scholarly journals Excited State Dynamics of 8-Vinyldeoxyguanosine in Aqueous Solution Studied by Time-Resolved Fluorescence Spectroscopy and Quantum Mechanical Calculations

Molecules ◽  
2020 ◽  
Vol 25 (4) ◽  
pp. 824
Author(s):  
Lara Martinez-Fernandez ◽  
Thomas Gustavsson ◽  
Ulf Diederichsen ◽  
Roberto Improta
Keyword(s):  
Excited State ◽  
Density Functional ◽  
Radiative Decay ◽  
Decay Channel ◽  
Photophysical Properties ◽  
Time Resolved ◽  
Td Dft ◽  
Bonding Properties ◽  
Purine Ring ◽  
Vinyl Group

The fluorescent base guanine analog, 8-vinyl-deoxyguanosine (8vdG), is studied in solution using a combination of optical spectroscopies, notably femtosecond fluorescence upconversion and quantum chemical calculations, based on time-dependent density functional theory (TD-DFT) and including solvent effect by using a mixed discrete-continuum model. In all investigated solvents, the fluorescence is very long lived (3–4 ns), emanating from a stable excited state minimum with pronounced intramolecular charge-transfer character. The main non-radiative decay channel features a sizeable energy barrier and it is affected by the polarity and the H-bonding properties of the solvent. Calculations provide a picture of dynamical solvation effects fully consistent with the experimental results and show that the photophysical properties of 8vdG are modulated by the orientation of the vinyl group with respect to the purine ring, which in turn depends on the solvent. These findings may have importance for the understanding of the fluorescence properties of 8vdG when incorporated in a DNA helix.

scholarly journals Excited-State Dynamics of Room-Temperature Phosphorescent Organic Materials Based on Monobenzil and Bisbenzil Frameworks

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3904
Author(s):  
Kaveendra Maduwantha ◽  
Shigeyuki Yamada ◽  
Kaveenga Rasika Koswattage ◽  
Tsutomu Konno ◽  
Takuya Hosokai
Keyword(s):  
Excited State ◽  
Density Functional ◽  
Room Temperature ◽  
Photophysical Properties ◽  
Density Functional Theory Calculations ◽  
Time Resolved ◽  
Excited State Dynamics ◽  
Unique Material ◽  
Potential Applications ◽  
Time Resolved Photoluminescence

Room-temperature phosphorescent (RTP) materials have been attracting tremendous interest, owing to their unique material characteristics and potential applications for state-of-the-art optoelectronic devices. Recently, we reported the synthesis and fundamental photophysical properties of new RTP materials based on benzil, i.e., fluorinated monobenzil derivative and fluorinated and non-fluorinated bisbenzil derivative analogues [Yamada, S. et al., Beilstein J. Org. Chem. 2020, 16, 1154–1162.]. To deeply understand their RTP properties, we investigated the excited-state dynamics and photostability of the derivatives by means of time-resolved and steady-state photoluminescence spectroscopies. For these derivatives, clear RTP emissions with lifetimes on the microsecond timescale were identified. Among them, the monobenzil derivative was found to be the most efficient RTP material, showing both the longest lifetime and highest amplitude RTP emission. Time-resolved photoluminescence spectra, measured at 77 K, and density functional theory calculations revealed the existence of a second excited triplet state in the vicinity of the first excited singlet state for the monobenzil derivative, indicative of the presence of a fast intersystem crossing pathway. The correlation between the excited state dynamics, emission properties, and conformational flexibility of the three derivatives is discussed.

scholarly journals Excited-State Dynamics of Room-Temperature Phosphorescent Organic Materials Based on Monobenzil and Bisbenzil Frameworks

2020 ◽  
Author(s):  
Kaveendra Maduwantha ◽  
Shigeyuki Yamada ◽  
Kaveenga Rasika Koswattage ◽  
Tsutomu Konno ◽  
Takuya Hosokai
Keyword(s):  
Excited State ◽  
Density Functional ◽  
Room Temperature ◽  
Photophysical Properties ◽  
Density Functional Theory Calculations ◽  
Time Resolved ◽  
Excited State Dynamics ◽  
Unique Material ◽  
Potential Applications ◽  
Time Resolved Photoluminescence

Room-temperature phosphorescent (RTP) materials have been attracted tremendous interest owing to their unique material characteristics and potential applications for state-of-the-art optoelectronic devices. Recently, we have reported a synthesis and fundamental photophysical properties of new RTP materials based on benzil, i.e., fluorinated monobenzil derivative and fluorinated and non-fluorinated bisbenzil derivative analogues [Yamada, S. et al, Beilstein J. Org. Chem. 2020, 16, 1154–1162.]. To further understand their RTP properties, here we investigated the excited-state dynamics and photostability of the derivatives by means of time-resolved and steady-state photoluminescence spectroscopies. For these derivatives, clear RTP emissions with lifetimes on the microsecond timescale were identified. Among them, the monobenzil derivative was found to be the most efficient RTP material, showing both the longest lifetime and highest amplitude RTP emission. Time-resolved photoluminescence spectra measured at 77 K and density functional theory calculations revealed the existence of a second excited triplet state in the vicinity of the first excited singlet state for the monobenzil derivative, indicative of the presence of a fast intersystem crossing pathway. A discussion of the correlation between the excited state dynamics, emission properties, and conformational flexibility of the three derivatives is presented.

scholarly journals Characterization of Excited States in a Multiple-Resonance-Type Thermally Activated Delayed Fluorescence Molecule Using Time-resolved Infrared Spectroscopy

