Results of interesting data

1. Supervised By :
Dr. Aniruddha Chakraborty
School of Basic Science
IIT Mandi
Presented By:
Piyush Sharma (V21047)
MSc. Chemistry
School of Basic Science
Presented on: 13 June

2. KFNVSLKDKL
Content
1. Introduction: Aromaticity & Huckle Rule
2. Paramagnetic Ring current
3. Computational study
4. Ongoing Work
5. Future Aspects

3. Introduction
Aromaticity: A property of conjugated cycloalkenes in which the stabilization of the molecule is
enhanced due to the ability of the electrons in the π orbitals to delocalize.
The Criteria For Aromaticity :
Molecule must be completely conjugatedbe
completely conjugated
Molecule must satisfy Huckel’s Rule.
Molecule must be planar
Molecule must be cyclic

4. Introduction
Huckle Rule : It is based on Molecular Orbital calculations, predicts that electron rings will constitute
an aromatic system only if the number of electrons in the ring is of the form 4n +2, where n is zero or
any position integer.
Considering Aromaticity, a compound can be classified in one of three ways
Aromatic: A cyclic, planar, completely conjugated compound with 4n+2 ∏ electrons.
Antiaromatic: A cyclic, planar, completely conjugated compound with 4n ∏ electrons.
Not aromatic (nonaromatic): A compound that lacks one(or more) of the following requirements
for aromaticity: being cyclic planar, and completely conjugated
Ref:

5. Introduction
Aromatic
Compounds
Non Aromatic
Compounds
Anti Aromatic
Compounds

6. Continued…
Ref: Smith, M. and March, J.(2007) Advanced Organic Chemistry. USA: John Wiley & Sons, Inc

7. We know comp has a closed ring or e
Paramagnetic Ring Current
Ref: Smith, M. and March, J.(2007) Advanced Organic Chemistry. USA: John Wiley & Sons, Inc
Aromatic Compounds are example
of delocalised bonding
Molecules have delocalised ring
current
We can determine this ring current
by using NMR
Antiaromatic systems exhibit a paramagnetic ring current which causes protons on the outside of the
ring to be shifted upfield while any inner protons are shifted downfield,
in sharp contrast to a diamagnetic ring current, which causes shifts in the opposite directions.
Compounds that sustain a paramagnetic ring current are called paratropic
The value of the chemical shift of a proton in an NMR spectrum depends on the electron density of its
bond; the greater the density of the electron cloud surrounding or partially surrounding a proton, the
more upfield is its chemical shift.

8. Computational Study
Huckel MO: This is an approximate method which simplifies variation method to treat planar
conjugated hydrocarbons.
It is assumed that the s orbitals can be treated as localized bonds and the calculation involve
only ∏ electron. Electron electron repulsions are average out.
Hartree Fock Theory : This theory is fundamental to much of electronic structure theory.
It is the basis of molecular orbital (MO) theory, which posits that each electron's motion
can be described by a single-particle function (orbital) which does not depend explicitly
on the instantaneous motions of the other electrons.
Semi Empirical Method: Treatment used certain simplifying assumptions but still
include all electron.
Semi empirical calculations are less accurate than ab initio method but much faster
and cheaper and calculation of some very large molecules are possible only with SEM
method
Ref: Smith, M. and March, J.(2007) Advanced Organic Chemistry. USA: John Wiley & Sons, Inc

9. Computational Study
MO calculations
Used to obtain structure,
energy(heat of formation), dipole
moment, I.E. & other prop..
Ab initio or semi empirical
methods
Not only for stable ones but also
for unstable molecule that are not
possible by experimental
measurements
Ref: Smith, M. and March, J.(2007) Advanced Organic Chemistry. USA: John Wiley & Sons, Inc

10. Ongoing work
Method Basis Set Charge Dihedral Angle Energy (in Hartree)
Ground State DFT B3LYP 6-311G 0 139.36 -463.299321
1,1'-biphenyl
Use Gaussian 09 software and IIT
Mandi HPC Cluster

11. Ongoing work
Method Basis Set Charge Dihedral Angle Energy (in Hartree)
Ground state DFT B3LYP 6-311G 0 104.68 -1044.667246
2,2'-disilyl-1,1'-biphenyl
Use Gaussian 09 software and IIT
Mandi HPC Cluster

12. Ongoing work
Method Basis Set Charge Dihedral Angle Energy (in Hartree)
Ground state DFT B3LYP 6-311G 0 129.65 -694.21
1,1':4',1''-terphenyl
Use Gaussian 09 software and IIT
Mandi HPC Cluster

13. Ongoing work
Method Basis Set Charge Dihedral Angle Energy (in Hartree)
Ground state DFT B3LYP 6-311G 0 142.95 -994.22
1,1':4',1'':4'',1'''-quaterphenyl
Use Gaussian 09 software and IIT
Mandi HPC Cluster

14. Ongoing work
Method Basis Set Charge Dihedral Angle Energy (in Hartree)
Ground state DFT B3LYP 6-311G 0 158.84 -540.726116
9,10-dihydrophenanthrene
Use Gaussian 09 software and IIT
Mandi HPC Cluster

15. Ongoing work
Method Basis Set Charge Dihedral Angle Energy (in Hartree)
Ground state DFT B3LYP 6-311G 0 144.37 --1387.228858
1,1':4',1'':4'',1''':4''',1'''':4'''',
1'''''-sexiphenyl
Use Gaussian 09 software and IIT
Mandi HPC Cluster

16. Future Aspects
Computational Study Of Interlinked multiple
Benzene molecule
Analysis Of Conjugation Present In The Molecule

17. THANK YOU