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Helicenes, with their unique helical structures, have long captured the interest of synthetic chemists, not only as end products, but also as versatile platforms for further chemical transformations. However, transforming [6]helicene into planar coronene typically requires harsh conditions and poses significant challenges. Herein, we demonstrate that replacing the terminal benzene ring of [6]helicene with a thiophene ring enables its photochemical transformation into coronene. Sulfur oxidation of the thiophene ring enables the corresponding thermal transformation, and the terminal tetrafluorination of the opposite benzene ring further accelerates this process, yielding 1,2‐difluorocoronene, as confirmed by X‐ray crystallography. The transformation begins with an intramolecular Diels–Alder reaction, whose activation energy is significantly lowered by these structural changes. Our findings underscore the utility of strategic modifications such as sulfur oxidation and fluorination in promoting this "helix‐to‐disc" conversion and opening new avenues for synthesizing functional polycyclic aromatics. [ABSTRACT FROM AUTHOR]

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A simple method for obtaining triplet-triplet absorption (TTA) spectra and triplet state (T1) lifetimes of long-lived triplets is presented and demonstrated with the polycyclic aromatic hydrocarbon coronene (both normal and perdeuterated forms) in a polymer matrix at room temperature. The TTA spectra obtained with a camera flash and a spectrophotometer are noisier but otherwise identical to those obtained with a state-of-the-art flash photolysis apparatus. The triplet lifetimes obtained from transient absorption are identical to the phosphorescence lifetimes of the same samples.

Polycyclic aromatic hydrocarbons (PAHs) are significant pollutants found in petroleum products. There is ample literature on the biodegradation of PAHs containing less than five rings, but little has been done on those with more than five rings. Coronene (CRN), a seven-ring-containing PAH, has only been shown to be degraded by one bacterial strain. In this study, a bacterial strain 10SCRN4D was isolated through enrichment in the presence of CRN and 10% NaCl (w/v). Analysis of the 16S rRNA gene identified the strain as Halomonas caseinilytica. The strain was able to degrade CRN in media containing 16.5–165 μM CRN with a doubling time of 9–16 hours and grew in a wide range of salinity (0.5–10%, w/v) and temperature (30–50°C) with optimum conditions of pH 7, salinity 0.5%–10% (w/v), and temperature 37°C. Over 20 days, almost 35% of 16.5 μM CRN was degraded, reaching 76% degradation after 80 days as measured by gas chromatography. The strain was also able to degrade smaller molecular weight PAHs such as benzo[a]pyrene, pyrene, and phenanthrene. This is the first report of Halomonas caseinilytica degrading CRN as the sole carbon source in high salinity, and thus highlights the potential of this strain in bioremediation.

An organometallic complex of coronene (Cor) and chromium (Cr) was designed and used as a catalyst in a simulated process in which a CO2 molecule is captured, activated, and then reacts with a hydrogen molecule (H2) to yield formic acid (HCOOH). The structural characteristics and local aromaticity are due to the similarity in the binding scheme with the bis(benzene)chromium (Cr-Bz2). Such a molecular fragment, referred to here as a “Clar’s site”, involves a single chromium atom that binds to CO2 by transferring electron density through backdonation. Therefore, the capture of CO2 outside the Cr3-Cor2 complex allows for the carrying out of a hydrogenation process that involves the breaking of one of the C−O bonds, the double addition of hydrogen, the formation of HCOOH and its release, regenerating the structure of the Cr3-Cor2 complex. The thermodynamic and kinetic results of this reaction are analyzed, as well as the nature of the orbitals and the relevant interactions of this process. This work explores a new concept for the creation of single atom catalysts (SACs), taking advantage of the high electron density around the metallic center and the sandwich architecture, having shown that it can perform the catalytic reduction of CO2.

Using the methods of quantum chemistry, the energy effects of the interaction of partially oxidized graphene-like planes with each other and the effect on this characteristic of the nature of the functional groups present in the oxidized graphene-like planes, as well as the dimensions of the graphene-like planes themselves, were clarified. It was established that the reaction between the hydroxyl and aldehyde groups of two interacting graphene-like planes is the most thermodynamically probable, regardless of the dimensions of the graphene-like planes. The reaction between two carboxyl groups of different graphene-like planes is the least thermodynamically probable. To create nanocomposites by interacting graphene-like planes with each other, it is necessary that the graphene-like planes contain hydroxyl and aldehyde groups.

An organometallic complex of coronene (Cor) and chromium (Cr) was designed and used as a catalyst in a simulated process in which a CO2 molecule is captured, activated, and then reacts with a hydrogen molecule (H2) to yield formic acid (HCOOH). The structural characteristics and local aromaticity are due to the similarity in the binding scheme with the bis(benzene)chromium (Cr-Bz2). Such a molecular fragment, referred to here as a "Clar's site", involves a single chromium atom that binds to CO2 by transferring electron density through backdonation. Therefore, the capture of CO2 outside the Cr3-Cor2 complex allows for the carrying out of a hydrogenation process that involves the breaking of one of the C−O bonds, the double addition of hydrogen, the formation of HCOOH and its release, regenerating the structure of the Cr3-Cor2 complex. The thermodynamic and kinetic results of this reaction are analyzed, as well as the nature of the orbitals and the relevant interactions of this process. This work explores a new concept for the creation of single atom catalysts (SACs), taking advantage of the high electron density around the metallic center and the sandwich architecture, having shown that it can perform the catalytic reduction of CO2. [ABSTRACT FROM AUTHOR]

