Abstract
A novel iridium(III) complex-based chemosensor bearing the 5,6-bis(salicylideneimino)-1,10-phenanthroline ligand receptor was developed, which exhibited a highly sensitive and selective color change from colorless to yellow and a visible turn-off luminescence response upon the addition of Cu(II) ions. The interactions of this iridium(III) complex with Cu2+ ions and thirteen other cations have been investigated by UV-Vis absorption titration, emission titration, and 1H NMR titration.
Highlights
The copper(II) ion plays a significant role in a number of physiological processes in living organisms, but is an important environmental pollutant [1]
Aberrant levels of Cu2+ ions can result in oxidative stress, and has been linked with the development of Indian childhood cirrhosis, prion disease, Menkes disease, Parkinson’s disease and Wilson disease [2]
A number of Cu2+-selective chemosensors that employ the chromogenic [4,5,6,7], fluorogenic [8,9,10,11,12,13,14,15], or electrochemical [16,17,18] properties of molecules have been reported in the literature
Summary
The copper(II) ion plays a significant role in a number of physiological processes in living organisms, but is an important environmental pollutant [1]. We designed and synthesized a novel cyclometalated iridium(III) complex [Ir(peq)2(sa2p)] (denoted as 1) containing two 2-phenylquinoline (peq) C‘N ligands and a single 5,6-bis(salicylideneimino)-1,10-phenanthroline (sa2p) tetradentate Schiff base receptor (Figure 1), which could function as both a colorimetric and luminescent chemosensor for Cu2+ detection. The interaction of the Cu2+ ion with the tetradentate Schiff base receptor can induce electron transfer from the metal center to the sa2p ligand, thereby influencing the photophysical behaviour of the iridium(III) complex. To a stirring solution of concentrated H2SO4 (30 mL) in an ice bath, 1,10phenanthroline (5.0 g, 23.8 mmol) was added. The precipitate was collected, washed with water and dried under vacuum to give the cyclometalated [Ir(peq)2Cl2] dimer. A suspension of the dimer [Ir2(peq)4Cl2] (127.22 mg, 0.5 mmol) and 5,6-bis(salicylideneimino)-1,10-phenanthroline (sa2p) (200.71 mg, 0.22 mmol) in ethylene glycol was refluxed overnight under a nitrogen atmosphere. The binding constants (K) were determined from the Benesi2Hildebrand plot [60]
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