Themed collection Emerging Frontiers in Aromaticity

This themed collection reflects on the relevance of aromaticity in modern chemistry by highlighting the most recent discoveries and views, offering a selection of articles on a wide variety of relevant subjects.

In this perspective, different expert opinions are gathered on the definition and concept of aromaticity.

Nanocarbons, such as fullerenes, carbon nanotubes, and graphenes, have long inspired the scientific community.

A novel buckybowl and its chiral hybrids featuring eight-membered rings and helicene units have been synthesized and characterized. The resulting hybrid and its complex with C₆₀ show promising ambipolar transport characteristics.

Substituent effects in antiaromatic homoHPHAC⁺ and aromatic homoHPHAC³⁺ were investigated by NMR, crystal structure, redox, absorption, and DFT calculation analyses.

Measurements using chemical double mutant cycles show that electron-withdrawing groups lead to remarkable increases in the stability of aromatic interactions, and the magnitude of the effect is much larger in water than in chloroform solution.

Design of anti-Kasha emitters based on the J-coupling of azulenes and molecular rigidity imposed by antiaromatic/aromatic embedding.

A series of closed-shell kekulene homologues and an open-shell carbonylated cycloarene derivative were synthesized successfully by controlling the temperature and gas atmosphere of a Bi(OTf)₃-catalyzed cyclization reaction.

We report a novel family of boraolympicenes with fully-fused boron-doping at their π-skeletons. The resulting boraolympicenyl radical anion featured a resonant stability under inert conditions benefiting from the borataalkene-containing aromatic resonant form.

Saddle-shaped nanographene encompassing a pyrrolopyrrole core possesses an unusual propensity to oxidize (E_HOMO = −4.44 eV) while being stable at ambient conditions.

Aromatic or antiaromatic ring currents – why not both? We use experimental NMR chemical shifts to identify both local and global ring currents in π-conjugated molecules.

Here, we report a new on-surface synthetic strategy to precisely introduce five-membered units into conjugated polymers from specifically designed precursor molecules that give rise to low-bandgap fulvalene-bridged bisanthene polymers.

We describe unique polyhalogenated heteroarene candidates for site-selective cross-coupling, which shows high catalytic performances in the functionalization of polycyclic metalla-aromatics with excellent photophysical properties.

Well-defined metallacycloprop-1-ene complexes have only previously been isolated with a metal center bearing one vinyl moiety. We have successfully obtained the first examples of structurally characterized spiro bi(metallacycloprop-1-ene) complexes.

We have demonstrated that carborane fused heterocycles can definitely be considered as non-2D aromatic compounds; therefore, their aromatic character was significantly overestimated in earlier studies.

π-Extended porphyrins fused with benzo[4,5]imidazo[2,1-a]isoindole, showing unique electronic and photophysical properties, were newly synthesized. A long-lived charge-separated state was revealed upon coordination of C₆₀ to zinc porphyrin AMIm-2.

We report the smallest 4f-metalla-aromatic molecule of PrB₂⁻ exhibiting σ and π double aromaticity and multiple Pr–B bond characters.

The design of (1) Möbius aromatic interlocked boron wheel Mn₂B₁₀H₁₀, (2) Hückel aromatic boron analogs of naphthalene (M₂@B₁₀H₈; M = Mn and Fe), and (3) metal boride monolayers (FeB₅ and Fe₂B₅), creating a molecules to materials continuum.

Metal clusters, such as iron–sulfur clusters, play key roles in sustaining life and are intimately involved in the functions of metalloproteins.

The comprehensive analysis of non-redundant PDB macromolecular structures investigating anion distributions around all aromatic molecules in available biosystems is presented.

An enhanced N-directed electrophilic C–H borylation methodology has been developed that provides access to azaborine containing helicenes.

Placing aromatic molecules in a chiral optical cavity can break time-reversal symmetry and generate polariton ring currents with a linearly polarized pump. Such currents can be probed by circular dichroism, with one order of magnitude enhancement.

Electron delocalization in contorted polycyclic aromatic hydrocarbon (PAH) molecules was examined through 3D isotropic magnetic shielding (IMS) contour maps built around the molecules using pseudo-van der Waals surfaces.

The four possible pyrrocorphin isomers were prepared. Remarkably, they show regiochemically dependent aromaticity attributed to the presence of a 16-membered, 18 π-electron aromatic ring-current.

Racemic resolution of diketone-embedded cycloparaphenylenes by derivatization with a chiral auxiliary provides scalable access to enantiopure hoops with chiroptical properties.

Structural and theoretical analysis of a highly-charged [8]cycloparaphenylene reveals drastic elliptic distortion and unique metal encapsulation of the macrocyclic host upon reduction.

The direct C–H amidation of metallapentalyne has been achieved under mild conditions in which key 1,5-bromoamidated intermediates was determined.

A series of dihetero[8]helicenes have been synthesized in a stereoselective manner through an organosulfur-based synthetic strategy, which has enabled clarifying the effect of the endocyclic atoms on physical properties.

Highly stable peri-tetracene analogues with a high degree of singlet biradical character were synthesized in a very simple route, and their crystal structures and semiconducting properties were investigated.

Synthesis of a triangular [Pd₂Ru]⁺ complex with delocalized metal–metal bonding between non-adjacent elements of the periodic table, double aromaticity and overlap of d-AOs with different angular momentum.

The field of aromaticity has grown extensively in recent decades, and new or unusual forms of aromaticity have been explored. But what exactly is aromaticity? It has always been a fuzzy and disputable concept, yet, is it now fuzzier than ever before?