Coronene emits phosphorescence only at cryogenic temperatures in the absence of oxygen. To achieve room‐temperature phosphorescence (RTP), coronene has been incorporated into various host materials to prevent non‐radiative deactivation of the incorporated molecules. Among host materials, crystalline porous materials homogeneously incorporate luminescent molecules and prevent their aggregation. Therefore, they have attracted attention as potential host materials. Although coronene incorporated into a crystalline porous material exhibited RTP in previous studies, the host material exhibited high affinity for oxygen, allowing the expression of RTP only under anoxic conditions. Therefore, RTP has not been achieved in air. Herein, we incorporate coronene into cage‐like sodalite‐type porous organic salts (s‐POSs) composed of tetrasulfonic acid with an adamantane core (4,4',4",4"'‐[adamantane‐1,3,5,7‐tetrayl]tetrabenzenesulfonic acid; AdPS) and triphenylmethylamines modified with substituents at the para‐position of the benzene rings (TPMA−X, X=methyl [Me], Br, I), which have low oxygen affinities and different degrees of heavy‐atom effects on incorporated coronene. The combination of the oxygen barrier due to the low affinity of s‐POSs for oxygen and the external heavy‐atom effect of bromine and iodine exposed on the pore surface enabled the incorporated coronene to exhibit RTP in air (phosphorescence lifetime with more than microseconds). [ABSTRACT FROM AUTHOR]

The possibilities of activation of carbon electrodes by oxidized multiwalled carbon nanotubes and hybrid nanomaterials based on carbon nanotubes and coronene, which can be considered as an elementary fragment of graphene, were studied. The electrochemical properties of the modified electrodes by the example of graphite slate electrodes and carbon electrodes obtained by screen printing were studied by the method of cyclic voltammetry. It is shown that the modification of the electrode surface with carbon nanotubes significantly increases the efficiency of electrochemical processes in both systems, which indicates the prospects for the use of pencil graphite in electroanalysis and for the creation of bioelectrodes. However, contrary to expectations, the adsorption of coronene on oxidized multiwalled carbon nanotubes reduces the observed effect. A scheme of the proposed interaction between nanotubes and coronene is presented in order to explain the obtained results. Simulation of the processes of electrocatalytic oxidation-reduction of methylene blue on modified electrodes confirms the proposed scheme for the interaction of oxidized carbon nanotubes and c-oronene. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are significant pollutants found in petroleum products. There is ample literature on the biodegradation of PAHs containing less than five rings, but little has been done on those with more than five rings. Coronene (CRN), a seven-ring-containing PAH, has only been shown to be degraded by one bacterial strain. In this study, a bacterial strain 10SCRN4D was isolated through enrichment in the presence of CRN and 10% NaCl (w/v). Analysis of the 16S rRNA gene identified the strain as Halomonas caseinilytica. The strain was able to degrade CRN in media containing 16.5-165 µM CRN with a doubling time of 9-16 hours and grew in a wide range of salinity (0.5-10%, w/v) and temperature (30-50°C) with optimum conditions of pH 7, salinity 0.5%-10% (w/v), and temperature 37°C. Over 20 days, almost 35% of 16.5 µM CRN was degraded, reaching 76% degradation after 80 days as measured by gas chromatography. The strain was also able to degrade smaller molecular weight PAHs such as benzo[a]pyrene, pyrene, and phenanthrene. This is the first report of Halomonas caseinilytica degrading CRN as the sole carbon source in high salinity, and thus highlights the potential of this strain in bioremediation. [ABSTRACT FROM AUTHOR]

Sunlight‐driven photochemical reactions are an important tool for sustainable organic synthesis. However, compared with ground states, for which the effects of structure on properties and reactivity are well established, the understanding of excited states is limited. In particular, an improved understanding of aromaticity and antiaromaticity in excited states is necessary to develop strategic photochemical methods for synthesizing polycyclic aromatic compounds. Herein, using density functional theory (DFT)‐optimized structures, the ground singlet (S0) and lowest triplet (T1) states of coronene and corannulene were compared. Bond length analysis demonstrated that both triplet corannulene and triplet coronene bear a partial resemblance to benzene. Nucleus‐independent chemical shift (NICS(0), NICS(1.7)ZZ, NICS scans) and anisotropy of the induced current density (ACID) calculations were carried out to compare the induced magnetic currents in these molecules. This analysis demonstrated rather weak π‐conjugation and partial antiaromaticity in the S0 state of each molecule. In contrast, a combination of circular induced currents and pronounced antiaromaticity was found in the T1 state of each molecule. However, the T1 of corannulene exhibited higher stability, which should facilitate functionalization. Consequently, corannulene is considered more suitable for photochemical applications. [ABSTRACT FROM AUTHOR]

Metal oxide hexagonal ZnO thin film with thickness of approximately 509 nm was successfully grown on a glass/ITO substrate by electrochemical deposition. It was observed that Zn and O were homogeneously distributed in the thin film and crystals formed in the (100), (002), (101), (102) and (201) planes. The ZnO surface morphology was characterized by cauliflower-like structures which were composed of nanorods. Coronene organic semiconductor nanowire (~503 nm thick) was deposited on glass/ITO/ZnO by a physical vapor deposition technique. Additionally, UV–Vis spectrometry measurements revealed that the maximum absorption value of the heterojunction was observed at the near-ultraviolet region, and the maximum absorption coefficient (α) value was determined to be 3.55 × 106 m−1. Also, the bandgap (Eg) value of the heterojunction was 3.24 eV. After Ag metal contacts were grown on ZnO and coronene surfaces, electrical characterization of the Ag/ZnO/coronene/Ag heterojunction was performed in the dark and under 20 mW cm−2 light intensity. The electrical analysis indicated that the diode ideality factor (n), series resistance (Rs), and barrier height ( ∅ b ) values of the Ag/ZnO/coronene/Ag hybrid heterojunction decreased under illumination, while the reverse saturation current (I0) value increased. The photocurrent (Iph), photoresponsivity (R) and photosensitivity (S) of the heterojunction were determined at 20 mW cm−2 light intensity under reverse and forward bias, and values of 3.73 × 10–5 A, 0.23 A W−1 and 5.47 × 10–8 S m W−1 were obtained, respectively. In addition, the photovoltaic parameters of the heterojunction were examined, and short-circuit current (Isc), maximum power point current (Impp), open-circuit voltage (Voc), maximum power point voltage (Vmpp) and fill factor (FF%) values of 1.41 × 10–6 A, 8.76 × 10–7 A, 0.06 V, 0.03 V and 31% were observed, respectively. These findings indicate that the fabricated heterojunction is highly photoresponsive and shows photodiode and photovoltaic properties. [ABSTRACT FROM AUTHOR]

