The molecular structure and conformational characteristics of some specific benzodiazepine receptor ligands: A molecular orbital study of C3-substituted betacarboline derivatives
- Univ. of Helsinki (Finland)
- Univ. of Kuopio (Finland)
- Univ. of Joensuu (Finland)
The molecular structures of the benzodiazepine receptor ligands {beta}-carboline-3-carboxylic acid (BCCA), its methyl, ethyl, and propyl esters (BCCM, BCCE, and BCCP, respectively), and 3-CN-{beta}-carboline (BC-3-CN) have been investigated on a minimal basis STO-3G level of accuracy. For BCCM, BCCE, and BCCP semiempirical AM 1 calculations have also been performed. Fully optimized molecular geometries are reported. Comparisons with available experimental structures indicate that minimal basis results may have a useful predictive value. For the mobile ester side chains, a study of chosen points on the conformational surface was made. Both the STO-3G and the AM 1 results give the planar conformers is the most stable structures with small barriers to internal rotation, provided the ester side chain remains extended. The calculated STO-3G rotational barriers are higher than are the corresponding AM 1 barriers. Partial optimization, i.e., of side-chain structure parameters only, seems sufficient to map the conformational characteristics of these compounds. The orientation of the dipole moment vector and its magnitude may have consequences for possible interaction with a receptor. On the basis of the sidechain internal dynamics, the intramolecular flexibility tends to be confined to certain regions of conformational space.
- OSTI ID:
- 6323376
- Report Number(s):
- CONF-8904365-; CODEN: IJQCB
- Journal Information:
- International Journal of Quantum Chemistry; (USA), Vol. 16; Conference: International symposium on quantum biology and quantum pharmacology, St. Augustine, FL (USA), 1-8 Apr 1989; ISSN 0020-7608
- Country of Publication:
- United States
- Language:
- English
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