical Properties ◽  
Photochemical Reactions ◽  
Free Energies ◽  
Excitation Energies ◽  
Functional Theory ◽  
Vertical Excitation ◽  
Screening Study

Azoarene photoswitches are versatile molecules that interconvert from their E-isomer to their Z-isomer with light. Azobenzene is a prototypical photoswitch but its derivatives can be poorly suited for in vivo applications such as photopharmacology due to undesired photochemical reactions promoted by ultraviolet light and its relatively short half-life (t1/2) of the Z-isomer (2 days). Experimental and computational studies suggest that these properties (λmax of the E isomer and t1/2 of the Z-isomer) are inversely related. We identified isomeric azobisthiophenes and azobisfurans from a high-throughput screening study of 1700 azoarenes as photoswitch candidates with improved λmax and t1/2 values relative to azobenzene. We used density functional theory to predict the activation free energies, reaction free energies, and vertical excitation energies of the E- and Z-isomers of 2,2- and 3,3-substituted azobisthiophenes and azobisfurans. The half-lives depend on whether the heterocycles are 𝜋-conjugated or cross-conjugated with the diazo 𝜋-bond. The 2,2-substituted azoarenes both have t1/2 values on the scale of 1 hour, while the 3,3-analogues have computed half-lives of 40 (thiophene) and 230 (furan) years. The 2,2-substituted heteroazoarenes have significantly higher λmax absorptions than their 3,3-substituted analogs: 76 nm for azofuran and 77 nm for azothiophene.

scholarly journals Ab initio studies of two pyrimidine derivatives as possible photo-switch systems

Open Physics ◽  
2013 ◽  
Vol 11 (9) ◽  
Author(s):  
András Csehi ◽  
Clemens Woywod ◽  
Gábor Halász ◽  
Ágnes Vibók
Keyword(s):  
Excited State ◽  
Hydrogen Transfer ◽  
Covalent Bond ◽  
Excitation Energies ◽  
Complete Active Space ◽  
Vertical Excitation ◽  
Singlet States ◽  
Self Consistent Field ◽  
Intramolecular Hydrogen ◽  
Vertical Excitation Energies

AbstractThe six lowest lying electronic singlet states of 8-(pyrimidine-2-yl)quinolin-ol and 2-(4-nitropyrimidine-2-yl)ethenol have been studied theoretically using the complete active space self-consistent-field (CASSCF) and M’ller-Plesset second-order perturbation theory (MP2) methods. Both molecules can be viewed as consisting of a frame and a crane component. As a possible mechanism for the excited-state relaxation process an intramolecular hydrogen transfer promoted by twisting around the covalent bond connecting the molecular frame and crane moieties has been considered. Based on this idea we have attempted to derive abstracted photochemical pathways for both systems. Geometry optimizations for the construction of hypothetical reaction coordinates have been performed at the MP2 level of theory while the CASSCF approach has been employed for the calculation of vertical excitation energies along the pathways. The results of the calculations along the specific twisting displacements investigated in this study do not support the notion of substantial twisting activity upon excitation of any of the five excited states at the planar terminal structures of the torsion coordinates of both molecules. However, the present analysis should be considered only as a first, preliminary step towards an understanding of the photochemistry of the two candidate compounds. For example, we have not performed any excited state geometry optimizations so far and the estimates of vertical excitation energies do not take dynamical electron correlation into account. Further work on this subject is in progress.

Excited states of acrolein: abinitio model studies on α,β-unsaturated carbonyl compounds

1982 ◽  
Vol 60 (5) ◽  
pp. 601-606 ◽  
Author(s):  
Katherine Valenta ◽  
Friedrich Grein
Keyword(s):  
Excited State ◽  
Excited States ◽  
Carbonyl Compound ◽  
Carbonyl Compounds ◽  
Excitation Energies ◽  
Vertical Excitation ◽  
Model Studies ◽  
Unsaturated Carbonyl Compound ◽  
Vertical Excitation Energies

As an explanation of the stereochemistry of photoaddition between α,β-unsaturated carbonyl compounds and olefins, Wiesner suggested that the excited state of the α,β-unsaturated carbonyl compound is pyramidal at the β-carbon. It is shown by abinitio SCF and CI studies that for acrolein in the 1nπ*, 3nπ*, and 3ππ* excited states the β-carbon remains planar. In addition, vertical excitation energies for the 1nπ* and 1ππ*, and adiabatic excitation energies for the 1nπ* and 3nπ* states of trans-acrolein have been calculated.

COSMO-RI-ADC(2) excitation energies and excited state gradients

2018 ◽  
Vol 20 (24) ◽  
pp. 16354-16363 ◽  
Author(s):  
Sarah Karbalaei Khani ◽  
Alireza Marefat Khah ◽  
Christof Hättig
Keyword(s):  
Excited State ◽  
Excitation Energies ◽  
Vertical Excitation ◽  
Vertical Excitation Energies

Evaluating vertical excitation energies and excited state analytic gradients in solution at COSMO-ADC(2).

Charge-Transfer Properties of Dye-Sensitized Solar Cells via Long-Range-Corrected Density Functional Theory

2008 ◽  
Vol 1120 ◽  
Author(s):  
Bryan Matthew Wong
Keyword(s):  
Density Functional Theory ◽  
Excited State ◽  
Charge Transfer ◽  
Solar Cell ◽  
Long Range ◽  
Density Functional ◽  
Dipole Moments ◽  
Excitation Energies ◽  
Functional Theory ◽  
Excited State Dipole Moments

AbstractThe excited-state properties in a series of solar cell dyes are investigated with a long-range-corrected (LC) functional which provides a more accurate description of charge-transfer states. Using time-dependent density functional theory (TDDFT), the LC formalism correctly predicts a large increase in the excited-state electric dipole moment of the dyes with respect to that of the ground state, indicating a sizable charge separation associated with the S1 ← S0 excitation. The performance of the LC-TDDFT formalism, illustrated by computing excitation energies, oscillator strengths, and excited-state dipole moments, demonstrates that the LC technique provides a consistent picture of charge-transfer excitations as a function of molecular size. In contrast, the widely-used B3LYP functional severely overestimates excited-state dipole moments and underestimates the experimentally observed excitations, especially for larger dye molecules. The results of the present study emphasize the importance of long-range exchange corrections in TDDFT for investigating the charge-transfer dynamics in solar cell dyes.

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