It is known that the addition of a small amount of carbon nanomaterials significantly improves the mechanical properties of composites with a metal matrix. One of the most important, promising and available metals as a matrix for such modification is aluminum. However, at the interface between the carbon material and Al, aluminum carbides of different composition are formed, which are brittle and have the main disadvantage - solubility in water. Therefore, the appearance of aluminum carbide is a serious problem, since it contributes to the formation of defects, which, when the composite is deformed, leads to cracking of the composite due to the presence of microneedles. In this regard, in order to predict the features of the interaction of aluminum itself with the surface of carbon nanomaterials, it is advisable to model such processes using quantum chemistry methods. The aim of the work was to reveal the effect of temperature on the chemical interaction of aluminum clusters with native, boron-, silicon-, and nitrogen-containing graphene-like planes (GLP). All the calculated by three methods (B3LYP/6-31G(d,p), MP2/6-31G(d,p) and PBE0/6-31G(d,p)) values of the dependence of the Gibbs free energy on temperature for different cluster sizes of aluminum and graphene-like clusters are the highest for native graphene-like planes. In all cases, the values of the Gibbs free energy increase with temperature. The lowest values of the temperature dependence of the Gibbs free energy vary as dependent on the size of the reactant models and research methods, this is especially characteristic of the presence of boron and silicon atoms in the graphene-like clusters. Therefore, the absence of heteroatoms in the composition of the nanocarbon matrix contributes to the fact that aluminum carbide islands should not be formed in the carbon-containing nanocomposite with aluminum, which negatively affects the physical and chemical characteristics of the resulting nanocomposite. [ABSTRACT FROM AUTHOR]

Mono and dual lead (Pb)-doped models of graphene were investigated in this work by means of performing density functional theory (DFT) calculations. Coronene was considered in this work as a representative structure of graphene in a molecular scale. For dual Pb-doped models, two conformations of Cis and Trans were investigated by putting two Pb atoms at the same side of graphene in the Cis model and locating two Pb atoms at the opposite sides in the Trans model. The models were optimized to obtain the minimized energy structures, which were confirmed by the evaluated non-imaginary frequencies. Molecular and atomic features were obtained to recognize the effects of Pb dopant on structural and electronic features of graphene for making a comparison for the investigated models. As the main achievements of this work, the models were successfully optimized by better benefits of formation of the Cis model in comparison with the other models. Based on the evaluated electronic features, developments of further applications could be expected for such models systems. [ABSTRACT FROM AUTHOR]

Adsorption of the sorbic acid drug onto the surface of coronene/fullerene/fullerene like nanocages was investigated by theoretical calculations. Our results showed that the sorbic acid drug connects the nanoclusters through oxygen and hydrogen atoms. Due to the adsorption of the sorbic acid drug, there are significant changes in chemical descriptors and nonlinear optical properties. Energy gap values of all nanocluster systems are reduced, resulting in enhance in the conductivity of systems except for fullerene. All complex's ultraviolet (UV) visible wavenumber is blue-shifted and especially for coronene and fullerene complex, the values are very high. The enhancement for different functional group wavenumbers in the Raman spectrum indicates that it is possible to make a nanocage sensor for the detection of these compounds using surface-enhanced Raman scattering (SERS). Docking gives good values of atomic contact energies and suitable for drug delivery. [ABSTRACT FROM AUTHOR]

New organic frameworks (COFs) employing two coronene molecules forced to adopt a parallel conformation thus forming a molecular reactor are proposed. These COFs exhibit different distances between the coronene units, thus creating diverse electronic environments. The simulation of the trapping of CO2 and H2 molecules in the reactor hollow having distinct anchor fragments yields in the two cases formic acid. The analysis of the reaction profile allowed us to propose a thermodynamically favored process. The nature of the frontier molecular orbitals in the involved processes is also discussed. Reaction profile of CO2 and H2 process to yield formic acid. [ABSTRACT FROM AUTHOR]

Bonding and aromaticity in the bowl-shaped C5v and planar D5h geometries of corannulene and the planar D6h geometry of coronene are investigated using 3D isosurfaces and 2D contour plots of the isotropic magnetic shielding σiso(r) and, for planar geometries, of the out-of-plane component of the shielding tensor σzz(r). Corannulene and coronene both feature conjoined shielded “doughnuts” around a peripheral six-membered carbon ring, suggesting strong bonding interactions and aromatic stability; a deshielded region inside the hub ring of corannulene indicates that this ring is antiaromatic, more so in planar corannulene. The switch from the planar to the bowl-shaped geometry of corannulene is shown to enhance both bonding and the local aromaticities of the five- and six-membered rings; these factors, in addition to ring strain reduction, favour the bowl-shaped geometry. The most and least shielded bonds in both corannulene and coronene turn out to be the spoke and hub bonds, respectively. The higher π electron activity over spoke bonds in planar corannulene and coronene is supported by σzz(r) contour plots in planes 1 Å above the respective molecular planes; these findings about spoke bonds are somewhat unexpected, given that ring current studies indicate next to no currents over spoke bonds.

The residues generated from the anodizing industry contain metallic ions like Al3+, and the presence of these pollutants in water bodies cause serious concern because of the ecological and human health risks. The adsorption of heavy metal ions is a widely used option due to it is an easy to implement, eco-friendly, and cost-effective process. This work reports the effect of different surfaces on the adsorption process of Al3+ ions to clarify the adsorption mechanism of the ions using molecular dynamics simulations. The models of three adsorbents: hydroxyapatite (HAP), an activated carbon (AC), and clinoptilolite (CLI) were computationally investigated to identify the most suitable adsorbent. The calculated adsorption isotherms allowed the evaluation of three different adsorbent materials for the removal of Al3+ ions from an aqueous solution. The findings were compared with experimental data of Al3+ adsorption onto bone char and a good qualitative similarity with experimental data was obtained for the HAP model. The results obtained by simulation as well as the experimental data fit satisfactorily to the Freundlich model, the fitting parameters show differences less than 3 % between the simulated and experimental data. For the three adsorbents, the simulated data fit better to the Freundlich isotherm adsorption model, suggesting heterogeneous adsorption on surfaces with variable adsorption capacity in each case. To study the adsorption mechanism, density profiles, RDFs, number of H-bonds, molecular minimum distances and intermolecular interactions were calculated. The efficiency of Al3+ ion adsorption is strongly influenced by the hydrophilic or amphiphilic nature of the adsorbent surface, as well as by the solvation structure of the ions in the solution. In each system, the solvation phenomenon occurs, although only the AC adsorbent exhibits it to a lesser extent compared to CLI and HAP surfaces. The CLI model had the highest adsorption capacity, due to its intense hydrophilic behavior, which leads to greater affinity and stability in the water molecules adsorbed on its surface and, therefore, allows a greater adsorption of Al3+ ions. [Display omitted] • Direct water adsorption and indirect Al3+ ion adsorption is mediated by solvated water molecules. • Formation of hydrogen bonds between water and adsorbents is crucial for Al3+ ion adsorption. • The pre-adsorbed water into clinoptilolite plays a fundamental role in the adsorption capacity. • The results for hydroxyapatite model support qualitative the experimental observations. [ABSTRACT FROM AUTHOR]

