1
|
Lodowski P, Jaworska M. Theoretical Investigation of Iridium Complex with Aggregation-Induced Emission Properties. Molecules 2024; 29:580. [PMID: 38338325 PMCID: PMC10856369 DOI: 10.3390/molecules29030580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 01/11/2024] [Accepted: 01/18/2024] [Indexed: 02/12/2024] Open
Abstract
The mechanism of aggregation-induced emission (AIE) for the bis(1-(2,4-difluorophenyl)-1H-pyrazole)(2-(20-hydroxyphenyl)-2-oxazoline)iridium(III) complex, denoted as Ir(dfppz)2(oz), was investigated with use DFT and the TD-DFT level of theory. The mechanism of radiationless deactivation of the triplet state was elucidated. Such a mechanism requires an additional, photophysical triplet channel of the internal conversion (IC) type, which is activated as a result of intramolecular motion deforming the structure of the oz ligand and distorting the iridium coordination sphere. Formally, the rotational movement of the oxazoline relative to the C-C bond in the oz ligand is the main active coordinate that leads to the opening of the triplet channel. The rotation of the oxazoline group and the elongation of the Ir-Nox bond cause a transition between the luminescent, low-lying triplet state with a d/π→π* characteristic (T1(eq)), and the radiationless d→d triplet state (T1(Ir)). This transition is made possible by the low energy barrier, which, based on calculations, was estimated at approximately 8.5 kcal/mol. Dimerization, or generally aggregation of the complex molecules, blocks the intramolecular movement in the ligand and is responsible for a strong increase in the energy barrier for the T1(eq)⇝T1(Ir) conversion of triplet states. Thus, the aggregation phenomenon blocks the nonradiative deactivation channel of the excited states and, consequently, contributes to directing the photophysical process toward phosphorescence. The mechanism involved in locking the nonradiative triplet path can be called restricted access to singlet-triplet crossing (RASTC).
Collapse
Affiliation(s)
| | - Maria Jaworska
- Institute of Chemistry, University of Silesia in Katowice, Szkolna 9, 40-006 Katowice, Poland;
| |
Collapse
|
2
|
Chi W, Sun PP. Restriction of photoinduced electron transfer as a mechanism for the aggregation-induced emission of a trityl-functionalised maleimide fluorophore. Phys Chem Chem Phys 2023; 25:4193-4200. [PMID: 36655773 DOI: 10.1039/d2cp05194j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The restriction of intramolecular motion (RIM) and restricted access to a conical intersection (RACI) have been accepted as general working mechanisms for aggregation-induced emission (AIE) phenomena. However, as the family of AIE molecules grows, the RIM and RACl mechanisms cannot be used to fully understand some AIE phenomena. Herein, the restriction of the photoinduced electron transfer (RPET) state is proposed to rationalize the AIE phenomena of trityl-functionalised maleimide molecule based on density functional theory calculations. The "state-crossing from a locally excited to an electron transfer state" (SLEET) model was employed to predict the ON/OFF molecular PET in solution and solid states. According to the SLEET model, we showed that a non-emissive electron transfer excited state leads to the fluorescence quenching of trityl-functionalised maleimide in solution. However, due to the reduced polarity of the environment in aggregates, the electron transfer state is thermodynamically inaccessible, and a low-lying locally excited state exhibits intense emission. These findings provide a theoretical foundation to understand the working mechanisms of AIE molecules and the design of new AIEgens. We expect that the RPET mechanism can be used to screen potential AIEgens using the SLEET model.
