Chemiluminescence of a cyclometallated iridium(III) complex and its application in the detection of cysteine

Abstract

Chemiluminescence (CL) of a cyclometallated iridium (III) complex {tris[1-(2,6-dimethylphenoxy)-4-(4-chlorophenyl)phthalazine]iridium(III)} in the presence of potassium permanganate and oxalic acid is reported for the first time. Cysteine exhibits sufficient enhancing effect on the CL generated from the cyclometallated iridium(III) complex, which make it possible for the sensitive detection of cysteine using a flow-injection-chemiluminescence (FI-CL) method. The optimum conditions for the chemiluminescence emission were investigated. Under the optimal condition, the linear range for the determination of cysteine was 1.0 × 10(-9) -5.0 × 10(-6) mol/L with a detection limit of 6.9 × 10(-10) mol/L. A relative standard deviation of 1.6% was obtained for eight replicate determinations. The mechanisms of CL are proposed and the emitting species was identified as the metal-to-ligand charge-transfer (MLCT) excited states of the iridium complex.

Aldehyde bearing bis-cyclometalated Ir(III) complex as selective photoluminescence turn-on probe for imaging intracellular homocysteine

“…Huang and coworkers designed an iridium(III) complex which showed high specificity towards Hcy on basis of the cyclization of aldehyde with thiol [23]. Among them, iridium(III) complex has received considerable attention in the light-emitting electrochemical cells [24] and in the detection of analytes, including oxygen [25], thrombin, cocaine and K + [26], cations [27][28][29], anions [30,31], Cys [32][33][34][35], both Cys and Hcy [36][37][38][39] due to its high photoluminescent efficiencies, relatively long lifetimes and significant Stokes shifts.…”

Chemiluminescence detection with water-soluble iridium(iii) complexes containing a sulfonate-functionalised ancillary ligand

“…Cyclometalated iridium(III) complexes have been widely explored as electrochemiluminescence (ECL) reagents [1][2][3][4][5][6][7][8][9] because of their wide range of emission colours and high luminescence efficiencies, which offer greater sensitivity than the benchmark tris(2,2 0 -bipyridine)ruthenium(II) ([Ru(bpy) 3 ] 2+ ) reagent, and the ability to create multi-coloured ECL systems. [10][11][12][13][14] Preliminary studies suggest that cyclometalated iridium(III) complexes could also provide superior chemiluminescence detection of various analytes, [15][16][17][18][19][20][21] but the limited solubility of many commercially available iridium(III) complexes in aqueous solution has restricted their application.…”

Cyclometalated iridium(III) chelates—a new exceptional class of the electrochemiluminescent luminophores

“…Under optimum conditions, the decreased CL intensity was proportional with the concentration of tryptophan in the range from 5.0 × 10 −7 to 2.0 × 10 −5 M with the detection limit of 8.2 × 10 −8 M. The proposed method can be applied for the determination of tryptophan in its pharmaceutical formulations. A similar approach has been applied by Dong et al in the detection of cysteine [ 106 ]. The homoleptic iridium(III) complex with three cyclometalating 1-(2,6-dimethylphenoxy)-4-(4-chlorophenyl)phthalazine ligands were adopted as active luminophore in the presence of potassium permanganate (oxidant) and oxalic acid (co-reactant).…”