The unique light-driven enzyme protochlorophyllide oxidoreductase (POR) is an important model system for understanding how light energy can be harnessed to power enzyme reactions. The ultrafast photochemical processes, essential for capturing the excitation energy to drive the subsequent hydride- and proton-transfer chemistry, have so far proven difficult to detect. We have used a combination o...

We present a femtosecond pump-probe study of the primary events of nitrosyl chloride (ClNO) photochemistry in solution. Following 266 nm photolysis, the resulting evolution in optical density is measured for ClNO dissolved in acetonitrile, chloroform, and dichloromethane. The results demonstrate that photolysis results in the production of a photoproduct that has an absorption band maximum at 2...

A quantum yield of •i•e = 2.3 x 10 '4 (+_ 4 X 10 -•) was determined for the photochemical degradation of 4nitrophenol over the wavelength range of 300 to 370 nm in ice pellets (pH 5.6). Five reaction products were identified: hydroquinone, benzoquinone, 4-nitrosophenol, nitrate, nitrite, and the likely formation of organic polymers. The similarities of these results to the observations from 4-n...

Azetidinyl substituents have been recently used to improve the fluorescence quantum yield of several classes of fluorophores. Herein, we demonstrate that other useful photochemical processes can be modulated using this strategy. In particular, we prepared and measured the quantum yield of photorelease of a series of 7-azetidinyl-4-methyl coumarin esters and compared it to their 7diethylamino an...

Photosynthetic characteristics along with phototolerance and photoinhibition of photosystem II (PS II) were monitored in Synechocystis sp. PCC 6803 wild type (KC) and its psbAII mutants viz., I6 (N322I, I326F, and F328S), G6 (N267Y), and H7 (Y254C and I314V) that have up to three point mutations, localized in the D-E loop of the D1 polypeptide of PSII reaction centre. These strains exhibited en...

This work identifies LOW QUANTUM YIELD OF PHOTOSYSTEM II1 (LQY1), a Zn finger protein that shows disulfide isomerase activity, interacts with the photosystem II (PSII) core complex, and may act in repair of photodamaged PSII complexes. Two mutants of an unannotated small Zn finger containing a thylakoid membrane protein of Arabidopsis thaliana (At1g75690; LQY1) were found to have a lower quantu...

The synthesis of the meso-tetra(pyren-1-yl)porphyrin (1) was successfully accomplished by means of the pyrrole condensation with pyrene-1-carb-aldehyde in acidic media. Its metallization was carried out in an almost quantitative yield to obtain the corresponding complexes of Ni(II) (2), Cu(II) (3) and Zn (4). Their photophysical properties such as fluorescence quantum yield and energy transfer ...

Ruthenium(II) polypyridine complexes are among the most popular sensitizers in photocatalysis, but they face some severe limitations concerning accessible excited-state energies and photostability that could hamper future applications. In this study, borylation of heteroleptic ruthenium(II) cyanide with ?-diimine ancillary ligands is identified as a useful concept to elevate photoactive metal-t...

This review article is the second of the comprehensive series on survey of the microwave photochemical and photocatalytic processes, and is focused specially on the microwave-assisted photochemical applications of the electrodeless discharge lamps (EDLs) in organic synthesis. The concept of microwave organic photochemistry is an important issue in synthetic chemistry and material science, and i...