Selenium substitution effects on excited-state properties and photophysics of uracil: a MS-CASPT2 study

2020 ◽  
Vol 22 (21) ◽  
pp. 12120-12128 ◽  
Author(s):  
Qin Peng ◽  
Yun-Hua Zhu ◽  
Teng-Shuo Zhang ◽  
Xiang-Yang Liu ◽  
Wei-Hai Fang ◽  
...  
Keyword(s):  
Excited State ◽  
Substitution Effects ◽  
Selenium Substitution

We have employed the MS-CASPT2 approach to explore selenium substitution effects on the excited state properties and photophysics of uracil.

Excited state intramolecular proton transfer in julolidine derivatives: an ab initio study

2018 ◽  
Vol 20 (38) ◽  
pp. 25031-25038 ◽  
Author(s):  
Šimon Budzák ◽  
Denis Jacquemin
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Ab Initio ◽  
Intramolecular Proton Transfer ◽  
Substitution Effects ◽  
Ab Initio Study

We have studied, using ab initio tools, a series of fluorescent julolidine derivatives, undergoing Excited State Intramolecular Proton Transfer (ESIPT) and some unexpected substitution effects have been found.

scholarly journals Density Functional Theory Study of Substitution Effects on the Second-Order Nonlinear Optical Properties of Lindquist-Type Organo-Imido Polyoxometalates

Symmetry ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1636
Author(s):  
Emna Rtibi ◽  
Benoit Champagne
Keyword(s):  
Density Functional Theory ◽  
Excited State ◽  
Charge Transfer ◽  
Density Functional ◽  
Energy Charge ◽  
Substitution Effects ◽  
First Hyperpolarizability ◽  
Functional Theory ◽  
State Approximation ◽  
Donor And Acceptor

Density functional theory and time-dependent density functional theory have been enacted to investigate the effects of donor and acceptor on the first hyperpolarizability of Lindquist-type organo-imido polyoxometalates (POMs). These calculations employ a range-separated hybrid exchange-correlation functional (ωB97X-D), account for solvent effects using the implicit polarizable continuum model, and analyze the first hyperpolarizabilities by using the two-state approximation. They highlight the beneficial role of strong donors as well as of π-conjugated spacers (CH=CH rather than C≡C) on the first hyperpolarizabilities. Analysis based on the unit sphere representation confirms the one-dimensional push-pull π-conjugated character of the POMs substituted by donor groups and the corresponding value of the depolarization ratios close to 5. Furthermore, the use of the two-state approximation is demonstrated to be suitable for explaining the origin of the variations of the first hyperpolarizabilities as a function of the characteristics of a unique low-energy charge-transfer excited state and to attribute most of the first hyperpolarizability changes to the difference of dipole moment between the ground and that charge-transfer excited state.

scholarly journals Kinetic Prediction of Reverse Intersystem Crossing in Organic Donor–Acceptor Molecules

2020 ◽  
Author(s):  
Naoya Aizawa ◽  
Yu Harabuchi ◽  
Satoshi Maeda ◽  
Yong-Jin Pu
Keyword(s):  
Excited State ◽  
Rate Constants ◽  
Rational Design ◽  
Molecular Structures ◽  
Theoretical Expression ◽  
Substitution Effects ◽  
Intersystem Crossing ◽  
Predictive Tool ◽  
Spin Flip ◽  
Wide Range

Reverse intersystem crossing (RISC), the uphill spin-flip process from a triplet to a singlet excited state, plays a key role in a wide range of photochemical applications. Understanding and predicting the kinetics of such processes in vastly different molecular structures would facilitate the rational design of new materials. Here, we demonstrate a theoretical expression that successfully reproduces experimental RISC rate constants ranging over five orders of magnitude in twenty different molecules. We show that the spin flip occurs across the singlet–triplet crossing seam involving a higher-lying triplet excited state where the semi-classical Marcus parabola is no longer valid. The present model explains the counterintuitive substitution effects of bromine on the RISC rate constants of newly synthesized molecules, providing a predictive tool for material design.<br>

scholarly journals The Photoisomerization Pathway(s) of Push-Pull Phenylazoheteroarenes

