Introduction to Unnatural Foldamers - Metallofoldamers: Supramolecular Architectures from Helicates to Biomimetics - page 69

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Figure 2.26 - h Phg-OBn precipitated from ethanol

observed by means of an optical and an electron microscope, respectively. (b, d) Crystals of
Boc- L -Phe- D -Oxd-(R)-b

(a, c) Crystals of Boc- L -Phe- D -Oxd-(S)-b

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- h Phg-OBn precipitated from ethanol observed by means of an optical
and an electron microscope, respectively. Reprinted with permission from Ref. [72]. Copyright
2010 American Chemical Society.

between an amidic hydrogen of one side chain and a carbonyl oxygen of the other amidic
moiety, while the second one is between the second amidic hydrogen and the carbonyl
oxygen of the Oxd ring. The crystal packing therefore consists of parallel chains with a
helical arrangement (Figure 2.27) running along the c axis. The formation of a ternary
helix in the solid state is in agreement with the SEM analysis as the crystals of Boc- L -
Phe- D -Oxd-( S )-b

3 - h Phg-OBn from methanol appear elongated in one direction with a
hexagonal cross-section.

Figure 2.27 Space filling model showing the helical arrangement of one of the chains of
Boc- L -Phe- D -Oxd-( S )-b

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- h Phg-OBn: (a) top view, (b) view along the c axis. Reprinted with per-
mission from Ref. [72]. Copyright 2010 American Chemical Society.