3 From the Discovery of Self-Assembling Dendrons,
Dendrimers, and Dendronized Polymers to a Materials
Genome Approach to Biological-Like Complex Systems
In 1982, a year after the naming of Hermann Staudinger Haus, while continuing to
develop methodologies for polymer and organic chemistry, our research in Case
Western Reserve University departed from the work done in Iasi, in Hermann
Staudinger Haus, and in Kennedy’s laboratory. The most influential on our way
of thinking were Aaron Klug [11, 12], with his work on the elucidation of the
assembly of rod-like and icosahedral viruses; Helmut Ringsdorf [13], with his work
on liquid crystals and mimics of biological membranes; and Jean-Marie Lehn [7,
14–17], with his work on supramolecular chemistry and supramolecular polymers. I
was particularly influenced by a lecture of Klug on his work, which immediately
received the Nobel Prize [11], in which he stated: “The study of the structure of a
virus or an assembly of molecules in a cell helps us to understand how they function
in complex biological systems.” This sentence is usually interpreted to mean
“structure determines function” and the methodology represents the definition of
structural biology and of molecular biology. Structural and molecular biology
elucidate the functioning of complex biological assemblies by determining their
structure under conditions as close as possible to those encountered in vivo. The
role of chemistry is to predict the structure that provides a function. Therefore, we
decided to develop a building block that would mimic the structural events
exhibited by biological macromolecules such as proteins, but be simpler to synthesize in a large diversity of monodisperse structures and, further, to elaborate the
principles that are required to predict the primary structure of a macromolecule that
determines a particular function (Fig. 1). Being able to mimic at least at the most
primitive level, the self-assembly of rod-like and icosahedral viruses with synthetic
monodisperse macromolecules, as Klug elucidated by his work, would be a good
starting point. For a number of years we had no good ideas on how to approach this
problem. The Story of the discovery of self-assembling dendrons and dendrimers
and self-organizable dendronized polymers is reported in more detail elsewhere
and therefore it will be mentioned only briefly here.
One day during the mid-1980s, Alfred Saupe came to my office with two
publications. The first one was on the first lyotropic biaxial nematic liquid crystal
[18]. The second publication was a brief communication reporting the first thermotropic biaxial nematic liquid crystal [19]. The thermotropic biaxial nematic liquid
crystal was only monotropic. Saupe mentioned that Helmut Ringsdorf advised him
to contact me in order to help him transform the monotropic phase into an
enantiotropic one. I looked at the structure of the molecule published by Malthe ˆte
[19] and I explained to Saupe that this would be a simple experiment: functionalization of the molecule (consisting of a combination of disc-like and rod-like
segments) at the end of the rod-like part with a polymerizable group that after
polymerization should transform the monotropic phase into an enantiotropic phase
(Fig. 2).
From Synthetic Macromolecules to Biological-Like Complex Systems
179
Dendrimers, and Dendronized Polymers to a Materials
Genome Approach to Biological-Like Complex Systems
In 1982, a year after the naming of Hermann Staudinger Haus, while continuing to
develop methodologies for polymer and organic chemistry, our research in Case
Western Reserve University departed from the work done in Iasi, in Hermann
Staudinger Haus, and in Kennedy’s laboratory. The most influential on our way
of thinking were Aaron Klug [11, 12], with his work on the elucidation of the
assembly of rod-like and icosahedral viruses; Helmut Ringsdorf [13], with his work
on liquid crystals and mimics of biological membranes; and Jean-Marie Lehn [7,
14–17], with his work on supramolecular chemistry and supramolecular polymers. I
was particularly influenced by a lecture of Klug on his work, which immediately
received the Nobel Prize [11], in which he stated: “The study of the structure of a
virus or an assembly of molecules in a cell helps us to understand how they function
in complex biological systems.” This sentence is usually interpreted to mean
“structure determines function” and the methodology represents the definition of
structural biology and of molecular biology. Structural and molecular biology
elucidate the functioning of complex biological assemblies by determining their
structure under conditions as close as possible to those encountered in vivo. The
role of chemistry is to predict the structure that provides a function. Therefore, we
decided to develop a building block that would mimic the structural events
exhibited by biological macromolecules such as proteins, but be simpler to synthesize in a large diversity of monodisperse structures and, further, to elaborate the
principles that are required to predict the primary structure of a macromolecule that
determines a particular function (Fig. 1). Being able to mimic at least at the most
primitive level, the self-assembly of rod-like and icosahedral viruses with synthetic
monodisperse macromolecules, as Klug elucidated by his work, would be a good
starting point. For a number of years we had no good ideas on how to approach this
problem. The Story of the discovery of self-assembling dendrons and dendrimers
and self-organizable dendronized polymers is reported in more detail elsewhere
and therefore it will be mentioned only briefly here.
One day during the mid-1980s, Alfred Saupe came to my office with two
publications. The first one was on the first lyotropic biaxial nematic liquid crystal
[18]. The second publication was a brief communication reporting the first thermotropic biaxial nematic liquid crystal [19]. The thermotropic biaxial nematic liquid
crystal was only monotropic. Saupe mentioned that Helmut Ringsdorf advised him
to contact me in order to help him transform the monotropic phase into an
enantiotropic one. I looked at the structure of the molecule published by Malthe ˆte
[19] and I explained to Saupe that this would be a simple experiment: functionalization of the molecule (consisting of a combination of disc-like and rod-like
segments) at the end of the rod-like part with a polymerizable group that after
polymerization should transform the monotropic phase into an enantiotropic phase
(Fig. 2).
From Synthetic Macromolecules to Biological-Like Complex Systems
179