Supramolecular Helical Architectures Dictated by Folded and Extended Conformations of the Amino Acid in Ternary CuII/Diamine/Racemic Amino Acid Complexes
✍ Scribed by Palani Sivagnana Subramanian; Eringathodi Suresh; Luigi Casella
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 203 KB
- Volume
- 2007
- Category
- Article
- ISSN
- 1434-1948
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✦ Synopsis
Abstract
The ternary Cu^II^ complexes [Cu(D,L‐phe)(bpy)]·(ClO~4~) (1), [Cu(D,L‐phe)(phen)(H~2~O)]·ClO~4~·H~2~O (2), and [Cu(L‐phe)(bpy)(H~2~O)]·ClO~4~·H~2~O (3) (bpy = 2,2′‐bipyridine, phen = 1,10‐phenanthroline) adopt helical structures in the crystal state, as determined by an X‐ray structural analysis. The supramolecular helical assembly of these complexes was also investigated by single‐crystal X‐ray crystallography. The complexes derived from racemic amino acids (1 and 2) undergo spontaneous resolution in the solid state to form separate helical chains of the ternary complex that carry a single enantiomer of the amino acid. In the case of complex 1, the two helical chains resulting from the L‐ and D‐phe complexes bear opposite chirality, which means that the bulk crystalline sample is racemic. In contrast, the two helical chains generated by L‐ and D‐phe complexes in 2 have the same twist and pack together in a right‐handed assembly. The (P)/(M) handedness of the helical chains is dictated by the conformational chirality (λ/δ) of the chelate rings of the D/L‐aminoacids.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)