Electronic properties such as density of state, energy gap, HOMO (the highest occupied molecular orbital) level, LUMO (the lowest unoccupied molecular orbital) level and density of bonds, as well as spectroscopic properties like infrared (IR), Raman scattering, force constant, and reduced masses for coronene C24, reduced graphene oxide (rGO) C24O5 and interaction between C24O5 and NO2 gas molecules were investigated. Density functional theory (DFT) with the exchange hybrid function B3LYP with 6-311G** basis sets through the Gaussian 09 W software program was used to do these calculations. Gaussian view 05 was employed as a supplementary software to investigate the geometrical structure of C24, C24O5 and the interaction of C24O5 with NO2 gas molecule. It shows the energy gap of coronene C24 3.5 eV because the effect of quantum confinement and the Coulomb interaction geometry greatly influence the quasi-particle band gap and C24Ox where x = 1–7 was from 0.89 eV to 1.6862 eV a function of number of oxygen atoms and compared with the experiment value of graphene oxide which was between 1 eV and 2.2 eV. The spectroscopic properties were compared with the experiment value of graphene, graphene oxide and NO2 longitudinal optical (LO) modes of 1 585, 1 582 and 1 600 cm−1, respectively. The transition state of the interaction of rGO with nitrogen dioxide and Gibbs energy, enthalpy, activation entropy and reaction at various temperatures between 25°C and 100°C were calculated. The activation energy of C24O5 with nitrogen dioxide decreases with increasing temperature. [ABSTRACT FROM AUTHOR]

To determine the electrical modulus, dielectric properties, and ac conductivity of Coronene semiconductor layer, we have produced Al/Coronene/n-Si structure by using the thermally evaporation and spin coating method. The variation of dielectric constant (ε′), dielectric imaginary part (ε″), tangent loss (tanδ), electrical modulus (M′ and M″), and ac electrical conductivity (σac) with voltage and frequency of Coronene semiconductor layer have been investigated in the frequency range of 1 kHz – 1 MHz and at the selected voltages (0.0–0.4 V with steps 0.02 V). It is found that theε′andε″values decrease with increasing frequency while an increase is observed in tanδ, σac, and the real (M′) and the imaginary (M″) of the electrical modulus. The ε′, ε″, tanδ, σac, M′, and M″ values have been determined as 6.53, 8.58, 1.31, 0.0477 S/cm, 0.0561 and 0.0477 for 1 kHz and 0.0046, 0.129, 2.78, 7.17 S/cm, 0.278, and 7.74 for 1 MHz at 0.0 V, respectively. [ABSTRACT FROM AUTHOR]

Bilayer graphene (BLG), which changes its electronic properties significantly depending on the interplanar distance and rotation angle, is a hot research topic. We successfully synthesized discrete BLG models by bridging two coronenes with a 1,8‐naphthalene linkage (C2). Owing to the large rotational energy, the syn‐ and anti‐atropisomers of C2 could be isolated. X‐ray crystallographic analysis revealed that the syn‐form (C2S) is an AB stacking type and the anti‐form (C2A) is a chiral twisted bilayer graphene (TBG) type. Therefore, the anti‐form of C2 was optically resolved and characterized by circular dichroism (CD) and circularly polarized luminescence (CPL) spectroscopy. The Cotton effect was observed in the CD spectra at the longest absorption wavelength, and the corresponding bisignate CPL spectra were observed. The dissymmetry factors |glum| of C2A were found to be 2.0×10−3 at 435 nm and 1.2×10−3 at 450 nm. [ABSTRACT FROM AUTHOR]

Fused polycyclic aromatic compounds are interesting materials for organic electronics applications. To fine‐tune photophysical or electrochemical properties, either various substituents can be attached or heteroatoms (such as N or S) can be incorporated into the fused aromatic backbone. Coronenes and heterocoronenes are promising compounds in this respect. Up until now, the possibilities for varying the attached fused heteroaromatics at the coronene core were quite limited, and realizing both electron‐withdrawing and ‐donating rings at the same time was very difficult. Here, a series of pyridine, anisole and thiophene annulated tetraareno[a,d,j,m]coronenes has been synthesized by a facile two‐step route that is a combination of Suzuki‐Miyaura cross‐coupling and a following cyclization step, starting from three different diarenoperylene dibromides. The contorted molecular π‐planes of the obtained cata‐condensed tetraarenocoronenes were analyzed by single‐crystal X‐ray crystallography, and the photophysical and electrochemical properties were systematically investigated by UV/Vis spectroscopy and cyclovoltammetry. [ABSTRACT FROM AUTHOR]

Photosensitization analyses of models of (–HC = CH–)n assisted coronene-cytosine complexes assigned by Cor-n-Cyt; n varying by 0, 1, 2, and 3, were investigated in this work by performing density functional theory (DFT) calculations. The investigated models were optimized and chemical descriptors were evaluated. To achieve the goal of this work, energy levels of the highest occupied and the lowest unoccupied molecular orbitals (HOMO and LUMO) were evaluated to reach the absorption energy requirement for innovating photosensitizer (PS) compounds. The models indicated that the complex formations could help the structures to participate in interactions easier than the singular models, in which HOMO-LUMO descriptors indicated lower required absorption energy for them to increase their safety for human health level. The required absorption energies of complexes with n = 0, 1, and 2, were in ultraviolet (UV) region whereas that of complex with n = 3 was moved to visible region. In this regard, the idea of new PS compounds innovation was examined here to introduce Cor-n-Cyt complexes for possible applications in photodynamic therapy (PDT). [ABSTRACT FROM AUTHOR]

