Synthesis of chiral p -conjugated assemblies using aza helicene-phosphole ligands

1. Synthesis of chiral p-conjugated assemblies using azahelicene-phosphole ligands Sébastien Graule Phosphorus and Molecular Materials UMR 6226

2. Challenge : chiral wave-guides (information encoding) Synthesis of stable materials displaying huge optical rotation ! Optimisation = structural diversity Cécile Le Luyer , Claudine Garapon, Stéphan Guy (LPCML, Villeurbanne, France) L. Guy (ENS Lyon)

3. Advantages Drawbacks Difficulty to get structural diversity! Long and hard synthetic route! P Hexahelicene M Hexahelicene • Chiral derivatives : • high specific optical rotations • ([]D25= +3600) • Thermally and chemically • stable Helicenes : helicoidal shape + p-conjugated system

4. p Pd(CH3CN)42+ P,Nchelates : Stereoselective coordination chemistry Trans-effect p p C. Fave, M. Hissler, K. Sénéchal, I. Ledoux, J. Zyss, R. Réau Chem. Commun.,2002, 1674 Pyridyl-phosphole : Easily delocalised p-system Reactive P-atom Chem. Rev. 2006, 106, 4681

5. Our approach : phosphole-based azahelicenes - Synthesis of phosphole based azahelicenes • Stereoselective self-assembly of these P,N-ligands with • metallic ions Metal ions • Chiroptical properties M= Pd, Pt

6. Synthesis of (phospholyl)aza[4]-helicenes Model molecules

7. UV-Vis: l= 406 nm l = 390 nm Synthesis of (phospholyl)aza[4]-helicenes Model molecules Inversion of the helix and P-atom 15 Å

8. P N Pd 4.1 Å Structural diversity using coordination chemistry A 77% - 82% B Only one pair of enantiomers (among 26 stereoisomers) !

9. P N Cu 15Å Chem. Commun., 2008, 850 Structural diversity using coordination chemistry A 77% - 82% Only one pair of enantiomers (among 25 stereoisomers) ! B

10. P N Cu P N Pd Model molecules with sophisticated architectures: Go beyond model molecules : chiral phosphole-based azalicenes

11. 31P NMR CDCl3 Synthesis of Racemic(phospholyl)aza[6]-helicenes

12. 81 MHz31P NMR in CDCl3 Resolution of azahelicene-diyne Chiral HPLC Chiralcel OD-H, Hexane/ethanol 1:1, 1ml/min Dr. Nicolas Vanthuyne and Pr. Christian Roussel (ENSSPICAM, Marseille)

13. Mixture of diastereoisomers in equilibrium (P-inversion) 15 kcal.mol-1 P, Sp P, Rp configuration

14. Specific Optical Rotations (CH2Cl2, 0.01 - 0.02 M) = +1273 = +908 = +13116 Molar rotations (CH2Cl2) = +23082 x MM / 100 Chiroptical properties of hexaazahelicene complexes N P Optically pure helix (chiral HPLC) Square-planar Tetrahedral =

15. PdII PdII Synthesis of helically molecules via Coordination New investigation

16. Conclusion Structural diversity… … With other metals (Pt, Au, Ru…) Optical rotation Tuning of chiroptical properties ! Focus on formation of helicoidal molecules upon coordination

17. Thanks • Pr Régis Réau, Dr Jeanne Crassous • Dr Christophe Lescop • Shen Wenting HPLC: Dr. Nicolas Vanthuyne and Pr. Christian Roussel (ENSSPICAM, Marseille) X-Ray : Dr. Heinz Gornitzka PHOSHELIX

20. Optical rotation or optical activity is the rotation of linearly polarized light as it travels through certain materials Biot law : [a]Td= a/lC

21. NMR 31P 81 MHz31P NMR in CDCl3 δ : 19,6ppm 81 MHz31P NMR in CDCl3 δ : 13,2ppm

22. Eyring equation: ΔG ~ 16 kcal. mol-1 313K Coalescence temperature 323K 333K 328K NMR 31P :Temperature evolution 298K

23. Pd(II) Cu(I) Coordination 81 MHz31P NMR in CD2Cl2 δ : 5-6ppm 81 MHz31P NMR in CD2Cl2 δ : 76,1ppm

24. Circular Dichroism and Optical Rotation *[α]D23 = +2010 *[Φ]D23 = +10240 *[α]D23 = +1273 *[Φ]D23 = +23082 *[α]D23 = +908 *[Φ]D23 = +13116 * in CH2Cl2, 293K CD in CH2Cl2, 293K

25. UV-Visible