Nanofibrous films decorated with phosphorescent iridium(iii) complexes containing Ir-S-C-S structures for selective detection of Cu2+ ions in solution

Copper ions (Cu2+) play an indispensable role in both the human body and eco-environment, so it is crucial to create simple, highly sensitive and selective sensors to recognize Cu2+ ions. In this work, three efficient iridium(iii) complexes, [(L-1)(2)Ir(Czdtc)] (Ir1, L-1 = 6-phenylnicotinaldehyde), [(L-2)(2)Ir(Czdtc)] (Ir2, L-2 = 6-(4(trifluoromethyl)phenyl)nicotinaldehyde) and [(L-3)(2)Ir(Czdtc)] (Ir3, L-3 = 6-(4-methoxyphenyl)nicotinaldehyde) comprising a four-membered Ir-S-C-S ring backbone with 9H-carbazole-9-carbodithioate (Czdtc) as ancillary ligands, were synthesized within 10 minutes at room temperature, and developed as efficient chemical sensors to detect Cu2+ ions. Ir1-Ir3 exhibited broad emission bands peaking between 575 and 593 nm with PLQY in the range of 0.34-0.70 and lifetimes ranging from 1.3 to 1.8 mu s. In acetonitrile solution, they showed a sensitive response to Cu2+ ions with a low detection limit on the order of 10(-7) M with a stoichiometric ratio of 1 : 1, and distinct colorimetric changes (from orange-red to greenish-yellow) were observed by the naked eye. Nanofibrous films decorated with these complexes fabricated using the electrospinning technology could realize on-site detection of Cu2+ ions, based on an obvious contrasting luminescence color different from the background under a 365 nm UV lamp. Nanofibrous films decorated with the fast synthesized Ir1-Ir3 could be used as solid-phase sensing devices with low-cost, high efficiency and portability, providing a promising prospect for the detection of Cu2+ ions in the environment.