A-1407

The Systematic Study of the Three-Dimensional Structure of Molecules in Orienting Liquid Crystalline Media

Project Status: 3 Proposal review
Commencement Date: 18.09.2022
Duration in months: 36 months

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Participating Institutions

Partner

LEADING

Scientific Technological Center of Organic and Pharmaceutical Chemistry / Molecular Structure Research Center (MSRC)

Partner

PARTICIPATING

Yerevan State University (YSU)

Partner

PARTICIPATING

Institute of Organic Chemistry (IOKh)

Partner

COLLABORATOR

Moscow State University, Department of Chemistry

Partner

COLLABORATOR

Emory University / School of Medicine

Objective

Objective
The existence of strong solvent effects on structure determined by NMR spectroscopy of oriented molecules leads to an ambiguity of NMR structures determined in thermotropic liquid crystals. This is a major obstacle preventing this method from becoming as well established a structure determination method for small molecules as X-ray crystallography, electron diffraction, or microwave spectroscopy. Currently, it is known that the observed ambiguity of NMR structures is not a consequence of a real distortion of molecules because of interaction with solvent, but it is an artifact caused by unknown reasons.

We intend to understand the reasons for the observed solvent effects and create the methodology which will determine unambiguous, reliable and precise structural parameters of oriented molecules in liquid or liquid crystalline phases.

The main idea is to apply two important facts, which were obtained recently in NMR laboratory of MSRC NAS Armenia: the correlation of solvent effects on NMR structures with physico-chemical properties of used solvents and the absence of such effects in some of the solvents studied.

The primary goal of this investigation will be the further development of the mentioned method and its recognition as a structural method.

The first stage of the project, to be done during the first year, will be the systematic study of the solvent effects and understanding of their mechanisms. We hope to free the existing method from the impact of interfering interactions, which lead to solvent effects, and achieve significant improvement of reliability and precision of these NMR structures.

In the next stage, to be done during next two years, structures of a large series of organic compounds will be determined on the basis of the methodology developed during the first stage. Investigations will be done on a comparative basis, using data obtained by other structural methods, such as X-Ray crystallography, electron diffraction, and microwave spectroscopy. The main goals of this stage are to understand the advantages and disadvantages of this method, investigate its limitations, estimate its possible precision, compile and re-evaluate the results of earlier investigations performed using this method and create and support a Data Bank of NMR structures of oriented molecules, which will be available online.