Exploring Symmetry and Chirality in Molecules and Design

1. On left and right: Symmetry and Chirality in Molecules and Design David Avnir Institute of Chemistry The Hebrew University of Jerusalem Shenkar, 23/12/2014

2. 1. Why is a chemist visiting Shenkar’s design department?

4. Quasi-crystals Insulin Haemoglobin Diffusion-reaction pattern

5. Symmetry - a universal language of shape and structure Mirror symmetry Rotational and mirror symmetries combined Rotational symmetry

6. Our focus: Mirror symmetry Called also reflection symmetry, bilateral symmetry

7. Why is this symmetry called “mirror symmetry”? Combining an object with its mirror reflection produces that symmetry

8. Combining an object with its mirror reflection produces mirror symmetry

9. 2D mirror symmetry in chemistry

10. 3D molecular mirror symmetry Zeolite Carbon nanotube

11. Alexander McQueen (1969 – 2010)

12. 2D-Mirror symmetry, textile: scarves design Alexander McQueen

13. The basic 3D mirror symmetry in textile design for fashion

14. 3D mirror symmetry of the body preserved in textile design

15. 2. Moving away from mirror symmetry - chirality

21. Near symmetry in chemistry cyclohexane HIV Protease

22. Near-symmetry in McQueen’s design Bjork

23. Far-away from mirror symmetry

24. Far-away from mirror symmetry – because of design

25. Far-away from mirror symmetry – because of body posture

26. Far-away from mirror symmetry – because of body posture and design

27. Chirality and handedness When mirror symmetry is removed, a special property emerges: The object may come in two forms: a left-form and a right-form (handedness) * These left and right forms are called enantiomers * Enantiomers are different objects, but they look very similar. The similarity is because they are mirror-images of each other The difference is that they cannot coincide with each other.

28. If there is mirror symmetry, the object coincides with its mirror image, the object is achiral – and there is no pair of enantiomers

29. Chirality is an extremely important property in the natural sciences Life is based on left-handed amino acids and right-handed sugars

30. Why is it so important? To understand it let us take the case of spiral chirality

31. Diastereomeric (DS) interactions

32. The hand-glove interactions The interaction between a right-hand (Rh) and a right-glove (Rg) is different from the interaction of a right-hand (Rh) with a left-glove (Lg) Two different interactions: Rh-Rg Rh-Lg Comfortable vs. Very awkward

33. In the life-sciences chiral interactions are highly important Reason: All biological receptorsare chiral;therefore: The interaction: Left-molecule receptor and the interaction:Right-molecule receptor are different

34. “How would you like to live in a Looking-glass House, Kitty? I wonder if they'd give you milk, there? Perhaps Looking-glass milk isn't good to drink“ “Through the Looking Glasss, and What Alice Found There”, Lewis Carrol (1871)

35. Left-handed and right-handed molecules: * Taste differently * Smell differently * Can heal or kill (Thalidomide) Carvone (R): Spearmint (S): Caraway (kummel)

36. 3. Relevance of chirality considerations to design

37. Many textile design patterns are chiral But now we know that such designs can come in left or right forms; here they are:

38. The enantiomeric pair of the same design Why has McQueen selected the right spiral? Is it an important question for design?

39. Our biological receptor at focus: The chiral brain * The left and right hemispheres of the brain are very unequal * Therefore, no mirror symmetry – the brain is chiral * Specifically: the brain is a chiral information receptor * Therefore, if the information – visual – is chiral, DS interactions result between the brain and the information Therefore, left and right objects must be perceived differently by the brain

40. Psychology of aesthetic perception “When some pictures are mirror reversed, aesthetic evaluations of them change dramatically.” “When a painting is viewed in a mirror… even the meaning can change…” “ The first major finding… was that paintings containing left-to-right directional cues were preferred…” A. M. Mead and J. P. McLaughlin, Brain and Cognition, 20, 300 (1992)

42. Rembrandt’s 2D-chiral preferences N. Konstom, “Rembrandt’s use of models and mirrors”, Burlington Magazine, 99, 94 (1977)

43. Are chirality considerations relevant/important to textile design? First answer: Yes, the left enantiomer and the right enantiomer of the same design may be perceived aesthetically in a different way.

44. 4. Additional considerations in brief

45. Induction of chirality: Accessories

46. Induction of chirality by 3D texture

47. Illumination induces chirality Alexander McQueen

48. Randomness is always a source of chirality

49. Are these left- or right-handed? The specific label is not important: Handedness labeling is an agreed convention, not an inherent property like chirality itself

50. Chirality has a degree