Bonding and aromaticity in the bowl-shaped C5v and planar D5h geometries of corannulene and the planar D6h geometry of coronene are investigated using 3D isosurfaces and 2D contour plots of the isotropic magnetic shielding σiso(r) and, for planar geometries, of the out-of-plane component of the shielding tensor σzz(r). Corannulene and coronene both feature conjoined shielded "doughnuts" around a peripheral six-membered carbon ring, suggesting strong bonding interactions and aromatic stability; a deshielded region inside the hub ring of corannulene indicates that this ring is antiaromatic, more so in planar corannulene. The switch from the planar to the bowl-shaped geometry of corannulene is shown to enhance both bonding and the local aromaticities of the five- and six-membered rings; these factors, in addition to ring strain reduction, favour the bowl-shaped geometry. The most and least shielded bonds in both corannulene and coronene turn out to be the spoke and hub bonds, respectively. The higher π electron activity over spoke bonds in planar corannulene and coronene is supported by σzz(r) contour plots in planes 1 Å above the respective molecular planes; these findings about spoke bonds are somewhat unexpected, given that ring current studies indicate next to no currents over spoke bonds. [ABSTRACT FROM AUTHOR]

Coronene and corannulene are popular structures that have provided the basis for the investigation of extended carbon-based structures, like graphene, fullerene and their derivatives. Here we address the Jahn-Teller (JT) effects in electron paramagnetic resonance (EPR) spectroscopy of such molecules in ionic form. By density functional theory (DFT) and a Monte Carlo based sampling of the potential energy surface, we obtain three and five symmetry-related JT equivalent conformers in coronene and in corannulene ions, respectively. The structure and the interconversion between the JT distorted forms are discussed for their implication in EPR spectroscopy. The calculation of the g-tensor by DFT methods has also been benchmarked to serve as methodological approach for the investigation of more extended graphene molecules.

We have investigated computationally the effect of π-conjugated extension on the charge transfer properties of triphenylene and coronene; where we have added fused benzene or triazole rings in the parent molecule. The results showed that the six polycyclic aromatic hydrocarbons investigated are semiconductor molecules. The μ- values of molecules naphthotriphenylene (a1), tribenzocoronene (b1), and tristriazolecoronene (b2) were 1.5 to 21.5 times that of the corresponding μ+ values, suggesting that they are n-type organic semiconductors. Compared with the results obtained by the B3LYP and B3LYP + D3 methods, the charge transport mobility obtained using M06-2X, M06-2X + D3, and M08-HX showed the similar calculation results. [ABSTRACT FROM AUTHOR]

Orbital interactions of H 2 on edge sites of Ni-coronene. [Display omitted] • Ni adsorption on nanographene coronene could be used for hydrogen storage. • Ni sites on coronene can activate hydrogen molecules for catalytic hydrogenation. • A correlation between E ads (H 2) was found with charge at the Ni adsorption site. • The E ads (H 2) of Ni atoms is stronger at the Cor bridge edge sites. • H 2 adsorption depends on charge transfer from Ni, Ni-H, and Ni-C interactions. A computational study of a Ni atom in a coronene (Cor) molecule, as a model of a single-atom catalyst (SAC), was carried out using a DFT approach. The adsorption energy results of Ni on Cor (2.31–1.84 eV) are similar to those reported for extended graphene. Ni-Cor adsorption is preferred at edge sites and electron transfer from Ni to Cor occurs. H 2 adsorbs on Ni-Cor with 1.03–1.24 eV. Correlations were obtained between the H 2 adsorption energies and some properties of Ni-Cor. The results suggest that Ni-Cor could be used for hydrogen storage and also for catalytic hydrogenation of hydrocarbons. [ABSTRACT FROM AUTHOR]

[Display omitted] • Investigation of sensing nature of functionalized coronene quantum dot. • Frontier molecular orbitals and molecular electrostatic potential surface validates their chemical stability. • Higher adsorption energy was observed for gas molecules on quantum dot. • Light harvesting efficiency of functionalized quantum dots was elevated. • The designed quantum dots have potential applications in gas sensing and photosenstivity. The present study accounts for the structural and electronic properties of a zero-dimensional coronene quantum dot (QD) and its substituted structures with seven different functional groups. The substitution of functional groups lead to the alteration of the centrosymmetric geometry of the coronene flake and thus, incredible properties were observed for the functionalized QDs. The increment in the band gap after the substitution of the functional groups was responsible for the increase in the chemical stability. The cohesive energy however decreased for the functional QDs. Fourier transform Infrared spectra were traced for all the QDs to confirm the availability of the functional groups and their participation in the chemical reactivity. After the substitution of functional groups, the extremely enhanced light harvesting efficiency of functionalized QDs was obtained. Furthermore, the sensing capability of the functionalized QDs for CO, CO 2 , and NH 3 was also calculated and it was found that C-cyano, C-nitro, C-nitroso, C-pyrrolidine, and C-thionyl QDs have better sensing capabilities for CO 2 molecules. C-pyrrolidine had the highest value of light harvesting efficiency of about 96%. This reflects the potential photosensitive candidature of C-pyrrolidine. Therefore, the present study sets a perfect benchmark for designing and fabricating efficient photosensitive materials and gas-sensing devices using the introduced QDs in the near future. [ABSTRACT FROM AUTHOR]