2021 ◽  
Author(s):  
Yuushi Shimoda ◽  
Masaki Saigo ◽  
Tomohiro Ryu ◽  
Takumi Ehara ◽  
Kiyoshi Miyata ◽  
...  
Keyword(s):  
Excited State ◽  
Density Functional ◽  
Photophysical Properties ◽  
Delayed Fluorescence ◽  
Potential Surfaces ◽  
Time Resolved ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Multiple Resonance ◽  
Time Resolved Infrared Spectroscopy

We have investigated the correlation between the photophysical properties and the excited-state detailed characteristics in a multiple-resonance-type thermally activated delayed fluorescence (TADF) molecule, DABNA-1, using time-resolved infrared vibrational spectroscopy. In comparison of the distinctive vibrational spectra in the fingerprint region, 1000 - 1700 cm<sup>-1</sup>, to the simulated spectra by density functional theory calculations, we found the best calculation condition. On the basis of the calculations, we determined the excited-state geometries and molecular orbitals of the lowest excited singlet (S<sub>1</sub>) and triplet (T<sub>1</sub>) states as well as the ground state (S<sub>0</sub>). We revealed that the similarity of the potential surfaces between T<sub>1</sub> and S<sub>0</sub> suppresses the nonradiative decay and causes the high fluorescence quantum yield via TADF process.

scholarly journals An Insight into the Excitation States of Small Molecular Semiconductor Y6

Molecules ◽  
2020 ◽  
Vol 25 (18) ◽  
pp. 4118
Author(s):  
Xianshao Zou ◽  
Guanzhao Wen ◽  
Rong Hu ◽  
Geng Dong ◽  
Chengyun Zhang ◽  
...  
Keyword(s):  
Solar Cells ◽  
Excited State ◽  
Dft Calculations ◽  
Density Functional ◽  
Radiative Decay ◽  
Polymer Solar Cells ◽  
Distribution Analysis ◽  
Exciton Lifetime ◽  
Td Dft ◽  
Molecular Semiconductor

Y6 is a new type of non-fullerene acceptor, which has led to power conversion efficiencies of single-junction polymer solar cells over 17% when combined with a careful choice of polymeric donors. However, the excited state characteristics of Y6, which is closely correlated with its opto-electronic applications, are not clear yet. In this work, we studied the excited state properties of the Y6 solution and Y6 film, by using steady-state and time-resolved spectroscopies as well as time-dependent density functional theory (TD-DFT) calculations. UV-Vis absorption and fluorescence simulation, natural transition orbitals (NTOs) and hole-electron distribution analysis of Y6 solution were performed for understanding the excitation properties of Y6 by using TD-DFT calculations. The lifetimes of the lowest singlet excited state in Y6 solution and film were estimated to be 0.98 and 0.8 ns, respectively. Combining the exciton lifetime and photoluminescence (PL) quantum yield, the intrinsic radiative decay lifetimes of Y6 in the solution and film were estimated, which were 1.3 and 10.5 ns for the Y6 solution and film, respectively. Long exciton lifetime (~0.8 ns) and intrinsic radiative decay lifetime (~10.5 ns) of Y6 film enable Y6 to be a good acceptor material for the application of polymer solar cells.

scholarly journals Characterization of Excited States in a Multiple-Resonance-Type Thermally Activated Delayed Fluorescence Molecule Using Time-resolved Infrared Spectroscopy

2021 ◽  
Author(s):  
Yuushi Shimoda ◽  
Masaki Saigo ◽  
Tomohiro Ryu ◽  
Takumi Ehara ◽  
Kiyoshi Miyata ◽  
...  
Keyword(s):  
Excited State ◽  
Density Functional ◽  
Photophysical Properties ◽  
Delayed Fluorescence ◽  
Potential Surfaces ◽  
Time Resolved ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Multiple Resonance ◽  
Time Resolved Infrared Spectroscopy

We have investigated the correlation between the photophysical properties and the excited-state detailed characteristics in a multiple-resonance-type thermally activated delayed fluorescence (TADF) molecule, DABNA-1, using time-resolved infrared vibrational spectroscopy. In comparison of the distinctive vibrational spectra in the fingerprint region, 1000 - 1700 cm<sup>-1</sup>, to the simulated spectra by density functional theory calculations, we found the best calculation condition. On the basis of the calculations, we determined the excited-state geometries and molecular orbitals of the lowest excited singlet (S<sub>1</sub>) and triplet (T<sub>1</sub>) states as well as the ground state (S<sub>0</sub>). We revealed that the similarity of the potential surfaces between T<sub>1</sub> and S<sub>0</sub> suppresses the nonradiative decay and causes the high fluorescence quantum yield via TADF process.

Photophysical Properties of N-Methyl and N-Acetyl Substituted Alloxazine: A Theoretical Investigation

2021 ◽  
Author(s):  
Huimin Guo ◽  
Xiaolin Ma ◽  
Zhiwen Lei ◽  
Yang Qiu ◽  
Bernhard Dick ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Theoretical Investigation ◽  
Density Functional ◽  
Photophysical Properties ◽  
Time Dependent ◽  
Functional Theory ◽  
Td Dft ◽  
Dependent Density

The electronic structure and photophysical properties of a series of N-Methyl and N-Acetyl substituted alloxazine (AZs) were investigated with extensive density functional theory (DFT) and time-dependent density functional theory (TD-DFT)...

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.

Taming the excited state reactivity of imines – from non-radiative decay to aza Paternò–Büchi reaction

2021 ◽  
Author(s):  
Sunil Kumar Kandappa ◽  
Lakshmy Kannadi Valloli ◽  
Sapna Ahuja ◽  
Jayachandran Parthiban ◽  
J. Sivaguru
Keyword(s):  
Excited State ◽  
Radiative Decay ◽  
Photophysical Properties

This review highlights the excited state characteristics of imines and processes that govern their photochemical and photophysical properties.

Sign in / Sign up

Export Citation Format

Share Document