Singlet oxygen sensitization was determined from the relative intensity of the 1O2 emission band, which is centered around 1276 nm, using [Ru(bpy)3]2+ as the standard (ΦΔ = 0.56 in aerated MeCN) [49 (link)]. Quantum yields (ΦΔ) were calculated in accordance with the actinometric method described by Equation (4), where I denotes the integration of the emission band, A is the solution UV-Vis absorption at the excitation wavelength, and n is the solvent’s refractive index (n2/ns2 = 1 here, as MeCN was used in both). The [Ru(bpy)3]2+ standard is denoted by the subscript S. It is generally desirable to run such measurements in MeCN because this solvent does not quench the 1O2 state (unlike water), and its common use in the literature facilitates comparisons.
Emission spectra were measured on a PTI Quantamaster emission spectrometer equipped with a Hamamatsu R550942 near-infrared photomultiplier tube behind a 1000 nm long pass filter. Emission and excitation spectra were corrected for nonlinearities in lamp output and detector response. The longest wavelength in the excitation spectrum that maximized emission at 1276 nm was selected for the excitation wavelength. The emission spectra were collected over 1200–1350 nm and integrated with baseline correction. The values were generally reproducible within ±5%.
Emission spectra were measured on a PTI Quantamaster emission spectrometer equipped with a Hamamatsu R550942 near-infrared photomultiplier tube behind a 1000 nm long pass filter. Emission and excitation spectra were corrected for nonlinearities in lamp output and detector response. The longest wavelength in the excitation spectrum that maximized emission at 1276 nm was selected for the excitation wavelength. The emission spectra were collected over 1200–1350 nm and integrated with baseline correction. The values were generally reproducible within ±5%.