Creating and Manipulating π-Extended Quintulene on Surfaces - ChemistryViews

A curved nitrogen-doped nanocarbon synthesized that can flip shape and trap a gold atom at its center

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Precise Synthesis of Pyrene-Based Molecular Nanocarbons Driven by Dehydro-Diels–Alder Reactions

Molecular nanocarbons are critical bridges between small polycyclic aromatic hydrocarbons and extended graphene lattices, driving advances across materials science, optoelectronics, and quantum technologies. However, the atomically precise synthesis of such systems, particularly those featuring K-region and cove-type topologies, remains an enduring challenge. Here, we present a de novo modular strategy that overcomes this constraint by directing K-region growth via annulation of preorganized aryl acetylnaphthalene precursors with acetylenedicarboxylate. The strategy mirrors the hierarchical construction of pyrene by formally inserting naphthalene fragments into spatially defined molecular scaffolds. This method integrates Suzuki–Miyaura coupling with a Zn(OTf)2-catalyzed cascade comprising Friedel–Crafts alkylation, dehydro-Diels–Alder cycloaddition, and dehydrogenative aromatization. The platform affords structurally diverse pyrene-based molecular nanocarbons with programmable control over topology and dimensionality, spanning linear, contorted, and three-dimensional π-architectures. These results establish a generalizable blueprint for bottom-up synthesis of complex carbon-rich architectures with atomic precision.

pubs.acs.org

Size and Geometry Impact the Chiroptical Properties of Double Nanohoops

Conjugated nanohoops have attracted much attention in recent years due to their unique optoelectronic properties. A more complex geometry, in which two nanohoops are covalently linked to form a so-cal...

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(Chiro)optical Properties of π-Extended Spiro-Double Carbo[7]helicene

Helical nanographenes are a fascinating class of π-extended chiral nanocarbons, where structural helicity imparts intrinsic chirality and unique optoelectronic properties to the rigid carbon framework. In this work, we synthesized a hexa-peri-hexabenzocoronene-based π-extended spiro-double carbo[7]helicene. The helical distortion of the structure was unambiguously confirmed by X-ray crystallography. The optical properties were explored through UV–Vis absorption, fluorescence, and phosphorescence measurements, complemented by density functional theory (DFT) calculations. Remarkably, the π-extended spiro-double carbo[7]helicene exhibited thermally activated delayed fluorescence (TADF) at room temperature and phosphorescence at low temperatures. Chiral HPLC successfully resolved the enantiomers into three fractions: (PP), (MM), and the meso forms (PM)/(MP), and chiroptical studies of the pure enantiomers revealed a moderately high glum value of 1.58 × 10–3. Finally, the origin of the observed dissymmetry factors was rationalized by analyzing the transition electric dipole moments (TEDM) and transition magnetic dipole moments (TMDM) derived from time-dependent density functional theory (TD-DFT) calculations.

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[n]Helicenes with Red to Near‐Infrared (NIR) Emissions and Circularly Polarized Luminescence

Helicenes, chiral molecules with helical structures, are promising candidates for circularly polarized luminescence (CPL) materials. This review summarizes recent advances in red-to-NIR CPL-active he...

chemistry-europe.onlinelibrary.wiley.com

A Persistent Open-Shell m-QDM-Type Diindenoanthracene Diradicaloid with a Large Diradical Character

Indenofluorenes (IFs) have received great interest owing to their intrinsic antiaromaticity, open-shell diradical character, and narrow band gaps. Herein, we report the synthesis and comprehensive cha...

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Symmetry‐Breaking in Carbon Nanohoops Enables Room‐Temperature Ternary Single‐Molecule Switching

Three pyrene-embedded nanohoops with distinct molecular symmetries were synthesized. Symmetry engineering discretizes the tunneling pathways, yielding three stable conductance states at room temperat...

onlinelibrary.wiley.com

Computational method can calculate forces between large molecules with unprecedented accuracy

A puzzle in theoretical chemistry has been solved at TU Wien: A new computational method now makes it possible to calculate the forces between large molecules with unprecedented accuracy.

phys.org

Well-Structured Narrow Near-Infrared Absorption Based on Nonaggregated Hexarylene-Bisimide toward a Colorless Dye

