A C2-Symmetric Biphenyl-Bridged Bis-Aurone: Synthesis, Z/E Photoisomerization, and Conformational Insights from NMR Spectroscopy and DFT Analysis
- 1Istituto di Chimica Biomolecolare, Consiglio Nazionale delle Ricerche, Traversa La Crucca 3, I–07100 Sassari, Italy
Abstract
Aurones are naturally occurring flavonoids characterized by a benzofuran-3(2H)-one scaffold bearing an exocyclic benzylidene double bond. Herein, we report the synthesis and NMR-based structural characterization of a highly oxygenated biphenyl-bridged bis-aurone and its mono-condensation derivative. UV irradiation at 254 nm in deuterated acetone generated the corresponding E-containing photoisomers, whose formation was monitored by 1H NMR spectroscopy. For the bis-aurone, weak additional resonances indicated a minor species possibly corresponding to the doubly isomerized (E,E′) form. NOESY correlations provide constraints on the spatial arrangement of the bis-aurone in solution. Both isolated E-containing derivatives exhibit a pronounced downfield shift of one biphenyl aromatic proton. Conformational analysis is used to examine possible geometrical and magnetic-anisotropy contributions to this observation. The study focuses on synthesis, NMR observations of Z/E photoisomerization, and conformational interpretation; intrinsic photochemical efficiencies were not determined.
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BibTeX
@article{dettori2026c2symmetric,
title = {{A C2-Symmetric Biphenyl-Bridged Bis-Aurone: Synthesis, Z/E Photoisomerization, and Conformational Insights from NMR Spectroscopy and DFT Analysis}},
author = {Maria Antonietta Dettori and Davide Fabbri and Roberto Dallocchio and Nicola Culeddu and Emanuela Azara and Paola Carta},
journal = {Molecules},
year = {2026},
month = nov,
doi = {10.3390/molecules31213963},
url = {https://www.mdpi.com/1420-3049/31/21/3963},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - A C2-Symmetric Biphenyl-Bridged Bis-Aurone: Synthesis, Z/E Photoisomerization, and Conformational Insights from NMR Spectroscopy and DFT Analysis
AU - Maria Antonietta Dettori
AU - Davide Fabbri
AU - Roberto Dallocchio
AU - Nicola Culeddu
AU - Emanuela Azara
AU - Paola Carta
PY - 2026
DA - 2026/11/03
JO - Molecules
DO - 10.3390/molecules31213963
UR - https://www.mdpi.com/1420-3049/31/21/3963
AB - Aurones are naturally occurring flavonoids characterized by a benzofuran-3(2H)-one scaffold bearing an exocyclic benzylidene double bond. Herein, we report the synthesis and NMR-based structural characterization of a highly oxygenated biphenyl-bridged bis-aurone and its mono-condensation derivative. UV irradiation at 254 nm in deuterated acetone generated the corresponding E-containing photoisomers, whose formation was monitored by 1H NMR spectroscopy. For the bis-aurone, weak additional resonances indicated a minor species possibly corresponding to the doubly isomerized (E,E′) form. NOESY correlations provide constraints on the spatial arrangement of the bis-aurone in solution. Both isolated E-containing derivatives exhibit a pronounced downfield shift of one biphenyl aromatic proton. Conformational analysis is used to examine possible geometrical and magnetic-anisotropy contributions to this observation. The study focuses on synthesis, NMR observations of Z/E photoisomerization, and conformational interpretation; intrinsic photochemical efficiencies were not determined.
SN - 1420-3049
ER -