Search

The adsorption of polyaromatic hydrocarbons (PAHs) on metallic substrates has been of interest in the field of optoelectronics due to the possibility of designing complex materials with tunable properties through surface functionalization with organic molecules. Much of the modelling research in this field has focused on perfectly symmetrical (idealized) substrates. Limited research has investigated the effect of substrate irregularities, such as adatoms, on the binding of PAHs onto substrates. Here, we examine how the presence of substrate-bound adatoms affects the binding of coronene and hexahelicene monomers and dimers onto Au(111) and Cu(111) substrates using a density functional theory approach. We found that helicene monomers were more effectively able to adapt to the presence of the adatoms than coronene by coiling around the adatoms. Whereas upon adsorption on an ideal (111) surface, coronene can establish significantly stronger dispersive interactions than helicenes, adatom defects reverse the trend. For helicenes, the degree of flattening near the surface and molecular coiling were strongly influenced by the extent of the adatom defect, as a result of the interplay between the molecule’s drive to maximize overlap with the underlying surface and the enhanced reactivity of lower-coordinated adatoms.

The non-planar π-enlarged coronene-embedded coumarin achieved via pyranone-annulation and its cyanated derivative possess bright orange to red emission in both solution and solid states leaving scope for bio-imaging application. Multiple redox-states, frontier molecular orbital energy levels and strong co-facial π-stacking ability point out towards applications in organic optoelectronics.

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).

In previous studies, the Huckel-London-Pople-McWeeny (HLPM) method was used to calculate the "topological" ring currents and bond currents that are associated with the mono-altans, and the doubly and triply iterated altans, of corannulene and coronene and their respective dianions. This gave rise to some intriguing patterns in these currents, which were partially rationalized by a detailed examination of the lone nonbonding orbitals that each of these structures possesses. In the present work, the same HLPM approach is used to investigate whether analogous changes in bond-current patterns are observed when going from the neutral species to the dianions of the iterated altans derived from some other, simpler, "parents" having molecular graphs with a nullity of zero. The altans and iterated altans of three of the simplest parents are studied: the neutral species (altan)n-benzene, (altan)n-naphthalene, and (altan)n-azulene, with n = 1, 2, and 3, together with their corresponding dianions. Analogous bond-current patterns are indeed encountered, some of which are likewise rationalized by a detailed consideration of the nonbonding orbitals.

We have investigated the structures, electronic properties, hole and electron mobilities of perfluorinated, perchlorinated and percyanated coronene molecules, using the density functional theory (DFT) and Time Dependent DFT (TDDFT) at the B3LYP-D3/6-311++G(d,p) and $$\omega$$ B97XD/6-311++G(d,p) levels and Markus-Hush charge transfer theory. The calculated geometric parameters for coronene and perchlorocoronene are in good agreement with the experimental data. Our theoretical investigations have shown that B3LYP-D3 functional is suitable to well define vibrational assignments for studied molecules. The quantified effect of the complete substitution of peripheral hydrogen atoms with cyanide groups for the key properties relevant for optoelectronic and photonics such as electron affinities, ionization energies, HOMO-LUMO energies, reorganisation energies, optical absorption spectra, and electron mobilities were discussed. Compared to perfluorination and perchlorination, the percyanation of coronene considerably increases the adiabatic/vertical electron affinities (AEAs/VEAs), the electron mobilities, the HOMO-LUMO gap and reduces the LUMO energy level thus indicating an ambipolar behavior and air-stable material. We have discussed the possible implications of cyanide groups as important substitutes for the design of the new organic compounds useful in electronics.

