Pyrrolopyrrole aza-BODIPY dyes for ultrasensitive and highly selective biogenic diamine detection

•225 nm hypsochromic absorption shift and 12-fold fluorescence enhancement for BAs detection.•The low limit of detection and fast response time for BAs detection.•Practical application of visual detection of BAs vapors and monitoring fish spoilage. Biogenic diamines (BAs) are important compounds in food chemistry and life science. Because of structural similarity of amines and low concentration of BAs in real samples, it is exceedingly challenging to design and develop highly efficient probes for visual detection of BAs. To address this gap, we report ultrasensitive and highly selective pyrrolopyrrole aza-BODIPY (PPAB) probes for BAs detection. The detection mechanism study revealed first kinetic-control reaction of a B–N bond cleavage by BAs, and following two fast step reactions (transimination and hydrolysis) to yield much smaller conjugated molecules. The first kinetic-control reaction results in high selectivity towards BAs. The following reactions result in direct large conjugation change, leading to high sensitivity for the detection of BAs. Thus, with over 225 nm hypsochromic shift in the absorption maximum and 12-fold fluorescence enhancement process, PPAB probes showed high sensitivity for BAs with limit of detection up to ppb level and response time on the second timescale. Moreover, visual detection of BAs vapors and monitoring fish spoilage were successfully conducted by the low-cost, high-contrasting, quick-responsive fluorescent trademark of PPAB molecules by naked-eyes.