Theoretical study of chemosensor for fluoride and phosphate anions and optical properties of the derivatives of 2-(2-hydroxyphenyl)-1,3,4-oxadiazole

► The host sensors have much stronger affinity to F-/H2PO4- than to Cl− and Br−. ► The sensing signals are characterized as intramolecular charge transfer. ► HOXDn (n = 4-7) are candidates fluorescent and chromogenic sensors for F-/H2PO4-. ► HOXD2 and HOXD3 are promising luminescent and electron transport materials for OLEDs.