Molecular machines: Delving into the world of Supramolecualr Chemistry

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Molecular machines: Delving into the world of Supramolecualr Chemistry

  1. 1. Molecular Machines: Delving into the world of Supramolecular Chemistry Shreesha .V. Bhat3rd Sem, Dept of Medicinal Chemistry 1
  2. 2. Contents1. Molecular Machines – Introduction2. Supramolecular Chemistry and Mechanical Bon3. Catenanes and rotaxanes - Introduction - Synthesis - Molecular Shuttling4. Applications 2
  3. 3. Molecular machinesWhat is a molecular machine? 3
  4. 4. 4
  5. 5. Molecular Machines What is a molecular machine? “An assembly of a discrete number of molecularcomponents designed to perform mechanical-like movements as a consequence of appropriate external stimuli” Angew. Chem. Int. Ed. 2000, 39, 3348-3391. 5
  6. 6. Natural Molecular Machines- Biomotors 6
  7. 7. Artificial Molecular Motors 7
  8. 8. Artificial Molecular Motors 8
  9. 9. Supramolecular Chemistry Molecular Machines Supramolecular Chemistry Macromolecules Non-covalent Interactions Mechanical Bond 9
  10. 10. Mechanical BondNon-covalent interactionsMainly observed in mechanically intertwinedmolecules like catenanes and rotaxanes.Each component is intrinsically linked to theother resulting in a mechanical bond whichprevents dissociation without cleavage of one ormore covalent bonds. 10
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  13. 13. James Bond- Sir Fraser StoddartThird most cited chemist with more than 14,000citationsHas trained more than 300 Ph.Ds and postdoctorates 13
  14. 14. Catenanes and Rotaxanes 14
  15. 15. Catenanes and Rotaxanes 15
  16. 16. 16
  17. 17. Construction of Rotaxanes and Catenanes 17
  18. 18. DNA Catenanes & Rotaxanes 18
  19. 19. Synthesis of Catenanes and Rotaxanes1) Active template Strategy Hydrophobic Interactions Hydrogen Bonding Metal ligand co-ordination π donor- π acceptor interaction2) Click Chemistry3) Ring Closing Metathesis 19
  20. 20. First Synthesis of Catenanes and Rotaxanes •Solely based on statistical probability •Molecules were allowed to self-assemble •Less than 1 % yield 20
  21. 21. How can we make complex efficiently? 21
  22. 22. Template Effects for efficient synthesis 22
  23. 23. Template Effects for efficient synthesis 1) Hydrogen Bonding 23
  24. 24. Template Effects for efficient synthesis 2) Metal Co-ordination 24
  25. 25. Template Effects for efficient synthesis 3) Hydrophobic Interactions Chem. Lett. 1996,503-504 25
  26. 26. Template Effects for efficient synthesisCyclodextrins (CDs) are cyclic oligosaccharides consisting of sixor more α-1,4-linked D-glucopyranose rings. The conformation of CDs is a rigid, well-defined cavity with aconical shape. They have a Hydrophilic exterior, Hydrophobic InteriorThe binding interaction is based on a summation of weak effects,namely Van der Waals interactions and hydrophobic binding. 26
  27. 27. Template Effects for efficient synthesis 4) π – donor π- acceptor Interactions PNAS, 104, 2007, 234 27
  28. 28. 28
  29. 29. Click Chemistry As an Approach for Catenane/ Rotaxane synthesis 1,2,3 triazoleClick Chemistry is the chemistry tailored to generatesubstances quickly and reliably by joining units together.It is a modular reaction which gives very high yields andhas high atom economyAzide Alkyne Cycloaddition using Copper as a catalyst isone of the widely used click reactions 29
  30. 30. Click Chemistry 30
  31. 31. 31
  32. 32. End Capping by Click Reactions J. AM. CHEM. SOC. 2006, 128, 10388-10390 32
  33. 33. Synthesis of macrocycle Bis-p-phenylene-34-crown -10(BPP34C10) Tetrahedron, 57, 2001, 3799-3808 33
  34. 34. Catenane Synthesis BPPC34C10 dvts Bipyridinium Cyclophane Catenanes Tetrahedron, 57, 2001, 3799-3808 34
  35. 35. Functions- Molecular Switches and Molecular Shuttles 35
  36. 36. Incorporation of different stations for switching 36
  37. 37. Molecular Shuttling External Stimuli 1)Chemical-Acid- Base 2) Photochemical 3) Electrochemical- Redox 37
  38. 38. Principle Behind Shuttling 38
  39. 39. External Stimuli for Switching 39
  40. 40. Chemically Driven Stimuli JACS 1998, 120, 11932-11942. 40
  41. 41. Photochemically Driven Switches 41
  42. 42. Photochemically Driven Switches 42
  43. 43. Applications in Drug Delivery Macroscopic Transporters NanoElevators Nano Valves Molecular Rotors 43
  44. 44. Macroscopic Transport bysynthetic Molecular Machines 44
  45. 45. Tetraflourosuccinamide Maleamide stationstation 45
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  50. 50. ImplicationsLiquid transportation using photo-responsivesurfaces may prove useful for deliveringanalytes in lab-on-a-chip environments,Performing chemical reactions on a tinyscale without reaction vessels by bringingindividual drops containing different reactantstogether.In the Future, maybe you can move solidobjects just through a Laser Pointer!!!!! 50
  51. 51. Molecular Elevator 51
  52. 52. Molecular Elevator 52
  53. 53. MSNP- Mesoporous SilicaNanoparticles -Targeted Drug Delivery Nanoscale, 2009, 1, 16–39 53
  54. 54. In Step 1, the CBPQT4+ rings encircles the TTF units, constitutes the open position ofthe MSNPs and allows the cargo molecules to be loaded.In Step 2, the nanovalves are closed by oxidizing the TTF units with Fe(ClO4)3 to theTTF2+ dications and as a consequence of Coulombic repulsion, the tetracationicCBPQT4+ rings move to the DNP units.In Steps 3 and 4, the nanovalves are opened by reducing the dications back to theneutral TTF units whereupon the CBPQT4+ rings move back to the TTF units, thusreleasing the cargo 54
  55. 55. ConclusionsThe Beauty of Supramolecular Chemistry, with itsInterlocked molecules converts a Chemist into anArtist who delves into the world of catenanes androtaxanes.Synthetic Molecular Machines have really wideapplications in the field of electronics, sensors anddrug delivery.The Molecular shuttling mechanisms of rotaxaneshave wide implications in targeted drug delivery,and can be explored further. 55
  56. 56. 56http://www.catenane.net/home/linksnew.h
  57. 57. AcknowledgementsMy Sincere thanks to Mr. Mohit Tyagi (Phd Scholar)for introducing me to this wonderful topic, andanswering my innocent questions with greatpatience. 57
  58. 58. Thank You 58
  59. 59. QUIZ 59

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