Using computational methods to predict NMR spectra for polyether compounds
- UNCW Author/Contributor (non-UNCW co-authors, if there are any, appear on document)
- Krysten Scott Adams (Creator)
- Institution
- The University of North Carolina Wilmington (UNCW )
- Web Site: http://library.uncw.edu/
- Advisor
- Ned Martin
Abstract: Naturally occurring polyether ring compounds have been studied extensively over
the past several years because of their importance as biologically active hemolytic and
neurotoxic substances produced by various marine phytoplankton species. These
substances contain varying numbers of ether rings of varying sizes. This research was
performed to predict NMR spectra, including chemical shifts and coupling constants, of
such polyether ring compounds. A literature search was performed to determine the
frequency of ring size occurrence within the known toxins and each structure was broken
down into three-ring segments. Models of each of these three-ring substructures were
built in Spartan and a conformer search was done followed by a semi-empirical energy
minimization on the lower energy conformers. Once the most energetically favorable
conformers of each compound were determined, they were submitted to the North
Carolina Supercomputing Center to perform a Hartree-Fock single point energy
calculation, as well as a calculation of isotropic shielding values using the GIAO (Gauge
including atomic orbital) method. From these values, chemical shifts were calculated.
Energy values were used to determine the distribution among the various conformers by
using a Boltzmann function. With this distribution data a prediction of chemical shifts for
each ring structure was developed as the weighted average of the chemical shifts
computed for each contributing conformer. Proton-proton coupling constants were also
calculated using dihedral angles measured from the several minimum energy conformers
and applying a modified Karplus equation to each one. Again, application of the
Boltzmann function gave a weighted average coupling constant. These numbers were used to produce a library of NMR spectral data, which should be useful for determining
the structures of novel polyether toxins.
Using computational methods to predict NMR spectra for polyether compounds
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Created on 1/1/2009
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Additional Information
- Publication
- Thesis
- A Thesis Submitted to the University of North Carolina at Wilmington in Partial Fulfillment Of the Requirements for the Degree of Master of Science
- Language: English
- Date: 2009
- Keywords
- Nuclear magnetic resonance spectroscopy, Polyethers, Spectrum analysis
- Subjects
- Polyethers
- Nuclear magnetic resonance spectroscopy
- Spectrum analysis