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We herein report a new set of supramolecular nanotools for the generation and modulation of singlet fission (SF) of noncovalent/covalent pentacene dimers. Two molecules of a pentacene monomer with bulky substituents are facilely encapsulated by a polyaromatic capsule, composed of naphthalene-based bent amphiphiles, in water. The encapsulated noncovalent dimer converts to otherwise undetectable triplet pairs and an individual triplet in high quantum yields (179% and 53%, respectively) even under high dilution conditions. Within the capsule, a covalently linked pentacene dimer with bulky groups generates two triplet pair intermediates in parallel, which are hardly distinguished in bulk solution, in excellent total quantum yield (196%). The yield of the individual triplet is enhanced by 1.6 times upon encapsulation. For both types of pentacene dimers, the SF features can be readily tuned by changing the polyaromatic panels of the capsule (i.e., anthracene and phenanthrene). acceptedVersion

To develop a new type of synthetic saccharide clusters with changeable fluorescent colors, we herein designed a multisaccharide-coated aromatic micelle. The new cluster forms in water through the quantitative assembly of bent polyaromatic amphiphiles bearing three mannose groups. The spherical assembly, with a ~2 nm-sized polyaromatic core and ~18 saccharide pendants, is stable even under high dilution conditions (up to 0.02 mM). The emission intensity and color of the saccharide cluster can be altered from moderate blue ( Φ F = 19%) to strong red, orange, and green ( Φ F up to 67%) upon encapsulation of hydrophobic fluorescent dyes in water. Moreover, the present fluorescent clusters, both with and without the dyes, display selective interactions with mannose-binding proteins in vitro.

Host-guest structures and properties have been widely studied using relatively small dyes (1 nm) without bulky groups, due to their smooth incorporation, efficient host-guest interactions, and high analytical accessibility. In this report, on the other hand, three types of sterically demanding organic dyes trapped by a polyaromatic cage were investigated by spectroscopic analyses on the basis of supramolecular interactions. Coumarins with two bulky substituents are bound by the cage in aqueous solution. The resultant caged dyes show unusual emission enhancement, depending on the difference of a single heteroatom in their substituents. The color of perylene bisimides with two bulky substituents is remarkably changed from yellow to red upon caging. This peculiarity stems from the twist of the substituents in the cage, revealed by the combination of absorption and theoretical studies. Furthermore, tetrasubstituted, bulky porphyrins are caught by the cage in aqueous solution. The caged bulky dyes also display altered color and absorption properties, which remain intact even under acidic conditions. In contrast to typical covalent functionalization and previous host-guest studies toward small and non-bulky dyes, the unusual, non-covalent spectroscopic modulation of the large and bulky dyes can be accomplished for the first time by the present cage, featuring a prolate polyaromatic framework with four openings.

We herein report the quantitative formation of a new aromatic micelle from bent pentacene-based amphiphiles in water. Upon encapsulation, perylene bisimide dyes form a parallel stacked dimer and graphene nanosheets comprise few layer sheets with small lateral size., For exploitation of a new class of aromatic micelles, we synthesized a bent pentacene-based amphiphilic molecule through Diels–Alder reaction. The amphiphiles bearing two trimethylammonium tethers assemble into a spherical aromatic micelle, with an average core diameter of 1.5 nm, in water at room temperature. The new aromatic micelle efficiently encapsulates perylene bisimide (PBI) dyes and graphene nanosheets (GNS) in water. The encapsulated PBI dyes form a parallel stacked dimer, exhibiting characteristic absorption and emission bands. In addition, the encapsulated GNS are composed of few-layer graphene sheets with an average lateral size of ∼7 nm, as confirmed by Raman spectroscopy. The resultant, aqueous host–guest complexes are stable even after three weeks in water under ambient conditions.

Ring- and tube-shaped molecules like crown ethers and cyclodextrins play a fundamental role in supramolecular chemistry since their initial discovery. To date, numerous intriguing properties and reactivities have been reported based on their unique inner microenvironments. While inner spaces encircled by aliphatic and/or small aromatic frameworks have been heavily investigated, tubular structures that feature polyaromatic frameworks remained largely unexplored until 2010, despite their undisputable potential. Polyaromatic rings provide appealing photophysical and electrochemical properties and thus allow for the construction of new functional cylindrical nanospaces. This feature article describes the recent progress in the synthesis and application of short tubular molecules bearing multiple (≥3) polyaromatic rings (e.g., anthracene, pyrene, chrysene, and HBC). The polyaromatic tubes reported herein display characteristic properties such as strong fluorescent emission, a selective molecular binding ability, efficient host-guest energy transfer and open-closed structural transformations.