AFM and DFT study of diverse self-organization pattern of aminothiacalix[4]arene

Here we report on the diverse self-assembly behavior of aminothiacalix[4]arene (ATCA) drop-casted or spin-coated onto a silicon substrate. The nanofilms of ATCA feature the picket-fence domains composed of rod-shaped crystals with the mean size of ca. 700 nm, as well as the ornate patterns composed of interdigitating 3.5-mu m grooves and periodically alternating ridge-like framework, with the ridge diameter 90 +/- 20 nm and ridge spacing of ca. 3.5 mu m. DFT calculation of possible ATCA dimers revealed a favorable arrangement of ATCA monomers either in a face parallel fashion expanding into the 1D channel structure or in a face antiparallel fashion affording the 1D zigzag chain structure. UV/Vis spectroscopy and powder X-ray diffraction data provided further evidence to the existence of thermodynamically favorable pi-stacked and hydrogen-bonded ATCA associates in solution and solid state.