ELECTRON AFFINITY AND N'M'R' STUDIES OF PYRONES

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• ELECTRON AFFINITY AND N.M.R. STUDIES OF PYRONES
• - A THEORETICAL STUDY
• VEENA.S.B.
• Dept. of chemistry
• S.N.College for women, Kollam

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• Computational chemistry
• It involves taking known theory and
• solving chemical problems using computer
  software.

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• Areas of application
• Single molecule calculations
• Vibrational frequencies, electron distribution,
  ionization potentials, electron affinities,
  dipole-moments, spin-orbit coupling constants.
• Assemblies of molecules
• Thermodynamic properties
• Enthalpies and free energies.
• Reactions of molecules.
• Relative rate constants
• Structures of transition states

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• Pyrones
• Pyrones are keto derivatives of pyrans
• 1,2 (or a) pyran 2 (or a) pyrone 1,4(or g)
  pyran 4 (or g) pyrone

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Pyrones show anti-microbial properties

• Condensed pyrone systems like chromones are
  colouring matter of flowers.

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• Objective and scope of the
• Present investigation
• Molecular electronic structures have been
  successfully investigated by the Density
  Functional Theory (DFT).
• The Density Functional (B3LYP) calculations
  using aug-cc-pvdz has been carried out to
  estimate the nuclear magnetic shielding tensors
  of 4-pyrone and 2-pyrone in gas phase.

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• Z-matrix of 2-pyrone and 4-pyrone were
  constructed . The HF total energies,energies of
  radicals and nuclear magnetic shielding tensors
  were calculated using B3LYP/aug-cc-pvdz.

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• Results and Discussion
• Electron affinity values of 4-pyrone and
  2- pyrone are -9.8297 and -7.3298
• kcal mol-1 respectively. The negative values
  indicate that energy has to be supplied to
  convert neutral molecule to radical.

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Conclusion

• Electron affinity values are negative.
• Nuclear magnetic shielding tensors calculated are
  in agreement with the experimental values and
  support the aliphatic nature of the ring.

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Acknowledgement

• Dr.S.Suma, Lecturer(sr.scale),Dept. of Chemistry,
  S.N. College for women, Kollam.
• Prof.(Dr.).K.R.Srivathsan,Director,IIITM-K
• Prof.(Dr.)M.S.Gopinathan,Emeritus
  Professor,IIITM-K
• Dr.T.K.Manojkumar,Asst. Professor,IIITM-K

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• THANK YOU