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Selection of conformational states in self-assembled surface structures formed from an oligo(naphthylene-ethynylene)
Y Ning1, J R Cramer1, A Nuermaimaiti1
1Interdisciplinary Nanoscience Center (iNANO) and Danish National Research Foundation: Danish-Chinese Centre for Self-Assembly and Function of Molecular Nanostructures on Surfaces, 8000 Aarhus C, Denmark.
The Journal of Chemical Physics
|March 16, 2015
Summary
Molecular flexibility drives complex surface self-assembly. This study reveals how specific molecular conformations are selected through steric interactions, leading to ordered structures on gold surfaces but varied states on copper surfaces.
Area of Science:
- Surface science
- Supramolecular chemistry
- Materials science
Background:
- Molecular conformational flexibility can increase the complexity of self-assembled structures on surfaces.
- Systematic studies on the selection of specific molecular conformations during surface self-assembly are limited.
Purpose of the Study:
- To investigate the selection of molecular conformational states during surface self-assembly.
- To understand the role of intermolecular interactions in controlling conformational selection.
- To explore the influence of different metal substrates (Au(111) and Cu(111)) on self-assembly behavior.
Main Methods:
- High-resolution scanning tunneling microscopy (STM) for visualizing surface structures.
- Density Functional Theory (DFT) calculations for modeling molecular interactions and conformations.
- Statistical analysis of molecular conformations.
Main Results:
- On Au(111), molecules self-assembled into ordered brick-wall and lamella phases, each utilizing specific subsets of the molecule's eight possible conformations.
- On Cu(111), isolated molecules exhibited a distribution across all possible conformational states, suggesting substrate-dependent selection.
- Steric interactions between naphthalene units were identified as the primary driver for conformational selection.
Conclusions:
- Surface self-assembly processes actively select specific molecular conformations, influenced by intermolecular interactions and substrate properties.
- The study demonstrates a mechanism for controlling the complexity and ordering of supramolecular structures through molecular design and substrate choice.
- Findings advance the understanding of structure formation in systems with high conformational diversity.
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