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

Abstract

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-vis and NMR spectroscopies showed the formation of extended aggregates through hydrogen-bonding and π-π 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.

Supramolecularly Engineered Functional π-Assemblies Based on Complementary Hydrogen-Bonding Interactions

“…53 Concentration-dependent UVvis absorption study of the 1:1 mixture of 17 and Mel in CHCl 3 showed an assembly process that proceeds by a nucleationelongation mechanism with the nucleation factor · (= K nuc /K elong ) of 0.01 (Figures 17b and 17c). Because the assembly process of most soluble PBI dyes into onedimensional columnar aggregates obeys isodesmic mechanism with · = 1, the markedly low · value of the 1:1 mixture reflects the hierarchical association of hydrogen-bonded complexes.…”

Recent advance of photochromic diarylethenes-containing supramolecular systems

“…Supramolecular chemistry [1] has been one of the most attractive research topic of modern chemistry, and is still receiving rapid progresses in multidisciplinary fields, such as supramolecular photochirogenesis [2,3], organic electronic devices [4,5] and biocompatible materials [6]. Stimuli-responsive supramolecular systems is particularly intriguing because they provides an attractive approach for creating novel materials that are capable of responding to environmental changes [7][8][9].…”

Integration of electro-active π-conjugated units in nanosegregated liquid-crystalline phases

“…36 Supramolecular aggregations of PTCBI derivatives based on hydrogen-bonding have also been reported. 37 In this study, we synthesized LC PTCBI derivatives bearing oligosiloxane moieties at the terminal positions of the alkyl side chains.…”