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Construction Of Near Infrared Chiroptical Switches Based On Electrochromic Viologens

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Construction Of Near Infrared Chiroptical Switches Based On Electrochromic Viologens

Construction Of Near Infrared Chiroptical Switches Based On Electrochromic Viologens

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  • 引用美国国家研究院的“驾驭光”的战略报告中的话,指出光学和光子学的发展将在本世纪给人类的生活带来非常大的改变! 指出:如何实现驾驭光是多方位的,研究已经取得进展,但可做的事情非常多,如更加深入的理论研究、新材料、新器件、及新方法的开发等
  • 一个分子是否具有光学活性,最根本的是看它的镜像是否和原来的重合,如果不重合则具有光学活性。 具有对称中心,镜面,的分子的镜像是和原来的分子重合的,所以具有对称中心,镜面和旋转反映轴的分子是没有光学活性的,只有具有旋转对称轴或者不具有任何对称元素的分子才可能具有光学活性。

Transcript

  • 1. Construction of Near-Infrared Chiroptical Polymers Based on Electrochromic viologens Peking University Deng Jian 2007.07.18
  • 2. Outline
    • Background
    • Hypothesis
    • Theories
    • Experimentals and Properties
    • Near-Infrared Chiroptical Properties
    • Summaries and Plans
  • 3. Background
    • As we peer into the next century, we foresee developments in optics that will change our lives in ways that today we can hardly even contemplate.
    • The role of optics in research, which already cuts across nearly all fields of science and technology, will be limited only by our imagination.
    • Harnessing Light by National Research Council of US in 1998
    To fully explore the utility of light, new theory must be developed for a better understanding of the nature and the behavior of light when interacting with matters; and new materials and devices must be developed for a better control (e.g. in terms of methodology, extent and efficiency) of light. Challenges:
  • 4. Chiral Photonics Chiral Photonics: Studies making use of the unique chiroptical properties, such as polarization and circular dichroism, of a chiral material as well as of other optical phenomena arose from the unique chiral asymmetric structure for various photonics applications such as lasing, light waveguiding, sensoring, and information storage etc.
    • Display
    • Chiroptical switch
    • Chiral fluorescent sensor
    • Chiral lasing
    • Chiral waveguide
    • Nonlinear optics
    • Optical storage media
    Chiral Recognition 1-D photonic Ordering Circular Birefringence and Dichroism Helical waveguide usable for selective filtering, scattering and coupling Chiroptical switch triggered by light Feringa, Ben L. et al. Chiral photonics, Inc.
  • 5. Potential uses: NIR Chiroptical Polymers
    • Polarization control (in particular for integrated systems)
    • Sensoring and information storage
    • EO Modulator via Polarization
    Z. Y. Wang, E. K. Todd, X. S. Meng, J. P. Gao, J. Am. Chem. Soc . 2005, 127 , 11552. Phase vs polarization
  • 6. Chirality Molecular Chirality Chirality in Nature Supramolecular Chirality
  • 7. Symmetry Chirality of a molecule is a symmetry properties Asymmetric :no any symmetry element (C 1 ) Dissymmetric: only axes of rotation (C n and D n )
  • 8. Light and Chiroptical Properties Electromagnetic waves Optical rotation Circular Dichroism
  • 9. α , θ (degree) d=cell length (cm) d’=cell length (dm) c=concentration (M) c’=concentration (g/cm 3 ) n=refractive index ε=absorption coefficient (M -1 cm -1 ) λ=wavelength of incident light (nm) Polarimeter and Circular dichroism Spectrometer
  • 10.  
  • 11. Kramers-Kronig relation
    • Inter-relationship between ORD and CD Curves
    Rosenfeld’s equation:
    • Dependence of ORD and CD on wavelength
    λ 1 λ 2
  • 12. JACS 1998,120, 6185
    • Dependence of ORD and CD on chromophore interaction
    Kirkwood’s Coupled Oscillator Model Noncoplanar Non-perpendicular Proper distance
  • 13. Hypothesis
    • Appropriate introduction of electro/photochromic chromophores into a suitable chiral structure should lead to Electrically or Optically controllable chiroptical properties, which should find wide applications in areas where polarization control is of concern.
