Nitric‐Oxide‐Releasing aza‐BODIPY: A New Near‐Infrared J‐Aggregate with Multiple Antibacterial Modalities

Spatial electronic communications of chromophores are both theoretically and practically fascinating. Despite intramolecular or intermolecular exciton coupling was observed in multichromophoric oligomers and J-aggregates, respectively, it is unusual that they both occur in the same molecule. Herein, ethene-bridged aza-BODIPY dimers with intramolecular exciton splitting have been developed. By encapsulating the dimer into F-127 polymer, J-type aggregated nanoparticles were produced, which showed obvious intermolecular exciton coupling and dramatically redshifted absorption and emission peaks at 936 and 1003 nm, respectively. The fabricated nanoagents have high photothermal conversion ability (η = 60.3 %) and are ultra-photostable, leading to complete tumor ablation with 915 nm laser irradiation. This phototherapeutic nanoplatform through modulating both intra-and intermolecular exciton couplings is a valuable paradigm for developing photothermal agents for tumor treatment.

Unique Double Intramolecular and Intermolecular Exciton Coupling in Ethene‐Bridged aza‐BODIPY Dimers for High‐Efficiency Near‐Infrared Photothermal Conversion and Therapy

Guo

Yang

et al. 2022

Excited‐State THz Vibrations in Aggregates of Pt^II Complexes Contribute to the Enhancement of Near‐Infrared Emission Efficiencies**

Wei

Chen

et al. 2023

The exploration of deactivation mechanisms for near-infrared(NIR)-emissive organic molecules has been a key issue in chemistry, materials science and molecular biology. In this study, based on transient absorption spectroscopy and transient grating photoluminescence spectroscopy, we demonstrate that the aggregated Pt II complex 4H (efficient NIR emitter) exhibits collective out-of-plane motions with a frequency of 32 cm À 1 (0.96 THz) in the excited states. Importantly, similar THz characteristics were also observed in analogous Pt II complexes with prominent NIR emission efficiency. The conservation of THz motions enables excited-state deactivation to proceed along low-frequency vibrational coordinates, contributing to the suppression of nonradiative decay and remarkable NIR emission. These novel results highlight the significance of excited-state vibrations in nonradiative processes, which serve as a benchmark for improving device performance.

Tuning Shortwave‐Infrared J‐aggregates of Aromatic Ring‐Fused Aza‐BODIPYs by Peripheral Substituents for Combined Photothermal and Photodynamic Therapies at Ultralow Laser Power

Guo,

Sheng,

Pan

et al. 2024

Achieving photothermal therapy (PTT) at ultralow laser power density is crucial for minimizing photo‐damage and allowing for higher maximum permissible skin exposure. However, this requires photothermal agents to possess not just superior photothermal conversion efficiency (PCE), but also exceptional near‐infrared (NIR) absorptivity. J‐aggregates, exhibit a significant redshift and narrower absorption peak with a higher extinction coefficient. Nevertheless, achieving predictable J‐aggregates through molecular design remains a challenge. In this study, we successfully induced desirable J‐aggregation (λabsmax: 968 nm, ε: 2.96 × 105 M‐1 cm‐1, λemmax: 972 nm, ФFL: 6.2%) by tuning electrostatic interactions between p‐conjugated molecular planes through manipulating molecular surface electrostatic potential of aromatic ring‐fused aza‐BODIPY dyes. Notably, by controlling the preparation method for encapsulating dyes into F‐127 polymer, we were able to selectively generate H‐/J‐aggregates, respectively. Furthermore, the J‐aggregates exhibited two controllable morphologies: nanospheres and nanowires. Importantly, the shortwave‐infrared J‐aggregated nanoparticles with impressive PCE of 72.9% effectively destroyed cancer cells and mice‐tumors at an ultralow power density of 0.27 W cm‐2 (915 nm). This phototherapeutic nano‐platform, which generates predictable J‐aggregation behavior, and can controllably form J‐/H‐aggregates and selectable J‐aggregate morphology, is a valuable paradigm for developing photothermal agents for tumor‐treatment at ultralow laser power density.