Long-range proton-fluorine coupling constants ( J ) are helpful for the structure elucidation of fluorinated molecules. However, their magnitude and sign can change with the relative position of coupled nuclei and the presence of substituents. Here, trans-4-tert-butyl-2-fluorocyclohexanone was used as a model compound for the study of the transmission of J . In this compound, the J was measured to be +5.1 Hz, which is five times larger than the remaining J in the same molecule ( J = +1.0 Hz and J = +1.0 Hz). Through a combination of experimental data, natural bond orbital (NBO) and natural J-coupling (NJC) analyses, we observed that stereoelectronic interactions involving the π system of the carbonyl group are involved in the transmission pathway for the J . Interactions containing the π system as an electron acceptor (e.g., σ → π and σ → π ) increase the value of the J , while the interaction of the π system as an electron donor (e.g., π → σ ) decreases it. Additionally, the carbonyl group was shown not to be part of the transmission pathway of the diequatorial J coupling in cis-4-tert-butyl-2-fluorocyclohexanone, revealing that there is a crucial symmetry requirement that must be fulfilled for the π system to influence the value of the J in these systems.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1002/mrc.5248 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Efficient synthesis of fluorinated triphenylenes with enhanced arene-perfluoroarene interactions in columnar mesophases.
Beilstein J Org Chem
December 2024
Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), CNRS-Université de Strasbourg (UMR 7504), F-67034 Strasbourg, France.
The high potential of non-covalent arene-fluoroarene intermolecular interactions in the design of liquid crystals lies in their ability to strongly promote self-assembly, improve the order and stability of the supramolecular mesophases, and enable tuneability of the optical and electronic properties, which can potentially be exploited for advanced applications in display technologies, photonic devices, sensors, and organic electronics. We recently successfully reported the straightforward synthesis of several mesogens containing four lateral aliphatic chains and derived from the classical triphenylene core self-assembling in columnar mesophases based on this paradigm. These mesogenic compounds were simply obtained in good yields by the nucleophilic substitution (SFAr) of various types of commercially available fluoroarenes with the electrophilic organolithium derivatives 2,2'-dilithio-4,4',5,5'-tetraalkoxy-1,1'-biphenyl (2Li- ).
View Article and Find Full Text PDFExpression of hyperconjugative stereoelectronic interactions in borazines.
Chem Commun (Camb)
January 2025
Institute of Organic Chemistry, Faculty of Chemistry, University of Vienna, Währinger Strasse 38, 1090, Vienna, Austria.
This paper discusses hyperconjugative stereoelectronic effects in borazines. A series of alkyl-substituted borazines were synthesized and analysed by NMR spectroscopy and X-ray diffraction. Supported by NBO analyses, the significant decreases in coupling constant for the CH groups adjacent to the boron atoms are consistent with the presence of and interactions.
View Article and Find Full Text PDFEnhanced Proton-Coupled Electron-Transfer Reactivity by a Mononuclear Nickel(II) Hydroxide Radical Complex.
Inorg Chem
December 2024
Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States.
The synthesis, characterization, and reactivity of a NiOH core bearing a tridentate redox-active ligand capable of reaching three molecular oxidation states is presented in this paper. The reduced complex [LNiOH] was characterized by single-crystal X-ray diffraction analysis, depicting a square-planar NiOH core stabilized by intramolecular H-bonding interactions. Cyclic voltammetry measurements indicated that [LNiOH] can be reversibly oxidized to [LNiOH] and [LNiOH] at very negative reduction potentials (-1.
View Article and Find Full Text PDFSubstituted thiourea incorporated rhodamine-based chemosensors for selective detection of aluminium ions.
Spectrochim Acta A Mol Biomol Spectrosc
March 2025
CSIR-Institute of Minerals and Materials Technology, Materials Chemistry Department, CSIR-IMMT, P.O.: R. R. L., Bhubaneswar 751013, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India. Electronic address:
Various metal ions' contemporary utility, biological essence and environmental impact have stimulated their selective and sensitive detection, particularly when present in traces. In this context, methodological explorations relying on structural and functional modulations of prime components and interactive parameters have been pivotal in developing chemosensors for selective detection of such metal ionic inputs. In this investigation, three thiourea-incorporated rhodamine B derivatives varying in their substituent modified covalent architectures were synthesized, and their photophysical signalling responses were monitored in the presence of different metal ions.
View Article and Find Full Text PDFLigand Effects on the Emission Characteristics of Molecular Eu(II) Luminescence Thermometers.
J Am Chem Soc
December 2024
Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.
Discrete molecular organometallic europium(II) complexes are promising functional materials due to their ability to behave as highly sensitive band-shift luminescence thermometers. Furthering our understanding of the design principles salient to the emission behavior of such systems is important for developing them in this emerging application. To this end, a series of pseudo--symmetric organometallic europium(II) complexes bearing systematically varying ligand sets were synthesized and characterized to probe the influence of subtle structural modification on their optical properties.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!