Preparation of a Perylenebisimide Acceptor with Serinol and Nonadecyl-Swallowtail Imides for Use in Molecular Rectification

Several attempts were made to add 2-amino-1,3-propanediol to the acceptor perylene monoanhydride (PMA). The theoretical product, N-(10-nonadecyl)-N'-(1,3-dihydroxypropan-2-yl)perylene-3,4,9,10-bis(dicarboximide), is intended for use in unimolecular rectification because the perylenebisimide core is classified as a good acceptor due to its high electron affinity. Rectification usually utilizes donor-σ-acceptor molecules, whose localized orbitals permit electron transfer when placed between metal electrodes of asymmetric voltages. However, according to an “asymmetric rectification” analysis, an electron can pass from one electrode, through the LUMO of the acceptor, and then to the other electrode when said electrodes are held at certain voltages, and result in rectification if the acceptor is closer to one electrode than to the other.12 Electrical properties are typically measured on a monolayer of rectifying molecules. The desired perylenebisimide (PBI) must be amphiphilic in order to successfully form a monolayer to be used in Langmuir–Blodgett deposition, so that when deposited on a water layer, the molecules will arrange vertically, with the hydrophilic moiety going into the water and the hydrophobic moiety facing upward. Therefore, hydrophilic serinol and a hydrophobic nonadecyl swallowtail were used to achieve such amphiphilic properties when attached to the two ends of PBI. Several difficulties arose from the reactions used to synthesize the PBI, such as unknown impurities, even after purification via column chromatography; potential by-products; non-planar orientations, which could have affected 1H-NMR spectra; and intramolecular interactions. It is unclear why some of the reactions, though published in literature, were unsuccessful. Nevertheless, the reactions and results discussed in this text are useful for devising methods for further efforts to synthesize the target PBI