Rearrangements of N-octyl-D-gluconamide fibers and bilayers on gold and silicon surfaces

N-Octyl-D-gluconamide (1) is known to form noncovalent quadruple helices in bulk aqueous media. Upon adsorption to mica these fibers survive; on gold they rearrange to give a head-to-tail bilayer. This is the thermodynamicall y most stable arrangement found in 3D-crystals. Upon heating to 86 degrees C, a rearrangement to a tail-to-tail bilayer occurs. This cannot be detecte d in atomic force microscopy (AFM) height diagrams, but leads to pronounced changes of phase shifts in the tapping mode of AFM. Tapping also induces a reversal of the bilayer rearrangement.