Absolute Phosphorescence Quantum Yields of Singlet Molecular Oxygen in Solution Determined Using an Integrating Sphere Instrument

2015 ◽  
Vol 87 (4) ◽  
pp. 2360-2366 ◽  
Author(s):  
Naoya Hasebe ◽  
Kengo Suzuki ◽  
Hiroaki Horiuchi ◽  
Hiromi Suzuki ◽  
Toshitada Yoshihara ◽  
...  
Keyword(s):  
Molecular Oxygen ◽  
Quantum Yields ◽  
Integrating Sphere ◽  
Singlet Molecular Oxygen

Solvent effect on the reactivity of monosubstituted phenols towards singlet molecular oxygen (O2(1Δg)) in alkaline media

1993 ◽  
Vol 71 (8) ◽  
pp. 1247-1252 ◽  
Author(s):  
Marta Luiz ◽  
María I. Gutiérrez ◽  
Graciela Bocco ◽  
Norman A. García
Keyword(s):  
Molecular Oxygen ◽  
Rate Constant ◽  
Reaction Pathway ◽  
Aqueous Media ◽  
Solvent Polarity ◽  
Alkaline Media ◽  
Quantum Yields ◽  
Quenching Rate ◽  
Singlet Molecular Oxygen ◽  
Quenching Rate Constant

The influence of solvent polarity on the dye-sensitized photooxidation (singlet molecular oxygen (O2(1Δg)) mediated) of a series of para-substituted phenolates was studied. Kinetic evidence obtained shows that the overall and the pure chemical interactions, phenolate–O2(1Δg), depend on the solvent polarity in a different way. This is clearly reflected in the efficiency of O2(1Δg) photooxidation of the substrates: surprisingly, the photooxidation quantum yield increases as the overall quenching rate constant decreases. The substrate photooxidation quantum yields obtained ranged from 0.05 to 0.15, the upper limit corresponding to a moderately polar medium (a benzene–methanol mixture) and the lower to an aqueous medium. We conclude that a high solvent polarity favours only the obtainment of the encounter complex (O2(1Δg)–phenolate), whereas the reactive step is affected in much the same way as those processes where charges are neutralized along the reaction pathway. The results obtained are discussed in terms of a partly polar excited state complex between O2(1Δg) and the phenolates. The rate constant for the reactive pathway in both organic and aqueous media is correlated with the Hammet-type substituent constant R−.

The photolysis of ozone by ultraviolet radiation. IV. Effect of photolysis wavelength on primary step

1970 ◽  
Vol 319 (1537) ◽  
pp. 273-287 ◽  
Keyword(s):  
Quantum Yield ◽  
Ultraviolet Radiation ◽  
Molecular Oxygen ◽  
Ozone Concentration ◽  
Pressure Range ◽  
Quantum Yields ◽  
Ultraviolet Region ◽  
Singlet Molecular Oxygen ◽  
Weak Absorption ◽  
Absorption Tail

Quantum yields for the photolysis of ozone have been measured at six wavelengths in the region 248 to 334 nm. The quantum yield for the photolysis of pure ozone increases linearly with ozone concentration over the pressure range employed for λ ≤ 310 nm, but is virtually independent of [O 3 ] at λ = 334 nm. At all wavelengths the quantum yield, extrapolated to zero ozone pressure, is near 4. Addition of H 2 to the ozone markedly increases the quantum yield at all wavelengths except λ = 334 nm. Dilution of the ozone by O 2 reduces the quantum yield; at high [O 2 ] the quantum yield tends to zero. It is shown that the results are consistent with the production of singlet molecular oxygen (in the 1 ∆ g or 1 ∑ + g states) in the primary step at all wavelengths in the ultraviolet region. For λ ≤ 302 nm the atomic product is in the excited, 1 D, state, O 3 + hv (λ ≤ 302nm) → O 2 ( 1 ∑ + g or 1 ∆ g ) + O( 1 D), but with increasing wavelength the efficiency of O( 1 D) production drops rapidly, and at λ = 334 nm the atomic product is almost exclusively O( 3 P). O 3 + hv (λ = 334 nm) → O 2 ( 1 ∑ g + or 1 ∆ g ) + O( 3 P). Thus it appears that ozone photolysis in the weak absorption tail of the Huggins band does not proceed with conservation of spin. Some possible implications of the laboratory observations in atmospheric photochemistry are considered.

