We report the crystal structure of 5, 7 –dihydroxy 4-methylcoumarin (HC) and its ratiometric sensing behavior towards F− and AcO− in aqueous DMSO. HC shows an outstanding feature in its crystal structure by forming a hexamer constituting of six O atoms via H-bonding, mimicking the chair form of cyclohexane. The detection limit for HC towards F− and AcO− are 1.12 × 10−8 (M) and 2.55 × 10−7(M) respectively. Interestingly, HC is selective towards F− in a mixture of anions. The mechanism of detection of anions by HC was established through 1H NMR titration. The practical utility has been explored by F− and AcO− detection in solid state. © 2019 Elsevier B.V.