Fluorescent probes with fluorescence emission in the NIR-II window have been widely studied due to increased imaging depth. However, the currently reported NIR-II fluorescent probes present some disadvantages, such as complicated synthesis routes and low fluorescence quantum yields (QYs). The shielding strategy has been used in the development of NIR-II probes to improve their QYs. So far, this strategy has only been used for the symmetric NIR-II probes, especially those based on the benzo[1,2-c:4,5-c']bis([1,2,5]thiadiazole) (BBTD) skeleton. T...
