Dipole-induced, thermally stable lamellar structure by polar aromatic silane.

Controlled self-assembly of polar aromatic silane leads to the formation of well-ordered lamellar structures. Graphite-like features are clearly visible with a scanning electron microscope (SEM). In addition, X-ray diffraction (XRD) patterns suggest a d spacing of 14.28 A along the z-axis and 4.42 A in the xy plane, which all agree with theoretical modeling. Constructing multistacks of silane molecules with a high degree of ordering is a daunting task. Amorphous monolayers are frequently reported. Aggravated van der Waals interaction, pi-pi electron overlapping, and solvophobic interactions can all lead to the formation of multistacks. The importance of a dipole to the ordered stacking is essentially unknown. This work suggests that a strong dipole-dipole interaction can be another important driving force in forming lamellar structures. The resulting large electrostatic interactions between the dipole and water provide an excellent thermal stability for these lamellas up to 350 degrees C. Organized, layered structures with a permanent dipole can be used in piezoelectric devices or as active surfaces to bind polar molecules, such as toxic gas, methanol, or DNA.

Self-assembled nanolayers of conjugated silane with pi-pi interlocking.

The packing of electronic molecules into planar structures and an ensured pi-pi interaction within the plane are preferred for efficient organic transistors. Thin films of organic electronics are exemplar, but the widely adopted molecular design and associated fabrication lead to limited ordering in multistack construction motifs. Here we demonstrate self-assembled nanolayers of organic molecules having potential electronic utility using an amphiphilic silane as a building block. Unlike a cross-linked (tetrahedral) configuration found in conventional siloxane networks, a linear polymer chain is produced following silane polycondensation. As a result, hydrophobic branches plus a noncovalent pi-pi interlocking between the molecules promote planar packing and continuous stacking along the surface normal. In contrast to conventional pi-pi stacking or hydrogen bonding pathways in a fibrous construct, multistacked nanolayers with coexisting pi-pi and herringbone interlocking can provide unmatched properties and processing convenience in molecular electronics.