4-(8′-Hydroxyquinolin-7′-yl)methyleneimino-1-phenyl-2,3-dimethyl-5-pyzole as a fluorescent chemosensor for aluminum ion in acid aqueous medium

• A novel 8-hydroxyquinoline carbaldehyde Schiff-base is synthesized.
• The fluorescence sensor can be synthesized and performed easily.
• The probe exhibits higher selectivity and sensitivity for Al3+ in acid aqueous medium.
• The fluorescent changes were attributed to PET and ESIPT mechanism.

A new fluorescent Al3+-sensor (L) was designed and synthesized from 8-hydroxyquinoline-7-carbaldehyde (HQ7A) and 4-aminopyrine. The sensor exhibited high selectivity and sensitivity “off-on” fluorescent responses toward Al3+ in methanol/water (1:9, v/v, acetate buffer, pH 4.5), with about 26-fold enhancement in fluorescence intensity and high sensitivity with the detection limit for Al3+ as low as 10−7 M level. The sensor showed a significant fluorescent enhancement for Al3+ over a wide range of tested metal ions. These suggested that L could be served as a highly selective and sensitive fluorescence sensor for aluminum ion in acid medium, indicating the potential application in acid aqueous environment.

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