A novel selective fluorescent chemosensor for Fe (3+) ions based on phthalonitrile dimer: synthesis, analysis, and theoretical studies

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.