ISSN:
0749-1581
Keywords:
1H NMR
;
Lanthanide-induced shift (LIS)
;
Conformational analysis of highly flexible molecules
;
Steepest descent (STEED) LIS calculation algorithm
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
A new method and computer program for LIS calculations of highly flexible molecules was developed using molecular geometries obtained by randomly varied dihedral angles (up to ten angles rotating freely and independently from each other are possible) as start conformations for a STEEpest Descent (STEED) search algorithm to find minima characterized by the R factor at the ‘LIS R factor hyper surface.’ This STEED-LIS method allows easy, accurate and rapid access to the probable global minimum of the R factor depending on up to ten variable dihedral angles. This means that LIS investigations of highly flexible molecules with more than one freely rotating dihedral angle are no longer complicated and time consuming, but can be carried out automatically using the developed programs [JLLISSD (with interactive parameter dialogue) and LISSDEMU (using parameter input files prepared by LISSDINP)]. The results obtained are in very good agreement with known or reported preferred conformations of the investigated test compounds, propan-1-ol, butan-1-ol and ethyl p-methoxycinnamate.
Additional Material:
1 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/mrc.1260310411
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