2006 F1 Self-Assembly 1

8/8/2019 2006 F1 Self-Assembly 1

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Ck80 Organic Nanochemistry

Self-assembly

Organic Nanochemistry

Spring 2006

Kurt Gothelf


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Nanotechnology my first encounter

Engines of Creation: The Coming Era of Nanotechnology

K. E. Drexler, Fourth Estate, 1990

Nanosystems: Molecular Maschinery, Manufacturing, and Computation

K. E. Drexler, John Wiley and Sons, 1992

K. E. Drexler


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Design and fabrication of nano-structures

Miniaturization of known systems

Apply methods resembling nature

Develop new methods


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Bottom up versus Top down


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NANOTECHNOLOGY APPROACHES

Top-down

Bottom-up


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Self-assembly

Non-covalent interactions: Hydrogen bondsMetal coordination complexesVan der Waals interactionsHydrophobic interactionsElectrostatic interactions

Equilibrium conditions: Rejects defectsSelf-healing(Assembly by many reversible weak interactions)

Whitesides et al. Science254 1312 (1991).

Molecular self-assembly is the spontaneous association of moleculesunder equilibrium conditions into stable, structurally well definedaggregates joined by non-covalent bonds.


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Self-assembled structures of nature

Egg and sperm

Governor of California


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Function of the cell is based onself-assembly


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Building molecular nanostructures

Traditional organic synthesis

Polymer chemistry

Self-organization into polydisperse aggregates(Self-organization)

Self-assembly into monodisperse aggregates

(Molecular self-assembly)


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Molecular interaction leading tomolecular organization

Self-organization

Molecular self-

assembly(Specific molecular

recognition)

Forming monodisperse assemblies


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Examples Polydisperse structures membranes, micelles and vesicles

self-assembled monolayers

monolayers on colloides coordination chemistry on surfaces

polymers

crystals

Monodisperse structures compounds made by conventional organic synthesis

dendrimers

supramolecular chemistry (closed shell structures)

molecular recognition by DNA and analoges

countles other interactions in biologial systems


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Cell membrane


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Hydrophobic and hydrophilic interactions

Selv-organisring


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Arrangement of phospholipides


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Flexibility of membranes

Inside cell

Cell membrane

Vesicle containing

waste material

Outside cell


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LM-techn


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Ultrathin Organic Films

a) Langmuir film: film at the water-air interface

b) Langmuir-Blodgett film (LB): mono- or multi-layers transferred from the

water-air interface onto a solid substrate.

c) Self-assembled monolayers: molecular assemblies that are formed

spontaneously on a surface by the immersion into a solution of an activesurfactant in an organic solvent


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Nature the master of

self-assembly


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The central dogma


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DNA


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Using DNA as an encoding materialto assemble nanostructures

DNA-helix

C

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Forskellige DNA-kder

med 15 baser = 415

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Information i DNA

1g rent DNA

indeholder information svarende til1012 compact discs!


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Example: Kinetics of DNA hybridization

Steed & Atwood Supramolecular Chemistry

Ck80 O i N h i


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Proteins

Ck80 O i N h i t


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Ribosomet aflser mRNA ogudfrer proteinsyntese



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Ribosomer er ca. 28 nm i diameter,og kan ses ved elektronmikroskopi

Ribosomer mRNA Proteinkde



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Ribosomet studeres i dag i atomar detalje

en plet en klump 200.000 atomer

Ref. Poul Nissen, iNANO



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Ribosomets indre



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Whitesides definitions1) Self-assembly involves association by many weak, reversible, interactions to obtain

a final structure that represents a thermodynamic, minimum. Incorrect structuralunits are rejected in the dynamic, equilibrium assembly. This equilibration allows

high fidelity in the process.2) Self-assembly occurs by a modular process. The formation of stable subassemblies

by sequential covalent processes precedes their assembly into the final structure.This mechanism allows for efficient assembly from the preformed units [a"convergent synthesis," in the therms of organic chemistry].

3) Only a small number of types of molecules are normally involved in modular self-assembly. Consequently, a limited set of binding interactions is required to causethe final structure to form. This principle minimizes the amount of informationrequired for a particular structure.

4) Self-assembly often displays positive cooperativity.

5) Complementarity in molecular shape provides the foundation for the association

between components. Shape-dependent association based on van der Waals andhydrophobic interactions can be made more specific and stronger, by hydrogenbonding and electrostatic interactions.



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g y

Self-assembly at the meso-scale



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g y

Mesoscopic Self-assembly

Whitesides and co-workers, SCIENCE, 284 948 (1999)



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Self-assembled electrical network

Whitesides and co-workersSCIENCE 289 1170 (2000).

2006 F1 Self-Assembly 1

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