Pattern Recognition and Visual Detection of Aldehydes Using a Single ESIPT Dye

Area of Science:

• Analytical Chemistry
• Organic Chemistry
• Materials Science

Background:

• Accurate discrimination and quantification of aldehydes are challenging due to their similar chemical reactivities.
• Manipulating reaction pH can alter aldehyde reactivity and Schiff base stability for analytical applications.

Purpose of the Study:

• To design and synthesize novel benzothiazole-based fluorescent molecules for aldehyde sensing.
• To investigate the influence of substituent positions on aldehyde detection capabilities.
• To develop a pH-mediated sensor array for reliable aldehyde discrimination and identification.

Main Methods:

• Synthesis of three benzothiazole-based fluorescent molecules (BS1-BS3) with varying amino group positions.
• Evaluation of fluorescence response in the presence of formaldehyde at different pH levels.
• Construction of a pH-mediated sensor array (BS1SA) using the most responsive molecule (BS1).

Main Results:

• Only BS1, with an ortho-substituted amino group, showed a significant fluorescence response to formaldehyde, attributed to Excited-State Intramolecular Proton Transfer (ESIPT).
• BS2 and BS3 exhibited negligible responses, highlighting the importance of substituent position.
• The BS1SA demonstrated reliable discrimination of seven different aldehydes and identification of unknown samples.
• BS1 was successfully used to create a fluorescent test paper for visual detection of formaldehyde vapor.

Conclusions:

• The ortho-amino substituted benzothiazole derivative (BS1) is a highly effective fluorescent probe for aldehyde sensing.
• A pH-mediated sensor array (BS1SA) offers a robust platform for aldehyde discrimination and identification.
• The developed fluorescent test paper provides a simple and visual method for formaldehyde vapor detection.