Extended π-conjugated systems are often insoluble, and their aggregation manner greatly affects their absorption spectra. This study produced a planar, soluble, and nonaggregated hexarylene-bisimide (HB) with appropriate substituents. The single-crystal X-ray structure of HB confirmed the planar molecular structure with small twist angles and the dimerization behavior of HB in the solid state. The concentration-dependent 1H NMR experiments in CDCl3 indicated that the association constant Kdimer is 4.6 × 103 M–1 at 298 K and ΔGdimer (298 K) = −20.8 kJ mol–1. The longest absorption of HB at the monomeric state exhibits a sharp and intense peak at 921 nm (ε = 230,000 M–1 cm–1, full width at half-maximum = 718 cm–1) in toluene. 75% of the absorption of HB above 400 nm appears in the near-infrared region, thus giving a practically colorless solution. Magnetic circular dichroism spectra of a series of oligorylene-bisimides reveal the predominant contribution of the linear polyene-like conjugation over the annulene-like conjugation for larger [n]oligorylene-bisimides.

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Synthesis and Characterization of a π-Extended Clar’s Goblet

Concealed non-Kekulé polybenzenoid hydrocarbons have no sublattice imbalance yet cannot be assigned a classical Kekulé structure, leading to an open-shell ground state with potential applications in o...

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N‐Doped Nonalternant Molecular Bowl/Saddle Hybrids

N-Doped molecular bowl/saddle hybrids were developed via core-expansion synthetic strategy. Owing to the structural features containing both positive and negative curvatures, these molecules exhibit ....

onlinelibrary.wiley.com

Fused Octapyrrolyl Cyclooctatetraene with Large NIR-II Faraday Rotation

The increased mechanical flexibility, solution processability, ease of fabrication, and high Verdet constants have made organic Faraday rotators a promising alternative to conventional inorganic magneto-optical (MO) materials. Despite this, organic Faraday rotators have not been developed to address near-infrared (NIR) MO applications, limiting their device applications. Here, we describe a three-step synthesis and MO characterization of a fused octapyrrolyl cyclooctatetraene (FOPCOT) which exhibits a record high Verdet constant of a small molecule in the NIR-II region. Notably, the cyclooctatetraene core is constructed in a three-step one-pot reaction whereby a N,N′-dipyrrolyl acetylene is generated and immediately reacted with Rosenthal’s complex to produce the corresponding zirconacycle intermediate in situ. The cascade is completed with a copper-mediated transmetalation that reductively eliminates to yield the octapyrrolyl cyclooctatetraene. This transformation offers a distinct alternative to conventional methods for pyrrole incorporation into polycyclic aromatic hydrocarbons. Stoichiometric oxidation with AgPF6 affords the oxidized analogues FOPCOT•+ and FOPCOT2+, which display strong optical absorptions at 1743 and 1198 nm, respectively. Magnetic circular dichroism study on spin-coated thin films of FOPCOT2+ yielded a maximum Verdet constant of −2.5 × 105 deg T–1 m–1 at 1224 nm.

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Stable Cycloparaphenylene Diradical Dications with Macrocyclic Aromaticity

The first crystalline diradical dication [9]CPP2•2+ was successfully synthesized via an oxidation reaction under the support of weakly coordinating anion. Both experimental and theoretical analyses c...

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Triplet Spin Delocalization and Temperature Dependence for Adiabatic and Non-Adiabatic Z–E Isomerization Pathways in Azoarenes

Photoswitching molecules like the azoarenes have myriad potential applications, ranging from energy storage to targeted drug delivery. Upon irradiation, azoarenes convert from an E-form to a Z-form. T...

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Expanding Chemistry of Expanded Helicenes

This review presents recent advances in the chemistry of expanded helicenes, defined as helicenes containing linearly fused benzene rings, as novel aromatic compounds. This review begins with a summa...

chemistry-europe.onlinelibrary.wiley.com

Solution-phase stabilization of a cyclocarbon by catenane formation

Cyclo[N]carbons, molecular rings consisting solely of N carbon atoms, have previously been studied in the gas phase and on surfaces at cryogenic temperatures, but they are generally considered too rea...

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