    260 nm 394, 605 nm 394 nm Structural Design I: 605 394 260
  • 14. Structural Design II and Contents of Researches
  • 15. (R)-BEBPP (R)-BEBPB (R)-CBEBPB Axially Dissymmetric Compounds:
  • 16. Synthetic Approach:
  • 17. 4 mg / 1 mL 0.1 M Bu 4 NClO 4 DMF - 0.7 V
  • 18. 4 mg / 1 mL 0.1 M Bu 4 NClO 4 DMF - 0.7 V
  • 19. Demonstration of electrochemical Switching of CD signals of ( R )-CBEBPB in 0.1 M Bu4NClO4/DMF. (a) first reduction at -0.5 V for 5 s; (b) recovered tetracation by bubbling slowly nitrogen into the solution; (c) second reduction at -0.7 V for 1 min. Demonstration of electrochemical Switching of CD signals of ( R )-CBEBPB by tin. (a) first reduction by tin bubling nitrogen; (b) recovered tetracation by bubbling slowly air into the solution; Repeat (a) and (b) five times.
  • 20. Near-infrared chiroptical properties ORD caculated from experimental data (a) (b) J.Phys.Chem. A, 2003, 107 , 2524 J.Am.Chem.Soc., 2004, 126 , 7514
  • 21. R-BEBPB Rotational strength calculated from this diagram.via formula (a). ORD calculated via formula (b).
  • 22. R-CBEBPB
  • 23. R-CBEBPB Reduced
  • 24. 1. [ α ] D 23.9 = -224.5 o (4.0 mg/10 mL DMF), Mn:5295 2. [α] D 23.7 = -399 o (4.0 mg/10 mL DMF), Mn:15477, PD:1.42 Polymer Based on Model Compounds
  • 25.  
  • 26. 1. [ α ] D 23.9 = -100.0 o (4.0 mg/10 mL DMF), M n :6695 Grafting: 50% 2. [ α ] D 23.9 = -?, Mn:? Grafting: 50%
  • 27.  
  • 28.  
  • 29. DJ-E-55
  • 30. Helical polymers:
  • 31. Alkynyl Monomer
  • 32. Synthesis of achiral monomers
  • 33. Synthesis of chiral monomers based on L-lactic acid
  • 34. 含羧基的分子溴化后,不好分离。 溴化时,炔基会被加成。 应该先溴化,再引入手性单元和炔键。
  • 35. Synthesis of chiral monomers based on L-alanine
  • 36. 对甲苯甲酰氯的活性比溴乙酰溴的活性低,可以在水中进行反应。 此反应尽管产率低但是可以发生,产率低的原因可能是苄溴和氨基 发生了反应,自然就想到把氨基保护起来,所以就选择了 BOC-L-alanine 。
  • 37. Synthesis of chiral monomers based on BOC-L-alanine
  • 38.  
  • 39. Rh + (BDN)[B(C 6 H 5 ) 4 ] - Synthesis of Catalysts
  • 40. Rh(COD)(tos)(H 2 O)
  • 41. Polymerization of monomers
  • 42.  
  • 43. DT1 Samples [M 0 ] [M 0 ]/[Cat] T/ 0 C Time/h Solvent Yield/% M n PD [a] D DJ-C-85 0.08 100 50 12 THF 84 5896 1.25 DJ-C-79 0.08 100 r.t. 12 THF 68 6478 1.61 -86 THF 6338 1.51 -123 DJ-C-95 0.16 100 r.t 24 THF 85 9115 1.56 -182.5 DJ-D-7-2 0.1 100 r.t 20 THF 85 7792 1.69 -217.5 DJ-D-7-3 0.16 200 r.t. 20 THF 77 7882 1.9 -341.5 DJ-D-7-4 0.1 100 0 20 THF 83 7344 2.46 -479
  • 44. poor resolution of polymer small optical rotation small molecular weight
  • 45. Samples [M 0 ] [M 0 ]/[Cat] T/0C Time/h Solvent Yield/% M n PD [a] D / 0 C DJ-D-13-A 0.1 50 30 1 64 10683 -571 DJ-D-13-B 0.2 200 50 1 84 40522 -1616.5
  • 46. ? A yellow solid product. [α] D 20.7 = -755.5 0 (4 mg/10 mL MeCN) [α] D 20.7 = +743.0 0 (4 mg/10 mL DMF) poor resolution of polymer small optical rotation small molecular weight
  • 47. Summaries and Plans
    • Axially Dissymmetric Compounds
    • Synthesis of model compounds based on 1,1’-binaphthyl.
    • A series of properties relating with chiroptical switches.
    • Near-infrared chiroptical properties.
    • Achieving the designed tasks.
    • Optimized chiroptical properties via optimizing the conditions of measures.
    • Theoretical calculation:
    • Understanding the relationship between the chiroptical properties and structures.
    • Improving the properties by redesigning the structures.
    • 7. Synthesis of polymer based on the model compound.
    • 8. Properties of polymer:
    • In solution.
    • Film.
  • 48.
    • Helical Polymers
    • Synthesis of monomers containing:
    • Alkynyl.
    • Chiral center.
    • Bromomethyl or sulphonic acid ester or group brominated.
    • Introduction of alkynyl bond after bromination.
    • 3. Not achieving the designed tasks.
    • The main problems:
    • The small optical rotation.
    • The small molecular weight
    • The poor solubility.