Collapse
Affiliation(s)
- Weijie Chi
- Department of Chemistry, School of Science, Hainan University, Haikou 570228, China.
| | - Ping-Ping Sun
- Department of Chemistry, School of Science, Hainan University, Haikou 570228, China.
| |
Collapse
|
3
|
Mao W, Chi W, He X, Wang C, Wang X, Yang H, Liu X, Wu H. Overcoming Spectral Dependence: A General Strategy for Developing Far-Red and Near-Infrared Ultra-Fluorogenic Tetrazine Bioorthogonal Probes. Angew Chem Int Ed Engl 2022; 61:e202117386. [PMID: 35167188 DOI: 10.1002/anie.202117386] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Indexed: 02/05/2023]
Abstract
Bioorthogonal fluorogenic dyes are indispensable tools in wash-free bioimaging of specific biological targets. However, the fluorogenicity of existing tetrazine-based bioorthogonal probes deteriorates as the emission wavelength shifts towards the NIR window, greatly limiting their applications in live cells and tissues. Herein, we report a generalizable molecular design strategy to construct ultra-fluorogenic dyes via a simple substitution at the meso-positions of various far-red and NIR fluorophores. Our probes demonstrate significant fluorescence turn-on ratios (102 -103 -fold) in the range 586-806 nm. These results will greatly expand the applications of bioorthogonal chemistry in NIR bioimaging and biosensing.
Collapse
Affiliation(s)
- Wuyu Mao
- Huaxi MR Research Center, Department of Radiology, Functional and Molecular Imaging Key Laboratory of Sichuan Province, Frontiers Science Center for Disease-related Molecular Network, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Huaxi Research Building, 001 4th Keyuan road, 610041, Chengdu, China
| | - Weijie Chi
- Fluorescence Research Group, Singapore University of Technology and Design, 8 Somapah Road, 487372, Singapore, Singapore
| | - Xinyu He
- Huaxi MR Research Center, Department of Radiology, Functional and Molecular Imaging Key Laboratory of Sichuan Province, Frontiers Science Center for Disease-related Molecular Network, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Huaxi Research Building, 001 4th Keyuan road, 610041, Chengdu, China
| | - Chao Wang
- Fluorescence Research Group, Singapore University of Technology and Design, 8 Somapah Road, 487372, Singapore, Singapore
| | - Xueyi Wang
- Huaxi MR Research Center, Department of Radiology, Functional and Molecular Imaging Key Laboratory of Sichuan Province, Frontiers Science Center for Disease-related Molecular Network, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Huaxi Research Building, 001 4th Keyuan road, 610041, Chengdu, China
| | - Haojie Yang
- Huaxi MR Research Center, Department of Radiology, Functional and Molecular Imaging Key Laboratory of Sichuan Province, Frontiers Science Center for Disease-related Molecular Network, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Huaxi Research Building, 001 4th Keyuan road, 610041, Chengdu, China
| | - Xiaogang Liu
- Fluorescence Research Group, Singapore University of Technology and Design, 8 Somapah Road, 487372, Singapore, Singapore
| | - Haoxing Wu
- Huaxi MR Research Center, Department of Radiology, Functional and Molecular Imaging Key Laboratory of Sichuan Province, Frontiers Science Center for Disease-related Molecular Network, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Huaxi Research Building, 001 4th Keyuan road, 610041, Chengdu, China
| |
Collapse
|
4
|
Mao W, Chi W, He X, Wang C, Wang X, Yang H, Liu X, Wu H. Overcoming Spectral Dependence: A General Strategy for Developing Far‐Red and Near‐Infrared Ultra‐Fluorogenic Tetrazine Bioorthogonal Probes. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202117386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Wuyu Mao
