Overview
This lecture covers the concept of molecular self-assembly, its types, key roles in chemistry, biology, and materials science, and notable examples and applications.
Introduction to Molecular Self-Assembly
- Molecular self-assembly is the process where molecules arrange into defined structures without outside guidance.
- There are two types: intermolecular (between molecules) and intramolecular (within a single molecule, often called folding).
Supramolecular Systems and Interactions
- A key concept in supramolecular chemistry, guided by non-covalent interactions (hydrogen bonding, metal coordination, hydrophobic, van der Waals, pi-stacking, electrostatic).
- Self-assembly yields diverse structures like colloids, micelles, vesicles, liquid crystals, and Langmuir monolayers.
- Enables complex topologies, like Borromean rings, with DNA used as a building block in some cases.
- Essential for biological macromolecular assemblies including membranes, DNA helices, and protein structures.
- Misassembled proteins can lead to diseases like prion-related neurodegeneration.
- Seen in natural nanostructures like gecko adhesion organs.
Multimers and Genetic Complementation
- Proteins may self-assemble into multimers from polypeptides encoded by the same or different alleles.
- Intragenic complementation occurs when mixed multimers from different mutants have enhanced function.
Nanotechnology and Bottom-Up Fabrication
- Molecular self-assembly is foundational for bottom-up nanotechnology, programming structure via molecular design.
- Contrasts with top-down approaches like lithography.
- DNA nanotechnology uses self-assembly for constructing 2D and 3D lattices and as templates for assembling nanoparticles.
Two-Dimensional Monolayers
- Single molecular layers form at interfaces through 2D self-assembly, examples include Langmuir-Blodgett films.
- Scanning tunneling microscopy proved non-surface active molecules also self-assemble in ordered structures.
- 2D crystal engineering aims to design highly crystalline nanostructures.
Key Terms & Definitions
- Molecular self-assembly — spontaneous organization of molecules into stable, well-defined structures.
- Intermolecular — interactions or assembly occurring between two or more molecules.
- Intramolecular — folding or assembly within a single molecule.
- Supramolecular chemistry — study of chemical systems composed of a discrete number of assembled molecular subunits.
- Non-covalent interactions — chemical interactions not involving the sharing of electron pairs (e.g., hydrogen bonding, van der Waals).
- Multimer — protein complex formed by self-assembly of two or more polypeptide chains.
- Bottom-up nanotechnology — constructing materials from molecular components via self-assembly.
Action Items / Next Steps
- Review examples of molecular self-assembly in nature and technology.
- Study types of non-covalent interactions and their roles in assembly.
- Explore additional resources on 2D crystal engineering and DNA nanotechnology.