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Theoretical Study on Luminescent Properties of Organic Materials

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Computational and Theoretical Chemistry".

Deadline for manuscript submissions: 30 July 2024 | Viewed by 5281

Special Issue Editor


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Guest Editor
Institute of Molecular Sciences and Engineering, Institute of Frontier and Interdisciplinary Science, Shandong University, Qingdao 266237, China
Interests: luminescence mechanism; AIE; ESIPT; TADF; RTP

Special Issue Information

Dear Colleagues,

Organic luminescent materials have attracted increasing attention owing to their potential applications in chemosensors, fluorescent probes, laser dyes, and optoelectronic devices. The development of novel, highly efficient, and stable organic luminescent materials remains a big challenge and typically relies on trial-and-error methods. Theoretical studies on the photophysical and photochemical properties of organic luminescent materials with state-of-the-art ab initio excited-state methods can not only provide in-depth insights into the excited-state dynamics but also deliver theoretical guides for developing novel potential organic luminescent materials.

This Special Issue will focus on theoretical studies of the luminescent properties of organic materials. The topics include the sensing mechanism of fluorescent probes; the working mechanism of aggregation-induced emission (AIE) luminogens; and theoretical studies on the excited-state dynamics of organic luminescent materials with excited-state intramolecular proton transfer (ESIPT), thermally activated delayed fluorescence (TADF), and room-temperature phosphorescence (RTP) properties. In addition, the scope of this Special Issue also covers the development of theoretical methods in dealing with the excited-state properties of organic luminescent materials. Full research papers, short communications, reviews, and perspective articles are all welcome.

Prof. Dr. Panwang Zhou
Guest Editor

Manuscript Submission Information

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Keywords

  • luminescence mechanism
  • AIE
  • ESIPT
  • TADF
  • RTP

Published Papers (6 papers)

