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. Author manuscript; available in PMC: 2023 Mar 14.
Published in final edited form as: Angew Chem Int Ed Engl. 2022 Jan 27;61(12):e202115704. doi: 10.1002/anie.202115704

Figure 1.

Figure 1.

Photophysical and chemiluminescence properties of the IrCL probes measured in air (A−C), as well as under different O2 environments (D−F). (A) Electronic absorption spectra depicting ligand-based transitions (280−400 nm) and the metal-to-ligand charge transfer (MLCT) transitions. (B) Excitation (dotted lines) and emission (solid lines, λex = 450 nm) spectra for the IrCL probes, where similar bathochromic shifts are observed. (C) Chemiluminescence emission spectra of the IrCL probes. In vitro ratiometric chemiluminescence responses of (D) IrCL-1, (E) IrCL-2 and (F) IrCL-3 to O2. While the emission intensity at 530 nm remains relatively unaffected, the corresponding triplet emission is clearly quenched by increasing O2 concentrations. (G) Stern-Volmer plots generated from the O2-dependent chemiluminescence ratiometric responses of the IrCL probes. As reflected by the slopes, IrCL-1 demonstrates a higher O2 sensitivity in comparison to IrCL-2 and IrCL-3. The solid blue circle represents the response by IrCL-1 in the presence of pure O2. [IrCL] = 20 μM in pure DMSO (photophysics) or 50% DMSO-PBS buffer (10 mM, pH = 7.4) mixtures. Error bars are ±SD for n = 3 independent experiments.