The new coumarin derivative cyclotetraphosphazene fluorometric chemosensor with reversible, high selective and sensitive for Fe3+ ion detection

•The new coumarin-based cyclotetraphosphazene (OCCTP) was synthesized and characterized.•The photophysical and chemosensor properties of the compound was determined.•The complex stoichiometry of OCCTP and selective analytes was determined as 1:2 (L/M).•The limit of detection of sensor was calculated as 1.87 μM for Fe3+ ion.•The OCCTP with high selectivity, sensitivity, instantly and reversible responding to Fe3+ ion.