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Multifunctional and Reactive Enantiopure Organometallic Helicenes: Tuning Chiroptical Properties by Structural Variations of Mono‐ and Bis(platinahelicene)s
Author(s) -
Anger Emmanuel,
Rudolph Mark,
Norel Lucie,
Zrig Samia,
Shen Chengshuo,
Vanthuyne Nicolas,
Toupet Loïc,
Williams J. A. Gareth,
Roussel Christian,
Autschbach Jochen,
Crassous Jeanne,
Réau Régis
Publication year - 2011
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201101866
Subject(s) - helicene , enantiopure drug , chemistry , circular dichroism , moiety , enantiomer , diastereomer , crystallography , optical rotation , metal , chirality (physics) , photochemistry , stereochemistry , density functional theory , enantioselective synthesis , computational chemistry , molecule , organic chemistry , catalysis , chiral symmetry , nambu–jona lasinio model , physics , quantum mechanics , quark
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) 9 a 1 can isomerize into the homochiral ( P , P )‐ and ( M , M )‐bis(Pt III –[6]helicene) 9 a 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 9 a 1 and 9 a 2 , σ–π conjugation between the helicenes and the PtPt moiety may contribute strongly to the optical rotation and electronic circular dichroism.