In Situ Scanning Tunneling Microscopy of Solvent-Dependent Chiral Patterns of 1,4-Di[4-N-(trihydroxymethyl)methyl carbamoylphenyl]-2,5-didodecyloxybenzene Molecular Assembly at a Liquid/Highly Oriented Pyrolytic Graphite Interface

Solvent effect on chirality of 1,4-di[4-N-(trihydroxymethyl)methyl carbamoylphenyl]-2,5-didodecyloxybenzene (DTCD) self-assembled adlayer on highly oriented pyrolytic graphite (HOPG) is investigated by in situ scanning tunneling microscopy using tetrahydrofuran (THF), 1-phenyloctane (PO), 1-octanol, and 1,2,4-trichlorobenzene (TCB) as solvent. Different chiral patterns arc acquired in these solvents, suggesting that the chiral assembly of DTCD is solvent-dependent. With use of THF or PO as solvent, chiral patterns with windmill-shaped tetramer units are observed. In contrast, a racemic lamellar structure is revealed in I-octanol.. The coadsorption of I-octanol molecules makes an important contribution to the formation of racemic lamellar structure. A structure transition from racemic lamellar structure to tetramer-based chiral patterns is observed with removal of I-octanol molecules by thermal annealing. When TCB is used as solvent, a chiral meshy structure is formed at the TCB/HOPG interface. The results reported here demonstrate that solvent can significantly affect the chirality in molecular self-assembly and provide a potential approach to finely tune the chiral molecular architectures on solid surfaces.