Self-Assemblies, Folding, and Properties of Perylene Monomers, Oligomers, and Polymers - Molecular Self-Assembly: Advances and Applications - page 157

The AFM stretching revealed single-molecule unfolding behavior
of foldamers and quantified the nonequilibrium doubly folded, singly
folded, and unfolded states statistically. The analysis also revealed
a single energy barrier while rupturing N S. Finally, the employed

loading rate was sufficient to allow considerable foldamers to return
to the folded or partially folded states.

π

5.5 Specific Molecular Assemblies: Molecular

Codes

When molecules reach certain size, their interaction among
themselves or with another type of molecules can behave like
molecular codes. More specifically, molecules can recognize selves or
other complementary partners. Such molecular recognition leads to
molecular self-assemblies. Of particular importance, the molecular
codes dictate which molecule will assemble with which molecule.
The consequence is that molecular codes actually control reaction
pathways. In the living cell, preferred self-organization directs and
regulates specific reactions, often at very dilute concentrations (

∼

nM)
while competing with a myriad of other possible reactants without
physical barriers. Nature accomplishes this multifarious task by using
dynamic molecular recognition to sort reactive centers according to
inherent molecular codes, thus augmenting their effective molarity
both efficiently and specifically. Weak secondary forces available
for molecular encoding include dispersion forces, coulombic
interactions, hydrogen bonding, solvophobic forces, metal

−

ligand,

π−π

and stacking interactions [47,48]. Relatively few characters

like size, shape, and charge create such complex molecular codes,
often required to balance molecular rigidity and flexibility. Using
the interactive forces simultaneously and synergistically produces
molecular self-sorting effects or heteromolecular assemblies that
control reaction pathways.

5.5.1 Self-Assembly Direct Specific Reactions

Current studies on molecular self-assembly mostly finish by
characterizing the structural features of the self-organized nano-
objects, such as nanospheres or nanorods. It should be emphasized
that molecular self-assemblies have the capacity to direct
specific reaction pathways that are otherwise difficult to achieve.
Specifically,

π−π

interactions are used as the major driving force to