Passt genau: Bei der Umsetzung von C60 mit einer Mischung von Cycloparaphenylenen (CPPs) verkapselte [10]CPP selektiv C60 unter Bildung von [10]CPP⊃C60 (siehe Bild). Entsprechende komplementäre Wirt‐Gast‐Komplexe könnten sich als nützlich für die Trennung höherer Fullerene und Kohlenstoffnanoröhren nach Größe und Form erweisen.

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Graphene quantum dots (GQDs) have received considerable attention for their potential applications in the development of novel optoelectronic materials. In the generation of optoelectronic devices, the development of GQDs that are regulated in terms of their size and dimensions and are unoxidized at the sp 2 surfaces is desired. GQDs functionalized with bulky FrØchets dendritic wedges at the GQD periphery were synthesized. The single-layered, size-regulated structures of the dendronized GQDs were revealed by atomic force microscopy. The edge-functionalization of the GQDs led to white-light emission, which is an uncommon feature.

This article reports production protocols for nanographenes and the effect of the reaction conditions on their structures and optical properties. These fundamental studies are of value for exploring suitable reaction conditions for the production of nanographenes with desirable properties. Graphite, finely crushed graphite powders, and artificial graphite, all of which are commercially available, are employed. Nanographenes are produced by the acid-assisted oxidative cleavage of the parent carbons followed by neutralization and deionization. The use of dialysis membranes for the size separation of nanographenes offers nanographenes with a specific size distribution, thereby allowing their structures and optical properties to be compared. Experiments demonstrate that small amounts of acids (60 ml of conc. H2SO4 and 20 mL of 60% HNO3) and oxidation for 12 h promotes a more efficient and cost-effective production of nanographenes from 2 g of a carbon source. The functionalization of the nanographene edges with p-propargyloxybenzyl amine confirms that the armchair edge with two carboxy groups is the dominant edge structure, irrespective of the carbon source.

Self-assembled supramolecular polymers consist of molecular components that are held together through noncovalent interactions. The reversible noncovalent interactions can be used to produce healable, stimuli-responsive, and switchable supramolecular polymers. This new class of intelligent polymer materials, with macroscopic properties that might be turned on and off by external stimuli, has helped supramolecular polymer chemistry to gain momentum within the field of polymer science. [1] The design of wellorganized polymer architectures requires the integration of certain supramolecular components that must be capable of creating the strong noncovalent interactions necessary for producing an appreciable degree of polymerization. Multiple hydrogen-bonding, [2] hydrophobic, [3] cation-dipole, [4] CH/p, [5] and aromatic electron donor-acceptor [6] interactions are often employed in the synthesis of functional supramolecular polymers.Supramolecular porphyrin polymers have recently attracted attention because of their creative applications in photoactive devices. Coordination-driven self-assembly is one of the most useful approaches for building large and elaborate porphyrin architectures. [7] However, self-assembly of porphyrins in organic media, driven by weak noncovalent forces, such as van der Waals and CH/p interactions, is very limited, [8] even though the porphyrin moiety possesses a flat and electron-rich surface that creates the possibility of attractive van der Waals, stacking, and charge-transfer interactions. Recently, we have developed a bisporphyrin cleft connected by a pyridine dicarboxamide linker that assembles to form a unique complementary dimer in organic media. [9] The competitive complexation of a flat, electron-deficient aromatic guest into the bisporphyrin cleft leads to a p donor-acceptortype host-guest complex. [10] These supramolecular motifs should be useful for the synthesis of supramolecular porphyrin polymers. [11] To investigate this strategy, a p donor-acceptor-type host-guest motif was incorporated into the heteroditopic monomer 1. The electron-deficient guest moiety, 4,5,7-trinitrofluorenone-2-carboxylate (TNF), can bind within the bisporphyrin cleft through a charge-transfer interaction, and iterative head-to-tail host-guest complexation should produce a new supramolecular polymer (Figure 1). Herein, we report the novel molecular recognition-directed supramolecular polymerization of monomer 1 in solution and solid state.The self-assembly of 1 was studied in solution using fluorescence and UV/Vis absorption spectroscopies (see Figure S1 in the Supporting Information). The fluorescence spectrum of 1 in toluene was temperature dependent; strong emission bands (l ex = 501 nm) at 363 K were observed at 657 and 719 nm, which are characteristic of a porphyrin core, but the emission bands gradually diminished upon cooling the solution. When the temperature reached 263 K, 80 % of the emission was quenched. The TNF moiety is a good energy acceptor. Therefore, this quenching can be rationa...

