A Photolockable Polyaromatic Capsule Designed via Regiochemical Substitution.

Photocontrol over host frameworks is an elegant way to manipulate host-guest composites, yet the majority of previous systems suffer from long irradiation time and narrow guest scope, and are restricted to intramolecular photoreactions in organic solvents. Herein we present a photolockable polyaromatic capsule with high guest binding abilities in water. The capsule assembles from bent amphiphiles featuring two 2-subsutituted anthracene panels, which shows high stability against dilution and undergoes intermolecular [4+4] photo-oligomerization upon short light irradiation (<10 min).

Bioinspired Binding and Conversion of Linear Monoterpenes by Polyaromatic Coordination Capsules.

Linear monoterpenes, versatile reaction biosubstrates, are bound and subsequently converted to various cyclic monomers and oligomers with excellent selectivity and efficiency, in natural enzymes. We herein report bioinspired functions of synthetic polyaromatic cavities toward linear monoterpenes in the solution and solid states. The cavities are provided by polyaromatic coordination capsules, formed by the assembly of Pt(II) ions and bent bispyridine ligands with two anthracene panels.

Umbrella-Shaped Amphiphiles: Internal Alkylation of an Aromatic Micelle and Its Impact on Cavity Features.

To develop new hybrid micelles with alkyl/polyaromatic core-shell structures, we synthesized umbrella-shaped amphiphiles bearing a bent anthracene dimer with a linear alkyl chain (i.e., octyl and hexadecyl groups).

Facile access to pyridinium-based bent aromatic amphiphiles: nonionic surface modification of nanocarbons in water.

Efficient water-solubilization of nanocarbons is desirable for both their biological and material applications, but so far has mainly relied on covalent modifications or amphiphiles featuring ionic side-chains. Here, we report a facile 2-4-step synthesis of pyridinium-based, bent aromatic amphiphiles with modular (i.e.

Facile Processing of Unsubstituted π-Conjugated Aromatic Polymers through Water-solubilization Using Aromatic Micelles.

π-Conjugated aromatic polymers (πCAPs) are central components of functional materials yet suffer from insolubility without multiple covalent substituents on their backbones. We herein disclose a new strategy for the facile processing of unsubstituted heterocyclic πCAPs (i.e.

Aromatic micelles: toward a third-generation of micelles.

Micelles are useful and widely applied molecular assemblies, formed from amphiphilic molecules, in water. The majority of amphiphiles possess an alkyl chain as the hydrophobic part. Amphiphiles bearing hydrophilic and hydrophobic polymer chains generate so-called polymeric micelles in water.

Caged bulky organic dyes in a polyaromatic framework and their spectroscopic peculiarities.

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.

Expanding the Protecting Group Scope for the Carbonyl Olefin Metathesis Approach to 2,5-Dihydropyrroles.

Chiral pyrrolidine derivatives are important building blocks for natural product synthesis. Carbonyl olefin metathesis has recently emerged as a powerful tool for the construction of such building blocks from chiral amino acid derivatives. Here, we demonstrate that the supramolecular resorcinarene catalyst enables access to chiral 2,5-dihydropyrroles under Brønsted acid catalysis.

Supramolecular Singlet Fission of Pentacene Dimers within Polyaromatic Capsules.

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.

An atropisomeric ML cage mixture displaying guest-induced convergence and strong guest emission in water.

Introduction of atropisomeric axes into a bent bispyridine ligand leads to the quantitative formation of a complex mixture of atropisomeric ML cages upon treatment with metal ions. Whereas the isomer ratio of the obtained cage mixture, consisting of up to 42 isomers, is insensitive to temperature and solvent, the quantitative convergence from the mixture to a single isomer is accomplished upon encapsulation of a large spherical guest, namely fullerene C. The observed isomerization with other guests depends largely on their size and shape (, <10 and 82% convergence with planar triphenylene and bowl-shaped corannulene guests, respectively).

An Aromatic Micelle-Based Saccharide Cluster with Changeable Fluorescent Color and its Protein Interactions.

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 ca.

Concentration-Dependent Self-Assembly of an Unusually Large Hexameric Hydrogen-Bonded Molecular Cage.

The sizes of available self-assembled hydrogen-bond-based supramolecular capsules and cages are rather limited. The largest systems have volumes of approximately 1400-2300 Å . Herein, we report a large, hexameric cage based on intermolecular amide-amide dimerization.

N-Doping of Polyaromatic Capsules: Small Cavity Modification Leads to Large Change in Host-Guest Interactions.

To gain insight into the host functions of a nanocavity encircled by both polyaromatic panels and heteroatoms, nitrogen-doped polyaromatic capsules were successfully synthesized from metal ions and pyridine-embedded, bent anthracene-based ligands. The new capsules display unique host-guest interactions in the isolated cavities, which are distinct from those of the undoped analogues. Besides the inclusion of Ag ions, the large absorption change of fullerene C and altered emission of a BODIPY dimer are observed upon encapsulation by the present hosts.

