Photoluminescent Sensor for Fe³⁺ Based on Calix[4]arene-Derivative-Modified UiO-66-NH₂

Iron is an important ion that regulates many metabolic functions in the human body, and its deficiency or overload can cause serious health problems. In view of this, the development of tools that can quantify iron in aqueous media is quite valuable. A new material based on a metal-organic framework (MOF) and a calixarene derivative (CALIX), here named CALIX@UiO-66-NH₂, was successfully prepared and used as a luminescent sensor for iron ions in a water matrix containing various metal ions. The post-synthetic modification was demonstrated to be efficient on the MOF (UiO-66-NH₂) modification, leading to a hybrid platform. The effect of the combination of both components (MOF and CALIX) led to a platform more sensitive to iron detection than the independent compounds. The CALIX@UiO-66-NH₂ sensor shows a linear response toward Fe³⁺ ions with satisfactory linearity (R² = 0.994) within the concentration range of 6.74 × 10⁻⁶−1.72 × 10⁻⁵ mol L⁻¹. The limit of detection was determined to be as low as 1.6 mg L⁻¹. The data demonstrate that CALIX@UiO-66-NH₂ is an excellent probe for detecting Fe³⁺, as confirmed by almost complete fluorescence suppression.

Keywords:
Fe³⁺ detection; calixarene; metal-organic framework; post-synthetic modification; fluorescent sensor