Chiral recognition by CD-sensitive dimeric zinc porphyrin host. 2. Structural studies of host-guest complexes with chiral alcohol and monoamine conjugates.
J Am Chem Soc
; 123(25): 5974-82, 2001 Jun 27.
Article
em En
| MEDLINE
| ID: mdl-11414831
ABSTRACT
A structural study of complexes formed between a dimeric zinc porphyrin tweezer (host) and chiral monoalcohols and monoamines derivatized by a bidentate carrier molecule (guest) confirmed that their CD couplets arise from the preferred porphyrin helicity of 11 host-guest complexes. NMR experiments and molecular modeling of selected tweezer complexes revealed that the preferred conformation is the one in which the L (larger) group protrudes from the porphyrin sandwich; this preferred helicity of the complex determines the CD of the complexes. It was found that the porphyrin ring-current induced (1)H chemical shifts and molecular modeling studies of the complex lead to the assignments of relative steric size of the L (large)/M (medium) substituents attached to the stereogenic center. The assignments, in turn, are correlated with the sign of the CD exciton couplet that establishes the absolute configuration at the stereogenic center. Variable-temperature NMR experiments proved that the observed increase in CD amplitude at lower temperatures derives from conformational changes in the preferred offset geometry between two porphyrin rings.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Zinco
/
Álcoois
/
Aminas
/
Metaloporfirinas
Tipo de estudo:
Diagnostic_studies
/
Prognostic_studies
Idioma:
En
Revista:
J Am Chem Soc
Ano de publicação:
2001
Tipo de documento:
Article
País de afiliação:
Estados Unidos