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Assembly of π‐Conjugated Phosphole Azahelicene Derivatives into Chiral Coordination Complexes: An Experimental and Theoretical Study
Author(s) -
Graule Sebastien,
Rudolph Mark,
Shen Wenting,
Williams J. A. Gareth,
Lescop Christophe,
Autschbach Jochen,
Crassous Jeanne,
Réau Régis
Publication year - 2010
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.200903234
Subject(s) - phosphole , helicene , enantiopure drug , chemistry , metal , crystallography , circular dichroism , molecule , stereochemistry , enantioselective synthesis , organic chemistry , catalysis
Aza[ n ]helicene phosphole derivatives have been prepared from aza[ n ]helicene diynes by the Fagan–Nugent route. Their photophysical properties (UV/Vis absorption and emission behavior) have been evaluated. Their behavior as P,N chelates towards coordination to Pd II and Cu I has been investigated: metal–bis(aza[ n ]helicene phosphole) assemblies are formed by a highly stereoselective coordination process, as demonstrated by X‐ray crystallography. An aza[6]helicene phosphole bearing an enantiopure helicene part has been obtained, which allows the preparation of enantiopure Pd II and Cu I complexes with original topologies and high molar rotation (MR) and circular dichroism (CD). The structure–property relationship established from the experimental data has been studied in detail by theoretical studies (TDDFT calculations of UV/Vis, CD, and MR). Aza[ n ]helicene phosphole derivatives show π conjugation extended over the entire molecule, and its influence on the MR of aza[6]helicene phosphole 5 c has been demonstrated. Finally, it has been shown that the nature of the metal (coordination geometry and electronic interaction) can have a great impact on the amplitude of the chiroptical properties in metal–bis(aza[ n ]helicene phosphole) assemblies.