- Huaxi MR Research Center Department of Radiology Functional and Molecular Imaging Key Laboratory of Sichuan Province Frontiers Science Center for Disease-related Molecular Network National Clinical Research Center for Geriatrics West China Hospital Sichuan University Huaxi Research Building, 001 4th Keyuan road 610041 Chengdu China
| | - Weijie Chi
- Fluorescence Research Group Singapore University of Technology and Design 8 Somapah Road 487372 Singapore Singapore
| | - Xinyu He
- Huaxi MR Research Center Department of Radiology Functional and Molecular Imaging Key Laboratory of Sichuan Province Frontiers Science Center for Disease-related Molecular Network National Clinical Research Center for Geriatrics West China Hospital Sichuan University Huaxi Research Building, 001 4th Keyuan road 610041 Chengdu China
| | - Chao Wang
- Fluorescence Research Group Singapore University of Technology and Design 8 Somapah Road 487372 Singapore Singapore
| | - Xueyi Wang
- Huaxi MR Research Center Department of Radiology Functional and Molecular Imaging Key Laboratory of Sichuan Province Frontiers Science Center for Disease-related Molecular Network National Clinical Research Center for Geriatrics West China Hospital Sichuan University Huaxi Research Building, 001 4th Keyuan road 610041 Chengdu China
| | - Haojie Yang
- Huaxi MR Research Center Department of Radiology Functional and Molecular Imaging Key Laboratory of Sichuan Province Frontiers Science Center for Disease-related Molecular Network National Clinical Research Center for Geriatrics West China Hospital Sichuan University Huaxi Research Building, 001 4th Keyuan road 610041 Chengdu China
| | - Xiaogang Liu
- Fluorescence Research Group Singapore University of Technology and Design 8 Somapah Road 487372 Singapore Singapore
| | - Haoxing Wu
- Huaxi MR Research Center Department of Radiology Functional and Molecular Imaging Key Laboratory of Sichuan Province Frontiers Science Center for Disease-related Molecular Network National Clinical Research Center for Geriatrics West China Hospital Sichuan University Huaxi Research Building, 001 4th Keyuan road 610041 Chengdu China
| |
Collapse
|
5
|
Abedi SAA, Chi W, Tan D, Shen T, Wang C, Ang ECX, Tan CH, Anariba F, Liu X. Restriction of Twisted Intramolecular Charge Transfer Enables the Aggregation-Induced Emission of 1-( N, N-Dialkylamino)-naphthalene Derivatives. J Phys Chem A 2021; 125:8397-8403. [PMID: 34546046 DOI: 10.1021/acs.jpca.1c06263] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Understanding the mechanisms of aggregation-induced emission (AIE) is essential for the rational design and deployment of AIEgens toward various applications. Such a deep mechanistic understanding demands a thorough investigation of the excited-state behaviors of AIEgens. However, because of considerable complexity and rapid decay, these behaviors are often not experimentally accessible and the mechanistic comprehension of many AIEgens is lacking. Herein, utilizing detailed quantum chemical calculations, we provide insights toward the AIE mechanism of 1-(N,N-dialkylamino)-naphthalene (DAN) derivatives. Our theoretical analysis, corroborated by experimental observations, leads to the discovery that modulating the formation of the twisted intramolecular charge transfer (TICT) state (caused by the rotation of the amino groups) and managing the steric hindrance to minimize solid-state intermolecular interactions provides a plausible explanation for the AIE characteristics of DAN derivatives. These results will inspire the deployment of the TICT mechanism as a useful design strategy toward AIEgen development.
