A potential-controlled switch on/off mechanism for selective excitation in mixed electrochemiluminescent systems

Abstract

We demonstrate the complete, rapid, and reversible switching between the emissions from two electrogenerated chemiluminescence (ECL) systems contained within the same solution, controlled by simple modification of the applied potential. The fundamental bases of the approach are the ability to selectively 'switch on' luminophores at distinct oxidation potentials, and an intriguing observation that the emission from the well-known electrochemiluminescent complex, fac-Ir(ppy) 3 , (where ppy is 2phenylpyridinato), can be selectively 'switched-off' at high overpotentials. The dependence of this phenomenon on high concentrations of the co-reactant implicates quenching of the excited [Ir(ppy) 3 ]* state by electron transfer. Rapid spectral scanning during modulation of the applied potential reveals well resolved maxima for mixtures comprising either green and red or green and blue luminophores, illustrating the vast potential of this approach for multiplexed ECL detection.

Electrogenerated chemiluminescence from newly synthesized α-diimine-ligated heteroleptic iridium(III) complexes

“…Lee and coworkers reported the synthesis and characterization of new iridium complexes of (pq) 2 Ir(acac) and (pq) 2 Ir(tmd) (pq = 2-phenylquinoline anion, acac = acetylacetonate anion, and tmd = 2,2′,6,6′-tetramethylhepta-3,5-dione anion) with much higher ECL efficiencies at 589 and 593 nm compared to that of Ru(bpy) 3 2+ [16]. Subsequently, a large number of novel iridium(III) complexes with various ligands have been prepared for ECL studies [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32]. In particular, heteroleptic iridium(III) complexes such as Ir(dfppy) 2 (bpy) [27] and Ir(dfppy) 2 (PyBiz) [32] (dfppy = 2-(2,4-difluorophenyl) pyridine, PyBiz = 2-(2-pyridyl)benzimidazolato-N,N′) as the primary cyclometalating ligand have shown the highly enhanced ECL response compared to that of Ru(bpy) 3 2+ .…”

“…Among those heavy-metal complexes, cyclometalated iridium(III) complexes are, in particular, given strong attention as promising ECL emitters especially for the development of bright OLEDs in flat panel displays and highly sensitive ECL detection because they exhibit high ECL efficiency . Up to now, The cyclometalated iridium(III) complexes have been applied for the ECL detection of the antibiotics [19], ammonium ion [20], cancer cell [21], ammonia [24], and cytosensing [26]. Since the ECL emission wavelengths in cyclometalated iridium(III) complexes can be tuned from the near-infrared to blue via changing the structure of the ligand, they are particularly useful in the development of multichannel ECL-based assays [15,28,32].…”

Imaging Analysis Based on Electrogenerated Chemiluminescence

“…Reproduced from Ref. [108], copyright 2013, with permission of American Chemical Society Ru(bpy) 3 2? ECL and a green reference light from a light emitting diode, as shown in Fig.…”

“…The dependence of the rate of the quenching reaction on the concentration of co-reactant implicates that the switchoff phenomenon is due to the oxidative quenching of Ir(ppy) 3 * by the TPrA ?Á [108]. In addition, tunable ECL emission from three-color ECL system consisting of a deep red emitter [Ru(bpy) 2 (dm-bpy-dc)] 2?…”

Iridium(III)‐Doped Core‐Shell Silica Nanoparticles: Near‐IR Electrogenerated Chemiluminescence in Water

“…Most importantly, unlike ruthenium(II) complexes that typically show emission centered between 600 and 650 nm, iridium(III) complexes have the ability to span the emission range from the near-IR [16,17] to deep blue, [18] which is useful in the development of multichannel analytical techniques. [19] This can be obtained by careful selection of the cyclometalated ligand (N C) [20,21] or by introduction or modification of the ancillary ligands, (L X/O O). [22] In recent years, tuning of the ECL colors are also obtained by mixing of standard [Ru(bpy) 3 ] 2 + and various iridium complexes, the so-called mixed-annihilation systems, which provided further evidence of the iridium complexes versatility for obtaining multi-color ECL.…”