Determination of Fluorescence Yields, Singlet Lifetimes and Singlet Oxygen Yields of Water‐Insoluble Porphyrins and Metalloporphyrins in Organic Solvents and in Aqueous Media

Abstract

Abstract— Fluorescence quantum yields and singlet lifetimes for a wide range of hydrophilic to hydrophobic porphyrins and metalloporphyrins have been determined in toluene, methanol or acetone. Photosensitized singlet oxygen yields have been determined in the same solvents. For some porphyrins, the same quantities were determined in an aqueous medium, through use of an amphiphilic polymer to solubilize the porphyrin sensitizer and target molecule, 1, 3‐diphenylisobenzofuran. Because rate constants for the deactivation of singlet oxygen (kd) and for its reaction with a target molecule (ka) are unknown in such aqueous polymer systems, a new method was developed for evaluating yields of singlet oxygen formation that also provides a value for the ratio kd/ka. A variation observed in quantum yield of singlet oxygen production for the aqueous polymer system with variation in initial concentration of the target molecule is discussed.

Sensitized Photochemical CO2 Reduction by Hetero‐Pacman Compounds Linking a ReI Tricarbonyl with a Porphyrin Unit

“…[b] PLQY measurements conducted versus tetraphenylporphyrin in toluene as the reference standard ( Φ =0.11), see Ref. .…”

Tricationic Porphyrin Conjugates: Evidence for Chain-Structure-Dependent Relaxation of Excited Singlet and Triplet States

“…518 [14,4] 555 [6,9] 592 [5,5] the case with porphyrin aggregates. 24 In the P-(Lys) n conjugate, however, the strong electrostatic repulsion between the heavily positively charged polylysine side chains appears large enough to potentially weaken interactions which lead to stacking of the solvated porphyrin rings.…”

Efficient intersystem crossing using singly halogenated carbomethoxyphenyl porphyrins measured using delayed fluorescence, chemical quenching, and singlet oxygen emission

“…20,[22][23][24] Conventionally ϕ ∆ , the singlet oxygen quantum yield, is obtained from Stern-Volmer plots of the data as shown in equation 5. 20, 22, 23, 25…”

“…The spin orbit coupling produced by iodine or bromine facilitates intersystem crossing into the triplet state, which enables energy transfer to molecular oxygen. 1,5,22,23,28,29 Energy transfer from the porphyrin in the triplet state to molecular oxygen generates singlet oxygen, which then degrades DPBF. 30 …”

“…20,22,23 To summarize, a reaction mixture (4 mL) of DPBF (~5 x 10 -5 M) and porphyrin (5-10 x10 -6 M) was prepared and promptly dispensed in a (1 cm x 1 cm) quartz cuvette. The absorbance of the reaction was monitored at 552 nm to determine the absorption of the photosensitizer at the excitation wavelength and at 408 nm to monitor DPBF depletion.…”