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Internet Electronic Journal of Molecular Design - IEJMD, ISSN 1538-6414, CODEN IEJMAT
| ABSTRACT - Internet Electron. J. Mol. Des. August 2005, Volume 4, Number 8, 537-544 |
Conformations of 2-Phenyl-3-Pyridylpropenoic Acid (α-Phenyl Pyridylcinnamic Acid)
Dimers - A Computational Study
István Pálinkó
Internet Electron. J. Mol. Des. 2005, 4, 537-544
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Abstract:
Cinnamic acid analogs are not only important parts of the shikimic
acid metabolic pathway of higher plants but it is possible to
assemble, particularly from those containing oxygen or
nitrogen heteroatoms, various patterned structures kept together
with CH…O or CH…N hydrogen bonds. The fundamental unit of
these structures is the acid dimer, e.g., the dimer of E and
Z-2-phenyl-3-pyridylpropenoic acids of this study, which may exist in
many conformations. As a preparation for a detailed
conformational analysis of the patterned structures, it was decided
to study the conformational behavior of these acid dimers,
containing the N heteroatom in all possible positions of the
aromatic ring. The conformational behavior of any
cinnamic acid analogs in the dimeric form has not been studied
before. The conformational search module of the HyperChem package was
used for the conformational
analysis of the acid dimers with the
PM3 semiempirical method. Calculations were
performed for isolated dimers, i.e., without solvent. The
conformational search identified many conformers of the acid
dimers. Although their numbers amounted to hundreds, they were
found to fill the conformational space unevenly, in a highly
symmetric nature. The distribution patterns were typical for the
stereoisomers, but resembled to each other irrespective to the
position of the nitrogen atom. It was proved to be possible to study
the conformational behavior of cinnamic acid analogs in their
dimeric forms for the first time. Large number of conformers was
identified and they were found the fill the conformational space in
a patterned way.
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