Paradoxical fluorescein-naphthalene Salamo-Salen-Salamo Zn(II) complex as a H2PO4−-targeted chemosensor and its application in water samples

Abstract

Chemical materials with different properties could be directionally synthesized by introducing various functional groups into a molecular system. Here, an unusual naphthalene-fluorescein Salamo-Salen-Salamo-type Zn(II) complex was first developed as a fluorogenic chemosensor (ZnSS) based on a grafting design strategy. The in situ chemosensor ZnSS exhibits selective and efficient fluorogenic detection towards dihydrogen phosphate ion (H2PO4−) with off-on style in DMSOHEPES buffer. The synthesized chemosensor ZnSS could be applied to quantitatively analyze H2PO4− ion in rain water and tap water. Fluorescence quantum yield calculation was performed to study the luminescent properties of these compounds. Moreover, the mutual equilibrium of H2PO4− ion was studied by the transition state theory and vibration analysis of density functional theory (DFT). Time-dependent DFT (TDDFT) and electrostatic potential (ESP) calculations further explain the fluorescence emission characteristics and electronic excitation behavior in the sensing process.