3,3′,5,5′-tetramethyl-N-(9-anthrylmethyl)benzidine: A dual-signaling fluorescent reagent for optical sensing of aliphatic aldehydes

Ronghua Yang, Ke'an Li*, Feng Liu, Na Li, Fenglin Zhao, Wing Hong CHAN

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

30 Citations (Scopus)


A new optical chemical sensor for continuous monitoring of aliphatic aldehydes has been proposed based on the reversible chemical reaction between a new sensing reagent, 3,3′,5,5′-tetramethyl-N-(9-anthrylmethyl)benzidine (TMAB), and the analytes. TMAB, containing two receptors and two fluorescent reporters, can perform dual fluorescence responses corresponding to the reactions of hydrogen ion and carbonyl compound. When immobilized in a plasticized poly(vinyl chloride) membrane, TMAB extracts aliphatic aldehydes from aqueous solution into the bulk membrane phase and reacts with the analyte by forming a Schiff base. Since the extraction equilibrium and chemical reaction are accompanied by fluorescence increase of the sensing membrane, the chemical recognition process could be directly translated into an optical signal. At pH 3.20, the sensor exhibits a dynamic detection range from 0.017 to 4.2 mM n-butyraldehyde with a limit of detection of 0.003 mM. The forward response time (t95) of the sensor is 3-5 min, and the reverse response time is 5-7 min. The responses of the sensor toward different kinds of aldehydes and ketones depend on the lipophilicity and the reactivity of the analytes. Since the fluorescence enhancement of the sensing membrane at 296 nm/410 nm is only related to the formation of Schiff base, the measurement of aldehydes is independent of pH.

Original languageEnglish
Pages (from-to)3908-3914
Number of pages7
JournalAnalytical Chemistry
Issue number15
Publication statusPublished - 1 Aug 2003

Scopus Subject Areas

  • Analytical Chemistry


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