ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1978.tb06942.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

Abstract—A new spectroscopic method has been developed in our laboratory for perturbation of singlet‐triplet transitions in organic molecules by O2. A dilute solution (10‐2‐10‐4M) of the molecule to be studied in various solvents is pressurized in a bomb with O2at 100 atm (10MPa) for 3–10h. The pressure is released, the solution pipetted into a sample tube, sealed, and frozen to a rigid glass state at 77 K. Then the luminescence spectra and excitation spectra of the sample are scanned.For benzene‐O2we have evidence for a weak complex with a mild perturbation and a strong complex, with various new combination states. For the strong complex, the T1→ S emission and excitation spectrum is observed, and also the T2← S excitation spectrum. The T1→ S emission for the benzene‐O2complex is seen as a highly resolved emission at 77 K in the glass solvent, but also at 298 K as a poorly resolved emission (induced triplet–triplet fluorescence in the complex). Variousupconversion simultaneous transitionsanddownconversion simultaneous transitionsare observed, e.g. (3Blu+1Σ+g), (3Blu+1Δg)upconversions, and the (3Blu+1Σ+g), (3Blu+1Δg)downconversions; thus, in the latter, the third π, π* triplet is revealed for the first time. A novel structure for the benzene–O2strong complex is proposed as ananf jamelmodel.Forpyridine–O2andperdeuteropyridine–O2we observe the T1→ S emission for the first time; it is π,

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1978.tb06943.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1978.tb06944.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

Abstract—Several hemeprotein‐catalyzed reactions generate products of the type expected from the cleavage of a high energy intermediate. For some systems, the formation, in high yield, of a carbonyl compound in its excited triplet state has been firmly established on the basis of (i) equivalence of the chemiluminescence and phosphorescence spectra of the expected products; (ii) energy transfer to sensitizers containing heavy atoms and (iii) occurrence of photoproducts. The excited species appears to be generated within the enzyme and shielded from quenching by oxygen. It may be quenched, however, via long‐range triplet‐singlet energy transfer.This work strongly supports our hypothesis that excited electronic states are also formed in biological systems which are not necessarily bioluminescent. One of the functions which peroxidases may thus fulfill might be the utilization of the potential of photochemistry in the absence o

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1978.tb06945.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1978.tb06946.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

Abstract—The possibility of1O2(1Δg) participation in the oxidation of polyphenols and quinones has been investigated in two systems: (1) the system involving autooxidation leading to oxidative polymerization and destruction, and (2) the modified Trautz‐Schorigin reaction, i.e. oxidation of polyphenols and HCHO with H2O2in concentrated alkaline solutions. The red band with maximum at 635 nm observed in chemiluminescence of pyrocatechol, adrenaline, pyrogallol, gallic acid, adrenochrome andp‐benzoquinone corresponds to the transition 2O2(1Δg) → 2O2(3Σ‐g). Emission bands in the range 475–540 nm arise from the superposition of the 2O2(1Δg) → 2O2(3Σ‐g) transition and radiative deactivation of excited oxidation products. In system (2) chemiluminescence has a broad band from 580 nm beyond 800 nm and much higher intensity than in system (1). Formaldehyde was found to enhance light emission in system (1) by a factor of about 30. The influence of solvents, including D2O in which1O2has varying lifetimes, on kinetics of chemiluminescence as well as quenching effect of β‐carotene, hydroquinone, cysteine, bilirubin and biliverdin strongly support the involvement of1O2in the chemilumin

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1978.tb06947.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

Abstract—Photooxidation of synthetic melanins and natural soil humic acids in a model system: polymer + OH‐+ O2+ solvent, initiated by irradiation with wavelengths longer than 300 nm, is accompanied by chemiluminescence with the maximum absolute intensity 104− 5 × 105photons s‐1. Prolonged photoirradiation results in the decrease of both dark and photoinduced EPR signals and decrease of absorption in the spectral range 240–600 nm, indicating destruction of the aromatic core of polymers. Rate of photooxidation and chemiluminescence intensity increases in D2O, in comparison with H2O, by a factor of about 3. Inhibitors of free radicals and O21Δg‐quenchers diminish chemiluminescence by 20–97%. Chemiluminescence spectra measured with cut‐off filters and a calibrated photo‐multiplier operating in the single photon counting mode have emission bands at 480–500, 570 and 615–650 nm. The red band has been assigned to the emission from 2 O2(1Δg1Δg) dimols, and the blue‐green band to the sensitized chemiluminescence of fluoresc

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1978.tb06948.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

Abstract—Exploratory experiments using simulated conditions indicate that the terpene, (+)‐limonene can serve to detect O2(1Δg) in polluted atmospheres.1O2attack on limonene results in the formation of specific oxidation products in a specific distribution; quantitative identification of these products is a highly specific test fo

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1978.tb06949.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1978.tb06950.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

Abstract—The photosensitized oxygenation of cholesterol in liposomal membranes results in the formation of the characteristic singlet oxygen product, 3β‐hydroxy‐5α‐cholest‐6‐ene‐5‐hydroperoxide. The yield of this product was found to be strongly temperature dependent with 6‐ to 7‐fold increase above the transition temperature of the membrane using 1,2‐dipalmitoyl‐sn‐glycero‐3‐phosphorylcholine or 1.2‐dimyristoyl‐sn‐glycero‐3‐phosphorylcholine. In contrast, the formation of the radical autoxidation products of cholesterol was not significantly enhanced in these systems by higher temperatures. We conclude from the results that the oxidation of cholesterol by singlet oxygen in the artificial membranes is affected by both membrane fluidity and amount of hematoporphyrin incorporated into the membrane. The ratio of cholesterol to phospholipid which affects the morphology of membranes is a crucial factor in determinin

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1978.tb06951.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY