Structures, Chiroptical Properties, and Unexpectedly Facile Helical Inversion of Highly Elongated Anthracene-Fused Expanded Helicenes.

Helical fused anthracenes were elongated by fusing additional aromatic units at both ends to yield novel expanded helicenes. Compounds [5]HA2N and [7]HA consisting of 19 and 21 benzene rings, respectively, were synthesized by fourfold cycloisomerization of the corresponding terminal alkyne precursors. The helical structures were confirmed by X-ray crystallographic analysis, where the aromatic frameworks stacked effectively with the helical turn numbers exceeding two.

Pseudohelicene chemosensor displaying ternary signaling stimulated by hydrostatic pressure and solvent.

Herein, we report the serendipitous discovery of a racemic chemosensor ([2]HA2) that outputs three signal patterns (1/0/-1) in response to two external stimuli (hydrostatic pressure and solvent); these signals can be observed by hydrostatic pressure spectroscopy.

Azaylide-based gemini amphiphiles displaying unique self-assembling behavior an even-odd effect of alkyl linker chain length.

Herein, we report a straightforward synthesis of azaylide-based gemini amphiphiles using bis(diphenylphosphino)alkanes the Staudinger reaction. The prepared gemini amphiphiles exhibited an even-odd effect in their self-assembly behavior depending on the length of the alkyl linkers. Furthermore, the assembled micelles had high host capability toward hydrophobic guests in water.

Solid-State Self-Assembly: Exclusive Formation and Dynamic Interconversion of Discrete Cyclic Assemblies Based on Molecular Tweezers.

In contrast to self-assembly in solution systems, the construction of well-defined assemblies in the solid state has long been identified as a challenging task. Herein, we report the formation of tweezers-shaped molecules into various assemblies through a solid-state self-assembly strategy. The relatively flexible molecular tweezers undergo exclusive and quantitative assembly into either cyclic hexamers or a porous network through classical recrystallization or the exposure of powders to solvent vapor, despite the fact that they form only dimers in solution.

Unusually Short H⋅⋅⋅H Contacts in Intramolecularly Cyclized Helically Fused Anthracenes.

The intramolecular coupling of dichloro-substituted helically fused anthracenes using the Yamamoto coupling yielded cyclized products with sterically congested molecular structures. The X-ray analysis and DFT calculations showed that the aromatic framework adopted a nonplanar structure with a twisted conformation about the newly formed single bond, which acts as a chiral axis. Interestingly, the X-ray structure obtained through the Hirshfeld atom refinement revealed short interatomic distances between the inner hydrogen atoms (1.

Structure and Chiroptical Properties of Anthra[1,2-a]anthracene-1-yl Dimers as New Biaryls.

Dimers of anthra[1,2-a]anthracene-1-yl units and its mesityl derivative were synthesized by Ni(0)-mediated coupling of the corresponding chloro derivatives as new biaryls. The X-ray analysis and DFT calculations revealed that two polycyclic aromatic units with nonplanar deformations took a twisted conformation about the single bond as a chiral axis. Enantiomers of the nonsubstituted compound were resolved by chiral HPLC, and the enantiopure samples showed intense Cotton effects at 321 nm in the circular dichroism (CD) spectra and emission bands at 449 nm in the circularly polarized luminescence (CPL) spectra with dissymmetry factor of |g| 3.

Discovery of internal rotation and conformers of 1,2-dichloroethane: the dawn of the concept of conformation.

In 1932, Mizushima and Higasi reported the dependence of the dipole moments of 1,2-dichloroethane on both temperature and solvent in the Proceedings of the Imperial Academy, Japan. This report was followed by their first proposal of the existence of conformers that exchanged by internal rotation about a C-C single bond based on experimental data. Their monumental work marked the beginning of the essential concept of conformation in modern stereochemistry.

Transformation of Highly Hydrophobic Triarylphosphines into Amphiphiles via Staudinger Reaction with Hydrophilic Trichlorophenyl Azide.

Owing to its hydrophobic properties and reactivity, triarylphosphines (PAr ) are promising precursors for the development of new amphiphiles. However, an efficient and reliable synthetic method for amphiphiles based on highly hydrophobic PAr is still required. Herein, a straightforward transformation of highly hydrophobic PAr into amphiphiles via the Staudinger reaction is reported.

Synthesis and Properties of Rubicene-Based Aromatic π-Conjugated Compounds as Five-Membered Ring Embedded Planar Nanographenes.

Polycyclic aromatic hydrocarbons consisting of two or three rubicene substructures were designed as π-conjugated compounds embedding five-membered rings. The target compounds with t-butyl groups were synthesized by the Scholl reaction of precursors consisting of 9,10-diphenylanthracene units, even though a partially precyclized precursor was required for the synthesis of the trimer. These compounds were isolated as stable and dark blue solids.

Structures and Supramolecular Properties of Inclusion Complexes of Anthracene-Triptycene Nanocages with Fullerene Guests and Their Dynamic Motion as Molecular Gyroscopes.

Three derivatives of macrocyclic cage compounds consisting of diarylanthracene and triptycene units were synthesized. These nanocages formed host-guest complexes with C and other fullerene guests as confirmed by H NMR and fluorescence spectroscopy. The association constant of the mesityl and 2,4,6-tributoxyphenyl derivatives with C was determined to be 2.

Synthesis, Structures, and Complexation with Phenolic Guests of Acridone-Incorporated Arylene-Ethynylene Macrocyclic Compounds.

Acridone units were incorporated into the arylene-ethynylene structure as polar arene units. Cyclic trimers consisting of three acridone-2,7-diyl units and three 1,3-phenylene units were synthesized by Sonogashira couplings via stepwise or direct route. X-ray analysis revealed that the trimer had a nearly planar macrocyclic framework with a cavity surrounded by three carbonyl groups.

A self-complementary macrocycle by a dual interaction system.

Self-complementary assembly is one of the most promising phenomena for the formation of discrete assemblies, e.g., proteins and capsids.

A pressure-induced ratiometric signalling chemosensor: a case of helical anthracenes.

One of the helical anthracenes, [4]HA, in which two fused anthracene ends are spatially arranged top and bottom, exhibits a ratiometric fluorescence response due to the hydrostatic pressure-dependent intramolecular [4+4] photocyclodimerization. This ratiometric signalling comes from the formation of an intramolecular stacked species and its subsequent photoreaction upon hydrostatic pressurization. The ratiometric indexes as a function of hydrostatic pressure may enable us to quantify an unknown pressure in solutions.

Structure and Photophysical Properties of 1,1,2,2-Tetra(1-anthryl)ethane: A C(sp )-C(sp ) Bond Substituted with Four Anthracene Units.

The title aromatic compound comprising four anthracene units was synthesized by the McMurry coupling of di(1-anthryl) ketone as a hydrogenated product in 65 % yield. The molecule forms a C symmetric structure with the ap conformation about the C(sp )-C(sp ) single bond, as revealed by X-ray analysis and DFT calculations. The UV/vis and fluorescence spectra of this compound were compared with those of anthracene, di(1-anthryl)methane, and 1,2-di(1-anthryl)ethane.

Synthesis, Structures, and Properties of Helically Fused Anthraquinones with Unusually Close Carbonyl-Carbonyl Contacts.

Electron-deficient aromatic ketones consisting of three fused anthraquinone units were synthesized by oxidation of the corresponding fused anthracenes. X-ray analysis revealed that these compounds had nonplanar helical structures with unusual contacts, C=O⋅⋅⋅C=O 2.467 Å, between the inner carbonyl groups.

Cyclic monoterpenes trapped in a polyaromatic capsule: unusual selectivity, isomerization, and volatility suppression.

Cyclic monoterpenes (CMTs) are intractable natural products with high volatility and strong odors so that there has been no molecular receptor capable of selectively and tightly trapping CMTs in both solution and the solid state. We herein report that a polyaromatic capsule acts as a functional nanoflask for CMTs with the following five features: (i) the capsule can selectively bind menthone from mixtures with other saturated CMTs in water. In contrast, (ii) treatment of the capsule with mixtures of menthone and π-conjugated CMTs gives rise to ternary host-guest complexes with high pair-selectivity.

Synthesis, Structures, and Electronic Properties of 2,7-Anthrylene-Based Azacyclophanes Bearing -, -, and -Phenylenediamine Linkers.

A series of novel azacyclophanes consisting of 2,7-anthrylene and phenylene units were designed and synthesized by the Buchwald-Hartwig coupling reaction to investigate their unique electronic properties in multiple oxidized states. Cyclic voltammetry showed that the -phenylene derivative exhibited three reversible oxidation waves, whereas the - and -phenylene derivatives showed two quasi-reversible oxidation waves due to the complicated intramolecular interaction between the oxidized units and neutral units. Moreover, the absorption spectra of the -phenylene derivative in different oxidation states showed absorption bands at 865 and 1025 nm, which were attributed to intramolecular charge-transfer interactions.

Synthesis of Azaylide-Based Amphiphiles by the Staudinger Reaction.

Catalyst- and reagent-free reactions are powerful tools creating various functional molecules and materials. However, such chemical bonds are usually hydrolysable or require specific functional groups, which limits their use in aqueous media. Herein, we report the development of new amphiphiles through the Staudinger reaction.

Complexation of an Anthracene-Triptycene Nanocage Host with Fullerene Guests through CH⋅⋅⋅π Contacts.

A bicyclic anthracene macrocycle containing two triptycene units at the bridgehead positions was synthesized by Ni-mediated coupling of the corresponding precursor as a cage-shaped aromatic hydrocarbon host. This cage host formed an inclusion complex with C or C guest in 1 : 1 ratio in solution. The association constants (K ) determined by the fluorescence titration method were 1.

Construction of Helical Structures with Multiple Fused Anthracenes: Structures and Properties of Long Expanded Helicenes.

Invited for the cover of this issue is Shinji Toyota and co-workers at Tokyo Institute of Technology and Okayama University of Science. The image depicts a spirally rising dragon to represent the helical molecular structures in the manuscript. Read the full text of the article at 10.

Construction of Helical Structures with Multiple Fused Anthracenes: Structures and Properties of Long Expanded Helicenes.

Polycyclic aromatic compounds consisting of four or five fused anthracene units were synthesized by PtCl -catalyzed cycloisomerization as novel long expanded helicenes. These compounds have helical structures with significant stacking of the terminal anthracene moieties at 0.33 nm interlayer distance.

Multiple Fused Anthracenes as Helical Polycyclic Aromatic Hydrocarbon Motif for Chiroptical Performance Enhancement.

Polycyclic aromatic hydrocarbons consisting of three fused anthracene units were designed as new π-conjugated compounds having helical structures. These expanded helicenes were synthesized by Pt-catalyzed cycloisomerization of the corresponding ethynyl-substituted precursors. The nonplanar and helical structure was confirmed by X-ray analysis and DFT calculations, and the barrier to helical inversion was estimated to be 34 kJ mol .

Novel Aromatics: Official Special Issue of ISNA-18.

An aromatic celebration: ChemPlusChem is pleased to publish a Special Issue on Novel Aromatics, guest-edited by Aiko Fukazawa, Shinji Toyota, Rik Tykwinski, and Wallace Wong. This project is associated with the organizers of the 18th International Symposium on Novel Aromatic Compounds (ISNA-18), to be held in Sapporo, Japan (July 21-26, 2019). The issue features fascinating, top-quality contributions covering nearly all aspects of "aromatic" chemistry, including synthesis, properties, and applications of acenes, annulenes, azulenes, fullerenes, polycyclic aromatic hydrocarbons, and thiophenes as well as porphyrins, corroles, and phthalocyanines.

Chemistry of Anthracene-Acetylene Oligomers XXVII. Iterative Synthesis, Structures, and Properties of Anthracene-Diacetylene Cyclic Oligomers with 10-Mesitylanthracene-1,8-diyl Units.

A series of cyclic oligomers consisting of 10-mesitylanthracene-1,8-diyl units and diacetylene linkers were synthesized as soluble π-conjugated compounds. Macrocyclic frameworks from dimer to octamer except heptamer were constructed from 1,8-diethynylanthracene derivatives by iterative coupling reactions. The rigid structure of the dimer, the strained structures of the trimer and the pentamer, and the belt-shaped structures of the other even-numbered oligomers were revealed by X-ray analysis and DFT calculations.

Exploration of Nano-Saturns: A Spectacular Sphere-Ring Supramolecular System.

Saturn-like systems consisting of nanoscale rings and spheres are fascinating motifs in supramolecular chemistry. Several ring molecules are known to include spherical molecules at the center of the cavity via noncovalent attractive interactions. In this Minireview, we generalize the molecular design, the structural features, and the supramolecular chemistry of such "nano-Saturns", which consist of monocyclic rings and fullerene spheres (mainly C ), on the basis of previous experimental and theoretical studies.