Arraying and Guest Inclusion of Soluble Metal-Organic Nanotubes Composed of Macrocyclic Paddle-Wheel Metal Complexes.

A new series of metal-organic nanotubes was constructed through one-dimensional assembly using molecular triangles or molecular squares composed of paddlewheel dirhodium complexes and bidentate axial ligands. The metal-organic nanotubes were significantly different from conventional solid metal-organic framework (MOF) motifs. They exhibit good solubility owing to the branched side chains at their periphery and demonstrate high orientation capabilities in thin films owing to their anisotropic structure.

Calamitic Liquid Crystals for Reversible Light-Modulated Phase Regulation Based on Arylazopyrazole Photoswitches.

Invited for the cover of this issue are the groups of Kentaro Tanaka at Nagoya University and Bart Jan Ravoo at the University of Münster. The image depicts the photoisomerization of a mesogen upon irradiation with different wavelengths of light. Read the full text of the article at 10.

Continuous Nanospace in Nanoporous Liquid Crystal Investigated by Xe NMR Spectroscopy.

Continuous nanopores within fluid materials could be used for novel chemical events such as the accommodation of guest molecules, unique arrays of the entrapped molecules, and chemical reactions in a dynamic molecular assembly. Columnar liquid crystals composed of a one-dimensionally stacked assembly of shape-persistent macrocycles form nanochannels owing to the intrinsic nanospace in the column. However, the existence of substantial nanoporosity has not been confirmed experimentally thus far.

Calamitic Liquid Crystals for Reversible Light-Modulated Phase Regulation Based on Arylazopyrazole Photoswitches.

The design of responsive liquid crystals enables a diversity of technological applications. Especially photochromic liquid crystals gained a lot of interest in recent years due to the excellent spatiotemporal control of their phase transitions. In this work we present calamitic light responsive mesogens based on a library of arylazopyrazole photoswitches.

Design of supramolecular hybrid nanomaterials comprising peptide-based supramolecular nanofibers and generated DNA nanoflowers through rolling circle amplification.

The artificial construction of multicomponent supramolecular materials comprising plural supramolecular architectures that are assembled orthogonally from their constituent molecules has attracted growing attention. Here, we describe the design and development of multicomponent supramolecular materials by combining peptide-based self-assembled fibrous nanostructures with globular DNA nanoflowers constructed by the rolling circle amplification reaction. The orthogonally constructed architectures were dissected by fluorescence imaging using the selective fluorescence staining procedures adapted to this study.

Thermally Stable Array of Discrete Cs on a Two-Dimensional Crystalline Adlayer of Macrocycles both in Vacuo and under Ambient Pressure.

A periodic monolayer array of discrete Cs was generated on an atomically flat Au(111) surface with the aid of a template adlayer. The template was a two-dimensional (2D) array of molecular pits prepared on an Au(111) surface through 2D crystallization of shape-persistent macrocycles composed of four carbazole and four salphens/Ni-salphens with a 1 nm hollow. Scanning tunneling microscopy imaging under ultra-high vacuum revealed that the square-shaped macrocycles, with 1.

Mesogenic discrete metallofoldamer for columnar liquid crystal.

A mesogenic metallofoldamer [(1-Ni)Pd] exhibits thermotropic columnar liquid crystalline properties. The metallofoldamer was prepared from two homochiral crescent-shaped precursors having β-diketonate ligands (1-Ni) through bridging by metal complexation; it exhibited a single helicity owing to the overlapping of both ends. The precursor and metallofoldamer formed similar hexagonal columnar phases.

A Light-Harvesting/Charge-Separation Model with Energy Gradient Made of Assemblies of meta-Pyridyl Zinc Porphyrins.

Self-assembly of porphyrins is a fascinating topic, not only for mimicking chlorophyll assemblies in photosynthetic organisms, but also for the potential of creating molecular-level devices. Herein, zinc porphyrin derivatives bearing a meta-pyridyl group at the meso position were prepared and their assemblies studied in chloroform. Among the porphyrins studied, one with a carbamoylpyridyl moiety gave a distinct H NMR spectrum in CDCl , which allowed the supramolecular structure in solution to be probed in detail.

Liquid-crystalline Metallomacrocycles Composed of Bis(hydroxypyridono)toluene Ligand and Cu Ions.

A series of π-extended chelating scaffolds incorporating two hydroxypyridone moieties were synthesized. X-ray crystallographic analysis revealed that a bis(hydroxypyridono)toluene ligand possessed a unique π-extended structure and exhibited efficient phase segregation from the aliphatic chains attached at the heterocyclic nitrogen. The bis-bidentate ligand formed a metal-coordination-induced macrocycle with Cu ions.

Near-infrared absorption by intramolecular charge-transfer transition in 5,10,15,20-tetra(N-carbazolyl)porphyrin through protonation.

A porphyrin coupled quadruply with N-carbazolyl groups at the meso positions has been synthesized. Because of the electron-withdrawing nature of the carbazole units at the porphyrin centre, the tetra(N-carbazolyl)porphyrin and the protonated derivative display unique absorption bands derived from intramolecular charge-transfer transition from the carbazoles to the porphyrin moiety.

Specific and Oriented Encapsulation of Fullerene C into a Supramolecular Double-Decker Cage Composed of Shape-Persistent Macrocycles.

