http://www.ugc-inno-nehu.com/events-2015.html#E10
3/14/2016 3:23:25 PM
Dr. Sankarampadi ARAVAMUDHAN NEHU
Shillong
1
SCHEME FOR THE CONTENTS OF NEXT 9 SLIDES : Slide #2 to #9
CHEMICAL SCIENCES:
Chemistry and the aiding branches
of Sciences
1)Spectroscopy, NMR/PMR
(analytical technique)
2) Computational Chemistry
3) Theoretical Chemistry
Computer Sciences
Hardware & Software
Programming, Algorithms,
Numerical Analysis; Statistics &
mathematics
Computational
Chemistry
Chemistry
Material
Sciences
Tools for structure
determination
SPECTROSCOPY
Laboratory
Instrumentation: Digital
Techniques &
Automation by
computer control
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Requires further investigation
for the chemical reality
Materials
Polymers
Physics
A fictitious structure
convinces the PMR results
Magnetic Resonance
Nuclear Magnetic Resonance
Spectroscopy of Proton Nuclei
Dr. Sankarampadi ARAVAMUDHAN NEHU
Shillong
2
Structural difference to note is that at CH=CH2
the double bond is absent in polymer.
–CH-CH2- (the NMR spectrum consists of
broad overlapped lines)
Experimental
Simulated
7.7
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7.8
7.9
Dr. Sankarampadi ARAVAMUDHAN NEHU
Shillong
5.35
5.5
5.65
3
Spectral parameters for the simulation are tabulated as follows:
The NMR spin parameters of
polymeric styrene parameters can
also be possible with a cyclic
structure which is only fictitious :
referred to as “Spin Book Keeping”
structure. For polystyrene
Would it be possible to
inquire for the chemical
existence of such
fictitious structure with
computational
Chemistry?
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Spin parameters of
the compound as
below result in a
spectrum similar to
that of polystyrene
Dr. Sankarampadi ARAVAMUDHAN NEHU
Shillong
4
Before making a beginning with the inquiry, the presenting author
could get convinced by the possible simulation with the spin
parameters that could result from the spin book keeping structure.
Simulation software: internet resource
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Dr. Sankarampadi ARAVAMUDHAN NEHU
Shillong
5
Visualizing a Cyclo addition by the ab initio SCF Methods;
a Case Study of Finding Rationale of a Fictitious “Spin bookkeeping” Structure
to Simulate NMR spectra.
Such a fictitious structure makes possibile the inclusion of certain spinspin coupling constants for simulation which, otherwise, is not simple
enough to infer. Obviously these Spin-Spin interactions occur by
mechanisms transmitted through bonds, and it is surprising that a
structure which is “fictitious”, can be revealing such through-bond routes
by which the exact simulation of the observed NMR spectra. Hence, it was
considered worth the while, trying to find out the stability criterion for a dimeric
Styrene with the possible QM methods by Geometry Optimization and verify
with the calculation of the chemical shifts for such a dimer. A thorough literature
survey of the possibility for the occurrence of such dimeric structure of styrene
molecule was not undertaken lest those conditions may build up a bias, for an
“Only Theoretical Model” by ab initio Calculations.
If three successive styrene units of polymer are considered then, if the through
bond interactions and circulation-induced fields of the third unit does not
influence the proton of the first unit, the entire polymer spectrum would
consists of merely dimeric styrene NMR, with possible line broadenings.
3/14/2016 3:23:25 PM
Dr. Sankarampadi ARAVAMUDHAN NEHU
Shillong
6
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Dr. Sankarampadi ARAVAMUDHAN NEHU
Shillong
7
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Dr. Sankarampadi ARAVAMUDHAN NEHU
Shillong
8
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Dr. Sankarampadi ARAVAMUDHAN NEHU
Shillong
9
Aromatic plane perpendicular to
double arrow head line
Aromatic plane perpendicular to
double arrow head line
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Dr. Sankarampadi ARAVAMUDHAN NEHU
Shillong
10
SCHEME FOR THE CONTENTS OF NEXT 9 SLIDES : Slide #11 onwards
Theoretical Chemistry
Quantum Chemistry
Computational Chemistry
Relevance of Small Molecule Computational Chemistry for
the Contexts of Biological Macro molecular Computations
CHEMISTRY
Computations with
moderate computational
facility as much an
average Desk top
Computer can support
Easily accessible and usable
provision for beginners
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?
BIOLOGY
Computations with HIGH POWER
computational facility / soft wares for
parallel processing systems and
preferably REQUIRE a full time
maintenance staff
Often referred to as in silico calculations
Dr. Sankarampadi ARAVAMUDHAN NEHU
Shillong
11
CG stands for Coarse Grained
Implications of these remarks to find the possibilities of how small molecule
Computational Chemistry can be an aid in the macromolecule computations. This
would have a bearing on conventional chemical sciences.
3/14/2016 3:23:25 PM
Dr. Sankarampadi ARAVAMUDHAN NEHU
Shillong
12
These four configurations have a maximum
variation by 6.27 Kcal/mole
Dr. Sankarampadi ARAVAMUDHAN NEHU
3/14/2016 3:23:25 PM
Shillong
13
17 th
step
Input str.
Neutral
zwitterion
29 th
step
These stages involve a proton transfer from methyl
group to carboxylic oxygen
Optimized Str.
Neutral non ionic
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Dr. Sankarampadi ARAVAMUDHAN NEHU
Shillong
14
Proton 8
An example of
Experimental
13C NMR
Spectra
The CMR image
enlarged view
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Dr. Sankarampadi ARAVAMUDHAN NEHU
Shillong
15
http://www.ugc-inno-nehu.com/compile/
http://www.ugc-inno-nehu.com/compile/07-2013-ICETCS-CUG-sa.pdf
http://www.ugc-inno-nehu.com/DBIBT/
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Dr. Sankarampadi ARAVAMUDHAN NEHU
Shillong
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