Redox-active Chiroptical Switching in Mono- and Bis-Iron-Ethynyl-Carbo[6]Helicenes Studied by Electronic and Vibrational Circular Dichroism and Resonance Raman Optical Activity

Chengshuo Shen (1) , Monika Srebro-Hooper (2) , Florian Krausbeck (3) , Thomas Weymuth (3) , Juan López Navarrete (4) , Francisco Ramirez (4) , Belen Nieto-Ortega (4) , Juan Casado (4) , Markus Reiher (3) , Jochen Autschbach (5) , Jeanne Crassous (1)

1 ISCR - Institut des Sciences Chimiques de Rennes
2 UJ - Uniwersytet Jagielloński w Krakowie = Jagiellonian University
3 ETH Zürich - Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich]
4 Universidad de Málaga [Málaga] = University of Málaga [Málaga]
5 SUNY Buffalo - University at Buffalo [SUNY]

Introducing one or two alkynyl-iron moieties onto a carbo[6]helicene results in organometallic helicenes (2 a,b) that display strong chiroptical activity combined with efficient redox-triggered switching. The neutral and oxidized forms have been studied in detail by electronic and vibrational circular dichroism, as well as by Raman optical activity (ROA) spectroscopy. The experimental results were analyzed and spectra were assigned with the help of first-principles calculations. In particular, a recently developed method for ROA calculations under resonance conditions has been used to study the intricate resonance effects on the ROA spectrum of mono-iron ethynylhelicene 2 a.

Keywords: organometallic helicenes; chiroptical switching; VCD; RROA; redox activity

Domains: Chemical Sciences; Coordination chemistry

Chengshuo Shen, Monika Srebro-Hooper, Florian Krausbeck, Thomas Weymuth, Juan López Navarrete, et al.. Redox-active Chiroptical Switching in Mono- and Bis-Iron-Ethynyl-Carbo[6]Helicenes Studied by Electronic and Vibrational Circular Dichroism and Resonance Raman Optical Activity. Chemistry - A European Journal, 2018, 24 (56), pp.15067-15079. ⟨10.1002/chem.201803069⟩. ⟨hal-01862498⟩