Recent progress in fluorescent chemosensors for selective aldehyde detection.

Aldehydes (R-CHO) are volatile and chemically active compounds prevalent in the environment, industrial chemicals, food fermentation, and human metabolism. Their release into the atmosphere can lead to pollution and adverse health effects, from mild irritation to severe respiratory and immune system damage. Among aldehydes, formaldehyde (FA) and acetaldehyde (AA) are notable indoor air pollutants with stringent safety limits set by organizations like WHO and OSHA. Current detection techniques, including gas and liquid chromatography, while highly accurate, are expensive and require trained personnel. Conventional sensors, such as semiconductor and chemiresistive types, offer portability and online detection but are hindered by poor selectivity and sensitivity. Optical chemosensors, which operate based on fluorescence or colorimetric changes induced by chemical interactions, have emerged as a promising alternative due to their high sensitivity, selectivity, cost-effectiveness, and portability. This review explores the advancements in optical chemosensors for aldehyde detection, emphasizing novel molecular designs utilizing mechanisms like imine bond formation, cyclization reactions, and aza-Cope rearrangements etc. The applications of these sensors in environmental monitoring, biomedical analysis, and other industries are highlighted, showcasing their potential for real-time, low-concentration detection of aldehydes in diverse settings.