Efficient green electrogenerated chemiluminescence from cyclometalated iridium(III) complex

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

“…In addition, the presence of electron withdrawing bromo group in the α-diimine ligand (complex 9) caused a red shifted by 9 nm compared to that of the α-diimine ligand without the modification (complex 2), whereas the addition of electron donating methyl group in the α-diimine ligand (complex 8) showed a blue shift of 19 nm compared to that of the α-diimine ligand without the modification (complex 2). These PL experimental results observed in this study indicate that the emission color can be tuned by changing the ancillary ligands, which is quite similar to the previous reports [32].…”

“…The ECL characteristics of newly synthesized α-diimine-ligated heteroleptic iridium(III) complexes were obtained in the presence of TPA as the coreactant for the iridium(III) ECL oxidation-reduction system in a static mode. TPA was used in this study because it is the most well characterized and shows the strongest emission among several co-reactants for Ru(bpy) 3 2+ and iridium(III) complex-based ECL [1][2][3][4][5][6][7][8]32]. The ECL emissions were obtained by sweeping the ECL emissions were obtained for each of those complexes upon sweeping the potential sufficiently positive (up to +1.7 V vs Fc 0/+ ) to oxidize both the complex and TPA in mixed solvent (CH 3 CN/50 mM PBS buffer, 75/25, v/v) at a glassy carbon electrode.…”

“…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]. Many research groups have been working in designing or modifying the ligands of the iridium(III) complexes in order to tune the emission color as well as to enhance the emission efficiency.…”

“…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+ .…”

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

“…Moreover, in most cases, lack of the ECL emission was observed when TPrA was applied as ECL co-reactant, most probably because TPrA • radical is not a strong enough reductant to populate the excited 3* Ir(ppy)(C^C) states by means of the electron transfer between 3* Ir(ppy)(C^C) + and TPrA • species. Very recently, Qi et al [ 83 ] reported ECL studies of novel Ir(24F 2 ppy) 2 (bip) complex with the negatively charged ancillary N^N ligand – the deprotonated form of 2-(2-pyridyl)benzimidazole − bipH. Intense green ECL emissions, characteristic for the 3* Ir(24F 2 ppy) 2 (bip) excited state, were observed in the annihilation and co-reactant processes.…”