Supramolecular nanofibers (SNFs) composed of low-molecular-weight π-conjugated molecules exhibit attractive optical and electrical properties and are expected to be the next optoelectronic materials. In this work, five crystalline SNFs have been constructed from three dehydrobenzoannulene (DBA) derivatives. The DBAs were designed to assemble in one dimension in a strategy based on anisotropic crystal growth. The crystallinity of the SNFs allowed the molecular arrangements in the SNFs to be determined. Therefore the mechanism of construction and correlations between the molecular arrangements and optical and electrical properties could be considered. The results clearly indicate that the properties of the SNFs are affected by the chemical structures and molecular arrangements. Moreover, one of the SNFs exhibits a high charge-carrier mobility (Σμ=0.61 cm(2) V(-1) s(-1)) because of its crystallinity and appropriate molecular arrangement. This systematic experimental study based on a proposed strategy has provided information for improving the electrical properties of SNFs. This strategy will lead to highly functional SNFs.

To modulate assembly manners of octadehydrodibenzo [12]annulene ([12]DBA) core in solid state, we first synthesized ortho-phenyl-substituted derivative 2 and investigated the effects of the substituents on the molecular stacking manner of the [12]DBA core.[12]DBA 2 yielded four types of crystals, which differ from that of the parent compound: Namely, the guest-free crystal possessing an offset stacking manner (I-GF), the solvate with a edge-to-face arrangement (II), the solvates with zigzag π-stacked arrangements (III and III¤), and the solvate with 1D π-stacked columnar arrangements (IV). In the crystals, the phenyl groups contribute to limiting the stacking geometry of the [12]DBA cores and to forming void spaces accommodating various guest species, allowing versatile molecular assembly manners hitherto known for [12]DBA derivatives. We revealed that the crystals showed structure dependent fluorescence and charge carrier behaviors.

Introduction of rigid aryl substituents into the periphery of a π-conjugated molecule changes its assembly manner from that of the parent compound, resulting in drastic changes of optical and electrical properties of the assembly. In this study, we revealed that ortho-thienyl substituted octadehydrodibenzo[12]annulene derivative 2 yielded two types of crystal structures with zigzag and one-dimensionally (1D) π-stacked motifs. Their thermal, optical, and electrical properties were investigated. Furthermore, we demonstrate that although the phenyl-and thienyl-substituted derivative (1 and 2, respectively) yielded closely resembled 1D π-stacked columns in their crystals (1-column and 2-II, respectively), arrangements of the columns are completely different due to subtle differences of the substituents. Such differences in the arrangements drastically affect the lifetime of charge carrier generated in crystals, although the intensity of the photoconductivity is almost the same in both crystals. These results can provide a new insight for tuning of the assembly's properties by changing the peripheral aryl substituents of π-conjugated molecules.

We present the crystal structure of a coaxially π-stacked discrete dimer of a [12]DBA derivative possessing six peripheral (tert-butoxycarbonyl)amino groups. The dimer has a significantly short interplanar distance (3.25 ¡), which is achieved by the sixfold intermolecular hydrogen bonds formed among the peripheral amide moieties. The adjacent dimers are isolated by bulky peripheral tert-butyl groups.Discrete supramolecular structures composed of a precise number of discotic π-conjugated molecules or discotic metal complexes are of substantial interest from the optical and electronic points of view as well as coordination programing. 1Till date, various discrete structures have been achieved using π-conjugated molecules such as porphyrin and phthalocyanine derivatives, 2 polycyclic aromatic hydrocarbons, 3 and transitionmetal ion complexes, 4 in well-defined coordination cages 5 or by applying ingeniously controlled (charge-assisted) hydrogenbonding templates.In connection with this, we became interested in the construction of coaxially π-stacked discrete assemblies of hexadehydrotribenzo [12]annulene ([12]DBA), 6 a π-conjugated cyclic molecule composed of three benzene rings and three acetylene units. [12]DBA is known to form complexes with metal species such as Ni(0) at its center pocket surrounded by three triple bonds.7 Therefore, coaxially stacked discrete assemblies of the complex would provide a new class of discrete metal arrays. 8 In this paper, we present the design, construction, and crystal structure of a discrete dimer, the smallest discrete assembly, of a [12]DBA derivative. As shown in Figure 1, we hypothesized that a monomer possessing functional groups capable of forming multi-hydrogen bonds and bulky groups in high symmetric positions can give a coaxially π-stacked discrete dimer, because the hydrogen-bonding groups can assist coaxial molecular stacking through directional intermolecular interactions and the appropriate bulky substituents allow the monomer to dimerize but prevent the dimer from stacking into higher aggregates. Based on the idea, we designed [12]DBA derivative 1 with six (tert-butoxycarbonyl)amino groups on its periphery, where amide groups are often applied to achieve a coaxially stacked one-dimensional supramolecular structure of discotic molecules. 9[12]DBA 1 was synthesized as shown in Scheme 1. Amino groups of 4,5-diiodo-1,2-diaminobenzene (2) were amidated with anhydrous tert-butoxycarbonyl to give bis[(tert-butoxycarbonyl)amino]benzene derivative 3. The Sonogashira coupling reaction of 3 with 1.5 equiv of trimethylsilylacetylene gave a mixture of mono-and dialkynylated 4a and 4b, which are difficult to separate. Desilylation of the mixture of 4a and 4b in the presence of tetrabutylammonium fluoride, on the other hand, allowed one to separate the resultant mono-and diethynylbenzene derivatives 5a and 5b by column chromatography. The precursor 5a was cyclotrimerized in the presence of Pd (0) catalyst to give 1.10 Although the association behavior of 1 in solution has not ...

Effects of ortho-Phenyl Substitution on Molecular Arrangements of Octadehydrodibenzo[12]annulene. -The effects of ortho-phenyl substitution in title compound (VI) are studied. The X-ray structures of (VI) and some of its solvates are given. -(HISAKI, I.; MANABE, N.; OSAKA, K.; SAEKI, A.; SEKI, S.; TOHNAI, N.; MIYATA*, M.; Bull. Chem. Soc. Jpn. 87 (2014) 2, 323-333, http://dx.doi.org/10.1246/bcsj.20130279 ; Dep. Mater. Life Sci., Grad. Sch. Eng., Osaka Univ., Suita, Osaka 565, Japan; Eng.) -M. Bohle 33-059