Details

Autor(en) / Beteiligte

• Nagorny, Sven
• Weingartz, Thea
• Namyslo, Jan C.
• Adams, Jörg
• Schmidt, Andreas

Titel

Correlation between Absorption and Substitution of Photochromic 1,2‐Bis(thienyl)ethenes (BTEs) Using Modified Spectroscopic Hammett Equations

Ist Teil von

• European journal of organic chemistry, 2023-01, Vol.26 (1), p.n/a

Ort / Verlag

Weinheim: Wiley Subscription Services, Inc

Erscheinungsjahr

2023

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Series of photochromic 1,2‐bis(thienyl)ethenes possessing perfluorocyclopentene backbones, either hydrogen or methyl groups at the β‐positions of the thiophenes, and a variety of substituents in their α'‐positions were prepared, which cover the range from electron‐donating to electron‐withdrawing (Me, −CH2OH, −OTBS, −TMS, −Br, 1,3‐dioxan‐2‐yl, pyridin‐4‐yl, −CH2OH, −COOH). As a linear free energy relationship the spectroscopic Hammett equation gives fair to excellent fits to the excitation energy of the absorption maxima of the ring‐opened as well as the ring‐closed forms of the BTEs, when Hammett substituent constants σp were replaced by Brown's modified substituent constants σp+ and σp−. Vice versa, hitherto unknown Hammett‐Brown substituent constants can be estimated from the UV spectra. Furthermore, we compared the experimentally measured absorption maxima with values which we calculated by three different methods (DFT STEOM‐DLPNO‐CCSD/def2‐TZVPP, TD‐DFT ωB97X‐D3/6‐31G*, TD‐DFT ωB97X‐D3/6‐311++G**). The Hammett‐Brown substituent constants of α'‐substituted BTEs (open and closed) correlate linearly with the excitation energies of the absorption maxima applying the spectroscopic Hammett equation.