The Balance Effect of π–π Electronic Coupling on NIR‐II Emission and Photodynamic Properties of Highly Hydrophobic Conjugated Photosensitizers

• Published in: Advanced science Vol. 11; no. 6; pp. e2307569 - n/a
• Main Authors: Zhu, Yulin, Lai, Hanjian, Gu, Ying, Wei, Zixiang, Chen, Lin, Lai, Xue, Han, Liang, Tan, Pu, Pu, Mingrui, Xiao, Fan, He, Feng, Tian, Leilei
• Format: Journal Article
• Language: English
• Published: Germany John Wiley & Sons, Inc 01.02.2024; Wiley
• Subjects: Efficiency; Electrons; Energy; Hydrogen; hydrogen bond; Nanoparticles; NIR‐II fluorescence imaging; organic π‐conjugated molecules; photodynamic therapy; Spectrum analysis; π–π interaction; NIR-II fluorescence imaging; organic π-conjugated molecules; photodynamic therapy; π-π interaction; hydrogen bond
• ISSN: 2198-3844; 2198-3844
• DOI: 10.1002/advs.202307569

Deep NIR organic phototheranostic molecules generally have large π‐conjugation structures and show highly hydrophobic properties, thus, forming strong π–π stacking in the aqueous medium, which will affect the phototheranostic performance. Herein, an end‐group strategy is developed to lift the performance of NIR‐II emitting photosensitizers. Extensive characterizations reveal that the hydrogen‐bonding interactions of the hydroxyl end group can induce a more intense π–π electronic coupling than the chlorination‐mediated intermolecular forces. The results disclose that π–π stacking will lower fluorescence quantum yield but significantly benefit the photodynamic therapy (PDT) efficiency. Accordingly, an asymmetrically substituted derivative (BTIC‐δOH‐2Cl) is developed, which shows balanced phototheranostic properties with excellent PDT efficiency (14.6 folds of ICG) and high NIR‐II fluorescence yield (2.27%). It proves the validity of the end‐group strategy on controlling the π–π interactions and rational tuning the performance of NIR‐II organic phototheranostic agents. The hydrogen‐bonding interactions of the hydroxy end group can induce a more intensive π–π electron coupling than the chlorination‐mediated intermolecular forces. π–π stacking will lower fluorescence quantum yield but significantly benefit the PDT efficiency. Therefore, by this end‐group strategy, the phototheranostic properties of the photosensitizers are finely tuned, and a more effective NIR‐II fluorescence‐guided PDT is accomplished.