Isomer shifts have been determined in ^{111-129}Cd by high-resolution laser spectroscopy at CERN-ISOLDE. The corresponding mean square charge-radii changes, from the 1/2^{+} and the 3/2^{+} ground states to the 11/2^{-} isomers, have been found to follow a distinct parabolic dependence as a function of the atomic mass number. Since the isomers have been previously associated with simplicity due to the linear mass dependence of their quadrupole moments, the regularity of the isomer shifts suggests a higher order of symmetry affecting the ground states in addition. A comprehensive description assuming nuclear deformation is found to accurately reproduce the radii differences in conjunction with the known quadrupole moments. This intuitive interpretation is supported by covariant density functional theory.
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http://dx.doi.org/10.1103/PhysRevLett.116.032501 | DOI Listing |
Sci Total Environ
January 2025
US Department of Agriculture, Agriculture Research Service, Hydrology and Remote Sensing Laboratory, Beltsville, MD, United States of America.
Metolachlor is the most heavily used member of acetanilide herbicides, which are noted for forming highly soluble metabolites in root zone soils soon after field application. The two primary metabolites of metolachlor, metolachlor ethane sulfonic acid (MESA) and metolachlor oxanilic acid (MOXA), retain the same chiral chemistry as their source and are important tracers of nitrate loading from agricultural cropland. New analytical methods for separating the isomers of MESA and MOXA, enable studies assessing changes in the abundance of atropisomer pairs of the carbon chiral enantiomers in environmental samples.
View Article and Find Full Text PDFOrg Biomol Chem
January 2025
Laboratory of Advanced Computation and Theory for Materials and Chemistry, Department of Chemistry, National Institute of Technology Warangal (NITW), Warangal, Telangana-506004, India.
The optical control of physiological processes with high precision using photoswitches is an emerging strategy for non-invasive diagnosis and therapies, providing innovative solutions to complex biomedical challenges. Light-responsive cyclic conjugated-dienes (cCDs) have long been recognized for their 4π-photocyclization; however, photoswitching behaviour in medium-sized cCDs has recently been reported, representing a pioneering discovery in the field. Reinforced by previous experimental evidence corroborating the Woodward-Hoffmann rules, this report provides insight into the origin of the exotic dual photoexcitation mechanism devised to achieve thermo-reversible photoswitching in large cCDs with cyclodeca-1,3-diene as a prototype.
View Article and Find Full Text PDFChem Commun (Camb)
January 2025
Department of Chemistry, Quantum Chemistry, TU Darmstadt, Peter-Grünberg-Str. 4, 64287 Darmstadt, Germany.
The two key parameters extracted from Mössbauer spectroscopy, isomer shift and quadrupole splitting, have well-known temperature dependencies. While the behavior of the values following a temperature change has long been known, its microscopic origins are less clear. For quantum chemical calculations - formally representing the situation at 0 K - significant discrepancies with the experiment can arise, especially at elevated temperatures.
View Article and Find Full Text PDFMolecules
January 2025
Institute of Organic Synthesis and Coal Chemistry of the Republic of Kazakhstan, 1 Alikhanov St., Karaganda 100008, Kazakhstan.
The synthetic availability and wide range of biological activity of hydrazides and hydrazones make them attractive subjects for investigation. In this study, we focused on synthesis of 2-methyl-5-nitro-6-phenylnicotinohydrazide-based hydrazones derived from the corresponding substituted aldehydes. The structure of the obtained compounds was studied using NMR spectroscopy and DFT calculations.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Tsinghua University, Chemistry, HeTian Building Dept. of Chemistry, Tsinghua University, Beijing, P. R. China, 100084, Beijing, CHINA.
Expanded heterohelicene composing of alternating linearly and angularly fused multi-resonance (MR) skeleton has garnered wide interest for their promising narrowband emission. Herein, a pair of sym- and asym-expanded heterohelicene isomers are firstly developed by merging boron/oxygen (B/O)-embedded MR triangulene and indolo[3,2,1-jk]carbazole units via one-shot synthesis. Owing to the fully resonating extended helical skeleton, the target heterohelicenes exhibit significantly narrowed spectra bandwidth while emission red-shifting, thus affording deep-blue narrowband emission with peak at around 460 nm, full-width-at-half-maximum (FWHM) of merely 18 nm and near-unity photoluminescence quantum yields.
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