Multifunctional and reactive enantiopure organometallic helicenes: tuning chiroptical properties by structural variations of mono- and bis(platinahelicene)s. - Université de Rennes Accéder directement au contenu
Article Dans Une Revue Chemistry - A European Journal Année : 2011

Multifunctional and reactive enantiopure organometallic helicenes: tuning chiroptical properties by structural variations of mono- and bis(platinahelicene)s.

Résumé

Acetylacetonato-platina[6]- and -platina[7]helicenes have been prepared from 2-pyridyl-substituted benzophenanthrene ligands by following a two-step cycloplatination reaction. The photophysical properties (UV-visible absorption and emission behavior) and chiroptical properties (circular dichroism and molar rotation) of the resolved enantiomers have been measured. These metallahelicenes constitute a novel family of easily accessible helicene derivatives that exhibit large and tuneable chiroptical properties that can be rationalized theoretically and compared to the parent [6]- and [7]carbohelicenes. Furthermore, they are red phosphors at room temperature and their large chiroptical properties can be modulated by oxidation of the metal center to Pt(IV). Hetero- and homochiral diastereomeric bis(metallahelicene)s that possess a rare Pt(III)-Pt(III) scaffold bridged by benzoato ligands have also been prepared. It is shown that the heterochiral (P,M)-bis(Pt(III)-[6]helicene) 9a(1) can isomerize into the homochiral (P,P)- and (M,M)-bis(Pt(III)-[6]helicene) 9a(2). Spectral assignments and an analysis of the optical rotation of these systems were made with the help of time-dependent density functional theory. The calculations highlight the contributions of the metal centers to the chiroptical properties. For 9a(1) and 9a(2), σ-π conjugation between the helicenes and the Pt-Pt moiety may contribute strongly to the optical rotation and electronic circular dichroism.

Dates et versions

hal-00875414 , version 1 (22-10-2013)

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Emmanuel Anger, Mark Rudolph, Lucie Norel, Samia Zrig, Chengshuo Shen, et al.. Multifunctional and reactive enantiopure organometallic helicenes: tuning chiroptical properties by structural variations of mono- and bis(platinahelicene)s.. Chemistry - A European Journal, 2011, 17 (50), pp.14178-98. ⟨10.1002/chem.201101866⟩. ⟨hal-00875414⟩
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