Excited-State (Anti)Aromaticity Explains Why Azulene Disobeys Kasha’s Rule

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61388963%3A_____%2F23%3A00575764" target="_blank" >RIV/61388963:_____/23:00575764 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/00216208:11310/23:10469685

Výsledek na webu

<a href="https://doi.org/10.1021/jacs.3c07625" target="_blank" >https://doi.org/10.1021/jacs.3c07625</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1021/jacs.3c07625" target="_blank" >10.1021/jacs.3c07625</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Excited-State (Anti)Aromaticity Explains Why Azulene Disobeys Kasha’s Rule

Popis výsledku v původním jazyce

Fluorescence exclusively occurs from the lowest excited state of a given multiplicity according to Kasha’s rule. However, this rule is not obeyed by a handful of anti-Kasha fluorophores whose underlying mechanism is still understood merely on a phenomenological basis. This lack of understanding prevents the rational design and property-tuning of anti-Kasha fluorophores. Here, we propose a model explaining the photophysical properties of an archetypal anti-Kasha fluorophore, azulene, based on its ground- and excited-state (anti)aromaticity. We derived our model from a detailed analysis of the electronic structure of the ground singlet, first excited triplet, and quintet states and of the first and second excited singlet states using the perturbational molecular orbital theory and quantum-chemical aromaticity indices. Our model reveals that the anti-Kasha properties of azulene and its derivatives result from (i) the contrasting (anti)aromaticity of its first and second singlet excited states (S1 and S2, respectively) and (ii) an easily accessible antiaromaticity relief pathway of the S1 state. This explanation of the fundamental cause of anti-Kasha behavior may pave the way for new classes of anti-Kasha fluorophores and materials with long-lived, high-energy excited states.

Název v anglickém jazyce

Excited-State (Anti)Aromaticity Explains Why Azulene Disobeys Kasha’s Rule

Popis výsledku anglicky

Fluorescence exclusively occurs from the lowest excited state of a given multiplicity according to Kasha’s rule. However, this rule is not obeyed by a handful of anti-Kasha fluorophores whose underlying mechanism is still understood merely on a phenomenological basis. This lack of understanding prevents the rational design and property-tuning of anti-Kasha fluorophores. Here, we propose a model explaining the photophysical properties of an archetypal anti-Kasha fluorophore, azulene, based on its ground- and excited-state (anti)aromaticity. We derived our model from a detailed analysis of the electronic structure of the ground singlet, first excited triplet, and quintet states and of the first and second excited singlet states using the perturbational molecular orbital theory and quantum-chemical aromaticity indices. Our model reveals that the anti-Kasha properties of azulene and its derivatives result from (i) the contrasting (anti)aromaticity of its first and second singlet excited states (S1 and S2, respectively) and (ii) an easily accessible antiaromaticity relief pathway of the S1 state. This explanation of the fundamental cause of anti-Kasha behavior may pave the way for new classes of anti-Kasha fluorophores and materials with long-lived, high-energy excited states.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10403 - Physical chemistry

Projekt

<a href="/cs/project/LTC20076" target="_blank" >LTC20076: Impact of Photoinduced Charge Migration on Photochemistry of Radicals and Switches</a><br>

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2023

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Journal of the American Chemical Society

ISSN

0002-7863

e-ISSN

1520-5126

Svazek periodika

145

Číslo periodika v rámci svazku

39

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

7

Strana od-do

21569-21575

Kód UT WoS článku

001067276100001

EID výsledku v databázi Scopus

2-s2.0-85174079996