scholarly journals Phosphorescent oxygen-sensing and singlet oxygen production by a biosynthetic silk

RSC Advances ◽  
2016 ◽  
Vol 6 (46) ◽  
pp. 39530-39533 ◽  
Author(s):  
Conor C. Horgan ◽  
Yong-Shen Han ◽  
Holly Trueman ◽  
Colin J. Jackson ◽  
Tara D. Sutherland ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Visible Light ◽  
Triplet State ◽  
Singlet Oxygen ◽  
Singlet State ◽  
Oxygen Sensing ◽  
Coiled Coil ◽  
Intersystem Crossing ◽  
Oxygen Production

A recombinant coiled-coil silk was utilised to immobilise heavy-metal-macrocycles which are known to undergo efficient intersystem crossing from the singlet state to the triplet state following excitation with visible light.

Photolysis of ketene. I

1968 ◽  
Vol 46 (14) ◽  
pp. 2353-2360 ◽  
Author(s):  
A. N. Strachan ◽  
D. E. Thornton
Keyword(s):  
Carbon Monoxide ◽  
Quantum Yield ◽  
Triplet State ◽  
Singlet State ◽  
Inert Gases ◽  
Inert Gas ◽  
Excited Singlet State ◽  
Intersystem Crossing ◽  
Excited Singlet ◽  
Increasing Temperature

Ketene has been photolyzed at 3660 and 3130 Å both alone and in the presence of the inert gases C4F8 and SF6. The quantum yield of carbon monoxide has been determined at both wavelengths as a function of pressure and temperature. At 3660 Å the quantum yield decreases with increasing pressure but increases with increasing temperature. At 3130 Å the quantum yield with ketene alone remains 2.0 at both 37 and 100 °C at pressures up to 250 mm. At higher pressures of ketene or with added inert gas the quantum yield decreases with increasing pressure. The results are interpreted in terms of a mechanism in which intersystem crossing from the excited singlet state to the triplet state occurs at both wavelengths, and collisional deactivation of the excited singlet state by ketene is single stage at 3660 Å but multistage at 3130 Å.

C70: intersystem crossing and singlet oxygen production

1992 ◽  
Vol 192 (2-3) ◽  
pp. 249-253 ◽  
Author(s):  
Rebecca R. Hung ◽  
Joseph J. Grabowski
Keyword(s):  
Singlet Oxygen ◽  
Intersystem Crossing ◽  
Oxygen Production

Activation energy barrier for intersystem crossing in platinum phthalocyanine

1976 ◽  
Vol 54 (6) ◽  
pp. 633-637 ◽  
Author(s):  
Tzer-Hsiang Huang ◽  
Klaus E. Rieckhoff ◽  
Eva-Maria Voigt
Keyword(s):  
Triplet State ◽  
Ground State ◽  
Energy Barrier ◽  
Singlet State ◽  
Quantum Yields ◽  
Intersystem Crossing ◽  
Singlet Ground State ◽  
Activation Energy Barrier ◽  
Excited Singlet ◽  
Platinum Phthalocyanine

Phosphorescence quantum yields and lifetimes of platinum phthalocyanine in α-chloronaphthalene solution are reported for temperatures from 1.3 K to 300 K. Activation energies of intersystem crossing are deduced and found to be Ea = 17 ± 3 cm−1 for crossing from the first excited singlet state to the lowest lying triplet state and Eap = 8 ± 1 cm−1 for crossing from the lowest lying triplet state to the singlet ground state.

scholarly journals Effective Singlet Oxygen Sensitizers Based on the Phenazine Skeleton as Efficient Light Absorbers in Dye Photoinitiating Systems for Radical Polymerization of Acrylates

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3085
Author(s):  
Ilona Pyszka ◽  
Zdzisław Kucybała ◽  
Beata Jędrzejewska
Keyword(s):  
Quantum Yield ◽  
Visible Light ◽  
Triplet State ◽  
Singlet Oxygen ◽  
Radical Polymerization ◽  
State Formation ◽  
Flash Photolysis ◽  
Comparative Method ◽  
Aromatic Rings ◽  
Light Absorbers

A series of dyes based on the phenazine skeleton were synthesized. They differed in the number of conjugated double bonds, the arrangement of aromatic rings (linear and/or angular system), as well as the number and position of nitrogen atoms in the molecule. These compounds were investigated as potential singlet oxygen sensitizers and visible light absorbers in dye photoinitiating systems for radical polymerization. The quantum yield of the singlet oxygen formation was determined by the comparative method based on the 1H NMR spectra recorded for the tested dyes in the presence of 2,3-diphenyl-p-dioxene before and after irradiation. The quantum yield of the triplet state formation was estimated based on the transient absorption spectra recorded using the nanosecond flash photolysis technique. The effectiveness of the dye photoinitiating system was characterized by the initial rate of trimethylolpropane triacrylate (TMPTA) polymerization. In the investigated photoinitiating systems, the sensitizer was an electron acceptor, whereas the co-initiator was an electron donor. The effectiveness of TMPTA photoinitiated polymerization clearly depended on the arrangement of aromatic rings and the number of nitrogen atoms in the modified phenazine structure as well as the quantum yield of the triplet state formation of the photosensitizer in the visible light region.