Photothermal therapy (PTT) has inherent advantages in the treatment of hypoxic tumors due to its optically controlled selectivity on tumor ablation and oxygen-independent nature. The subcellular organelle-targeting capability and photothermal conversion efficiency (PCE) at near-infrared (NIR) wavelength are the key parameters in the assessment of the photothermal agent (PTA). Here, we report that carbon dots (CDs) prepared by the hydrothermal treatment of coronene derivatives show a high PCE of 54.7% at 808 nm, which can be attributed to the narrow band gap and the presence of amounts of continuous energy bands on CDs. Moreover, the vibrations in the layered graphite structures of the CDs also increase the rate of nonradiative transition and thus enhance the PCE. Furthermore, the CDs also possess excellent photostability, biocompatibility, and cell penetration capability and could mainly accumulate in the lysosomes. These experiment results have proved that the CDs are suitable as an efficient NIR light-triggered PTA for efficient PTT against cancer.

The prediction of two-dimensional molecular self-assembly structures has always been a problem to be solved. The molecules with meta-dicarboxyl groups can self-assemble into a specific hexagonal cavity, which has an important influence on the prediction of molecular self-assembly structures and the application of functional molecules with meta-dicarboxyl groups. Two kinds of molecules with four pairs of meta-dicarboxyl groups, 1,3,6,8-tetrakis(3,5-isophthalic acid)pyrene (H8TIAPy) and 4′,4′″,4″″′,4″″″′-(ethene-1,1,2,2-tetrayl)tetrakis(([1,1′-biphenyl]-3,5-dicarboxylic acid)) (H8ETTB) molecules were chosen to observe the self-assembly behavior at the heptanoic acid/highly oriented pyrolytic graphite (HA/HOPG) interface. H8TIAPy molecules self-assembled into well-ordered quadrilateral structures and could be regulated into kagome networks with hexagonal pores by coronene (COR) molecules. H8ETTB molecules self-assembled into lamellar structures and transformed into acid-COR-acid-COR co-assembled structures at low concentration of COR solution and acid-COR dimer-acid-COR dimer co-assembled structures at high concentration of COR solution. The reason that H8ETTB molecules could not be regulated into hexagonal porous architecture was attributed to the steric hindrance by the similar length and width of H8ETTB molecules. The H8ETTB templates had stronger adsorption for COR than that of hexaphenylbenzene (HPB), regardless of the order of molecular introduction.

The applicability of stationary liquid phases for gas–liquid chromatography was evaluated. The scale for quantitative one-parameter estimation of their polarity was chosen. Absorption and luminescence spectra of the five indicators coumarin 153, coumarin 314, coronene, 4-dicyanomethylene-2-methyl-6-[4-(dimethylamino)styryl]-4H-pyran (DCM), and 3-aminophthalimide in solvents of different polarity were obtained at room temperature. The dependence of the fluorescence and absorption maxima wavelengths on the medium polarity was evaluated. Various spectroscopic polarity scales were compared to show that the coronene fluorescence scale was most appropriate. This scale was used to assess the polarity of some widespread phases (squalane, polydimethylsiloxane PMS-100, 3,3′-oxydipropionitrile, 2-ethylhexylsebacate, etc.) for gas-liquid chromatography. This approach was shown to be promising for preliminary selection of chromatographic stationary phases.

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 ...

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.

In this study, a twisted macrocycle was synthesized via ring closure of a double-helical aromatic oligoamide foldamer with two disulfide bridges. Single-crystal X-ray structure and NMR spectroscopy demonstrate the twisted conformation of macrocycle both in the solid state and in solution. As a result of the rearrangement of hydrogen bonding preference, the twisted conformation could be transformed to boxlike through protonation of the pyridine segments of macrocycle. In addition, the NMR titration experiments revealed that flat aromatic guests (e. g., coronene and perylene) could bind to the boxlike macrocycle with a 1 : 1 binding stoichiometry. The addition of base to the host-guest complexes resulted in conformational reversal of the macrocycle from boxlike to twisted as well as the release of guest.

