Neutral and cationic pyrrolidine-fused chlorins and isobacteriochlorins derived from meso-tetrakis(pentafluorophenyl)porphyrin undergo cycloreversion reactions in the gas phase, either when desorbed from a liquid matrix by ion bombardment or when electrosprayed. Cycloreversion occurs through loss of either neutral or charged moieties, with and without hydrogen and methyl radical migration, and both as high- and low-energy collision processes. For the doubly charged isobacteriochlorin, one-electron reduction with methyl loss occurs under ion bombardment and electrospray, through hypervalent pyrrolidinium radical formation.
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http://dx.doi.org/10.1002/rcm.1663 | DOI Listing |
Astrobiology
January 2025
NASA Goddard Space Flight Center, Greenbelt, Maryland, USA.
Meteoritic impacts on planetary surfaces deliver a significant amount of energy that can produce prebiotic organic compounds such as cyanides, which may be a key step to the formation of biomolecules. To study the chemical processes of impact-induced organic synthesis, we simulated the physicochemical processes of hypervelocity impacts (HVI) in experiments with both high-speed C projectiles and laser ablation. In the first approach, a C beam was accelerated to collide with ammonium nitrate (NHNO) to reproduce the shock process and plume generation of meteoritic impacts on nitrogen-rich planetary surfaces.
View Article and Find Full Text PDFCurr Med Chem
January 2025
Brazilian Nuclear Energy Commission, Nuclear Engineering Institute, Laboratory of Novel Radiopharmaceuticals and Nanoradiopharmacy, Rio de Janeiro, 21941906, Brazil.
This study discusses the chemical perspectives of the [18F]F-PSMA probe, a pivotal tool in prostate cancer imaging. [18F]Fluorine, a positron emitter with a half-life of 109.8 minutes, is produced in a cyclotron by bombarding [18O]-enriched targets with protons.
View Article and Find Full Text PDFNat Geosci
December 2024
Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, Paris, France.
Saturn's rings have been estimated to be as young as about 100 to 400 million years old according to the hypothesis that non-icy micrometeoroid bombardment acts to darken the rings over time and the Cassini observation indicated that the ring particles appear to be relatively clean. These young age estimates assume that the rings formed out of pure water ice particles with a high accretion efficiency of impacting non-icy micrometeoroid material ( ≳ 10%). Here we show, using numerical simulations of hypervelocity micrometeoroid impacts on a ring particle, that non-icy material may not be as readily accreted as previously thought.
View Article and Find Full Text PDFHere we report a simple self-masking technique for fabricating bioinspired broadband antireflection coatings on both single-crystalline and multicrystalline silicon wafers with the assistance of a polyimide tape. Subwavelength-structured moth-eye nanopillars, which exhibit superior antireflection performance over a broad range of visible and near-IR wavelengths, can be patterned uniformly on the wafer surface by applying a chlorine-based reactive ion etching (RIE) process. The resulting random nanopillars show improved antireflection properties compared with ordered nanopillars templated by colloidal lithography under the same RIE conditions.
View Article and Find Full Text PDFNanomaterials (Basel)
December 2024
Guangdong Provincial Key Laboratory of Electronic Functional Materials and Devices, Huizhou University, Huizhou 516007, China.
W-doped ZnO (WZO) films were deposited on glass substrates by using RF magnetron sputtering at different substrate bias voltages, and the relationships between microstructure and optical and electrical properties were investigated. The results revealed that the deposition rate of WZO films first decreased from 8.8 to 7.
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