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Optical Trapping of Nanoparticles
Published on: January 15, 2013
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Trapping Nanostructures on Surfaces through Weak Interactions
Vivien Rauch1, Yoshihiro Kikkawa2, Matthieu Koepf1
1Laboratoire de Chimie des Ligands à Architecture Contrôlée, Institut de Chimie, UMR 7177 CNRS-Université de Strasbourg, 4 rue Blaise Pascal, 67008 Strasbourg (France).
Chemistry (Weinheim an Der Bergstrasse, Germany)
|August 14, 2015
Summary
Researchers explored how zinc porphyrin derivatives with different side chains self-assemble into nanostructures. Solvent choice and evaporation rate significantly control the formation of molecular wires and rods on surfaces.
Area of Science:
- Supramolecular Chemistry
- Materials Science
- Nanotechnology
Background:
- Imidazole-functionalized phenanthroline-strapped zinc porphyrins (ZnPorphen) are of interest for their self-assembly properties.
- Controlling the assembly of these molecules is crucial for developing nanoscale materials and devices.
Purpose of the Study:
- To investigate the solution and interfacial assembly of ZnPorphen derivatives with alkyl and polyethylene glycol (PEG) side chains.
- To understand how solvent properties and evaporation dynamics influence the morphology of assembled nanostructures.
- To elucidate the role of surface-molecule interactions in directing noncovalent assembly.
Main Methods:
- Synthesis and characterization of imidazole-functionalized phenanthroline-strapped zinc porphyrins (ZnPorphen) with varying side chains (alkyl, PEG).
- Solution studies and Atomic Force Microscopy (AFM) imaging of molecular assemblies.
- Casting of ZnPorphen solutions onto highly oriented pyrolytic graphite (HOPG) and mica substrates.
Main Results:
- Solvent and evaporation time critically affected the morphology of ZnPorphen assemblies.
- Alkyl-ZnPorphen formed short rods on HOPG with fast evaporation in CHCl3, THF, or pyridine.
- Islands of aligned rows of longer wires were observed from methylcyclohexane (MCH) solutions, with 3D assembly upon slow MCH evaporation.
- PEG-ZnPorphen assembled into short wires on HOPG or fibers on mica after slow THF evaporation.
Conclusions:
- Surface-molecule interactions play a key role in the interfacial assembly of ZnPorphen derivatives.
- Parameters such as solvent choice and evaporation rate can be tuned to control the formation of specific nanostructures (rods, wires, fibers).
- This work provides insights into the noncovalent assembly mechanisms for creating molecular wires on surfaces.