An efficient strategy for the specific recognition of ellipsoidal fullerenes uses molecular containers with well-designed three-dimensional (3D) nanospaces. We describe the synthesis of a supramolecular double-decker cage composed of shape-persistent metallomacrocycles and pillar ligands. A discrete 3D nanospace was built within the molecular framework of the shape-persistent-macrocycle/bidentate-pillar molecule.

Columnar Liquid-Crystalline Macrocycles Synthesized via Metal Ion-Assisted Self-Assembly.

Columnar assemblies of liquid-crystalline (LC) macrocycles hold promise for the construction of nanochannels in fluid materials. Metal-assisted self-assembly is an efficient way to prepare LC macrocycles. A large π-conjugated ligand, 9,10-diphenylanthracene (DPA) bearing two β-diketones, was prepared as a building unit for the macrocycle, and a series of side chains were incorporated into the DPA to yield LC materials.

Columnar Liquid Crystals from a Giant Macrocycle Mesogen.

Columnar liquid crystals composed of a giant macrocyclic mesogen were prepared. The giant macrocyclic mesogen has a square hollow with a 2.5 nm diagonal, which was bounded by diindolo[3,2-b:2',3'-h]carbazole (diindolocarbazole) moieties as the edges and bis(salicylidene)-o-phenylenediamine (salphen) moieties as the corners.

Metal-Ion-Induced Switch of Liquid-Crystalline Orientation of Metallomacrocycles.

A new series of shape-persistent imine-bridged macrocycles were synthesized based on dynamic covalent chemistry. The macrocycles had an alternating sequence of dibenzothiophene and N,N'-bis(salicylidene)-ethylenediamine (salen) tethering branched alkyl chains. The macrocycles and tetranuclear metallomacrocycles bearing long and branched alkyl chains exhibited thermotropic columnar liquid-crystalline phases over a wide temperature range and the metallomacrocycles greatly depended on the characteristics of the coordinated metal ions.

Columnar liquid-crystalline metallomacrocycles.

We report synthesis of novel macrocyclic molecules and their metal complexes as well as their thermotropic columnar liquid-crystalline behavior. The macrocyclic ligands were prepared size-selectively based on dynamic covalent chemistry. X-ray study of a model macrocycle with short alkyl chains revealed that they were discrete and highly symmetric, with an inner vacant cavity of 9 Å diameter enclosed by a 56π planar ring composed of four bis(salicylidene)-o-phenylenediamine (salphen) moieties alternating with four carbazoles.

Electron donors and acceptors based on 2,7-functionalized pyrene-4,5,9,10-tetraone.

An efficient synthesis of 2,7-dibromo- and diiodo-pyrene(4,5,8,19)-tetraones led to strong donors and acceptors based on pyrene. They are versatile building blocks for conjugated materials and can be further applied in molecular electronics.

Double helices of a pyridine-appended zinc chlorophyll derivative.

Self-assembled structures formed from a pyridine-appended zinc chlorophyll derivative are reported. While the zinc complex forms cyclic oligomers in chloroform solution, as indicated by (1)H NMR studies (including diffusion-ordered spectroscopy), vapor pressure osmometry, and cold-spray ionization mass spectrometry, it forms double-stranded helical coordination polymers in the solid state, as revealed by single-crystal X-ray analysis.

Creation of a mixed-valence state from one-dimensionally aligned TTF utilizing the self-assembling nature of a low molecular-weight gel.

One-dimensional TTF assemblies have been obtained through the design of low molecular-weight gels, which show a characteristic absorption band at around 1750 nm upon I2 doping, assignable to a mixed-valence state of the TTF assemblies.

Quater-, quinque-, and sexithiophene organogelators: unique thermochromism and heating-free sol-gel phase transition.

A series of quater-, quinque-, and sexithiophene derivatives bearing two cholesteryl groups at the alpha-position, which are abbreviated as 4 T-(chol)(2), 5 T-(chol)(2), and 6 T-(chol)(2), respectively, have been synthesized. It has been found that these oligothiophene derivatives act as excellent organogelators for various organic fluids and show the unique thermochromic behaviors through the sol-gel phase transition. It was shown on the basis of extensive investigations, performed with UV-visible spectroscopy, circular dichroism (CD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM), that these gelators self-assemble into the one-dimensional structures in the organogels, in which the pi-block moieties of the oligothiophenes are stacked in an H-aggregation mode.

A coordination gelator that shows a reversible chromatic change and sol-gel phase-transition behavior upon oxidative/reductive stimuli.

A novel coordination gelator exhibits reversible chromatic and sol-gel phase-transition phenomena triggered by thermal and chemical stimuli.

Sol-gel polycondensation of tetraethyl orthosilicate (TEOS) in sugar-based porphyrin organogels: inorganic conversion of a sugar-directed porphyrinic fiber library through sol-gel transcription processes.

Sugar-appended porphyrins (1 a-e) with monosaccharide groups at their periphery have been rationally designed for a new class of gelating reagents. A few of these compounds have the tendancy to form one-dimensional aggregates stable enough to show successful gelation ability for DMF-alcohol mixed solvents. The aggregation mode in the specific columnar super structures has been evaluated in detail by UV-visible spectrometry (UV/Vis), circular dichroism (CD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM).

Novel host-guest organogels as stabilized by the formation of crown-ammonium pseudo-rotaxane complexes.

A dibenzo-24-crown-8 derivative bearing two cholesterol groups is either insoluble in or precipitates from most organic solvents, but its pseudo-rotaxane complex with a diammonium guest acts as a good gelator of aromatic solvents.