Highly efficient persistent (lifetime > 0.1 s) room-temperature phosphorescence (pRTP) chromophores are important for futuristic high-resolution afterglow imaging for state-of-the-art security, analytical, and bioimaging applications. Suppression of the radiationless transition from the lowest triplet excited state (T1) of the chromophores is a critical factor to access the high RTP yield and RTP lifetime for desirable pRTP. Logical explanations for factor suppression based on chemical structures have not been reported. Here we clarify a strategy to reduce the radiationless transition from T1 based on chemical backbones and yield a simultaneous high RTP yield and high RTP lifetime. Yellow phosphorescence chromophores that contain a coronene backbone were synthesized and compared with yellow phosphorescent naphthalene. One of the designed coronene derivatives reached a RTP yield of 35%, which is the best value for chromophores with a RTP lifetime of 2 s. The optically measured rate constant of a radiationless transition from T1 was correlated precisely with a multiplication of vibrational spin–orbit coupling (SOC) at a T1 geometry and with the Franck–Condon chromophore factor. The agreement between the experimental and theoretical results confirmed that the extended two-dimensional fused structure in the coronene backbone contributes to a decrease in vibrational SOC and Franck–Condon factor between T1 and the ground state to decrease the radiationless transition. A resolution-tunable afterglow that depends on excitation intensity for anticounterfeit technology was demonstrated, and the resultant chromophores with a high RTP yield and high RTP lifetime were ideal for largely changing the resolution using weak excitation light.

Closed, laser-induced optical transitions ("optical cycling transitions") of molecules can be used for state preparation and measurement in quantum information science and quantum sensing. Increasingly complex molecular species supporting optical cycling can provide new capabilities for quantum science, and it is not clear if there is a limit on their size or complexity. We explore Ca-O-L molecular constructs to support the optical cycling center, Ca, with ligands, L, being arenes. We find that L can be as large as coronene (i.e., CaOC24H11) without losing the diagonality of the Franck-Condon factor (FCF). Furthermore, L can be substituted with electron-withdrawing groups to improve the FCF. Larger L, beyond ∼7 rings, can disrupt the diagonality of the FCF by closing the HOMO-LUMO ligand electronic state gap and reordering with the local states on the cycling center. Overall, we find that optical cycling can be retained for arenes, and we offer a principle for their design.

Adsorption of 2,4,6-tribromoaniline (BA), 2,4,6-trifluoroaniline (FA) and 2,4,6-trichloroaniline (CA) onto the surface of coronene/fullerene/fullerene-like nanocages was investigated by theoretical...

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.

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 (e′), dielectric imaginary part (e″), 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 thee′ande″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 e′, e″, 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.

The development of optical materials with room temperature phosphorescence (RTP) and white light emission (WLEDs) is highly desirable and remains a challenging task. Herein, a porous metal–organic framework PCN-921 with a high quantum yield (ΦF = 93.6%) was achieved. To make full use of the advantages of the high porosity of PCN-921, we hierarchically encapsulated different guest molecules coronene and rhodamine B (RhB) into the framework. Unsurprisingly, the hybrid material coronene@PCN-921 was obtained after in situ encapsulation of the guest coronene into the framework, and it exhibits obvious RTP behavior with a long phosphorescence lifetime of 62.5 ns. Subsequently, second guest RhB molecules were introduced after soaking in RhB solution and the material RhB@coronene@PCN-921 was achieved. Interestingly, it exhibits white light emission with the CIE coordinates of (0.29, 0.34), and can be used as a high performance WLED lamp. This is the first work on dual-functional hybrid dyes@MOFs with hierarchical guest encapsulation for RTP and white light emission, which suggests the potential applications of MOFs in multifunctional optical devices.

