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http://www.ugc-inno-nehu.com/events-2015.html#E10
04/21/23 03:50 PM 1Dr. Sankarampadi ARAVAMUDHAN NEHU Shillong
Chemistry
MaterialsPolymers
Tools for structure determinationSPECTROSCOPY
Magnetic ResonanceNuclear Magnetic Resonance Spectroscopy of Proton Nuclei
A fictitious structure convinces the PMR results
Requires further investigation for the chemical reality
Computational Chemistry
SCHEME FOR THE CONTENTS OF NEXT 9 SLIDES : Slide #2 to #9
Computer SciencesHardware & SoftwareProgramming, Algorithms, Numerical Analysis; Statistics & mathematics
Laboratory Instrumentation: Digital Techniques & Automation by computer control
Material Sciences
Physics
CHEMICAL SCIENCES:Chemistry and the aiding branches of Sciences 1)Spectroscopy, NMR/PMR (analytical technique)2) Computational Chemistry 3) Theoretical Chemistry
04/21/23 03:50 PM 2Dr. Sankarampadi ARAVAMUDHAN NEHU Shillong
5.35 5.655.57.7 7.8 7.9
Experimental
Simulated
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)
04/21/23 03:50 PM 3Dr. Sankarampadi ARAVAMUDHAN NEHU Shillong
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
Spin parameters of the compound as below result in a spectrum similar to that of polystyrene
Would it be possible to inquire for the chemical existence of such fictitious structure with computational Chemistry?
04/21/23 03:50 PM 4Dr. Sankarampadi ARAVAMUDHAN NEHU Shillong
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
04/21/23 03:50 PM 5Dr. Sankarampadi ARAVAMUDHAN NEHU Shillong
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 spin-spin 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.
04/21/23 03:50 PM 6Dr. Sankarampadi ARAVAMUDHAN NEHU Shillong
04/21/23 03:50 PM 7Dr. Sankarampadi ARAVAMUDHAN NEHU Shillong
04/21/23 03:50 PM 8Dr. Sankarampadi ARAVAMUDHAN NEHU Shillong
04/21/23 03:50 PM 9Dr. Sankarampadi ARAVAMUDHAN NEHU Shillong
Aromatic plane perpendicular to double arrow head line
Aromatic plane perpendicular to double arrow head line
04/21/23 03:50 PM 10Dr. Sankarampadi ARAVAMUDHAN NEHU Shillong
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Relevance of Small Molecule Computational Chemistry for the Contexts of Biological Macro molecular Computations
Theoretical Chemistry
Quantum Chemistry
Computational Chemistry
Computations with moderate computational facility as much an average Desk top Computer can support
Easily accessible and usable provision for beginners
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
CHEMISTRY BIOLOGY
SCHEME FOR THE CONTENTS OF NEXT 9 SLIDES : Slide #11 onwards
04/21/23 03:50 PM 11Dr. Sankarampadi ARAVAMUDHAN NEHU Shillong
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.
CG stands for Coarse Grained
04/21/23 03:50 PM 12Dr. Sankarampadi ARAVAMUDHAN NEHU Shillong
These four configurations have a maximum variation by 6.27 Kcal/mole
04/21/23 03:50 PM 13Dr. Sankarampadi ARAVAMUDHAN NEHU Shillong
Input str.Neutral zwitterion
Optimized Str.
Neutral non ionic
17 th step
29 th step
These stages involve a proton transfer from methyl group to carboxylic oxygen
04/21/23 03:50 PM 14Dr. Sankarampadi ARAVAMUDHAN NEHU Shillong
Proton 8
An example of Experimental 13C NMR Spectra
The CMR image enlarged view
04/21/23 03:50 PM 15Dr. Sankarampadi ARAVAMUDHAN NEHU Shillong
http://www.ugc-inno-nehu.com/DBIBT/
http://www.ugc-inno-nehu.com/compile/
http://www.ugc-inno-nehu.com/compile/07-2013-ICETCS-CUG-sa.pdf
04/21/23 03:50 PM 16Dr. Sankarampadi ARAVAMUDHAN NEHU Shillong