Thiazolyl-substituted porphyrins as standards for singlet molecular oxygen photosensitization

2011 ◽  
Vol 15 (11n12) ◽  
pp. 1202-1208 ◽  
Author(s):  
Marek Scholz ◽  
Roman Dĕdic ◽  
Miriam Miguel ◽  
Rodolfo Lavilla ◽  
Santi Nonell
Keyword(s):  
Singlet Oxygen ◽  
Molecular Oxygen ◽  
Quantum Yields ◽  
Singlet Molecular Oxygen ◽  
Fluorescence Quantum Yields ◽  
Order Of Magnitude ◽  
Oxygen Standard

Thiazolyl- and bithiazolyl-substituted porphyrins have been characterized to assess their potential as new standards for singlet molecular oxygen photosensitization. Their absorption, fluorescence, phosphorescence and triplet–triplet spectra are slightly red-shifted relative to those of tetraphenylporphine (TPP), a well-established singlet molecular oxygen standard. Likewise, the singlet and triplet lifetimes, as well as the fluorescence quantum yields are roughly one order of magnitude smaller than those of TPP, while the triplet and singlet oxygen quantum yields increase concomitantly to ca. 1.

PDT-related photophysical properties of conformationally distorted palladium(II) porphyrins

2001 ◽  
Vol 05 (12) ◽  
pp. 853-860 ◽  
Author(s):  
A. WIEHE ◽  
H. STOLLBERG ◽  
S. RUNGE ◽  
A. PAUL ◽  
M. O. SENGE ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Molecular Oxygen ◽  
Photophysical Properties ◽  
Bathochromic Shift ◽  
Luminescence Spectroscopy ◽  
Quantum Yields ◽  
Triplet States ◽  
Singlet Molecular Oxygen ◽  
Time Resolved ◽  
Phosphorescence Quantum Yield

The photodynamic therapy (PDT) related photophysical properties of five palladium(II) porphyrins with increasing steric demand of the meso-substituents were investigated by steady state and time-resolved absorption and luminescence spectroscopy. The steric strain of the meso-substituents is reflected in a bathochromic shift of the B-band in the absorption spectra. In contrast to free-base porphyrins, the palladium(II) complexes exhibit only a very weak fluorescence with Φ Fl ~ 10-4. Instead, the corresponding triplet states of the porphyrins are formed via inter system crossing (ISC) with a quantum yield ΦISC of nearly unity. A phosphorescence quantum yield ΦISC of 10-4 was determined assuming dynamic quenching. The triplet state of all compounds is efficiently quenched by molecular oxygen, generating singlet molecular oxygen with a quantum yield of ΦΔ ~ 0.85. The various substitution patterns exerted no significant influence on the ISC rates or singlet oxygen quantum yields. Significant differences, on the other hand, were observed with respect to the triplet lifetimes, with a tendency of longer lifetimes for the porphyrins with sterically more demanding substituents (in air-saturated solution). All porphyrins were successfully incorporated into liposomes. The phototoxic activity of three compounds was investigated in cell suspensions. The use of the new porphyrinato-palladium(II) in PDT applications is discussed.

Reaction of indomethacin with singlet molecular oxygen

1980 ◽  
Vol 29 (10) ◽  
pp. 1337-1340 ◽  
Author(s):  
Richard S. Bodaness ◽  
Phillip C. Chan
Keyword(s):  
Molecular Oxygen ◽  
Singlet Molecular Oxygen
Sign in / Sign up

Export Citation Format

Share Document