Themed collection Emerging Frontiers in Aromaticity
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.
Aromaticity: Quo Vadis
In this perspective, different expert opinions are gathered on the definition and concept of aromaticity.
Synthesis of octagon-containing molecular nanocarbons
Nanocarbons, such as fullerenes, carbon nanotubes, and graphenes, have long inspired the scientific community.
Buckybowl and its chiral hybrids featuring eight-membered rings and helicene units
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 on paratropicity and diatropicity in π-extended hexapyrrolohexaazacoronene
Substituent effects in antiaromatic homoHPHAC+ and aromatic homoHPHAC3+ were investigated by NMR, crystal structure, redox, absorption, and DFT calculation analyses.
Substituent effects on aromatic interactions in water
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.
Rational design of anti-Kasha photoemission from a biazulene core embedded in an antiaromatic/aromatic hybrid
Design of anti-Kasha emitters based on the J-coupling of azulenes and molecular rigidity imposed by antiaromatic/aromatic embedding.
From closed-shell edge-extended kekulenes to open-shell carbonylated cycloarene diradicaloid
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.
Fully-fused boron-doped olympicenes: modular synthesis, tunable optoelectronic properties, and one-electron reduction
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 aza-nanographene with multiple odd-membered rings
Saddle-shaped nanographene encompassing a pyrrolopyrrole core possesses an unusual propensity to oxidize (EHOMO = −4.44 eV) while being stable at ambient conditions.
Disentangling global and local ring currents
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.
On-surface synthesis of non-benzenoid conjugated polymers by selective atomic rearrangement of ethynylarenes
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.
Heterocyclic Suzuki–Miyaura coupling reaction of metalla-aromatics and mechanistic analysis of site selectivity
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.
Synthesis and characterization of bi(metallacycloprop-1-ene) complexes
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.
Conjugation between 3D and 2D aromaticity: does it really exist? The case of carborane-fused heterocycles
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.
Aromatic heterobicycle-fused porphyrins: impact on aromaticity and excited state electron transfer leading to long-lived charge separation
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.
The smallest 4f-metalla-aromatic molecule of cyclo-PrB2− with Pr–B multiple bonds
We report the smallest 4f-metalla-aromatic molecule of PrB2− exhibiting σ and π double aromaticity and multiple Pr–B bond characters.
From a Möbius-aromatic interlocked Mn2B10H10 wheel to the metal-doped boranaphthalenes M2@B10H8 and M2B5 2D-sheets (M = Mn and Fe): a molecules to materials continuum using DFT studies
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.
An unexpected all-metal aromatic tetranuclear silver cluster in human copper chaperone Atox1
Metal clusters, such as iron–sulfur clusters, play key roles in sustaining life and are intimately involved in the functions of metalloproteins.
Mining anion–aromatic interactions in the Protein Data Bank
The comprehensive analysis of non-redundant PDB macromolecular structures investigating anion distributions around all aromatic molecules in available biosystems is presented.
Enhanced N-directed electrophilic C–H borylation generates BN–- and helicenes with improved photophysical properties
An enhanced N-directed electrophilic C–H borylation methodology has been developed that provides access to azaborine containing helicenes.
Polariton ring currents and circular dichroism of Mg-porphyrin in a chiral cavity
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.
Visualizing electron delocalization in contorted polycyclic aromatic hydrocarbons
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.
β-Trioxopyrrocorphins: pyrrocorphins of graded aromaticity
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.
Enantiopure nanohoops through racemic resolution of diketo[n]CPPs by chiral derivatization as precursors to DBP[n]CPPs
Racemic resolution of diketone-embedded cycloparaphenylenes by derivatization with a chiral auxiliary provides scalable access to enantiopure hoops with chiroptical properties.
Stretching cycloparaphenylene with encapsulated potassium cations: structural and theoretical insights into core perturbation upon four-fold reduction and complexation
Structural and theoretical analysis of a highly-charged cycloparaphenylene reveals drastic elliptic distortion and unique metal encapsulation of the macrocyclic host upon reduction.
Direct amidation of metallaaromatics: access to N-functionalized osmapentalynes via a 1,5-bromoamidated intermediate
The direct C–H amidation of metallapentalyne has been achieved under mild conditions in which key 1,5-bromoamidated intermediates was determined.
Asymmetric systematic synthesis, structures, and (chir)optical properties of a series of diheterohelicenes
A series of diheterohelicenes 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.
Synthesis, crystal structure and charge transport characteristics of stable peri-tetracene analogues
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.
“Bottled” spiro-doubly aromatic trinuclear [Pd2Ru]+ complexes
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.
A focus on aromaticity: fuzzier than ever before?
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?
About this collection
Although benzene was discovered almost two centuries ago, the attraction of aromaticity continues to intrigue chemists worldwide. This themed collection is introduced by guest editors Miquel Solà (Universitat de Girona), Israel Fernández (Universidad Complutense de Madrid), and Gabriel Merino (Cinvestav Mérida), who highlight the panorama of aromaticity research in modern chemistry. Their selection highlights the most recent methodological developments and unique aspects of aromaticity, such as metalla-aromaticity, macrocyclic aromaticity, 3D-aromaticity, Möbius aromaticity, and the aromaticity of polycyclic conjugated hydrocarbons and nanographenes.