Dual-Network Restriction in Dense EDTA-Metal Coordination Polymers for Highly Efficient and Stable Organic RTP in Aqueous System

Abstract

Organic room-temperature phosphorescence (RTP) materials are promising for bioimaging applications due to their tunable structures, excellent biocompatibility, and long-lived luminescence. However, the development of highly efficient organic RTP materials for aqueous systems remains challenging, as the organic phosphorescence is prone to being quenched by the dissolved oxygen in water. Herein, heteroaromatic carboxylic acids serve as ligand guests to construct a series of host-guest composites with nontoxic, dense EDTA-M (M = Ca, Mg, and Al) coordination polymer in water. These composites exhibit ultra-long pure RTP of guest molecules with phosphorescence quantum yield up to 53%, and lifetime up to 589.7 ms, due to the synergistic effect of dual-network structure: a coordinatively cross-linked network of EDTA-M, and a non-covalent bonded network formed by ligands and water molecules. The phosphorescence intensity is more than three times that of the composite with a single coordination network. Notably, the dual-network configuration can form a rigid and dense structure and block the intrusion of external H₂O and O₂ molecules to avoid phosphorescence quenching in water. As a result, the RTP of the composites remains unchanged after 1 month in water. Furthermore, the nanoparticles fabricated from composites and anionic surfactants can be successfully applied in in vivo imaging of mice for the stable RTP in water. This work provides a novel strategy for the development of high-performance RTP materials in aqueous systems.

Keywords

bioimaging / coordination polymers / dual-network / efficient RTP / water stability

References

[1] W. Zhao, Z. He, and B. Z. Tang, “Room-Temperature Phosphorescence From Organic Aggregates,” Nature Reviews Materials 5 (2020): 869–885.

[2] G. Yin, J. Zhou, W. Lu, et al., “Targeting Compact and Ordered Emitters by Supramolecular Dynamic Interactions for High-Performance Organic Ambient Phosphorescence,” Advanced Materials 36 (2024): 2311347.

[3] X. Luo, B. Tian, Y. Zhai, et al., “Room-Temperature Phosphorescent Materials Derived From Natural Resources,” Nature Reviews Chemistry 7 (2023): 800–812.

[4] Y. Zhang, H. Li, M. Yang, et al., “Organic Room-Temperature Phosphorescence Materials for Bioimaging,” Chemical Communications 59 (2023): 5329–5342.

[5] Y. Zhao, X. Ma, S. Cui, et al., “Achieving Near-Infrared Organic Room-Temperature Phosphorescence for High-Resolution Immune Response Monitoring and Bioimaging,” Angewandte Chemie International Edition 64 (2025): e202511784.

[6] B. Chang, J. Chen, J. Bao, T. Sun, and Z. Cheng, “Molecularly Engineered Room-Temperature Phosphorescence for Biomedical Application: From the Visible Toward Second Near-Infrared Window,” Chemical Reviews 123 (2023): 13966–14037.

[7] Y. Gong, G. Chen, Q. Peng, et al., “Achieving Persistent Room Temperature Phosphorescence and Remarkable Mechanochromism From Pure Organic Luminogens,” Advanced Materials 27 (2015): 6195–6201.

[8] M. Singh, K. Liu, S. Qu, et al., “Recent Advances of Cocrystals With Room Temperature Phosphorescence,” Advanced Optical Materials 9 (2021): 2002197.

[9] R. Tian, S. Gao, K. Li, and C. Lu, “Design of Mechanical-Robust Phosphorescence Materials Through Covalent Click Reaction,” Nature Communications 14 (2023): 4720.

[10] H. Gao and X. Ma, “Recent Progress on Pure Organic Room Temperature Phosphorescent Polymers,” Aggregate 2 (2021): e38.

[11] N. Gan, X. Zou, Z. Qian, et al., “Stretchable Phosphorescent Polymers by Multiphase Engineering,” Nature Communications 15 (2024): 4113.

[12] Q. Zhang, X. Zhang, J. Zhuang, and M. Pan, “Highly Two-Photon and X-Ray Excited Long-Persistent Luminescence in a Crystalline Host-Guest Aggregate,” Aggregate 5 (2023): e456.

[13] Y. Zhao, J. Yang, C. Liang, et al., “Fused-Ring Pyrrole-Based Near-Infrared Emissive Organic RTP Material for Persistent Afterglow Bioimaging,” Angewandte Chemie International Edition 63 (2023): e202317431.

[14] Y. Huang, Y. Liu, X. Zheng, J. Wu, Q. Ling, and Z. Lin, “Internal Locking and External Anchoring—A Strategy for Constructing Efficient and Ultralong Room-Temperature Phosphorescence Materials,” Advanced Optical Materials 13 (2025): 2500743.

[15] L. Gu, H. Shi, L. Bian, et al., “Colour-Tunable Ultra-Long Organic Phosphorescence of a Single-Component Molecular Crystal,” Nature Photonics 13 (2019): 406–411.

