Perylene Bisimide Derivatives With Self-assembling Functionalities: Self-assembling In Acid Medium

A fundamental task for scientists in the area of opto-electronic materials is to construct expected structures on molecular level, including two categories: molecular structure and supramolecular structure. There are still a list of challenges for tuning the aggregation structures and controlling their properties, although the chemical structures and properties can be pre-designed using available chemistry toolbox. Considering that the aggregation states play key roles in the determination of the opto-electronic performance of those emerging organic semiconduting materials, the modulation of secondary molecular interactions, the construction of 0-3 dimensional ordered nanostructures, the understanding of the relationship between aggregation structures and properties are crucial in this research field. Here we synthesized different dyes capable of self-assembling by using perylene-bisimide as building-block with n-type semiconductor nature, hydrogen-bond and n-n interactions as driving force to self-assemble. Their behaviors of self-assembling in acid atmospheres have been studied and the results are mainly summarized as following:1. Perylenebisimides with acetylethylenediamine, amino, and thiol functional groups have been synthesized. Their chemical structures have been characterized with modern techniques such as ~1H NMR, FTIR and element analyses.2. As a representative, the effects of acidity on the structure and morphology of perylenebisimides with acetylethylenediamine were investigated. Wire-like micro-structure with hundreds of micrometer in length and about 200nm in diameter have been derived in acetic acid. Their absorption spectra are characterized by "in phase" alignment of perylene chromophores. With decreasing of the concentration of acetic acid from100% to 40%, the length of micro-wires became shorter and the morphology turned into nanorods, the system changed from black to dark red, and the absorption feature at 645nm shifted to 571nm. When the concentration of acetic acid decrease from 40% to about 20%, nanorods decomposed and the morphology varied to leave-like;Meanwhile, the color of the system turned from dark red to red, and the absorption feature at 571nm shifted to around 587nm.3. The self-assembling process of perylenebisimides with acetylethylenediamine groups depended on the counterions of the acids. When hydrochloride acid, formadic acid, acetic acid and methylacrylate acid was applied as matrix for self-assembling, the nanostructures were predominantly amorphous articles, nanorods, long naowires, and nanowires.4. By replacement of the amide with larger porphyrin group, it has been observed that, the perylene-porphyrin dyad underwent a conversion of the aggregation states by inducing of trifluoro-acetic acid: for perylene-bisimide motif, from J-aggregate to H-aggregate;while for porphyrin motif, from J-aggregate to ill-defined aggregate. Meanwhile, the particles transformed from ordered crystalline to amorphous states.