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Research

11 pages, 7196 KiB  
Article
Boosting Blue Self-Trapped Exciton Emission in All-Inorganic Zero-Dimensional Metal Halide Cs2ZnCl4 via Zirconium (IV) Doping
by Ye Tian, Qilin Wei, Lian Duan and Chengyu Peng
Molecules 2024, 29(7), 1651; https://doi.org/10.3390/molecules29071651 - 6 Apr 2024
Viewed by 730
Abstract
Low-dimensional metal halides with efficient luminescence properties have received widespread attention recently. However, nontoxic and stable low-dimensional metal halides with efficient blue emission are rarely reported. We used a solvothermal synthesis method to synthesize tetravalent zirconium ion-doped all-inorganic zero-dimensional Cs2ZnCl4 [...] Read more.
Low-dimensional metal halides with efficient luminescence properties have received widespread attention recently. However, nontoxic and stable low-dimensional metal halides with efficient blue emission are rarely reported. We used a solvothermal synthesis method to synthesize tetravalent zirconium ion-doped all-inorganic zero-dimensional Cs2ZnCl4 for the first time. Bright blue emission in the range of 370 nm–700 nm with a emission maximum at 456 nm was observed in Zr4+:Cs2ZnCl4 accompanied by a large Stokes shift, which was due to self-trapped excitons (STEs) caused by the lattice vibrations of the twisted structure. Simultaneously, the PLQY of Zr4+:Cs2ZnCl4 achieve an impressive 89.67%, positioning it as a compelling contender for future applications in blue-light technology. Full article
(This article belongs to the Special Issue Theoretical Study on Luminescent Properties of Organic Materials)
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16 pages, 7120 KiB  
Article
Modulating the ESIPT Mechanism and Luminescence Characteristics of Two Reversible Fluorescent Probes by Solvent Polarity: A Novel Perspective
by Yang Wang, Hongyan Mu, Yuhang Sun, Jiaan Gao, Xiaodong Zhu and Hui Li
Molecules 2024, 29(7), 1629; https://doi.org/10.3390/molecules29071629 - 5 Apr 2024
Viewed by 525
Abstract
As reversible fluorescent probes, HTP-1 and HTP-2 have favourable applications for the detection of Zn2+ and H2S. Herein, the impact of solvent on the excited-state intramolecular proton transfer (ESIPT) of HTP-1 and HTP-2 was comprehensively investigated. The obtained geometric parameters [...] Read more.
As reversible fluorescent probes, HTP-1 and HTP-2 have favourable applications for the detection of Zn2+ and H2S. Herein, the impact of solvent on the excited-state intramolecular proton transfer (ESIPT) of HTP-1 and HTP-2 was comprehensively investigated. The obtained geometric parameters and infrared (IR) vibrational analysis associated with the intramolecular hydrogen bond (IHB) indicated that the strength of IHB for HTP-1 was weakened in the excited state. Moreover, structural torsion and almost no ICT behaviour indicated that the ESIPT process did not occur in HTP-1. Nevertheless, when the 7-nitro-1,2,3-benzoxadiazole (NBD) group replaced the H atom, the IHB strength of HTP-2 was enhanced after photoexcitation, which inhibited the twisting of tetraphenylethylene, thereby opening the ESIPT channel. Notably, hole-electron analysis and frontier molecular orbitals revealed that the charge decoupling effect was the reason for the fluorescence quenching of HTP-2. Furthermore, the potential energy curves (PECs) revealed that HTP-2 was more inclined to the ESIPT process in polar solvents than in nonpolar solvents. With a decrease in solvent polarity, it was more conducive to the ESIPT process. Our study systematically presents the ESIPT process and different detection mechanisms of the two reversible probe molecules regulated by solvent polarity, providing new insights into the design and development of novel fluorescent probes. Full article
(This article belongs to the Special Issue Theoretical Study on Luminescent Properties of Organic Materials)
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13 pages, 3621 KiB  
Article
TDDFT Study on the ESIPT Properties of 2-(2′-Hydroxyphenyl)-Benzothiazole and Sensing Mechanism of a Derived Fluorescent Probe for Fluoride Ion
by Tingting Wang, Meiheng Lv, Yuhang Zhang, Yue Gao, Zexu Cai, Yifan Zhang, Jiaqi Song, Jianyong Liu, Hang Yin and Fangjian Shang
Molecules 2024, 29(7), 1541; https://doi.org/10.3390/molecules29071541 - 29 Mar 2024
Cited by 1 | Viewed by 546
Abstract
The level of fluoride ions (F) in the human body is closely related to various pathological and physiological states, and the rapid detection of F is important for studying physiological processes and the early diagnosis of diseases. In this study, [...] Read more.
The level of fluoride ions (F) in the human body is closely related to various pathological and physiological states, and the rapid detection of F is important for studying physiological processes and the early diagnosis of diseases. In this study, the detailed sensing mechanism of a novel high-efficiency probe (PBT) based on 2-(2′-hydroxyphenyl)-benzothiazole derivatives towards F has been fully investigated based on density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods. F attacks the O-P bond of PBT to cleavage the dimethylphosphinothionyl group, and the potential products were evaluated by Gibbs free energy and spectroscopic analyses, which ultimately identified the product as HBT-Enol1 with an intramolecular hydrogen bond. Bond parameters, infrared vibrational spectroscopy and charge analysis indicate that the hydrogen bond is enhanced at the excited state (S1), favoring excited state intramolecular proton transfer (ESIPT). The mild energy barrier further evidences the occurrence of ESIPT. Combined with frontier molecular orbital (FMO) analysis, the fluorescence quenching of PBT was attributed to the photoinduced electron transfer (PET) mechanism and the fluorescence turn-on mechanism of the product was attributed to the ESIPT process of HBT-Enol1. Full article
(This article belongs to the Special Issue Theoretical Study on Luminescent Properties of Organic Materials)
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13 pages, 4511 KiB  
Article
Theoretical Investigation on the “ON-OFF” Mechanism of a Fluorescent Probe for Thiophenols: Photoinduced Electron Transfer and Intramolecular Charge Transfer