[16] Z. An, C. Zheng, Y. Tao, et al., “Stabilizing Triplet Excited States for Ultralong Organic Phosphorescence,” Nature Materials 14 (2015): 685–690.

[17] Z. Zhang, W. Xu, W. Xu, J. Niu, X. Sun, and Y. Liu, “A Synergistic Enhancement Strategy for Realizing Ultralong and Efficient Room-Temperature Phosphorescence,” Angewandte Chemie International Edition 59 (2020): 18748–18754.

[18] J. Wang, X. Gu, H. Ma, et al., “A Facile Strategy for Realizing Room Temperature Phosphorescence and Single Molecule White Light Emission,” Nature Communications 9, no. 1 (2018): 2963.

[19] R. Feng, H. Lv, and Q. Song, “Unlocking Room-Temperature Phosphorescence of Polycyclic Aromatic Hydrocarbons and Beyond via External Heavy-Atom Engineering,” Angewandte Chemie International Edition 65 (2025): e16177.

[20] X. Ma, W. Zhang, Z. Liu, H. Zhang, B. Zhang, and Y. Liu, “Supramolecular Pins With Ultralong Efficient Phosphorescence,” Advanced Materials 33 (2021): 2007476.

[21] S. Garain, B. Garain, M. Eswaramoorthy, S. Pati, and S. George, “Light-Harvesting Supramolecular Phosphors: Highly Efficient Room Temperature Phosphorescence in Solution and Hydrogels,” Angewandte Chemie International Edition 60 (2021): 19720–19724.

[22] Q. Huang, H. Gao, S. Yang, D. Ding, Z. Lin, and Q. Ling, “Ultrastable and Colorful Afterglow From Organic Luminophores in Amorphous Nanocomposites: Advanced Anti-Counterfeiting and In Vivo Imaging Application,” Nano Research 13 (2020): 1035–1043.

[23] Y. Deng, P. Li, J. Li, D. Sun, and H. Li, “Color-Tunable Aqueous Room-Temperature Phosphorescence Supramolecular Assembly,” ACS Applied Materials & Interfaces 13 (2021): 14407–14416.

[24] D. Guo, W. Wang, K. Zhang, et al., “Visible-Light-Excited Robust Room-Temperature Phosphorescence of Dimeric Single-Component Luminophores in the Amorphous State,” Nature Communications 15 (2024): 3598.

[25] W. Zhou, Y. Chen, Q. Yu, et al., “Ultralong Purely Organic Aqueous Phosphorescence Supramolecular Polymer for Targeted Tumor Cell Imaging,” Nature Communications 11 (2020): 4655.

[26] R. Wang, D. Ma, X. Kong, et al., “Metastable Supramolecular Assembly of Simple Monomers Enabled by Confinement: Towards Aqueous Phase Room Temperature Phosphorescence,” Angewandte Chemie International Edition 63 (2024): e202409162.

[27] X. Li, Y. Wang, Z. Zhang, S. Cai, Z. An, and W. Huang, “Recent Advances in Room-Temperature Phosphorescence Metal–Organic Hybrids: Structures, Properties, and Applications,” Advanced Materials 36 (2024): 2308290.

[28] Y. Q. Zhu, X. H. Wang, and M. X. Wu, “Intriguing Room Temperature Phosphorescence in Crystalline Porous Organic Frameworks,” Advanced Functional Materials 33 (2023): 2308096.

[29] B. Zhou, Z. Qi, and D. Yan, “Highly Efficient and Direct Ultralong All-Phosphorescence From Metal–Organic Framework Photonic Glasses,” Angewandte Chemie International Edition 61 (2022): e202208735.

[30] D. Li, Y. Yang, J. Yang, M. Fang, B. Z. Tang, and Z. Li, “Completely Aqueous Processable Stimulus Responsive Organic Room Temperature Phosphorescence Materials With Tunable Afterglow Color,” Nature Communications 13 (2022): 347.

[31] X. Zheng, Y. Huang, W. Lv, J. Fan, Q. Ling, and Z. Lin, “Nearly Unity Quantum Yield Persistent Room-Temperature Phosphorescence From Heavy Atom-Free Rigid Inorganic/Organic Hybrid Frameworks,” Angewandte Chemie International Edition 61 (2022): e202207104.

[32] A. R. Fiorucci, L. R. de Paula, E. A. Neves, and É. T. G. Cavalheiro, “Solubility of Alkali and Alkali Earth Salts of Dihydrogen Ethylenediaminetetraacetate in Aqueous Solutions,” Journal of Chemical and Engineering Data 47 (2002): 1510–1513.

[33] Y. Li, Z. Wu, Z. Huang, C. Yin, H. Tian, and X. Ma, “Activatable Red/Near-Infrared Aqueous Organic Phosphorescence Probes for Improved Time-Resolved Bioimaging,” National Science Review 12 (2025): nwae383.

[34] X. Dai, Z. Liu, Y. Ge, and P. Wei, “Ultralong Aqueous Organic Room-Temperature Phosphorescent Probes for In Vivo Time-Resolved Bioimaging,” Trends in Analytical Chemistry 168 (2023): 117339.

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