Supramolecularly Engineered Perylene Bisimide Assemblies Exhibiting Thermal Transition from Columnar to Multilamellar Structures

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• 作者：Shiki Yagai ; Mari Usui ; Tomohiro Seki ; Haruno Murayama ; Yoshihiro Kikkawa ; Shinobu Uemura ; Takashi Karatsu ; Akihide Kitamura ; Atsushi Asano ; Shu Seki
• 刊名：The Journal of the American Chemical Society
• 出版年：2012
• 出版时间：May 9, 2012
• 年：2012
• 卷：134
• 期：18
• 页码：7983-7994
• 全文大小：696K
• 年卷期：v.134,no.18(May 9, 2012)
• ISSN：1520-5126

文摘

Perylene 3,4:9,10-tetracarboxylic acid bisimide (PBI) was functionalized with ditopic cyanuric acid to organize it into complex columnar architectures through the formation of hydrogen-bonded supermacrocycles (rosette) by complexing with ditopic melamines possessing solubilizing alkoxyphenyl substituents. The aggregation study in solution using UV鈥搗is and NMR spectroscopies showed the formation of extended aggregates through hydrogen-bonding and 蟺鈥撓€ stacking interactions. The cylindrical fibrillar nanostructures were visualized by microscopic techniques (AFM, TEM), and the formation of lyotropic mesophase was confirmed by polarized optical microscopy and SEM. X-ray diffraction study revealed that a well-defined hexagonal columnar (Col_h) structure was formed by solution-casting of fibrillar assemblies. All of these results are consistent with the formation of hydrogen-bonded PBI rosettes that spontaneously organize into the Col_h structure. Upon heating the Col_h structure in the bulk state, a structural transition to a highly ordered lamellar (Lam) structure was observed by variable-temperature X-ray diffraction, differential scanning calorimetry, and AFM studies. IR study showed that the rearrangement of the hydrogen-bonding motifs occurs during the structural transition. These results suggest that such a striking structural transition is aided by the reorganization in the lowest level of self-organization, i.e., the rearrangement of hydrogen-bonded motifs from rosette to linear tape. A remarkable increase in the transient photoconductivity was observed by the flash-photolysis time-resolved microwave conductivity (FP-TRMC) measurements upon converting the Col_h structure to the Lam structure. Transient absorption spectroscopy revealed that electron transfer from electron-donating alkoxyphenyl groups of melamine components to electron-deficient PBI moieties takes place, resulting in a higher probability of charge carrier generation in the Lam structure compared to the Col_h structure.