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Supramolecular chirality induction in bis(zinc porphyrin) by amino acid derivatives: Rationalization and applications of the ligand bulkiness effect
Author(s) -
Borovkov Victor V.,
Yamamoto Naoyuki,
Lintuluoto Juha M.,
Tanaka Takumi,
Inoue Yoshihisa
Publication year - 2001
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.1039
Subject(s) - chemistry , chirality (physics) , porphyrin , supramolecular chemistry , zinc , rationalization (economics) , ligand (biochemistry) , supramolecular chirality , asymmetric induction , stereochemistry , combinatorial chemistry , organic chemistry , catalysis , enantioselective synthesis , crystal structure , receptor , biochemistry , physics , chiral symmetry breaking , quantum mechanics , nambu–jona lasinio model , quark , philosophy , epistemology
The achiral syn conformer (face‐to‐face) of the ethane‐bridged bis(zinc porphyrin) ( syn ‐ ZnD ) transforms into the corresponding chiral extended anti bis‐ligated species ( anti‐ ZnD ·L 2 ) in the presence of enantiopure ligands (L: amino acid derivatives). The mechanism of the supramolecular chirality induction is based on chiral ligand binding to zinc porphyrins and subsequent formation of either right‐ or left‐handed screw structures in anti‐ ZnD ·L 2 . The screw structure formation arises from steric interactions between the bulkiest substituent at the asymmetric carbon of the ligand and the peripheral ethyl groups of the neighboring porphyrin ring directed towards the covalent bridge. The sign and amplitude of the induced circular dichroism (CD) are dependent on the steric bulk of the substituents at the chiral center. The greater difference in size between the chiral center's substituents gives the stronger induced CD signal. Rationalization of the ligand bulkiness effect on chirality induction by amino acid derivatives, application of this supramolecular system for the determination of ligand absolute configuration, and relative bulkiness of the substituents at the asymmetric carbon are discussed. Chirality 13:329–335, 2001. © 2001 Wiley‐Liss, Inc.