Molecular self-assembly for macroporous rectangular pipes

Abstract

A small organic molecule, 4-dodecanoxy-2-trifluoromethylbenzamide, self-assembles to form a macroporous organic rectangular-shaped pipe, by simply dropping the hot ethanol solution onto silicon substrate. The pipe has parallelogram-like entrance with cross section of ~20 ㎛ and wall thickness of ~150 ㎚. Changing the tail length with 8, 10, 14, and 16 carbons affected the formations of pipes. 4-Tetradecanoxy-2-trifluoromethylbenzamide showed macroporous rectangular pipes, but the others did not form. The formation of the pipe was affected by the alkyl chain length. The supramolecular structure of pipes was investigated by SEM, XRD, DSC, and $^{13}C$ NMR. The spectral analyses show that the pipe is composed of two different polymorphs. It seems that the unusual rectangular-shaped pipe is the result of intermolecular interaction and cooperative structure evolution through drying-mediated self-assembly.