A novel colorimetric probe derived from isonicotic acid hydrazide for copper (II) determination based on internal charge transfer (ICT)

• A novel isonicotic acid hydrazide Schiff base was discovered as colorimetric probe for Cu (II) detection.
• Addition of Cu2+ to the solution of DHIH resulted in a rapid color change from colorless to yellow.
• An obvious new absorption band appeared at the range of 400–440 nm.
• The chemosensor was selective and sensitive for Cu (II) determination.

A novel isonicotic acid hydrazide Schiff base derivative N′-(3,5-di-tert-butyl-2-hydroxy-benzylidene) isonicotinohydrazide (DHIH) has been synthesized and developed as a high selective and sensitive colorimetric probe for Cu2+ determination. Addition of Cu2+ to the solution of DHIH resulted in a rapid color change from colorless to yellow together with an obvious new absorption band appeared at the range of 400–440 nm by forming a 1:1 complex. Experimental results indicated that the DHIH could provide absorption response to Cu2+ with a linear dynamic range from 1.0 × 10−5 to 1.0 × 10−4 mol/L. The detection limit of Cu2+ was 5.24 × 10−7 mol/L with good tolerance of other metal ions.

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