It has been shown that the quantum yield of the photochemical conversion of adenine and the corresponding nucleosides and nucleoside 5'-phosphates in liquid (pH 5.6 and 2.0) and frozen aqueous solutions do not exceed 10(-4). The quantum yield of the photoconversion of guanine-containing nucleosides and nucleoside 5'-phosphates in liquid aqueous solution (pH 5.6) after removal of oxygen by passing through nitrogen and in the frozen state do not exceed 0.3 x 10(-4). The quantum yield in oxygen-containing liquid aqueous solutions increase to 0.3 x 10(-3), i.e. to values commensurate with the quantum yield of pyrimidine photolysis.
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http://dx.doi.org/10.1093/nar/2.8.1365 | DOI Listing |
ACS Cent Sci
January 2025
College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China.
Multicomponent reactions (MCRs), highly sought-after methods to produce atom-, step-, and energy-economic organic syntheses, have been developed extensively. However, catalytic asymmetric MCRs, especially those involving radical species, remain largely unexplored owing to the difficulty in stereoselectively regulating the extraordinarily high reactivity of open-shell radical species. Herein, we report a conceptually novel catalytic asymmetric three-component radical cascade reaction of readily accessible glycine esters, α-bromo carbonyl compounds and 2-vinylcyclopropyl ketones via synergistic photoredox/Brønsted acid catalysis, in which three sequential C-C (σ/π/σ) bond-forming events occurred through a radical addition/ring-opening/radical-radical coupling protocol, affording an array of valuable enantioenriched unnatural α-amino acid derivatives bearing two contiguous stereogenic centers and an alkene moiety in moderate to good yield with high diastereoselectivity, excellent enantioselectivity and good -dominated geometry under mild reaction conditions.
View Article and Find Full Text PDFSmall
January 2025
Guangxi Key Laboratory of Optical and Electronic Materials and Devices, Guangxi Colleges and Universities Key Laboratory of Natural and Biomedical Polymer Materials, College of Materials Science and Engineering, Guilin University of Technology, No.12 Jian'gan Rd., Qixing District, Guilin, 541004, China.
Nonconventional Luminescent Materials (NLMs) with distinctive optical properties are garnering significant attention. A key challenge in their practical application lies in precisely controlling their emission behavior, particularly achieving excitation wavelength-independent emission, which is paramount for accurate chemical sensing. In this study, NLMs (Y1, Y2, Y3, and Y4) are synthesized via a click reaction, and it is found that excitation wavelength-dependent emission correlates with molecular cluster formation.
View Article and Find Full Text PDFSmall
January 2025
Department of Chemistry, National Taiwan University, Taipei, 10617, Taiwan.
Addressing the challenges of the efficiency and stability of red perovskite nanocrystals is imperative for the successful deployment of these materials in displays and lighting applications. the structural dynamic changes of red perovskite quantum dots (PQDs) are explored using a flow chemistry system to solve the above hurdles. First, the ultrabright red-emitting PQDs of CsPb(Br,I) are achieved by adjusting ligand distribution (oleic acid and oleyamine) in combination with different flow rates and equivalence ratios.
View Article and Find Full Text PDFAdv Mater
January 2025
Department of Physics, SUNY University at Buffalo, Buffalo, NY, 14220, USA.
Quasi-2D perovskite made with organic spacers co-crystallized with inorganic cesium lead bromide inorganics is demonstrated for near unity photoluminescence quantum yield at room temperature. However, light emitting diodes made with quasi-2D perovskites rapidly degrade which remains a major bottleneck in this field. In this work, It is shown that the bright emission originates from finely tuned multi-component 2D nano-crystalline phases that are thermodynamically unstable.
View Article and Find Full Text PDFJ Phys Chem B
January 2025
Institute of Physics, Lodz University of Technology, ul. Wólczańska 217/221, 93-590 Łódź, Poland.
Photocycloreversion reactions of three diarylethene derivatives whose structures differ only in the placement of two sulfur atoms in the cyclopentene rings are investigated. Despite the minuscule differences between the molecules, both the yields and times of the photoreactions vary considerably. Using UV-vis and infrared femtosecond spectroscopy and quantum chemical dynamics simulations, we elucidate the relationships among the quantum yield, electronic and vibrational relaxation time, and structural properties of the dithienylethene photoswitches.
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