scholarly journals Mechanisms of fluorescence quenching in prototypical aggregation-induced emission systems: excited state dynamics with TD-DFTB

2019 ◽  
Vol 21 (18) ◽  
pp. 9026-9035 ◽  
Author(s):  
Thierry Tran ◽  
Antonio Prlj ◽  
Kun-Han Lin ◽  
Daniel Hollas ◽  
Clémence Corminboeuf
Keyword(s):  
Density Functional Theory ◽  
Excited State ◽  
Fluorescence Quenching ◽  
Density Functional ◽  
Tight Binding ◽  
Time Dependent ◽  
Quenching Mechanism ◽  
Functional Theory ◽  
Aggregation Induced Emission ◽  
Fluorescence Quenching Mechanism

A recent implementation of time-dependent tight-binding density functional theory is employed in excited state molecular dynamics for the investigation of the fluorescence quenching mechanism in 3 prototypical aggregation-induced emission systems.

pH-related fluorescence quenching mechanism of pterin derivatives and the effects of 6-site substituents

2018 ◽  
Vol 96 (4) ◽  
pp. 404-410
Author(s):  
Lei Liu ◽  
Bingqing Sun
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Bonding ◽  
Fluorescence Quenching ◽  
Density Functional ◽  
Relaxation Processes ◽  
Quenching Mechanism ◽  
Functional Theory ◽  
Td Dft ◽  
Fluorescence Quenching Mechanism ◽  
Acidic Conditions

2-Amino-4-hydroxypteridine (pterin) and its derivatives serve as photooxidants and exhibit strong fluorescence. When they interact with hydrogen acceptors such as acetate and phosphate, their fluorescences are significantly quenched in acidic conditions (pH 4.9–5.5) but are retained in basic conditions (pH 10.0–10.5). This pH-related fluorescence quenching mechanism of pterin and its derivatives are fully investigated by using density functional theory (DFT) and time-dependent density functional theory (TD-DFT). Pterin and its derivatives are demonstrated to show favorable excited-state proton transfer (ESPT) abilities in acidic conditions that induce the experimentally observed fluorescence quenching. In contrast, the ESPT processes are found to be retarded due to the lack of strong hydrogen-bonding interactions in basic environments, which sustain their fluorescence. Interestingly, these ESPT processes are found to show different site specificities depending on the 6-site substituents. The introduction of electron-donating substituent activates the N1 site, making it the preferred ESPT site. By contrast, the introduction of an electron-withdrawing substituent activates the N5 site, making it the favorable ESPT site. The substitutions of different functional groups are found to affect the locations of acidic centers during the excitation and relaxation processes. This further affects the hydrogen-bonding patterns and ultimately brings site specificity to the ESPT process.

scholarly journals Ground- and excited-state characteristics in photovoltaic polymer N2200

RSC Advances ◽  
2021 ◽  
Author(s):  
Guanzhao Wen ◽  
Xianshao Zou ◽  
Rong Hu ◽  
Jun Peng ◽  
Zhifeng Chen ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Excited State ◽  
Steady State ◽  
Excited States ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Time Dependent ◽  
Functional Theory ◽  
Time Resolved ◽  
Dependent Density

Ground- and excited-states properties of N2200 have been studied by steady-state and time-resolved spectroscopies as well as time-dependent density functional theory calculations.

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