Influence of Multidirectional Interactions on Domain Size and Shape of 2-D Molecular Assemblies

The polymorphism of porphyrin 2D assemblies at the liquid-graphite interface: the effect of a polar solvent additive and a flexible spacer on the face-on and edge-on type molecular arrangements

Self-assembly structures of 5,10,15,20-tetrakis(4-substituted phenyl)porphyrins at the liquid-graphite interface were investigated by scanning tunneling microscopy. We found that the presence of a small amount of a polar solvent, i.e., only 0.5 vol% of octanoic acid in phenyloctane, significantly affected the selective formation of the face-on polymorph over the edge-on one likely due to the solvent-molecule interactions at the 2D interface.

Self-assembly of photochromic diarylethene-peptide conjugates stabilized by β-sheet formation at the liquid/graphite interface

Two-dimensional (2-D) self-assembly of diarylethene (DAE)-peptide conjugates at the octanoic acid/graphite interface was investigated by scanning tunnelling microscopy (STM). The open-ring isomer of a DAE-peptide conjugate formed a stable 2-D molecular assembly with an antiparallel β-sheet structure. Quantitative analysis of surface coverage depending on concentration revealed a stronger stabilization effect of the oligopeptide than that of the alkyl group with a similar side chain length.

Mechanism of Ostwald Ripening in 2D Physisorbed Assemblies at Molecular Time and Length Scale by Molecular Dynamics Simulations

Ostwald ripening can improve the long-range order of self-assembled monolayers by the growth of large domains and disassembly of smaller ones. Here, coarse-grained molecular dynamics simulations are used to study the dynamics of the stable assembly and the coarsening of defects of physisorbed monolayers of long-chain functionalized alkanes. Our results show that the partial desorption from the surface of one or more adsorbent molecules is the essential process that allows other adsorbent molecules to rearrange on the surface and thereby improve alignment. We also show that the ripening process is faster at higher temperature because the rate of partial desorption is higher.