Collapse
Affiliation(s)
| | | | | | | | | | - Esther Cai Xia Ang
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore, Singapore
| | - Choon-Hong Tan
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore, Singapore
| | | | | |
Collapse
|
6
|
Zhao X, Yao Q, Long S, Chi W, Yang Y, Tan D, Liu X, Huang H, Sun W, Du J, Fan J, Peng X. An Approach to Developing Cyanines with Simultaneous Intersystem Crossing Enhancement and Excited-State Lifetime Elongation for Photodynamic Antitumor Metastasis. J Am Chem Soc 2021; 143:12345-12354. [PMID: 34323480 DOI: 10.1021/jacs.1c06275] [Citation(s) in RCA: 58] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Heavy-atom-based photosensitizers usually exhibit shortened triplet-state lifetimes, which is not ideal for hypoxic tumor photodynamic therapy. Although several heavy-atom-free photosensitizers possess long triplet-state lifetimes, the clinical applicability is limited by their short excitation wavelengths, poor photon capture abilities, and intrinsically hydrophobic structures. Herein we developed a novel NIR heavy-atom-free photosensitizer design strategy by introducing sterically bulky and electron-rich moieties at the meso position of the pentamethine cyanine (Cy5) skeleton, which simultaneously enhanced intersystem crossing (ISC) and prolonged excited-state lifetime. We found that the 1O2 generation ability is directly correlated to the electron-donating ability of the meso substituent in cyanine, and the excited-state lifetime was simultaneously much elongated when the substituents were anthracene derivatives substituted at the 9-position. Our star compound, ANOMe-Cy5, exhibits intense NIR absorption, the highest 1O2 quantum yield (4.48-fold higher than Cy5), the longest triplet-state lifetime (9.80-fold longer than Cy5), and lossless emission intensity (nearly no change compared with Cy5). Such excellent photophysical properties coupled with its inherently cationic and hydrophilic nature enable the photosensitizer to realize photoablation of solid tumor and antitumor lung metastasis. This study highlights the design of a new generation of NIR photosensitizers for imaging-guided photodynamic cancer treatment.
Collapse
Affiliation(s)
- Xueze Zhao
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China
| | - Qichao Yao
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China
| | - Saran Long
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China
| | - Weijie Chi
- Fluorescence Research Group, Singapore University of Technology and Design, 487372, Singapore
| | - Yuxin Yang
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China
| | - Davin Tan
- Fluorescence Research Group, Singapore University of Technology and Design, 487372, Singapore
| | - Xiaogang Liu
- Fluorescence Research Group, Singapore University of Technology and Design, 487372, Singapore
| | - Haiqiao Huang
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China
| | - Wen Sun
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China.,Ningbo Institute of Dalian University of Technology, Dalian University of Technology, Ningbo 315016, China
| | - Jianjun Du
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China.,Ningbo Institute of Dalian University of Technology, Dalian University of Technology, Ningbo 315016, China
| | - Jiangli Fan
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China.,Ningbo Institute of Dalian University of Technology, Dalian University of Technology, Ningbo 315016, China
| | - Xiaojun Peng
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China.,Shenzhen Research Institute, Dalian University of Technology, Shenzhen 518057, China
| |
Collapse
|
7
|
Shen T, Wu X, Tan D, Xu Z, Liu X. Thermal equilibria between conformers enable highly reliable single-fluorophore ratiometric thermometers. Analyst 2021; 146:4219-4225. [PMID: 34076650 DOI: 10.1039/d1an00741f] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Fluorescent thermometers based on organic dyes play an important role in the visualization of dynamic temperature topography with high resolution. Many molecular thermometers contain two fluorophores with different temperature responses to achieve ratiometric temperature detection. However, the stability and reliability of such ratiometric thermometers are highly dependent on the susceptibility of the fluorophores towards photobleaching. Despite the use of single-fluorophore ratiometric thermometers in previous reports, the difficulty and complexity in their molecular design and synthesis severely hinder their widespread applicability. In this work, we have investigated the use of commercially available dyes (i.e., BD140 and LD688) with conformational isomers as ratiometric thermometers. Each of these dyes consists of a mixture of conformers with distinct UV-vis absorption and emission spectra. The thermal equilibrium of these conformers successfully enabled the development of ratiometric thermometers with good stability and reliability.
Collapse
Affiliation(s)
- Tianruo Shen
- Fluorescence Research Group, Singapore University of Technology and Design, 8 Somapah Road, Singapore 487372.
| | - Xia Wu
- Fluorescence Research Group, Singapore University of Technology and Design, 8 Somapah Road, Singapore 487372.
| | - Davin Tan
- Fluorescence Research Group, Singapore University of Technology and Design, 8 Somapah Road, Singapore 487372.
| | - Zhaochao Xu
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Xiaogang Liu
- Fluorescence Research Group, Singapore University of Technology and Design, 8 Somapah Road, Singapore 487372.
| |
Collapse
|