2020 ◽  
Author(s):  
Sergi Vela ◽  
Clemence Corminboeuf
Keyword(s):  
Molecular Dynamics ◽  
Excited State ◽  
Quantum Yield ◽  
Working Conditions ◽  
Azo Dyes ◽  
Conical Intersection ◽  
Substitution Effects ◽  
Isomerization Pathway ◽  
And Inversion

<div> <p>Azoheteroarenes are the most recent derivatives targeted to further improve the properties of azo-based photoswitches. Their light-induced mechanism for trans-cis isomerization is assumed to be very similar to that of the parent azobenzene. As such, they inherited from the controversy about the dominant isomerization pathway (rotation<i> vs.</i> inversion) depending on the excited state (nπ* <i>vs.</i> ππ*). While the controversy seems settled in azobenzene, the extent to which the same conclusions apply to the more structurally-diverse family of azoheteroarenes is unclear. Here, we unravel by means of non-adiabatic molecular dynamics, the photoisomerization mechanism of three prototypical phenyl-azoheteroarenes with an increasing push-pull<i> </i>character. The evolution of the rotational and inversion conical intersection energies, the preferred pathway, and the associated kinetics upon both nπ* and ππ* excitations can be linked directly with the push-pull substitution effects. Overall, we clarify the working conditions of this family of azo-dyes and identify a possibility to exploit push-pull substituents to tune their photoisomerization quantum yield.</p> </div> <br>

Construction of high efficiency non-doped deep blue emitters based on phenanthroimidazole: remarkable substitution effects on the excited state properties and device performance

2014 ◽  
Vol 16 (38) ◽  
pp. 20772-20779 ◽  
Author(s):  
Zhiming Wang ◽  
Ying Feng ◽  
Shitong Zhang ◽  
Yu Gao ◽  
Zhao Gao ◽  
...  
Keyword(s):  
Excited State ◽  
High Efficiency ◽  
Substitution Effects ◽  
Device Performance ◽  
Deep Blue ◽  
Blue Emitters

Remarkable substitution effects on the excited state properties and device performance are observed by tuning the coupling position.

Tuning the excited-state intramolecular proton transfer (ESIPT) process of indole–pyrrole systems by π-conjugation and substitution effects: experimental and computational studies

2020 ◽  
Vol 22 (3) ◽  
pp. 1409-1415 ◽  
Author(s):  
Nuonuo Zhang ◽  
Tingting Zhang ◽  
Liu Wen ◽  
Long Wang ◽  
Jiaying Yan ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Excited State ◽  
Proton Transfer ◽  
Intramolecular Proton Transfer ◽  
Substitution Effects ◽  
Computational Studies

A series of amino (NH)-type hydrogen-bonding (H-bonding) compounds, BNDAB-1–4, containing π-enlarged indole and β-ethoxycarbonyl-substituted pyrrole units were designed and synthesized.

scholarly journals The Photoisomerization Pathway(s) of Push-Pull Phenylazoheteroarenes

2020 ◽  
Author(s):  
Sergi Vela ◽  
Clemence Corminboeuf
Keyword(s):  
Molecular Dynamics ◽  
Excited State ◽  
Quantum Yield ◽  
Working Conditions ◽  
Azo Dyes ◽  
Conical Intersection ◽  
Substitution Effects ◽  
Isomerization Pathway ◽  
And Inversion

<div> <p>Azoheteroarenes are the most recent derivatives targeted to further improve the properties of azo-based photoswitches. Their light-induced mechanism for trans-cis isomerization is assumed to be very similar to that of the parent azobenzene. As such, they inherited from the controversy about the dominant isomerization pathway (rotation<i> vs.</i> inversion) depending on the excited state (nπ* <i>vs.</i> ππ*). While the controversy seems settled in azobenzene, the extent to which the same conclusions apply to the more structurally-diverse family of azoheteroarenes is unclear. Here, we unravel by means of non-adiabatic molecular dynamics, the photoisomerization mechanism of three prototypical phenyl-azoheteroarenes with an increasing push-pull<i> </i>character. The evolution of the rotational and inversion conical intersection energies, the preferred pathway, and the associated kinetics upon both nπ* and ππ* excitations can be linked directly with the push-pull substitution effects. Overall, we clarify the working conditions of this family of azo-dyes and identify a possibility to exploit push-pull substituents to tune their photoisomerization quantum yield.</p> </div> <br>

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