by Yuxi Wang, Meng Zhang, Wenzhi Li, Yi Wang and Panwang Zhou
Molecules 2023, 28(19), 6921; https://doi.org/10.3390/molecules28196921 - 3 Oct 2023
Cited by 3 | Viewed by 1084
Abstract
In this study, the sensing mechanism of (2E,4E)-5-(4-(dimethylamino)phenyl)-1-(2-(2,4dinitrophenoxy)phenyl)penta-2,4-dien-1-one (DAPH-DNP) towards thiophenols was investigated by density functional theory (DFT) and time-dependent DFT (TD-DFT). The DNP group plays an important role in charge transfer excitation. Due to the typical donor-excited photo-induced electron transfer (d-PET) process, [...] Read more.
In this study, the sensing mechanism of (2E,4E)-5-(4-(dimethylamino)phenyl)-1-(2-(2,4dinitrophenoxy)phenyl)penta-2,4-dien-1-one (DAPH-DNP) towards thiophenols was investigated by density functional theory (DFT) and time-dependent DFT (TD-DFT). The DNP group plays an important role in charge transfer excitation. Due to the typical donor-excited photo-induced electron transfer (d-PET) process, DAPH-DNP has fluorescence quenching behavior. After the thiolysis reaction between DAPH-DNP and thiophenol, the hydroxyl group is released, and DAPH is generated with the reaction showing strong fluorescence. The fluorescence enhancement of DAPH is not caused by an excited-state intramolecular proton transfer (ESIPT) process. The potential energy curves (PECs) show that DAPH-keto is less stable than DAPH-enol. The frontier molecular orbitals (FMOs) of DAPH show that the excitation process is accompanied by intramolecular charger transfer (ICT), and the corresponding character of DAPH was further confirmed by hole-electron and interfragment charge transfer (IFCT) analysis methods. Above all, the sensing mechanism of the turn-on type probe DAPH-DNP towards thiophenol is based on the PET mechanism. Full article
(This article belongs to the Special Issue Theoretical Study on Luminescent Properties of Organic Materials)
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13 pages, 5533 KiB  
Article
Short-Range Charge Transfer in DNA Base Triplets: Real-Time Tracking of Coherent Fluctuation Electron Transfer
by Lixia Zhu, Qi Li, Yongfeng Wan, Meilin Guo, Lu Yan, Hang Yin and Ying Shi
Molecules 2023, 28(19), 6802; https://doi.org/10.3390/molecules28196802 - 25 Sep 2023
Cited by 1 | Viewed by 897
Abstract
The short-range charge transfer of DNA base triplets has wide application prospects in bioelectronic devices for identifying DNA bases and clinical diagnostics, and the key to its development is to understand the mechanisms of short-range electron dynamics. However, tracing how electrons are transferred [...] Read more.
The short-range charge transfer of DNA base triplets has wide application prospects in bioelectronic devices for identifying DNA bases and clinical diagnostics, and the key to its development is to understand the mechanisms of short-range electron dynamics. However, tracing how electrons are transferred during the short-range charge transfer of DNA base triplets remains a great challenge. Here, by means of ab initio molecular dynamics and Ehrenfest dynamics, the nuclear–electron interaction in the thymine-adenine-thymine (TAT) charge transfer process is successfully simulated. The results show that the electron transfer of TAT has an oscillating phenomenon with a period of 10 fs. The charge density difference proves that the charge transfer proportion is as high as 59.817% at 50 fs. The peak position of the hydrogen bond fluctuates regularly between −0.040 and −0.056. The time-dependent Marcus–Levich–Jortner theory proves that the vibrational coupling between nucleus and electron induces coherent electron transfer in TAT. This work provides a real-time demonstration of the short-range coherent electron transfer of DNA base triplets and establishes a theoretical basis for the design and development of novel biological probe molecules. Full article
(This article belongs to the Special Issue Theoretical Study on Luminescent Properties of Organic Materials)
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13 pages, 2698 KiB  
Article
Computational Insights into Excited State Intramolecular Double Proton Transfer Behavior Associated with Atomic Electronegativity for Bis(2′-benzothiazolyl)hydroquinone
by Jinfeng Zhao and Chang Liu
Molecules 2023, 28(16), 5951; https://doi.org/10.3390/molecules28165951 - 8 Aug 2023
Cited by 24 | Viewed by 867
Abstract
Inspired by the distinguished regulated photochemical and photophysical properties of 2-(2′-hydroxyphenyl)benzazole derivatives, in this work, the novel bis(2′-benzothiazolyl)hydroquinone (BBTHQ) fluorophore is explored, looking at its photo-induced behaviors associated with different substituted atomic electronegativities, i.e., BBTHQ-SO, BBTHQ-SS and BBTHQ-Se compounds. From the structural changes, [...] Read more.
Inspired by the distinguished regulated photochemical and photophysical properties of 2-(2′-hydroxyphenyl)benzazole derivatives, in this work, the novel bis(2′-benzothiazolyl)hydroquinone (BBTHQ) fluorophore is explored, looking at its photo-induced behaviors associated with different substituted atomic electronegativities, i.e., BBTHQ-SO, BBTHQ-SS and BBTHQ-Se compounds. From the structural changes, infrared (IR) vibrational variations and simulated core-valence bifurcation (CVB) indexes for the dual hydrogen bonds for the three BBTHQ derivatives, we see that low atomic electronegativity could be conducive to enhancing hydrogen bonding effects in the S1 state. Particularly, the O4-H5⋯N6 of BBTHQ-SO and the O1-H2⋯N3 of BBTHQ-SSe could be strengthened to be more intensive in the S1 state, respectively. Looking into the charge recombination induced by photoexcitation, we confirm a favorable ESDPT trend deriving from the charge reorganization of the dual hydrogen bonding regions. By constructing the potential energy surfaces (PESs) along with the ESDPT paths for the BBTHQ-SO, BBTHQ-SS and BBTHQ-Se compounds, we not only unveil stepwise ESDPT behaviors, but also present an atomic electronegativity-regulated ESDPT mechanism. Full article
(This article belongs to the Special Issue Theoretical Study on Luminescent Properties of Organic Materials)
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