Graphdiyne, a recent addition to the family of 2D covalent organic nanosheet structures, is known for its structural stability and potential applications in catalysis, sensors, electronics and optoelectronics. The design and synthesis of graphdiyne analogues with well-defined structures and useful applications remains a challenging task for materials chemists. Herein, we report a novel, well-defined 2D nanosheet from a coronene–pyrene hybrid 2D material (COPY), with extended π conjugation through acetylenic linkages. The bulk synthesis of the polymeric network has been realized via Sonogashira coupling of 1,4,7,10-tetrabromocoronene and 1,3,6,8-tetraethynylpyrene. The nanosheet is characterized using HR-SEM, TEM, AFM, FT-IR, Raman, XRD and XPS techniques. Electrostatic potential mapping of COPY reveals complete π electron delocalization over the 2D framework with a relatively high electro-negative potential at the acetylenic linkages. Computational study reveals the high planarity of the structure as a result of Cs point group symmetry and the material has a tunable bandgap with respect to the number of coronene and pyrene rings. Extended conjugation in the material accounts for the significant electrical conductivity (1.16 × 10−3 S m−1) that is one order of magnitude higher than that of graphdiyne and comparable to the previously reported pyrediyne (a graphdiyne analogue). The large surface area and porous nature of the material were utilized for oil–water separation by incorporating melamine sponge and cotton fabric. The COPY-incorporated cotton fabric exhibited an oil–water separation efficiency of 95.5%. More importantly, the COPY in the melamine sponge exhibited superhydrophobicity with a contact angle of 154.4°. The oil–water separation efficiency, significant electrical conductivity and superhydrophobicity of the material suggest that COPY can be a valuable candidate in the field of water repellency, anti-corrosion and biosensing.

Carbon nanomaterials play important roles in modern scientific research. Integrating different carbon-based building blocks into nano-hybrid architectures not only takes full advantage of each component, but also brings in novel interfacial properties. Herein, we have employed density functional theory (DFT) calculations to investigate the effects of polymerization degree of coronene molecules encapsulated in single-walled carbon nanotubes (SWNTs) (19,0) on their interfacial properties. The present results reveal that the interfacial properties of the formed heterojunctions are remarkably regulated by the polymerization degree. For example, monomer- and dimer-encapsulated SWNTs are type-I heterojunctions in which interfacial excitation energy transfer is preferred, whereas interfacial charge carrier transfer is favorable in trimer- and polymer-encapsulated SWNTs because they are type-II heterojunctions. On the other hand, we have employed the time-domain nonadiabatic dynamics simulation approach to explore the interfacial carrier dynamics in type-II polymer-encapsulated SWNT heterojunctions. It is found that the electron and hole transfer processes are asymmetric and occur in opposite directions and at different rates. The former takes place from polymers to SWNTs in an ultrafast way (ca. 370 fs), whereas the latter occurs slowly from SWNTs to polymers (ca. 24 ps). A closer analysis uncovers the fact that the different carrier transfer rates mainly originate from the different densities of the acceptor states, energy differences and inter-state couplings between the donor and acceptor states. Finally, the present work demonstrates that the polymerization degree could act as a new regulating strategy to tune the interfacial properties of molecule-encapsulated SWNT heterojunctions.

Potassium-ion batteries have been envisioned to herald the age of low-cost and high-performance energy storage systems. However, the sparsity of viable components has dampened the progress of these energy devices. Thus, herein, we report coronene, a high-voltage cathode material that manifests a high-voltage of $4.1 \rm V$ enkindled by anion (de)insertion. This work not only illuminates the broad class of polycyclic aromatic hydrocarbons as prospective cathode materials but also sets a new benchmark for the performance of future organic cathode materials.

Coronene and its derivatives were synthesized using methanol inside Ca2+ ion-exchanged small-pore zeolites with an 8-membered ring window, such as LTA and RHO zeolites. The polyaromatic hydrocarbon product exhibited white fluorescence under UV light excitation, as characterized by UV-Vis absorption and fluorescence spectra, and fluorescence microscopy images. The formation of coronene and even larger polyaromatics from methanol could be attributed to the fact that Ca2+ ions, unlike the hydroxyl protons of acidic zeolite frameworks, effectively attract the π-electron clouds of benzene rings of small polycyclic intermediates with no disruption of the aromaticity, which leads to the rapid growth of the aromatic ring system. The molecular dimensions of the resultant polyaromatic product were determined by the confined α-cages of the LTA and RHO zeolites. This phenomenon could be extended to CHA zeolite with smaller pore sizes, restricting the molecular growth more severely than in the cases of LTA and RHO zeolites.

