Supramolecular redox-active system consisting of biomolecule

Journal of Inorganic Biochemistry

METAL COMPLEXES OF SMALL BIOMOLECULES

293

S U P R A M O L E C U L A R REDOX-ACTIVE SYSTEM C O N S I S T I N G OF

L08

BIOMOLECULE

T. Hirao, A. Nomoto, S. Yamazaki, T. Moriuchi, and A. Ogawa

Department of Applied Chemistry, Faculty of Engineering, Osaka University, Ycunada-oka, Suita, Osaka 565, Japan Biomolecules are liable to form an ordered structure, which provides a specific site for molecular recognition, electron transfer, and so on.

Introduction of a redox-active moiety to biomolecules is

envisaged to construct a novel self-ordered redox system. rotatory cyclopentadienyl rings. receptor systems.

Ferrocenes have reversible redox and two

These properties permit the construction of supramolecular redox-active

The synthesis and function of such a system bearing podand peptide pendant groups

are described here.

0

Treatment of 1,1' -ferrocenedicarboxylic acid chloride with

Me ~x'/

the peptides afforded the corresponding amides consisting of two pepdde pendant groups.

The ferrocene 1 beating podand

-Ala-Pro- moieties exhibited the Cotton effect in a CD spectrum. This result is in sharp contrast to the finding that the similar effect was not observed in the case of the ferrocene bearing one

Fe

.-. H" "0 0 4"~'~ N_v-~ N_.~,...-u-,,OEt 0 Me ~ ,~ 1

pendant group.

From the X-ray crystallographic analysis, the ferrocene 1 was revealed to be present in 13-sheetlike structure with hydrogen bonding between podand peptide chains (Fig. l).

Furthermore, a helical

molecular arrangement was observed in the molecular packing as shown in Fig. 2.

Top View

Fig. 1 Molecular structure of 1

Side View

Fig. 2 Molecular Packing of I