A novel selective fluorescent chemosensor for Fe$^{3+}$ ions based on phthalonitrile dimer: synthesis, analysis, and theoretical studies

Authors: SHAYA AL-RAQA, İPEK ÖMEROĞLU, DOĞAN ERBAHAR, MAHMUT DURMUŞ

Abstract: Phenyl-4,4-di(3,6-dibutoxyphthalonitrile) (3) was synthesized by the reaction of 1,4-phenylenebisboronic acid (1) and 4-bromo-3,6-dibutoxyphthalonitrile (2), using Suzuki cross-coupling reaction. The newly synthesized compound (3) was characterized by FT-IR, MALDI-MS, ESI-MS, $^{1}$H-NMR, $^{13}$C-NMR, and $^{13}$C-DEPT-135-NMR. The fluorescence property of phenyl-4,4-di(3,6- dibutoxyphthalonitrile) (3) towards various metal ions was investigated by fluorescence spectroscopy, and it was observed thatthe compound (3) displayed a significantly `turn-off? response to Fe$^{3+}$, which was referred to 1:2 complex formation between ligand (3) and Fe$^{3+}$. The compound was also studied via density functional theory calculations revealing the interaction mechanism of the molecule with Fe$^{3+}$ ions.

Keywords: Phthalonitrile, Suzuki cross-coupling, fluorescence, chemosensor, Fe$^{3+}$ ion

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