Methylthio BODIPY as a standard triplet photosensitizer for singlet oxygen production: a photophysical study

2019 ◽  
Vol 21 (36) ◽  
pp. 20403-20414 ◽  
Author(s):  
Ruth Prieto-Montero ◽  
Rebeca Sola-Llano ◽  
Raul Montero ◽  
Asier Longarte ◽  
Teresa Arbeloa ◽  
...  
Keyword(s):  
Singlet Oxygen ◽  
Singlet State ◽  
Oxygen Production ◽  
Photophysical Study

The detailed triplet and singlet state characterization of 3,5-dimethyl-2,6-diiodo-8-thiomethyl-pyrromethene (MeSBDP), a promising standard sensitizer for singlet oxygen production.

The radiation-induced formation of excited states of aromatic hydrocarbons in benzene and cyclohexane. III. Effect of singlet state quenchers

1972 ◽  
Vol 328 (1575) ◽  
pp. 481-496 ◽  
Keyword(s):  
Triplet State ◽  
Excited States ◽  
State Formation ◽  
Aromatic Hydrocarbons ◽  
Extinction Coefficient ◽  
Singlet State ◽  
Excited Singlet State ◽  
Intersystem Crossing ◽  
Excited Singlet ◽  
Radiation Induced

The contribution to naphthalene and pyrene triplet state formation of intersystem crossing from the excited singlet state has been determined for both cyclohexane and benzene solutions using the singlet state quenchers nitromethane and xenon. In agreement with the conclusions reported in part II, intersystem crossing plays an important role; under certain conditions up to 50 % of the total triplet yield in naphthalene-cyclohexane solutions has this origin. The extinction coefficient for naphthalene triplet absorption in cyclohexane at λ max = 412.5 nm is 20 000 ± 5000 1 mol -1 cm -1 .

scholarly journals Products of Docosahexaenoate Oxidation as Contributors to Photosensitising Properties of Retinal Lipofuscin

2021 ◽  
Vol 22 (7) ◽  
pp. 3525
Author(s):  
Małgorzata B. Różanowska ◽  
Anna Pawlak ◽  
Bartosz Różanowski
Keyword(s):  
Visible Light ◽  
Triplet State ◽  
Singlet Oxygen ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Wavelength Dependence ◽  
Oxidation Products ◽  
Quantum Yields ◽  
Excited Triplet ◽  
Uva Light

Retinal lipofuscin which accumulates with age in the retinal pigment epithelium (RPE) is subjected to daily exposures to high fluxes of visible light and exhibits potent photosensitising properties; however, the molecules responsible for its photoreactivity remain unknown. Here, we demonstrate that autooxidation of docosahexaenoate (DHE) leads to the formation of products absorbing, in addition to UVB and UVA light, also visible light. The products of DHE oxidation exhibit potent photosensitising properties similar to photosensitising properties of lipofuscin, including generation of an excited triplet state with similar characteristics as the lipofuscin triplet state, and photosensitised formation of singlet oxygen and superoxide. The quantum yields of singlet oxygen and superoxide generation by oxidised DHE photoexcited with visible light are 2.4- and 3.6-fold higher, respectively, than for lipofuscin, which is consistent with the fact that lipofuscin contains some chromophores which do contribute to the absorption of light but not so much to its photosensitising properties. Importantly, the wavelength dependence of photooxidation induced by DHE oxidation products normalised to equal numbers of incident photons is also similar to that of lipofuscin—it steeply increases with decreasing wavelength. Altogether, our results demonstrate that products of DHE oxidation include potent photosensitiser(s) which are likely to contribute to lipofuscin photoreactivity.

Synthesis and photodynamic properties of maltohexaose-conjugated porphyrins

2012 ◽  
Vol 16 (11) ◽  
pp. 1177-1185 ◽  
Author(s):  
Yuji Mikata ◽  
Minako Shibata ◽  
Yasuko Baba ◽  
Toyoji Kakuchi ◽  
Misaki Nakai ◽  
...  
Keyword(s):  
Hela Cell ◽  
Visible Light ◽  
Singlet Oxygen ◽  
Cell Line ◽  
Visible Light Irradiation ◽  
Water Soluble ◽  
Hela Cell Line ◽  
Free Base ◽  
Oxygen Production ◽  
Porphyrin Derivatives

A series of porphyrin derivatives with one to four maltohexaose moieties in their meso positions have been synthesized. Zinc or free-base m-THPP (5,10,15,20-tetrakis(m-hydroxyphenyl)-porphyrin) was used as the porphyrin platform. The reaction of m-THPP with 3-iodopropyl nonadecaacetylmaltohexaoside afforded a mixture of all possible combinations of glycoconjugated porphyrins having one to four maltohexaose moieties; monoglycosylated (Ac-1), bisglycosylated (Ac-cis-2 and Ac-trans-2), triglycosylated (Ac-3), and tetraglycosylated (Ac-4) porphyrins were obtained in 11–26% yield. Removal of acetyl groups at maltohexaose moiety afforded highly water-soluble glycoconjugated porphyrins 1–4. Zinc derivatives were synthesized in a similar manner. These maltohexaose-linked porphyrins exhibit remarkable water-solublity (530 mg/mL for 4). The singlet oxygen production ability upon visible light irradiation is not affected by the maltohexaose substitution. Photo- and dark cytotoxicities of the maltohexaose-conjugated porphyrins 1–4 and Zn-1–4 were examined against a HeLa cell line, which showed that the mono-maltohexaosylated derivative (1 and Zn-1) was the most effective photosensitizer for PDT.

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