Optical rotatory dispersion & circular dichorism

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Optical rotatory dispersion & circular dichorism

  1. 1. Optical Rotatory Dispersion & Circular Dichorism  Presented by:-  Sukhjeet kaur  M.Sc. (H) biotech(2)  130181106
  2. 2. CONTENT  ORD  PRINCIPLE  FUNDAMENTAL OF ORD  CD  COTTON EFFECT  ORD CURVES  APPLICATION  DIFFERENCE B/W ORD & CD  CONCLUSION
  3. 3. ORD  ORD is technique related to the optical activity  Rate of change of specific rotation with change in wave length  Optical rotation caused by compound changed with wavelength of light was first denoted by Biot in 1817
  4. 4. FUNDAMENTAL OF ORD  Plane polarized light  Optical activity  Specific rotation  Circular birefringence  Optical rotation  Elliphicity
  5. 5. Plane polarized light  Light from ordinary lamp consists of waves vibrating in many different planes  It is passed through Polaroid lens it is found to be vibrate in one plane is said to be plane polarized light
  6. 6. OPTICAL ACTIVITY  The compounds which are having the ability to rotate the plane of polarized light are called optical active compound  This property of compounds is called optical activity  Measured by Polarimeter  Dextrorotatory  Levorotatory
  7. 7. SPECIFIC ROTATION  The specific rotation ([α]) is an intensive property of a chemical compound, defined as the change in orientation of the plane of linearly polarized light as this light passes through a sample with a path length of 1 decimeter and a sample concentration of 1 gram per 1 millilitre  It is denoted by [α]
  8. 8. CIRCULAR BIREFRINGENCE  Birefringence is the optical property of a material having a refractive index that depends on the polarization and propagation direction of light  α= (nL-nR)π/ α
  9. 9. CIRCULAR DICHORISM Some material posses special properties of absorption of the light circularly light to different extent than the right circulary polarized light Chiral or asymmetric compounds produce CD spectrum
  10. 10. COTTON EFFECT This phenomenon was discovered in 1895 by the French physicist Aimé Cotton Combination of circular dichorism & circular birefringence
  11. 11. ORD CURVES  Plain curves  Anomalous curves  single cotton effect curves  multiple cotton effect curve
  12. 12. PLAIN CURVES  Normal smooth curves  Do not cross the zero rotation line  e.g.:- alcohols hydrocarbons
  13. 13. ANOMALOUS CURVES  Shows no. of extreme peaks & troughs
  14. 14. SCEC & MCEC  Two or more peaks & trough  e.g. ketosteroids  camphor
  15. 15. APPLICATION  CD/ORD of protein  Qualitative analysis of molecules  Enzyme co-factor evaluation  CD/ORD of proteins  CD as finger printing  CD/ORD of nucleic acids  CD of B-DNA is different as compared to A- DNA  Evidence for base stacking
  16. 16. CD/ORD of proteins  e.g:- L-lysine  Positive CD at 217nm  Negative CD at 197nm  Random coil :- ph 5.2  Alpha helical :- ph 11.0
  17. 17. QUALITATIVE ANALYSIS  Measuring by the specific rotation  α =100 α /lc   m =M α /100
  18. 18. Enzyme co-factor evaluation  Teng et.al carried out the spectrum of enzyme p-hydroxybenzoate
  19. 19. CD as finger printing  It acts as finger printing technique for trace amount of carbohydrate meterial  E.g. dermatan sulphate  heparitin sulphate  E.g :- pectin in the presence of citric acid& sucrose
  20. 20. CD of B-DNA & A-DNA
  21. 21. BASE STACKING  ORD spectrum of Polycytidylic acid shows at 292nm is 35,160deg/M/cm  HELICITY DETERMINED BY  Formaldehyde  Ethylene glycol
  22. 22. DIFFERENCE B/W ORD & CD ORD CD PLANE POLARIZED LIGHT DISPERSIVE PHENOMENA PLANE POLARIZED IS USED & IS NOT CONVERTED TO ELLIPTICAL LUGHT GRAPHS ARE OBTAINED BY SPECIFIC ROTATION V/S WAVELENGTH CIRCULARLY POLARIZED LUGHT ABSORPTIVE PHENOMENA CIRCULAR POLARIZED LIGHT IS USED & IS CONVERTED TO ELLIPICITY GRAPHS ARE OBTAINED MOLAR ELLIPICITY V/S WAVE LENGTH
  23. 23. INSTRUMENTATION OF ORD  Light source  Monochromator  Polarizer  Analyzer  Sample tube  photomultiplier
  24. 24. INSTRUMENTATION OF CD  Light source  Polarizer  Sample tube  Photomultiplier  Recorder
  25. 25. CD SPECTROSCOPE
  26. 26. CD/ORD  Simple and quick experiments  No extensive preparation  Relatively low concentrations/amounts of sample  Microsecond time resolution  Any size of macromolecule  Better resolution  Better sensitivity  Easier to assign
  27. 27. REFERENCE  WWW. Science direct.com  WWW.notes .com  Principles & techniques by Avinash Upadhyay  WWW.scribd.com
  28. 28.  THANK YOU

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