The present invention generally relates to fluoride receptor reagent compounds that are derived from one or more N-aryl or heteroaryl substituted 1,4,5,8-naphthalenetetracarboxydiimide (NDI) units. The invention also relates to associated methods for the detection of fluoride in a composition. π-electron orbitals present in the NDI unit of the reagents form a complex with fluoride anions. It is believed that the anion-π interaction results in a charge transfer process between the fluoride anion and the NDI unit, resulting in a number of measurable effects (e.g., colorimetric response).