The formation of two-dimensional supramolecular chiral lamellae by diamidemolecules at the solution/graphite interface: A scanning tunneling microscopy study

We report on a scanning tunneling microscopy (STM) study of a self-assemble d monolayer at the solution/graphite interface of long-chain molecules func tionalized with two amide groups in the middle. The diamide molecules were synthesized by the condensation of acid chloride with the appropriate diami ne. Our results have shown that the molecules organize side-by-side into we ll-ordered two-dimensional (2-D) lamellae through an interchain hydrogen-bo nded network. The molecularly resolved STM images indicate that these supra molecular lamellae express chirality due to the constraints of the intercha in hydrogen bonding, even though individual molecules are achiral. Supramol ecular lamellae with opposite chirality are spontaneously separated into cr ystalline domains of respective handedness. The structure of these 2-D lame llae is different from the cutoff of their three-dimensional crystals. The stability of the monolayer is very sensitive to the balance of adsorbate/su bstrate and interchain interactions. The domain boundaries have shown inter esting dynamic motion at different stages of the film growth.