Near-infrared organic photosensitizers with aggregation-induced emission and switchable fluorescence for fungal infection therapy

The development of near-infrared (NIR) photosensitizers with aggregation-induced emission (AIE) properties, switchable luminescence colors, and satisfactory photodynamic therapy (PDT) effects on the treatment of fungal infection is of great importance but very challenging. Herein, two ionic organic luminogens are constructed by employing diphenylamine, diphenylacrylonitrile/1,2-diphenylethene, and methylated quinoline cation as building blocks. It is found that the resulting compounds TCQF and TQF show apparent AIE properties and produce intense fluorescence with high photoluminescence quantum yields of up to 31.2% in the solid state. In the meantime, their emission colors can be switched between red and NIR and in the NIR region by mechanical force and solvent vapor, respectively, thereby enabling remarkable and reversible mechanochromism with emission variations of up to 104 nm. More excitingly, TCQF and TQF can efficiently generate ROS under the illumination of white light and show excellent antimicrobial activities and satisfactory PDT capabilities. Inspired by the unique anti-fungus properties, TCQF is employed as a biocompatible NIR photosensitizer for treating wound infection with C. albicans, and apparent PDT effects are achieved. This work provides a new direction for the development of multifunctional NIR materials with AIE properties.