Charge transfer cocrystallization with an electron rich donor (D) and electron deficient acceptor (A) is a useful method to prepare luminescent organic electronic materials. The electronic nature and photoluminescence property of charge transfer cocrystals are dependent on the choices of donor and acceptor as well as on the supramolecular network. Herein, we report a new polymorph of coronene : TCNB (2 : 3) charge transfer cocrystal that has unique crystal packing with infinite mixed D–A stacks separated by finite A–D–A triads. The new coronene:TCNB polymorph is red emissive (λmax ≈ 640 nm) with a photoluminescence quantum yield ≈ 5%. Theoretical calculations predict an ambipolar semiconductor nature owing to the electron transport along the infinite D–A stack and hole transport between the coronene molecules of adjacent A–D–A triads in the new cocrystal polymorph. The roles of the supramolecular architecture and the frontier molecular orbitals of donor/acceptor in dictating the optical and electronic properties were elucidated by theoretical studies.

Soot particles from flames were found to have quantum confinement behavior in recent UV–visible absorption measurements. However, the impact of surface functionalization was not considered in the previous interpretation. In this work, polycyclic aromatic hydrocarbon (PAH) clusters was selected as a model system of soot to explore the impact of surface functionalization on the optical properties. The HOMO–LUMO gap of PAH clusters with formyl group (–CHO) substitutions was computed using the B3LYP method with the 6-31G(d) basis set. The results showed that the HOMO–LUMO gaps of PAH clusters strongly depend on the surface coverage of –CHO groups on particle, and a higher coverage always yield a reduced gap value. Combining the observation from X-ray photoelectron spectroscopy measurements, the impact of functional groups was computed as 0.27–0.71 eV. Detailed analysis on the electronic structures of HOMO and LUMO reveals that the –CHO groups lower the LUMO energy to a great extent, while they have limited impact on the HOMO energy. Furthermore, we use the LUMO composition as a key descriptor to evaluate the impact of functionalization on LUMO energy, and a theoretical limit of gap reduction was calculated as 1.1 eV for both pyrene and coronene clusters.

Density functional theory is employed to model the chemisorption of ammonia on epoxy-containing polycyclic aromatic hydrocarbons (PAHs) and understand the reaction mechanism of ammonia addition on partially reduced graphene oxide flakes. Coronene (C24H12) and ovalene (C32H14) based four-epoxy group containing molecules are used to mimic the RGO surface properties. The reaction mechanism changing effect of a second ammonia molecule as well as explicit water molecules is considered. The proposed reaction mechanism consists of two steps: the migration of one epoxy group out of the modelled four-epoxy group formation to a thermodynamically less stable one and the nucleophilic addition of the ammonia molecule. The second step involves forming an amine group and reducing an epoxy group to a hydroxyl one. Interestingly, the forming amine group bonds to the carbon atom with the smallest bond order among the available ones and not necessarily to the carbon atom of the opening epoxy ring. Incorporating a second ammonia molecule has a negligible effect on the overall reaction mechanism, while in the presence of one water molecule, the reaction goes through a different pathway involving a trimolecular state during the nucleophilic addition. Including more than one water molecule or applying an implicit solvent model does not cause further changes in the reaction.

We report an NIR-based photoluminescent material, namely benzo-coronene diimide (CDI 2), and its use in the visualization of latent fingerprints (LFPs) and in the metal ion detection in an aqueous medium. CDI 2 exhibited nano-sized interlinked fibre structures forming ‘bowl’ shaped nanoarchitectures as red emitters with the Commission Internationale de l'Eclairage (CIE) coordinates (x, y) of (0.67, 0.33) with 100% colour purity in the solid state. CDI 2 was confirmed to be the potential candidate for the analysis of LFPs and the detection of Pd2+/Cu2+ in an aqueous medium.

