文摘
The two-dimensional supramolecular structures of a series of N,N鈥?bis(n-alkyl)naphthalenediimides (NDIs), whose chain lengths span from C3 to C18, at a liquid鈥揌OPG surface interface, studied by STM and FM-AFM, are assigned with the help of molecular dynamics/molecular mechanics calculations to demonstrate that the C3- and C4-NDIs show lamellar structures, the C4- to C12-NDIs show honeycomb (KAGOME) structures, and the C14- to C18-NDIs show lamellar structures again. The change in supramolecular structure depending on chain length can be explained semiquantitatively by the balance of entropy and enthalpy terms to show the importance of 鈥渟elf-avoiding walk鈥?of the alkyl chain in entropy terms.
Keywords:
supramolecular structure; naphthalenediimide; HOPG surface; STM; FM-AFM; molecular dynamics; entropy; self-avoiding walk