Photochemical investigation of the IR absorption bands of molecular oxygen in organic and aqueous environment

Abstract

It is shown that the weak IR absorption bands corresponding to the forbidden triplet-singlet transitions in oxygen molecules can be reliably studied in air-saturated solvents under ambient conditions using measurements of the photooxygenation rates of singlet oxygen traps (1,3-diphenylisobenzofuran or uric acid) upon direct excitation of oxygen molecules by IR diode lasers. The best results were obtained from comparison of the oxygenation rates upon direct and photosensitized singlet oxygen excitation. In the present paper, this method was applied to estimation of the absorbance (A(ox)) and molar absorption coefficients (ε(ox)) corresponding to the oxygen absorption bands at 765 and 1273 nm in carbon tetrachloride, acetone, alcohols and water. In carbon tetrachloride, the band at 1073 nm was also investigated. Correlation of the obtained data with the luminescence spectra and radiative rate constants of singlet oxygen, contribution of oxygen dimols and biological significance of the studied effects are discussed.

Photochemistry and Spectroscopy of Singlet Oxygen in Solvents. Recent Advances which Support the Old Theory

“…The low radiative rate constant (k r ) for 1270 nm a→X emission at low pressure in gases [21] and its essential enhancement in solvents [15,18] have been explained in a number of old papers [10,22,23]. Nowadays the total theoretical backgrounds of this theory are supported by numerous experimental studies [26][27][28][29][30][31][32] including recent experiments [33][34][35][36][37][38] on direct oxygen excitation. Thus, it can be interesting to present a short review of such backgrounds accounting a great importance of singlet oxygen photochemistry in solvents for modern medical diagnostics and therapy [39,40] as well as for some braches of chemical technology [5,32].…”

“…In free O 2 the corresponding magnetic radiation is determined in Fig. 1 by transitions 1 and 3 [4,34,35]. This is actually the transition 1 in Fig.…”

ssDNA damage dependence from singlet oxygen concentration at photodynamic interaction

“…Chemical trap method was used to register singlet oxygen emerged in solution under photodynamic interaction [8]. Fig.…”

Palladium Complexes of Azomethine Derivatives of Porphyrins as Potential Photosensitizers

“…TPP (mesotetraphenylporphin) was used as a standard, for which the quantum yield of singlet oxygen generation was taken equal to 0.65 ± 0.05. [23,24] 1,3-Diphenylisobenzofuran (DPIBF), the interaction of which with singlet oxygen takes place quantitatively with formation of colorless 1,2-dibenzoylbenzene product, was used as a chemical trap. [25] For the determination of quantum yields of singlet oxygen generation mixed solutions of the investigated compounds and DPIBF were prepared in a fixed volume of solvent.…”

“…The standard compound was TPP (meso-tetraphenylporphin), for which the quantum yield of singlet oxygen was assumed to be 0.65 ± 0.05. [23,24] Porphyrins were irradiated with light with a wavelength corresponding to the Q y absorption band. Change of optical density was Palladium Complexes of Azomethine Derivatives of Porphyrins as Potential Photosensitizers Figure 5.…”