Spiroligomer

Spiroligomers are kind of like artificial foldamers that do not fold.
In spiroligomers the monomers get connected by pairs of bonds. This is preventing torsion making these molecules stiff (on a small scale)
Spiroligomers are kind of like polyaromatic graphene like small molecules. Just with richer and fully controllable structure.

Spiroligomers in the context of APM targeting gem-gum factories

Advantages:

• High stiffness on small scales
• High scalability in quantity of synthesis (kg scales have been demonstrated)

Disadvantages:

• Low scalability – Synthesis suffers form the exponential drop in yield that is typical for synthetic chemistry
• Their stiffness may not be preservable when synthesized and post assembled to larger scales

Regarding the last point:
Longer linear polymers will certainly bend at some length due to the aspect ratio getting out of hand.
(See: Characteristic bending length)
But even when stacked sideways and somehow interlinked they may not lie flat on each other.
They may rather act like laminated springs (exactly due to their small scale stiffness)
That is if Van der Waals forces don't overpower kink angles that the (much stronger) covalent bonds would ideally desire.
(TODO: Find out if this small-scale-stiffness indeed can cause lower larger-scale-stiffness, or if this is not the case.)

Medical use

Spiroligomers being such foreign artificial structures are not (or only slow and partially?) degraded in organisms.
This can/may be:

• good for medical applications – stuff gets to target before being digested by proteases before that
• bad for medical applications – by the organism as foreign recognized stuff often causes undesired immune responses (see note below though)
• problematic for nature if produced in high quantity and then somehow spilled - persistent organic pollutants

Wikipedia (2021-07): "Spiroligomers are peptidomimetics, completely resistant to proteases, and not likely to raise an immune response." – (without reference)

All that though is of little relevance for non-medical applications like focused bootstrapping efforts
towards the identified far term goal of gemstone metamaterial on-chip nanofactories.

Related

• Highly polycyclic small molecule
• The "downward inward" aspect of: Expanding the kinematic loop
• Maybe a potential material to assembly with foldamer printers?
• Synthetic chemistry
• Stiffness

External links

• Wikipedia: Spiroligomer
• Wikipedia: Spiro compound - rings linked via a single atom without rotational freedom

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• Video (on youtube) [1] Google tech talk:
  "Clasp: Common Lisp using LLVM and C++ for Molecular Metaprogramming" by Christian Scafmeister 2015-07-10