Optical Chemosensors For The Gas Phase Detection Of Aldehydes: Mechanism, Material Design, And Application

Because of their high hazards and presence in various common scenarios (e.g., workplace, residence, or bio-conversion systems), aldehydes have attracted enormous attention in the research and development of chemical sensors and other detection methods that can provide the quick and sensitive detection of aldehydes, particularly in the gas phase, thus enabling the real-time monitoring of air pollution and impact to health and environment. Among all the detection methods, an optical chemosensor, which relies on aldehyde-triggered color or fluorescence emission change, is typically small in size, easy to operate, and low cost, offering great advantages over benchtop spectrophotometric or chromatographic instrumentation methods, which are large in size and non-portable, complicated to operate, and expensive to maintain. This review will provide a comprehensive overview of the most remarkable development in the gas phase detection of aldehydes (especially the highly volatile aliphatic aldehydes such as formaldehyde and acetaldehyde) in recent years, mostly focusing on the colorimetric, fluorometric, colorimetric/fluorometric dual-mode, and chemiluminescent sensing methods. The review is specifically centered on the discussion of the sensor mechanism in correlation with various molecular designs and materials structural engineering, which, when combined, would lead to maximum sensor performance with respect to both the detection sensitivity and selectivity. At the end of this paper, we also provide the future perspectives concerned with the future development of optical chemosensors and miniaturized device systems, which will be more suited for deployment in practical applications for the quick and onsite detection of aldehydes.