Search

New polyaromatic molecular tubes with a subnanometer pore (0.8 nm) were prepared. The tube bearing six sulfonate groups on the periphery and twelve methoxy groups at the openings provides a cylindrical hydrophobic cavity with a length of ∼1.3 nm. The aqueous tube can quantitatively bind one molecule of hydrocarbon guests in water with accompanying guest-induced emission enhancement (up to ∼3 times) of the host framework.

Polycyclic aromatic hydrocarbons (PAHs) are excellent building blocks for the creation of two‐dimensional (2D) nanosheets. However, large PAHs tend to exhibit poor or no solubility in organic solvents and water. To overcome this issue, we employed water‐soluble micellar capsules consisting of V‐shaped amphiphilic molecules. Characteristic electrochemical behavior was observed in 0.1 m H2SO4 in the presence of the water‐soluble capsules containing PAHs, such as ovalene, circobiphenyl, and dicoronylene. Furthermore, under these conditions, PAHs were released from the capsules, resulting in the formation of a 2D adlayer of PAHs at the electrochemical interface. Finally, using electrochemical scanning tunneling microscopy, we demonstrate that our molecular containers based on water‐soluble molecular capsules allow the facile preparation of 2D PAH adlayers in addition to structurally controlling nanostructure formation on Au surfaces. Packaged and delivered: Water‐soluble molecular capsules consisting of V‐shaped amphiphiles were designed for the uptake of polycyclic aromatic hydrocarbons (PAHs). The PAHs were released from the molecular containers in 0.1 m H2SO4 at an electrochemical interface, thus enabling the facile preparation of 2D PAH adlayers on an Au surface with controlled nanostructure formation (see picture). [ABSTRACT FROM AUTHOR]

Micelles are a versatile class of molecular assemblies typically composed of aliphatic molecules with hydrophilic groups. Polyaromatic molecules with hydrophilic groups, on the other hand, usually do not assemble into micellar structures in water but rather form columnar, π-stacked architectures. This Minireview article focuses on the recent development of aqueous micellar nanostructures with multiple oligoarylene rods or polyaromatic panels. The new micelles with spherical polyaromatic shells, which we name 'aromatic micelles', serve as functional molecular flasks with superior binding abilities for medium to very large molecules in water. [ABSTRACT FROM AUTHOR]

Bulk molybdenum disulfide (MoS2) itself is virtually insoluble in common organic solvents because of the tight stacks of multiple MoS2 nanosheets. Here we report that V-shaped polyaromatic compounds with non-ionic side chains can efficiently exfoliate and disperse the inorganic nanosheets. Simple grinding and sonication (less than total 1 h) of MoS2 powder with the V-shaped compounds gave rise to large MoS2 nanosheets highly dispersed in NMP through efficient host-guest S-π interactions. DLS and AFM analyses revealed that the lateral sizes (ca. 150-270 nm) and thicknesses (ca. 2-8 nm) of the products depend on the identity of the non-ionic side chains on the V-shaped dispersant. [ABSTRACT FROM AUTHOR]

In spite of wide-ranging previous studies on synthetic macrocycles, the installation of open-close functions into the frameworks remains a challenge. We present a new polyaromatic macrocycle capable of switching between open and closed forms in response to external stimuli, namely, base and acid. The macrocycle, which is prepared in three steps, has a well-defined hydrophobic cavity with a length of around 1 nm, surrounded by four pH-responsive acridinium panels. The open and closed structures were confirmed by single-crystal X-ray analysis. The cylindrical cavity can bind long hydrophilic molecules up to 2.7 nm in length in neutral water and then release the bound guests through a reversible open-to-closed structural change upon simple addition of base. [ABSTRACT FROM AUTHOR]

By the covalent linkage of two bent bisanthracene amphiphiles with a biphenyl spacer bearing hydrophilic pendants, we synthesized a new molecular clip with a C-shaped conformation. The molecular clip provides an acyclic, open cavity surrounded by four anthracene panels in water. In contrast to previous clip- and tweezers-like compounds as well as cage-shaped compounds, the C-shaped polyaromatic cavity displays unusual wide-ranging capturing abilities toward not only planar perylene-based pigments and cylindrical single-walled carbon nanotubes but also highly branched macromolecules (carbazole dendrimers). [ABSTRACT FROM AUTHOR]

The methyl group is a small substituent, usually showing relatively weak or no interactions with other functional groups and metal ions. Herein, we present the recognition of the number of methyl groups on synthetic and natural aromatic compounds (i.e., benzene and xanthine derivatives, respectively) by the 1 nm-sized polyaromatic cavity of a coordination capsule in water. Detailed competitive encapsulation experiments as well as X-ray crystallographic analysis revealed that multiple guest-host CH3-polyaromatic interactions in the confined nanospace are key driving forces for the high selectivity. [ABSTRACT FROM AUTHOR]

Nanocarbons are synthetic carbon-rich compounds with polyaromatic frameworks that have lately attracted attention as emerging functional materials. However, their extreme hydrophobicity and aggregation peculiarity, besides their shape and size diversities, precluded their study in solution, especially in 'green' water. More convenient and general solubilizing methods of nanocarbon frameworks are required by using non-covalent supramolecular interactions. Here we report a protocol for solubilizing a wide range of nanocarbons, that is, fullerenes (C60, C70, C84, and C120), polyarenes (tetracene, pentacene, perylene, coronene, and hexabenzocoronene), and carbon nanotubes (single-walled and multi-walled CNTs), in water through manual grinding with V-shaped polyaromatic amphiphiles. The obtained aqueous nanocomposites are composed of nanocarbons encircled by the polyaromatic frameworks of the amphiphiles through multiple aromatic-aromatic interactions. Notably, the encapsulated photosensitive nanocarbons, such as tetracene, pentacene, and fullerene dimer, exhibit unusual stability toward UV/Vis light. [ABSTRACT FROM AUTHOR]

Anisotropic expansion of a spherical M2L4 coordination capsule through the elongation of the ligand led to a new M2L'4 capsule. The expanded capsule provides an elliptical cavity encircled by polyaromatic frameworks with large openings and thereby can encapsulate elliptical fullerene C70 and monofunctionalized fullerene C60 in high yields. In addition, selective formation of a new M2L2L'2 capsule occurs by mixing the original M2L4 and expanded M2L'4 capsules in a 1:1 ratio upon addition of C60 or monofunctionalized C60 as a template molecule. [ABSTRACT FROM AUTHOR]

A fluorescent macrocycle containing four anthracene panels linked by meta-phenylene spacers and amino hinges was synthesized. The macrocycle adopts a twisted, compressed conformation that places embedded anthracene fluorophores in close contact. Emission from the convoluted macrocycle is highly solvatochromic and significantly enhanced as compared with that of the partial structures. [ABSTRACT FROM AUTHOR]

Discrete, well-defined stacks of the polarized aromatic pyrene-4,5-dione (1) were assembled in the cavities of organic-pillared coordination cages (2). The number (n) of stacked guests depends on the pillar length, and up to quintuple stacks (n = 5) were observed when long (16.5 Å) organic pillar ligands were incorporated. As previously reported, pyrene-4,5-dione (1) assembles into infinite columnar stacks in the solid state, but the present work demonstrates that the polarized 1 has a strong propensity to stack in layers even in the absence of crystal packing effects. For n = 2 and 3 structures, crystallographic studies revealed that 1 stacks by π-π interactions in the cavity in such a way that a net dipole moment is canceled. These results emphasize the important role of dipole-dipole interactions as well as π-stacking interactions in the formation of columnar stacks of 1. [ABSTRACT FROM AUTHOR]