<p>The synthesis of a fluorescent chemosensor (FurPy-Calix) based on a bis-pyrene-appended calix[4]arene derivative in a cone conformation is reported. The synthesized FurPy-Calix was characterized by ¹H and ¹³C NMR, elemental analysis, and ESI-MS analyses. Anion binding experiments revealed that this ligand exhibits excellent selectivity for HAsO₄²⁻ anion over other anions tested (HCO₃⁻, HPO₄²⁻, NO₃⁻, SO₄²⁻, ClO₂⁻, N₃⁻, F⁻, and I⁻). Additionally, pH influences on the sensing studies demonstrated that it is highly effective for detecting the hazardous HAsO₄²⁻ anion with a “turn-off” response at pH 8.0. The association constant (<i>Ks</i>_As(V)) for the 2:1 complex formed between FurPy-Calix and HAsO₄²⁻ ion was calculated to be 1.49 × 10³ from the fluorescence titration experiments. The calix[4]arene-based probe (FurPy-Calix) achieved a remarkable detection limit of 0.61&#xa0;μmol&#xa0;dm⁻³, exhibiting high sensitivity towards HAsO₄²⁻ ion. Furthermore, ¹H NMR spectral studies indicated that FurPy-Calix interacted with HAsO₄²⁻ ion through multiple hydrogen bonding interactions. The results suggest that this calix[4]arene based fluorescence probe could be utilized as a selective and sensitive photophysical sensor for the hazardous arsenate anion.</p> Graphical abstract <p></p>