The dipole-bound anions of pyridine, pyridazine, and pyrimidine are characterized using equation of motion coupled cluster singles and doubles calculations. These calculations predict that the anions of pyridine, pyrimidine and pyridazine are bound in the Born-Oppenheimer approximation by 0.05, 0.8, and 19.0 meV, respectively. The binding energies of pyrimidine and pyridazine are large enough that the anions will remain bound even when allowing for corrections to the Born-Oppenheimer approximation, while that of pyridine is a borderline case. We were unable to find a stable non-valence correlation-bound anion for pyrazine, which has a zero dipole moment.
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http://dx.doi.org/10.1021/acs.jpca.2c04040 | DOI Listing |
Angew Chem Int Ed Engl
January 2025
Texas A&M University, Chemistry, UNITED STATES OF AMERICA.
The functionalization of pyridines at positions remote to the N-atom remains an outstanding problem in organic synthesis. The inherent challenges associated with overriding the influence of the embedded N-atom within pyridines was overcome using n-butylsodium, which provided an avenue to deprotonate and functionalize the C4-position over traditionally observed addition products that are formed with organolithium bases. In this work, we show that freshly generated 4-sodiopyrdines could undergo transition metal free alkylation reactions directly with a variety of primary alkyl halides bearing diverse functional groups.
View Article and Find Full Text PDFPol J Vet Sci
September 2024
Department of Pharmacology and Toxicology, Faculty of Veterinary Medicine, University of Warmia and Mazury in Olsztyn, Oczapowskiego 13, 10-718 Olsztyn, Poland.
This study analysed the influence of montelukast (MON), a cysteinyl leukotriene receptor antagonist, and nifedipine, an L-type voltage-gated Ca2+ channel blocker, on the contractility of the porcine uterine smooth muscle. Myometrial strips were collected from the sexually immature (n=8), cyclic (12-14 days of the oestrous cycle; n=8) and pregnant (27-28 days of pregnancy; n=8) gilts and stimulated with a) MON or nifedipine at concentrations of 10-8-10-4 M and b) increasing concentrations of nifedipine after previous administration of MON at a concentration of 10-4 M. The changes in the tension, amplitude and frequency of contractions were determined with the Hugo Sachs Elektronik equipment for measuring isometric contractions.
View Article and Find Full Text PDFBiogerontology
December 2024
Postgraduate Program in Pharmacology, Health Sciences Center, Federal University of Santa Maria, Santa Maria, Brazil.
In cells, the term "cellular aging" represents a collection of biological changes that can precede the proliferative senescence states. Cells more resistant to proliferative senescence, such as the ones found in the basal layer of the epidermis, may also exhibit these aging patterns. Therefore, cellular aging events could be induced by endogenous signals named here as cellular aging triggers (CATs) components.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2024
Chinese Academy of Sciences, Institute of Chemistry, 2 Bei Yi Jie, Zhong Guan Cun, 100190, Beijing, CHINA.
Molecular frameworks have recently shown a great potential in atmospheric water harvesting, in which the water release at low temperatures is challenging. Anion-organic frameworks based on anion-coordination chemistry are presented herein to meet this challenge. These frameworks are prepared as tubular single crystals in pure water from the in-situ protonation and crystallization of pyridine-terminated triphenylamine derivatives with hydrochloric or hydrobromic acid.
View Article and Find Full Text PDFChem Asian J
December 2024
IIT Bhilai: Indian Institute of Technology Bhilai, Chemistry, INDIA.
Investigating solid-state photoreactivity, driven by crystal packing, has been a major enduring research theme in Crystal Engineering. Trans-3-styryl pyridine (3-StPy), an unsymmetric olefin, is photo-stable. However, when converted to a series of salts, they exhibited solid-state photoreactivity under UV irradiation.
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