Cyanide selective colorimetric and turn-on fluorimetric sensing by naphthohydrazide derivative and its application in real sample analysis

•Compound HNV behaves as selective colorimetric and turn-on fluorimetric sensor for cyanide in aqueous medium (H2O/DMSO, 7:3 v/v).•Both colourless solution and Whatman filter paper test strip of HNV turn to yellow in presence of CN− ion selectively.•Sensor HNV binds cyanide ion using its OH and NH protons, as confirmed by 1H NMR titration data.•Compound HNV can be used for the detection of trace amount of CN− in real water samples.