We employ low-temperature matrix-isolation FTIR spectroscopy and quantum chemical calculations to study the interaction between nucleobase uracil and coronene which models the graphene surface. To observe the dimer FTIR spectrum, we use a quartz microbalance that allows us to produce matrix samples with precisely determined concentrations of coronene and uracil (with the concentration ratio of 2.5:1:1000 for coronene:uracil:argon). The interaction between coronene and uracil results in spectral shifts of uracil spectral bands. These shifts do not exceed 10 cm−1. The maximum shifts are observed for the C=O stretching and NH out-of-plane vibrations of uracil. The structures and interaction energies of stacked and H-bonded coronene-uracil complexes are calculated at the DFT/B3LYP(GD3BJ)/aug-cc-pVDZ and MP2/aug-cc-pVDZ levels of theory. In total, 19 stable stacked and two H-bonded coronene-uracil dimer structures are found in the calculations. The interaction energy obtained for the most stable stacked dimer is −12.1 and −14.3 kcal/mol at the DFT and MP2 levels, respectively. The interaction energies of the H-bonded dimers do not exceed − 3 kcal/mol. The IR spectra of the studied monomeric molecules and of all the dimers are calculated at the DFT/B3LYP(GD3BJ)/aug-cc-pVDZ level of theory. The spectral shifts of the most stable stacked coronene-uracil dimer obtained in the calculations are in good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

The synthesis and photophysical properties of a soluble amide‐embedded coronene is reported. The key step in this synthesis is the twofold C−H activation of diazaperylene by a rhodium(III)Cp* catalyst. This unprecedented structural motif shows intense fluorescence in the near infrared region with a small Stokes shift and a distinct vibronic structure, which exhibits a slight extent of negative solvatochromism. Comparison of this compound with some relevant compounds revealed the importance of the amide incorporation in the peripheral concave region including an angular position to retain high aromaticity reflecting that of parent coronene. Treatment of this compound with Lewis acid B(C6F5)3 formed a bis‐adduct, which exhibited enhanced aromaticity as a consequence of the increased double bond character of the amide C−N bonds. [ABSTRACT FROM AUTHOR]

Recently, the capture of carbon dioxide, the primary greenhouse gas, has attracted particular interest from researchers worldwide. In the present work, several theoretical methods have been used to study adsorption of CO2 molecules on Li+-decorated coronene (Li+@coronene). It has been established that Li+ can be strongly anchored on coronene, and then a physical adsorption of CO2 will occur in the vicinity of this cation. Moreover, such a decoration has substantially improved interaction energy (Eint) between CO2 molecules and the adsorbent. One to twelve CO2 molecules per one Li+ have been considered, and their Eint values are in the range from −5.55 to −16.87 kcal/mol. Symmetry-adapted perturbation theory (SAPT0) calculations have shown that, depending on the quantity of adsorbed CO2 molecules, different energy components act as the main reason for attraction. AIMD simulations allow estimating gravimetric densities (GD, wt.%) at various temperatures, and the maximal GDs have been calculated to be 9.3, 6.0, and 4.9% at T = 77, 300, and 400 K, respectively. Besides this, AIMD calculations validate stability of Li+@coronene complexes during simulation time at the maximum CO2 loading. Bader’s atoms-in-molecules (QTAIM) and independent gradient model (IGM) techniques have been implemented to unveil the features of interactions between CO2 and Li+@coronene. These methods have proved that there exists a non-covalent bonding between the cation center and CO2. We suppose that findings, derived in this theoretical work, may also benefit the design of novel nanosystems for gas storage and delivery.

A series of novel coronene-based fluorescent materials have been synthesized through well-defined protocol from 1,2-dimethoxybenzene, with the key steps including Suzuki–Miyaura coupling and oxidative cyclodehydrogenation with ferric chloride. Fluorescence spectra investigations proved that they have emissions in the range λ 460-470 nm with excitation wavelength at λ 373 nm. It is found that different chromophores from substituents can significantly enhance the fluorescence intensities, which paves a new way of application of these materials in various fields. [ABSTRACT FROM AUTHOR]

The novel systems for hydrogen storage are of importance for the contemporary energetics. In this paper, we investigate hydrogen adsorption on planar (coronene) and bent (corannulene) adsorbent models by means of DFT-D3 and SAPT0 calculations. We also use the 'decoration' of the adsorbents with M (M = Li, Na) cations to improve H2 uptake. It was founded that corannulene adsorbs Li and Na cations almost equally compared with coronene. However, hydrogen adsorption is much more pronounced in the case of corannulene. Thus, for instance, adsorption energies (Ea) for the 1st and 4th H2 molecules adsorbed on Li+@coronene and Li+@corannulene are - 4.387, - 1.336 kcal/mol and - 5.047, - 3.477 kcal/mol, respectively. We also employ the independent gradient model (IGM) method to visualize interacting regions between cations, hydrogen and studied adsorbents. We accurately show the strong interactions between M+ and the adsorbent molecules as well as the weak ones between H2 and studied cations. The present results should provide in-depth analysis of the fundamentals of hydrogen storage using M+-decorated polyaromatic hydrocarbons. [ABSTRACT FROM AUTHOR]

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Coronene/n-Si Schottky structure has been fabricated by Coronene thin film deposited on n-Si substrate using the spin coating technique. The current-voltage (I-V) characteristics of the diode have been evaluated under various illumination intensities to determine photodiode behavior. Photovoltaic parameters of the fabricated diode have been calculated at different illumination intensities. The Coronene/n-Si diode presents a photovoltaic status with a maximum short-circuit current (Isc) of 13.1 μA and open circuit voltage (Voc) of 0.16 V under 100 mW/cm2 illumination intensity. The recombination process of the Coronene/n-Si diode shows the existence of bimolecular recombination mechanism associated with the trap levels in the band gap. Also, the series resistance and interface state density distribution of the photodiode have been estimated by capacitance-voltage (C-V) and conductance-voltage (G-V) characteristics at various frequencies. The experimental results indicated that the Al/Coronene/n-Si diode can be used as a photodiode in optoelectronic and photovoltaic applications. [ABSTRACT FROM AUTHOR]

