Aggregation-induced emission (AIE) molecules have attracted widespread attention due to their remarkable fluorescence properties in the aggregated state. However, the highly twisted structures of AIE molecules significantly disrupt the π-conjugations, thus resulting in weak absorption abilities (i.e., small molar absorption coefficients ε). To overcome this problem, herein we have proposed an efficient molecular design strategy: π-bridged dimer of AIE molecules. Accordingly, two series of AIE dimer molecules, TPE-BTO-Dimer 1‒6 and DTPE-BTO-Dimer 1‒6 with various π-bridged moieties, have been newly synthesized. In comparison to the corresponding AIE monomer molecules TPE-BTO and DTPE-BTO, the dimer molecules retain the AIE character while exhibit largely improved absorption abilities (the ε values are increased by 2.3‒3.7 times to 6.01‒9.54 × 104 M−1 cm−1) as well as significantly redshifted absorption maxima. The theoretical calculations have revealed that the π-bridged dimer strategy dramatically increases the oscillator strength of electron transition from the ground state to an excited state and thus results in a large ε. In the transient absorption studies, the local excited state components of dimer molecules are obviously higher than those of monomer molecules, which further confirms the effectiveness of π-bridged dimer strategy. Moreover, one of the AIE dimer molecules DTPE-BTO-Dimer 6 with near-infrared (NIR) emission has been applied in NIR fluorescence imaging-guided photothermal therapy. The very strong absorption ability has enabled its nanoparticles to exhibit a high photothermal conversion efficiency of 73% under the 655 nm laser irradiation and thus display a desired photothermal therapy performance.
| [1] |
Z. Zhao, H. Zhang, J. W. Y. Lam, and B. Z. Tang, “Aggregation-Induced Emission: New Vistas at the Aggregate Level,” Angewandte Chemie International Edition 59 (2020): 9888-9907.
|
| [2] |
X. Cai and B. Liu, “Aggregation-Induced Emission: Recent Advances in Materials and Biomedical Applications,” Angewandte Chemie International Edition 59 (2020): 9868-9886.
|
| [3] |
M. M. S. Lee, E. Y. Yu, J. H. C. Chau, J. W. Y. Lam, R. T. K. Kwok, and B. Z. Tang, “Expanding Our Horizons: AIE Materials in Bacterial Research,” Advanced Materials (2024): 2407707, https://doi.org/10.1002/adma.202407707.
|
| [4] |
J. Dai, H. Xue, D. Chen, X. Lou, F. Xia, and S. Wang, “Aggregation-Induced Emission Luminogens for Assisted Cancer Surgery,” Coordination Chemistry Reviews 464 (2022): 214552.
|
| [5] |
W. Xu, D. Jian, H. Yang, W. Wang, and Y. Ding, “Aggregation-induced Emission: Application in Diagnosis and Therapy of Hepatocellular Carcinoma,” Biosensors & Bioelectronics 266 (2024): 116722.
|
| [6] |
R. Xu, P. Zhang, Q. Shen, et al., “AIE Nanocrystals: Emerging Nanolights With Ultra-High Brightness for Biological Application,” Coordination Chemistry Reviews 477 (2023): 214944.
|
| [7] |
Z. Wang, Y. Zhou, R. Xu, et al., “Seeing the Unseen: AIE Luminogens for Super-resolution Imaging,” Coordination Chemistry Reviews 451 (2022): 214279.
|
| [8] |
S. Wang, X. Bi, H. Zhu, X. Ji, H. Lu, and Z. Shen, “Rational Design of Aggregation-Induced Emission-Active Bisboron Complexes (BOQHYs) for High-Fidelity Lipid Droplet Imaging,” Aggregate 6 (2025): e670.
|
| [9] |
P. Cen, J. Huang, C. Jin, et al., “Aggregation-Induced Emission Luminogens for in Vivo Molecular Imaging and Theranostics in Cancer,” Aggregate 4 (2023): e352.
|
| [10] |
S. Wu, Y. Yang, Y. Cheng, et al., “Fluorogenic Detection of Mercury Ion in Aqueous Environment Using Hydrogel-Based AIE Sensing Films,” Aggregate 4 (2023): e287.
|
| [11] |
G.-Q. Zhang, W. Feng, Z. Gao, et al., “A NIR Ratiometric Fluorescent Biosensor for Sensitive Detection and Imaging of α-L-Fucosidase in Living Cells and HCC Tumor-Bearing Mice,” Aggregate 4 (2023): e286.
|
| [12] |
F. Xiao, Y. Li, J. Li, et al., “A Family of Oligo(p-phenylenevinylene) Derivative Aggregation-Induced Emission Probes: Ultrasensitive, Rapid, and Anti-Interfering Fluorescent Sensing of Perchlorate via Precise Alkyl Chain Length Modulation,” Aggregate 4 (2023): e260.
|
| [13] |
K. Ren, B. Zhang, J. Guo, et al., “Aggregation-Induced Emission(AIE)for Next-Generation Biosensing and Imaging: A Review,” Biosensors & Bioelectronics 271 (2025): 117067.
