Understanding of the nature and extent of chemical bonding in uranyl coordination complexes is crucial for the design of new ligands for nuclear waste separation, uranium extraction from seawater, and other applications. We report here the synthesis, infrared spectroscopic characterization, and quantum chemical studies of a molecular uranyl-di-15-crown-5 complex. The structure and bonding of this unique complex featuring a distinctive 6-fold coplanar coordination staggered sandwich structure and an unusual non-perpendicular orientation of the uranyl moiety are evaluated using density functional theory and chemical bonding analyses. The results provide fundamental understanding of the coordination interaction of uranyl with oxygen-donor ligands.
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http://dx.doi.org/10.1039/c6cc07205d | DOI Listing |
Acta Crystallogr B Struct Sci Cryst Eng Mater
February 2025
CSIRO Division of Mineral Products, Port Melbourne, Victoria, Australia.
The crystallographic phase change from tetragonal litharge (α-PbO; P4/nmm) to orthorhombic massicot (β-PbO; Pbcm) has been studied by full-matrix Rietveld analysis of high-temperature neutron powder diffraction data collected in equal steps from ambient temperature up to 925 K and back down to 350 K. The phase transformation takes place between 850 and 925 K, with the coexisting phases having equal abundance by weight at 885 K. The product massicot remains metastable on cooling to near ambient temperature.
View Article and Find Full Text PDFAoB Plants
January 2025
Department of Biodiversity and Biostatistics, Institute of Biosciences of Botucatu, São Paulo State University (UNESP), Professor Antônio Celso Wagner Zagnin street, 250, District of Rubião Júnior, 18618-970, Botucatu City, São Paulo State, Brazil.
The anatomical and cytological characteristics of the mucilage-secretory system have been widely studied in Malvaceae. However, conflicting information regarding the morphological nature of secretory structures exists, and some remain poorly understood. In this sense, some secretory structures in Malvaceae are not characterized as typical isolated idioblasts, canals, or cavities.
View Article and Find Full Text PDFJ Opt Soc Am A Opt Image Sci Vis
August 2024
A criterion for the characterization of the retardance effects produced by depolarizing and nondepolarizing linear media on interacting light is established based on Mueller matrices algebra. A consistent general description of retardance properties is performed by means of a serial decomposition of the Mueller matrix into three components, namely an element that encompasses the enpolarizing and depolarizing properties sandwiched by two elliptical retarders containing complete and decoupled information on retardance. The inherent ambiguity derived from the coincident formal structure of rotation matrices and circular retarders is removed though the introduction of the entrance and exit intrinsic reference frames, leading to the concepts of the intrinsic entrance and exit linear retarders, which are defined from the Mueller matrix itself and that are independent of the laboratory reference frames used to represent the incident and emerging polarized light beams, respectively.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Institute of Chemistry Chinese Academy of Sciences, CAS Key Laboratory of Molecular Recognition and Function, CHINA.
A pair of axially chiral thermally activated delayed fluorescent (TADF) enantiomers, R-TCBN-ImEtPF6 and S-TCBN-ImEtPF6, with intrinsic ionic characteristics were efficiently synthesized by introducing imidazolium hexafluorophosphate to chiral TADF unit. The TADF imidazolium salts exhibited a high photoluminescence quantum yield (PLQY) of up to 92%, a small singlet-triplet energy gap (∆EST) of 0.04 eV, as well as reversible redox properties.
View Article and Find Full Text PDFChemistry
January 2025
University of Sussex, Department of Chemistry, School of Life Sciences, BN1 9QJ, Brighton, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND.
The synthesis, structures and magnetic properties of an η5-silole complex and an η5-stannole complex of erbium are reported. The sandwich complex anions [(η5-CpSi)Er(η8-COT)]- and [(η5-CpSn)Er(η8-COT)]-, where CpSi is [SiC4-2,5-(SiMe3)2-3,4-Ph2]2- (1Si), CpSn is [SnC4-2,5-(SiMe3)2-3,4-Me2]2- (1Sn) and COT = cyclo-octatetraenyl, were obtained as their [K(2.2.
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