This paper describes the design and synthesis of a new quinazolinone-based colorimetric chemosensor for highly selective sensing of CH-, AcO- and Cu2+ ions in aqueous acetonitrile solution. The synthesized compound as a two-faced chemosensor exhibited remarkable colorimetric responses from red to yellow in the presence of Cu2+ and red to violet in the presence of AcO- and CN- ions, which could be observed by naked eyes. In addition, an alternative approach was developed for highly selective sensing of CH based on stable complex formation of cyanide and copper ions. In addition, the paper strips coated with the synthesized chemosensor have been prepared for the detection of CH- ions. Furthermore, the mechanism of interaction between the chemosensor and CH- ions has been confirmed by the H-1 NMR titration experiments. (C) 2016 Elsevier B.V. All rights reserved.