Requirements for Terpene Cyclizations inside the Supramolecular Resorcinarene Capsule: Bound Water and Its Protonation Determine the Catalytic Activity.

The elucidation of the requirements for efficient catalysis within supramolecular host systems is an important prerequisite for developing novel supramolecular catalysts. The resorcinarene hexamer has recently been shown to be the first supramolecular catalyst to promote the tail-to-head terpene cyclization in a biomimetic fashion. We herein present the synthesis of a number of resorcinarene-based macrocycles composed of different ratios of resorcinol and pyrogallol units capable of self-assembly and compare the corresponding assemblies regarding their catalytic activity in the cyclization of monoterpenes.

Bent Anthracene Dimers as Versatile Building Blocks for Supramolecular Capsules.

This Account provides a comprehensive summary of our 1-decade-long investigations into bent anthracene dimers as versatile building blocks for supramolecular capsules. The investigations initiated in 2008 with the design of an anthracene dimer with a -phenylene spacer bearing two substituents on the convex side. Using the bent polyaromatic building block, we began to develop novel supramolecular capsules from two different synthetic approaches.

A Redox-Active Heterocyclic Capsule: Radical Generation, Oxygenation, and Guest Uptake/Release.

For the development of a redox-active supramolecular capsule with host function, we synthesized a bent heterocyclic amphiphile using phenothiazine panels capable of adopting three different states, i.e., neutral, radical, and oxygenated states.

En route to terpene natural products utilizing supramolecular cyclase mimetics.

Covering: literature up to 2018 Terpenes are a class of natural products characterized by remarkable structural diversity. Much of this diversity arises biosynthetically from a handful of linear precursors through the so-called tail-to-head terpene cyclization reaction. This reaction is one of the most complex observed in nature, and historically attempts to replicate it with non-enzymatic means have met with little success.

Polyaromatic nanocapsules as photoresponsive hosts in water.

Molecular containers that provide both stimuli-responsive assembly/disassembly properties and wide-ranging host capabilities in aqueous medium still remain a current synthetic challenge. Herein we report polyaromatic nanocapsules assembled from V-shaped amphiphilic molecules bearing a photoresponsive ortho-dianthrylbenzene unit in water. Unlike previously reported supramolecular capsules and cages, the nanocapsules quickly and quantitatively disassemble into monomeric species by a non-invasive light stimulus through structural conversion from the open to the closed form of the amphiphiles.

Catalysis inside the Hexameric Resorcinarene Capsule.

In this Account, we outline our investigation into the supramolecular resorcinarene capsule as a catalyst. Molecular capsules not only are of interest due to the similarities of their binding pockets with those of natural enzymes but also feature potential advantages for catalysis. Due to the restricted internal volume of the binding pockets, substrate selectivities are commonly observed.

Polyaromatic molecular tubes: from strategic synthesis to host functions.

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.

Brønsted Acid-Catalyzed Carbonyl-Olefin Metathesis inside a Self-Assembled Supramolecular Host.

Carbonyl-olefin metathesis represents a powerful yet underdeveloped method for the formation of carbon-carbon bonds. So far, no Brønsted acid based method for the catalytic carbonyl-olefin metathesis has been described. Herein, a cocatalytic system based on a simple Brønsted acid (HCl) and a self-assembled supramolecular host is presented.

Exploring Catalysis inside Self-assembled Supramolecular Containers.

Our group is interested in applying supramolecular host systems as catalysts for challenging transformations. Although a variety of supramolecular containers has been described in literature, their use as reaction chambers is still underexplored. We herein describe our first steps in this exciting interdisciplinary field of research.

Terpene Cyclizations inside a Supramolecular Catalyst: Leaving-Group-Controlled Product Selectivity and Mechanistic Studies.

The tail-to-head terpene cyclization is arguably one of the most complex reactions found in nature. The hydrogen-bond-based resorcinarene capsule represents the first man-made enzyme-like catalyst that is capable of catalyzing this reaction. Based on noncovalent interactions between the capsule and the substrate, the product selectivity can be tuned by using different leaving groups.

To catalyze or not to catalyze: elucidation of the subtle differences between the hexameric capsules of pyrogallolarene and resorcinarene.

The closely related, self-assembled resorcinarene and pyrogallolarene capsules display contrasting and puzzling encapsulation behaviors. Herein, we elucidate the reasons for these differences by combining experimental studies and DFT calculations. Furthermore, we report that, in contrast to the resorcinarene capsule, the pyrogallolarene derivative is not capable of catalyzing reactions with cationic transition states.

Advantages of Catalysis in Self-Assembled Molecular Capsules.

Control over the local chemical environment of a molecule can be achieved by encapsulation in supramolecular host systems. In supramolecular catalysis, this control is used to gain advantages over classical homogeneous catalysis in bulk solution. Two of the main advantages concern influencing reactions in terms of substrate and product selectivity.