Introduction to Unnatural Foldamers - Metallofoldamers: Supramolecular Architectures from Helicates to Biomimetics - page 52

3. For technological utility, one must be able to produce a foldamer efficiently, which will
generally include preparation of the constituent monomers in a stereochemically pure
form and optimization of heteropolymer synthesis.

This is Gellman's definition. Later, Moore proposed the following narrower definition:
“any oligomer that folds into a conformationally ordered state in solution, the structures
of which are stabilized by a collection of noncovalent interactions between nonadjacent
monomer units” [4]. This definition covers both “single-stranded foldamers that only fold
and multiple-stranded foldamers that both associate and fold.”
The investigation on these new structural scaffolds has blossomed in many laboratories
as they hold promise for addressing chemical, physico-chemical and biological problems
and represent a new frontier in research. Many groups have explored oligomers with a
wide backbone variety as potential foldamers. Figure 2.1 shows a graph of the research
articles published in the period 1996-2010, indicating the tremendous increase of interest
in the research topic.
As the final goal is the interaction of foldamers with living organisms, the
research is directed towards a mimic with a-peptidic secondary structures and their
biological functions without having to cope with the hydrolytic and metabolic
instability typical of a-peptides. Of course the foldamers that have been developed
contain various skeletons and differ both in structures and in applications. Synthetic
foldamers are far too numerous to be presented or even simply mentioned here, thus
in this introduction we will describe only some recent and typical examples. There is
averyinterestingbookonfoldamerswhich Ivan Huc and Stefan Hecht [5] published
in 2007 for Wiley; and several excellent reviews on various aspects of foldamer
chemistry recently appeared in several high-impact journals [6]. In contrast, metal-
lofoldamers have never been extensively and systematically described, thus this topic
fills a gap on this topic.
In a recent review, Guichard and Huc divided foldamers into two large families:
“biotic” foldamers and “abiotic” foldamers [7]. “Biotic” foldamers are molecules whose

Figure 2.1 Number of research articles concerning foldamers published in the period 1996
(bottom) to 2010 (top)

(source: Web of Science).