The adsorption of nucleobases (NBs) on pristine and aluminum-doped coronene (Al-coronene) has been studied theoretically using density functional theory (DFT) method in the presence/absence of external electric fields (EFs) having different strengths. The changes in geometric and electronic structures upon the adsorption were analyzed in order to reveal the sensitivity of pristine coronene and Al-coronene toward NBs. The results of theoretical calculations at wB97XD/6–31G(d,p) level of theory showed that the molecular adsorption of NBs on Al-coronene under the external EFs can induce significant change in Al-coronene conductivity. On the basis of calculated changes in band gap energy (ΔEg) and adsorption energy (Eads), it was found that electronic properties of Al-coronene, especially in presence of the applied EFs, are very sensitive to the adsorption of NBs. Finally, electronic structures analysis and full characterization of the surface interactions were performed using the quantum theory of atoms in molecules (QTAIM) to elucidate the nature of NB adsorption interaction. As a result, the enhanced electrical properties of NBs/Al-coronene-adsorbed complexes in the presence of the applied external EFs indicated promising perspectives for fabrication of new NBs-sensing devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • The adsorption of toremifene on coronene carboxylic acid-functionalized coronene. • Enhancement for Raman modes observed. • All of TOR-complexes had negative Gibbs free energy changes as a result of TOR adsorption. The adsorption of toremifene (TOR) on coronene (GG) and carboxylic acid-functionalized coronene (COOHGG) and doped with boron/nitrogen (BBGG/NNGG) has been researched using DFT and TD-DFT simulations. The chemical properties, AIM, and SERS were all considered when conducting this investigation. Intermolecular interactions emphasizing on reactive zones result from graphene acting as an electron acceptor and nucleophilic part of TOR acting as an electron-donor. All of the TOR-complexes had negative Gibbs free energy changes due to TOR adsorption. Enthalpy modifications also differ greatly across the doped complexes (-26.39 to −86.97 kJ/mol lin air and −65.39 to −86.97 kJ/mol in water) and GG complex (-2.55 kJ/mol in air and −40.58 kJ/mol in water). Our results show that the TOR with BBGG doped complex, with a binding energy of −55.73 kJ/mol in air, while in water adsorption with NNGG gives −90.92 kJ/mol, are the most stable complexes among the various systems under study. The GG complex has the lowest energy, followed by other doped complexes. After adsorption multiple modes of TOR have higher Raman intensities, and this is because of an amplification process brought on by the SERS effect. The presence of substituted COOHGG, BBGG and NNGG cages has a higher tendency to interact with the drug molecule than GG. From MD simulations, TOR had van der Waals energy of −147.293+/–22.370 kJ/mol, an electrostatic energy of −53.749 +/–33.825 kJ/mol, polar solvation energy of 112.531+/−30.651 kJ/mol, and a binding energy of −70.130+/–23.290 kJ/mol. [ABSTRACT FROM AUTHOR]

We performed reactive molecular dynamics (ReaxFF-MD) simulations to investigate host-guest interactions between the porous honeycomb supramolecular network formed by trimesic acid (TMA) and the following guests: coronene (COR), C 60 , C 84, and C 98 fullerenes, a 5-membered cyclodextrin macrocycle (CD5) and pentanoic acid (PA) molecules. Coronene imparts outstanding stability to the TMA network as compared to the other guests. Whereas the fullerenes destabilize the TMA network, CD5 and PA molecules induce a small stabilization. The mechanism of COR-enhanced stability involves synergistic effects between the COR-graphene and COR-TMA interactions. Strongly bound coronene molecules impose steric restraints on the twisting dynamics of carboxylic groups of TMA molecules. This impedes the breakage of hydrogen bonds between the cyclic dimers formed by opposing COOH groups of TMA molecules, which has a stabilizing effect on the network structure up to high temperatures. CD5 molecules have higher host-guest interactions than coronene, however, the TMA/CD5 network has lower thermal stability because CD5 molecules desorb from the pore due to its lower binding energy to graphene. Therefore, an adequate balance between host-guest and guest-surface interactions is required to increase the thermal stability of the host-guest superstructure. [Display omitted] • The thermal stability of the hexagonal network formed by trimesic acid (TMA) molecules on graphene is highly increased when guest coronene (COR) molecules adsorb within the pores. • Host-guest interactions do not necessarily increase the stability of the TMA network and in the case of the C 60 , C 84, and C 98 fullerenes a destabilization effect was observed. • The mechanism of COR-enhanced stability involves synergistic effects between the COR-graphene and COR-TMA interactions. • COR molecules strongly bound to the graphene surface inhibit the twisting dynamics of –COOH groups of TMA avoiding the breakage of hydrogen bonds and therefore conferring high stability to the TMA/COR superstructure. • Host-guest interactions are the main driving force in COR-induced phase transformation processes. [ABSTRACT FROM AUTHOR]

• Theoretical treatments of Coriolis interaction for the vibrational and rotational levels of a symmetric-top molecule. • Shifts of rotational lines in the high-resolution spectrum of benzene by Coriolis interactions. • Rotational contours of vibronic bands of Coronene which are considerably different with vibrational modes. • Intramolecular vibrational energy redistribution (IVR) enhanced by Coriolis interaction. Energy shifts by Coriolis interaction between the degenerate levels are discussed for aromatic hydrocarbons with D 6 h symmetry, benzene and coronene. The degenerate vibrations of e symmetry (the second-order irreducible representation) necessarily exist in a molecule with the n -fold symmetry axis (n ⩾ 3), of which the rotational levels are expressed by the oblate symmetric-top model. The high-resolution spectrum was accurately analyzed by applying the theoretical model of Coriolis interaction, which significantly shifts the vibrational and rotational levels. The Coriolis interaction enhances intramolecular vibrational energy redistribution (IVR) at high vibrational levels in the electronic excited state. A rapid decrease in the fluorescence quantum yield at the vibrational levels above 3000 cm−1 in the S 1 state of benzene (Channel 3) is shown to be mainly due to level mixing by Coriolis interaction. [ABSTRACT FROM AUTHOR]

