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Binding the Power of Cycloaddition and Cross-Coupling in a Single Mechanism: An Unexpected Bending Journey to Radical Chemistry of Butadiynyl with Conjugated Dienes.
J Phys Chem Lett
January 2025
Department of Chemistry, University of Hawai'i at Ma̅noa, Honolulu, Hawaii 96822, United States.
What if an experiment could combine the power of cycloaddition and cross-coupling with the formation of an aromatic molecule in a single collision? Crossed molecular beam experiments augmented with electronic structure and statistical calculations provided compelling evidence on a novel radical route involving 1,3-butadiynyl (HCCCC; X∑) radicals synthesizing (substituted) arylacetylenes in the gas phase upon reactions with 1,3-butadiene (CHCHCHCH; XA) and 2-methyl-1,3-butadiene (isoprene; CHC(CH)CHCH; XA'). This elegant mechanism merges two previously disconnected concepts of cross-coupling and cycloaddition-aromatization in a single collision event via the formation of two new C(sp)-C(sp) bonds and bending the 180° moiety of the linear 1,3-butadiynyl radical out of the ordinary by 60° to 120°. In addition to its importance to fundamental organic chemistry, this unconventional mechanism links two previously separated routes of gas-phase molecular mass growth processes of polyacetylenes and polycyclic aromatic hydrocarbons (PAHs), respectively, in low-temperature environments such as in cold molecular clouds like the Taurus Molecular Cloud (TMC-1) and in hydrocarbon-rich atmospheres of planets and their moons such as Titan, which revises the established understanding of low-temperature molecular mass growth processes in the Universe.
View Article and Find Full Text PDFSecond law of thermodynamics: Spontaneous cold-to-hot heat transfer in a nonchaotic medium.
Phys Rev E
November 2024
Program of Materials Science and Engineering, University of California, San Diego, La Jolla, California 92093, USA.
It has long been known that, fundamentally different from a large body of rarefied gas, when a Knudsen gas is immersed in a thermal bath, it may never reach thermal equilibrium. The root cause is nonchaoticity: as the particle-particle collisions are sparse, the particle trajectories tend to be independent of each other. Usually, this counterintuitive phenomenon is studied through kinetic theory and is not considered a thermodynamic problem.
View Article and Find Full Text PDFSensitive Low-Recoil VUV 1 + 1' REMPI Detection of ND.
J Phys Chem A
December 2024
Radboud University Nijmegen, Institute for Molecules and Materials, Heijendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
In molecular beam scattering experiments, an important technique for measuring product energy and angular distributions is velocity map imaging following photoionization of one or more scattered species. For studies with cold molecular beams, the ultimate resolution of such a study is often limited by the product detection process. When state-selective ionization detection is used, excess energy from the ionization step can transfer to kinetic energy in the target molecular ion-electron pair, resulting in measurable cation recoil.
View Article and Find Full Text PDFWarm Temperature is Associated With Reduced Body Mass and Diversification Rates While Increasing Extinction Risks in Cold-Adapted Seabirds.
Glob Chang Biol
December 2024
Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
Anthropogenic rapid warming has caused decreases in richness and body mass of birds following the metabolic theory of ecology; yet, the pervasiveness of these shifts remains controversial among different taxa. Here, by combining phylogenetic methods and fossil data, we synthesized spatial patterns of richness and body mass for 328 seabird species belonging to two groups: Procellariimorphae (PM) and non-Procellariimorphae (NPM). We found that the relationship between body mass and richness, as well as diversification rate, exhibits distinct patterns in these two groups.
View Article and Find Full Text PDFDrivers' reactions to real-world forward collision warnings at both macroscopic and microscopic longitudinal levels: A functional approach.
Accid Anal Prev
February 2025
Department of Civil and Urban Engineering, C2SMARTER Center, New York University, 6 MetroTech Center, Brooklyn, NY 11201, USA.
Understanding drivers' reactions to in-vehicle forward collision warnings (FCWs) is vital for advancing FCW design and improving road safety. However, past studies often used aggregated safety measures to analyze the drivers' reactions to FCWs, thereby at the microscopic level, limiting our ability to understand drivers' reactions to FCWs at particular timestamps immediately after FCWs are issued. Additionally, there has been a notable absence of studies at the macroscopic perspective focusing on analyzing how drivers' reactions to FCWs evolve over an extended period of time.
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