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.