Abstract We report a first-principles investigation of metal clusters (Ni 13 , Cu 13 and Fe 13) adsorbed on pristine and defective graphene quantum dots (QDs). It was observed that the presence of one vacancy in the QD increased the binding energy of the metal cluster as well as the electronic conductivity of the graphene. Among the metal clusters, the Cu 13 cluster produced the highest electrical conductivity on graphene and the lowest values of binding energies, which in turn, favored the chemical reactivity of the graphene QDs. Furthermore, the types of bonds produced between the metal clusters and the pristine or defective graphene were analyzed with the electron localized function (ELF) and non-covalent interaction (NCI) plots. The calculations presented here give an insight about the electronic and chemical properties of graphene interacting with metal clusters which are of interest for catalytic applications. Highlights • Ni 13 and Cu 13 clusters are bonded with two C atoms in the graphene QDs. • A carbon vacancy in the graphene QDs increased the adsorption energy. • Cu 13 /graphene systems are the most reactive. • The metal clusters transfer charge to the graphene QDs. [ABSTRACT FROM AUTHOR]

Highlights • A ratiometric method of oxygen sensing has been developed using benzo[ghi]perylene and coronene as dual emissive, single component oxygen nano-sensors. • Construction of the sensors is simple and they displayed linear plots at a low probe concentration. • The fluorescence quenching of monomer was used as a signal and the excimer emission acted as an internal reference being unaffected by molecular oxygen. • The methods can be used to estimate dissolved oxygen in liquids and 5–100% of oxygen concentration in gaseous mixtures. Abstract The development of novel single molecular probe based optical ratiometric oxygen sensor with simple fabrication, high sensitivity, and linear response is highly desirable. Herein, benzo[ghi]perylene (BzP) and coronene (Cron) were explored as dual-emissive ratiometric oxygen nano-sensors that displayed linear plots at a low probe concentration (6 μM). The sensor fabrication was simple, and the probes exhibited efficient fluorescence quenching of monomer emission by molecular oxygen. However, the excimer emission of probe remained unaffected. Thus a ratiometric method is developed based on the dual emitting luminophore. The method can be used to estimate dissolved oxygen in liquids and 5–100% of oxygen concentration in gaseous mixtures. [ABSTRACT FROM AUTHOR]

Abstract Polycyclic aromatic hydrocarbons of the general formula C 6 n 2H 6 n (coronene family) were used as molecular models of graphene quantum dots (GQDs). Absorption spectra of the model compounds were calculated by ZINDO/S method. The S 0 → S 1 transition energy (E 1) was found to decrease with n as E 1 = 4.75 × n −0.633 eV. This transition is forbidden in symmetric compounds but 'switches on' upon symmetry breaking. The energy of the first bright optical peak (E br) was found to decrease with n as E br = 6.31 × n −0.6 eV. The data obtained corroborate the earlier finding that the size-independent optical properties of GQDs are determined by relatively small isolated sp 2 clusters separated by sp 3 (oxygen-contained) 'defects' rather than the whole (corrupted) graphene sheets; such nanoparticles actually are not quantum dots. GQDs of pure (without defects) graphene sheets with fully π-conjugated sp 2 systems should exhibit size-dependent optical properties due to the quantum confinement effect. Graphical Abstract Unlabelled Image Highlights • Polycyclic aromatic hydrocarbons (PAHs) are models of graphene quantum dots. • Absorption spectra of the coronene family of PAHs are calculated by ZINDO/S method. • Absorption band energies decreases as a hyperbolic function of homologous index n. • Nanometer-sized graphene quantum dots have absorption bands in the visible region. [ABSTRACT FROM AUTHOR]

Abstract Quantum dots (QD) belong to a class of materials considered technologically important for their tunable absorption and emission properties and a huge application potential in optoelectronic technologies. To date, only simplified monolayer models of QDs and their dimers have been considered when modeling their absorption and/or emission spectra and effects of edge functionalization. Here, we analyze the optical properties of new type electron donor-acceptor bilayer quantum dot models based on coronene and its boron-nitride analogues (electron donors) with a 4,4-difluoro-4-bora-3a,4a-diaza- s -indacene dye (Bdp , an electron acceptor) dye by using time-dependent density functional theory. To understand the nature of transition shifts in electronic spectra, we use BN models with strong modification of the HOMO and LUMO: m-BNC (middle hexagonal ring CC bonds are substituted by BN), p-BNC (all peripheral CC bonds are substituted by BN), and f-BNC (all C atoms are replaced by B and N in an alternate manner). Adiabatic ionization potentials of all coronenes were also calculated. The obtained results show that significant interlayer charge transfer (CT) on excitation of bilayer QDs in S 1 , S 2 , and S 3 states from strong electron donors, coronene (6.93 eV) and m-BNC (6.52 eV), to Bdp will occur. As a result, one can observe only very weak absorption of CT-character in the low-energy spectrum region as well as strong fluorescence quenching of Bdp. On the contrary, for the weak electron donors, p-BNC (7.22 eV) and f-BNC (8.22 eV), strong Bdp -like absorption and fluorescence bands of local excitation character in the low-energy region are expected. Correlation of optical properties of bilayer QDs with ionization potentials of coronene monolayers has been founded. The obtained results can be useful for future graphene-based optoelectronic applications. Graphical Abstract Unlabelled Image Highlights • We studied changes in spectra of bilayer QDs consist of coronenes and BODIPY. • Correlation between electronic structure of coronenes and CT between layers exists. • We explained effects of BN substitution of coronenes on optical properties of QDs. [ABSTRACT FROM AUTHOR]

The Lennard–Jones potential and a continuum approach can be used to successfully model interactions between various regular shaped molecules and nanostructures. For single atomic species molecules, the interaction can be approximated by assuming a uniform distribution of atoms over surfaces or volumes, which gives rise to a constant atomic density either over or throughout the molecule. However, for heterogeneous molecules, which comprise more than one type of atoms, the situation is more complicated. Thus far, two extended modeling approaches have been considered for heterogeneous molecules, namely a multi-surface semi-continuous model and a fully continuous model with average smearing of atomic contribution. In this paper, we propose yet another modeling approach using a single continuous surface, but replacing the atomic density and attractive and repulsive constants in the Lennard–Jones potential with functions, which depend on the heterogeneity across the molecules, and the new model is applied to study the adsorption of coronene onto a graphene sheet. Comparison of results is made between the new model and two other existing approaches as well as molecular dynamics simulations performed using the LAMMPS molecular dynamics simulator. We find that the new approach is superior to the other continuum models and provides excellent agreement with molecular dynamics simulations.