Hier ist der Wirt der Gast — im Komplex zwischen C60 und Calix[S]arenen, die in Lösung und in einem Fall auch im Kristall untersucht wurden, ist Buckminsterfulleren nicht wie üblich das Wirt‐, sondern das Gastmolekül (siehe rechts). Die Struktur der Komplexe in Lösung wurde mit der Ringstrom‐Methode abgeleitet, basierend auf Ergebnissen der Röntgenstrukturanalyse; van‐der‐Waals‐Wechselwirkungen zwischen Wirt‐ und Gastmolekül spielen eine wichtige Rolle bei der Komplexierung in Lösung.

He then joined the group of Prof. Julius Rebek Jr. at The Scripps Research Institute (19992000). In 2000, he was promoted to an Associate Professor of Chemistry at Hiroshima University. He has been a Full Professor since 2007. His research interests embrace the development of photoactive supramolecular polymer materials and graphene-based functional materials. Takehiro Hirao received a BSc degree in chemistry in 2011, an MSc degree in organic chemistry in 2013, and a Ph.D. degree in 2016 in organic chemistry from Hiroshima University, Japan, under the supervision of Professor Takeharu Haino. After working as a postdoctoral researcher with Professor Jonathan L. Sessler at the University of Texas at Austin for two years, he accepted a position as an Assistant Professor of Chemistry at Hiroshima University in April 2018. His research currently focuses on the development of supramolecular polymeric ensembles.

Synthesis of an artificial receptor (1) based on monodeoxycalix[4]arene as a core structure and its binding behavior to various ureas are presented. The structures of the complexes were predicted by molecular dynamics-molecular mechanics calculations. The difference of the association constants can be explained by the comparison of the structure of the complexes.Recognition of a substrate in a biological receptor is one of the important processes in bioorganic transformations. Host-guest chemistry gives us valuable information about the mechanism of the recognition. 1) In recent studies, a number of artificial receptors and their functions have been reported. 2) Calixarene family plays an important role in the host-guest chemistry. 3) Calix[4]arene, the smallest member of the family, is known to have an ideal cone shape in non-polar solvent due to cyclic hydrogen bonding of four phenolic hydroxyl groups. Ethers of monodeoxycalix[4]arene 4) have several advantages i.e. increased solubility and larger flexibility than calix[4]arene. We focused our attention on the application of the flexible frame of this compound as a host molecule. Hence, we designed the receptor (1) having two benzoic acid moieties as the guest binding portions. Here, we report the synthesis and binding behavior of the receptor, and the molecular modeling consideration of its complexes using molecular mechanics calculation.Synthesis of 1 is started from calix[4]arene (2). 5) Treatment of 2 with methyl iodide in the presence of potassium carbonate gave calix[4]arene monomethyl ether. 6) The monomethyl ether was then treated with diethyl phosphite to afford the phosphate ester. Reductive cleavage of the phosphate group (K/liquid NH 3 , -78°C) gave 3 7) in good yield. Selective iodination at para position of phenol ring using ICl, followed by protection of phenolic hydroxyl groups by methoxymethyl chloride afforded diiodide (4). Introduction of guest binding part was carried out by palladium(0) catalyzed coupling reaction of 4 with 5. 8) Successive hydrolysis of ester function furnished the desired compound (1).It is known that there are three conformers with respect to the orientation of the ether groups in the trialkyl ether of the monodeoxycalix[4]arenes. 9) These conformers can be easily identified by the 1 H-NMR chemical shift values of the ether groups. According to the previously established criteria of the chemical shift change 9) with respect to those of the reference compounds, 2-methoxyxylene and 2-methoxymethoxyxylene, we can conclude that 1 has cone conformation. Hence, the two carboxyl groups of the host arranged in a same side suitable for the effective guest binding by the hydrogen bonds.Binding ability of 1 to a variety of urea guests was evaluated by 1 H-NMR titration technique in CDCl 3 . When added 1 to the guest solution, the N-H signal of propylene urea shifted to down field, suggesting the hydrogen bonding interaction between the N-H of the guest and the carboxyl groups of 1. Job's plot analysis (Fig.1) confirmed the 1:1 stoi...