화학공학소재연구정보센터
Applied Surface Science, Vol.433, 1075-1082, 2018
Concentration-dependent multiple chirality transition in halogen-bond-driven 2D self-assembly process
The concentration-dependent self-assembly of iodine substituted thienophenanthrene derivative (5,10-DITD) is investigated at the 1-octanic acid/graphite interface using scanning tunneling microscopy. Three kinds of chiral arrangement and transition of 2D molecular assembly mainly driven by halogen bonding is clearly revealed. At high concentration the molecules self-assembled into a honeycomb-like chiral network. Except for the interchain van der Waals forces, this pattern is stabilized by intermolecular continuous C = O center dot center dot center dot I center dot center dot center dot S halogen bonds in each zigzag line. At moderate concentration, a chiral kite-like nanoarchitecture are observed, in which the C = O center dot center dot center dot I center dot center dot center dot S and I center dot center dot center dot O = C halogen bonds, along with the molecule-solvent C = O center dot center dot center dot I center dot center dot center dot H halogen bonds are the dominated forces to determine the structural formation. At low concentration, the molecules form a chiral cyclic network resulting from the solvent coadsorption mainly by molecule-molecule C = O center dot center dot center dot I center dot center dot center dot S halogen bonds and molecule-solvent C = O center dot center dot center dot I center dot center dot center dot H halogen bonds. The density of molecular packing becomes lower with the decreasing of the solution concentration. The solution-concentration dependent self-assembly of thienophenanthrene derivative with iodine and ester chain moieties reveals that the type of intermolecular halogen bond and the number of the co-adsorbing 1-octanic acids by molecule-solvent C = O center dot center dot center dot I center dot center dot center dot H halogen bonds determine the formation and transformation of chirality. This research emphasizes the role of different types of halogen (I) bonds in the controllable supramolecular structures and provides an approach for the fabrication of chirality. (C) 2017 Elsevier B.V. All rights reserved.