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Long-wavelength fluorescent sensors with large Stokes shifts show useful applications in chemical biology and clinical laboratory diagnosis. We have recently reported [4-(4-{[3-(4-boronobenzamido)propyl]carbamoyl}quinolin-2-yl)phenyl]boronic acid that can selectively recognize d -ribose in a buffer solution of pH 7.4. However, the short emission wavelength (395 nm) and aggregation-caused quenching effect are not conducive to applications as a sensor. Novel diboronic acid compounds are synthesized using 2-(4-boronophenyl)quinoline-4-carboxylic acid as the building block and p -phenylenediamine as the linker. These compounds show aggregation-induced emission and fluorescence emission at about 500 nm. In addition, after binding to most carbohydrates, the aggregated state of the boronic acid–containing compounds is dissociated, resulting in fluorescence quenching. Using [4-(4-{[4-(3-borono-5-methoxybenzamido)phenyl]carbamoyl}quinoline-2-yl)phenyl]boronic acid as an example, addition of 55 mM of d -ribose resulted in the strongest quenching of 83% for all the tested carbohydrates, indicating selectively recognizing d -ribose. The reciprocal of the fluorescence intensity change showed a good linear relationship with the reciprocal of d -ribose concentration (R 2 ⩾ 0.99), indicating sensor binding to d -ribose in a ratio of 1:1 to form an inclusion complex. The fluorescence emission is red-shifted compared to 2-(4-boronophenyl)quinoline-4-carboxylic acid and its common derivatives, which provides a new method for the development of long-wavelength fluorescent sensors. [ABSTRACT FROM AUTHOR]

Small-molecule reactive species, such as reactive oxygen species, catecholamines, ions, sialic acid and gas signal molecules, are involved in many important biological events. For example, abnormal reactive oxygen species levels can lead to a range of cell dysfunctions and eventually cancer and neurodegenerative diseases. Therefore, the development of sensors for detecting small-molecule reactive species is of great significance for disease prevention, diagnosis and treatment. Boronic acid has been widely used for the selective recognition of sugars due to their obvious fluorescence change after combining with sugar, easily structure modification and good light stability. In recent years, a large number of boronic acid-based sensors that can selectively recognize small-molecule reactive species have been reported, however, there are few systematic reviews in this field, and lack of in-depth understanding of the identification mechanism and structure-activity relationship. In this review, boronic acid-based sensors detecting small-molecule reactive species (such as reactive oxygen species (H 2 O 2 , ONOO−, CLO−), catecholamines (dopamine, norepinephrine), sialic acid and sialic acid derivatives (sialic acid, sialic Lewis X, sialic Lewis Y) and ions (F−, Fe3+, Cu2+)) over the recent years (2015–2020) will be discussed, focusing on the fluorescence characteristics of the sensors and their potential in disease detection, and we are aiming to provide researchers with better inspiration. • Small-molecule reactive species are involved in many important biological events. • Boronic acid-based fluorescent sensors are widely used to detect small-molecule reactive species in organisms. • We review boronic acid-based sensors for small-molecule reactive species imaging. • We discuss the characteristic and response mechanism of the sensors. [ABSTRACT FROM AUTHOR]