|
| [14] |
S. Liu, Y. Li, Y. Yang, et al., “Lateral Flow Analysis Test Strips Based on Aggregation-induced Emission Technique: Principle, Design, and Application,” Biosensors & Bioelectronics 272 (2025): 117058.
|
| [15] |
S. Chen, Y. Pan, K. Chen, et al., “Increasing Molecular Planarity Through Donor/Side-Chain Engineering for Improved NIR-IIa Fluorescence Imaging and NIR-II Photothermal Therapy Under 1064 Nm,” Angewandte Chemie International Edition 62 (2023): e202215372.
|
| [16] |
S. Liu, R. Chen, J. Zhang, et al., “Incorporation of Planar Blocks Into Twisted Skeletons: Boosting Brightness of Fluorophores for Bioimaging Beyond 1500 Nanometer,” ACS Nano 14 (2020): 14228-14239.
|
| [17] |
S. Yang, J. Zhang, Z. Zhang, et al., “More Is Better: Dual-Acceptor Engineering for Constructing Second Near-Infrared Aggregation-Induced Emission Luminogens to Boost Multimodal Phototheranostics,” Journal of the American Chemical Society 145 (2023): 22776-22787.
|
| [18] |
C. You, Y. Zhu, J. Zhu, et al., “Strength in Numbers: A Giant NIR-II AIEgen With One-for-All Phototheranostic Features for Exceptional Orthotopic Bladder Cancer Treatment,” Angewandte Chemie International Edition 64 (2025): e202417865.
|
| [19] |
D. Zhou, G. Zhang, J. Li, et al., “Near-Infrared II Agent With Excellent Overall Performance for Imaging-Guided Photothermal Thrombolysis,” ACS Nano 18 (2024): 25144-25154.
|
| [20] |
J. Zhang, W. Liu, Y. Liu, et al., “A New Strategy to Elevate Absorptivity of AIEgens for Intensified NIR-II Emission and Synergized Multimodality Therapy,” Advanced Materials 35 (2023): 2306616.
|
| [21] |
Y. Lee, A. Jo, and S. B. Park, “Rational Improvement of Molar Absorptivity Guided by Oscillator Strength: A Case Study With Furoindolizine-Based Core Skeleton,” Angewandte Chemie International Edition 54 (2015): 15689-15693.
|
| [22] |
Y. Lee, D. Kim, and S. B. Park, “Systematic Exploration of Furoindolizine-Based Molecular Frameworks towards a Versatile Fluorescent Platform,” Chemistry - A European Journal 28 (2022): e202200533.
|
| [23] |
J. Dai, L. Yao, C. Wang, et al., “Molecular Conformation Engineering to Achieve Longer and Brighter Deep Red/Near-Infrared Emission in Crystalline State,” Journal of Physical Chemistry Letters 13 (2022): 4754-4761.
|
| [24] |
W. Zhu, M. Kang, Q. Wu, et al., “Zwitterionic AIEgens: Rational Molecular Design for NIR-II Fluorescence Imaging-Guided Synergistic Phototherapy,” Advanced Functional Materials 31 (2021): 2007026.
|
| [25] |
X. Yang, T. Yang, Q. Liu, et al., “Biomimetic Aggregation-Induced Emission Nanodots With Hitchhiking Function for T Cell-Mediated Cancer Targeting and NIR-II Fluorescence-Guided Mild-Temperature Photothermal Therapy,” Advanced Functional Materials 32 (2022): 2206346.
|
| [26] |
X. Lin, Z. Sun, S. Huang, et al., “Engineered Microglia-Exosomes Coated Highly Twisting AIE Photothermal Agents to Efficiently Cross Blood-Brain-Barrier for Mild Photothermal-Immune Checkpoint Blockade Therapy in Glioblastoma,” Advanced Functional Materials 34 (2024): 2310237.
|
| [27] |
C. You, L. Tian, J. Zhu, L. Wang, B. Z. Tang, and D. Wang, “The Midas Touch by Iridium: A Second Near-Infrared Aggregation-Induced Emission-Active Metallo-Agent for Exceptional Phototheranostics of Breast Cancer,” Journal of the American Chemical Society 147 (2025): 2010-2020.
|
| [28] |
W. Shao, F. Zhao, J. Xue, and L. Huang, “NIR-II Absorbing Organic Nanoagents for Photoacoustic Imaging and Photothermal Therapy,” BMEMat 1 (2023): e12009.
|
| [29] |
H. Zhao, H. Xiao, Y. Liu, and H. Ju, “Lanthanide-Doped Rare Earth Nanoparticles for near-Infrared-II Imaging and Cancer Therapy,” BMEMat 1 (2023): e12032.
|
| [30] |
F. Mi, N. Zhao, L. Jin, et al., “Conjugated Polymers as Photocatalysts for Hydrogen Therapy,” BMEMat (2024): e12126.
|
| [31] |
G. Liu, C. Wang, and G. Lu, “The Second Near-Infrared (NIR-II) Window Excitable/Emissive Organic/Polymeric Fluorescent Molecules for Bioimaging Application,” Journal of Innovative Optical Health Sciences 18 (2025): 2530002.
|
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2025 The Author(s). Aggregate published by SCUT, AIEI, and John Wiley & Sons Australia, Ltd.
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