To investigate the molecular-growth reactions of bay-region methyl-substituted polycyclic aromatic hydrocarbons (PAH) in the supercritical n-alkane-fuel pyrolysis environment, we have performed supercritical n-decane pyrolysis experiments with and without the dopant 4-methylchrysene (dopant concentration, 0.684 mg/g n-decane), in an isothermal, silica-lined stainless-steel flow reactor at 568 °C, 94.6 atm, and 133 s, conditions of rapid PAH growth. Analyses of the reaction products by high-pressure liquid chromatography with diode-array ultraviolet-visible absorbance and mass-spectrometric detection reveal that in the supercritical n-decane pyrolysis environment—where the aliphatic growth species methyl, ethylene, propene, and 1-butene are abundant—molecular growth of the four-ring 4-methylchrysene to high-ring-number PAH occurs chiefly through two routes, both of which take advantage of the bay-region position of 4-methylchrysene's methyl substituent. In the first route, 4-methylchrysene's resonance-stabilized arylmethyl radical 4-chrysenylmethyl attacks the aryl carbon just across the bay of 4-methylchrysene's structure to form the C19H12 methylene-bridged PAH 4H-cyclopenta[def]chrysene, whose resonance-stabilized radical 4-cyclopenta[def]chrysenyl reacts with methyl and ethylene in ring-expansion reactions that selectively produce the five-ring C20H12 benzo[a]pyrene and its derivatives 4- and 5-methylbenzo[a]pyrene. The arylmethyl radicals 4- and 5-benzo[a]pyrenylmethyl then undergo a series of reactions with n-decane's high-yield C2 C4 1-alkenes to selectively produce particular six- to nine-ring peri‑condensed benzenoid PAH such as dibenzo[a,e]pyrene, benzo[a]naphtho[2,3-e]pyrene, dibenzo[e,ghi]perylene, benzo[a]coronene, and naphtho[8,1,2-abc]coronene—all of whose yields increase dramatically with 4-methylchrysene doping. In 4-methylchrysene's second major route of molecular growth, 4-chrysenylmethyl's attack of the aryl carbon across the bay is followed by an intramolecular rearrangement that produces 4H-benzo[cd]fluoranthene, a non-fully aromatic C19H12 PAH with an internal five-membered ring. Reactions of the resonance-stabilized benzo[cd]fluoranthenyl radicals with methyl, propene, and 1-butene selectively produce the six-ring C22H12 indeno[1,2,3-cd]pyrene and four particular seven-ring C26H14 benzindeno[1,2,3-cd]pyrenes—each of which contains an internal five-membered ring, evidencing the distinctive molecular-growth pathways of bay-region methyl-substituted PAH in the supercritical n-alkane-fuel pyrolysis environment.

Density functional theory (DFT) calculations were used to examine the binding strength of one and two methane molecule(s) with graphene (62 and 186 carbon atoms) and model systems of aromatic hydrocarbons (benzene, pyrene, and coronene). We explored different possibilities of binding modes of methane such as one, two, and three C-H interacting with small π-systems. Two methane molecules were considered to bind from the same as well as opposite sides of the plane of benzene and other π-systems including graphene models. Our results show that methane molecule prefers to bind with three C-H…π interactions with all the π-systems except benzene. The preference of tripod configuration of methane on the surface of graphene systems strongly agrees with the neutron diffraction experiment of methane on graphitized carbon black. The binding strength is almost doubled by increasing the number of methane molecules from one to two. Importantly, two methane molecules prefer to bind on the same side rather than opposite sides of the plane of graphene due to stabilizing CH…HC interactions between them in addition to six C-H…π interactions. Interestingly, binding strength contributions from CH…HC interactions (approx. 0.4–0.5 kcal/mol) of two methane molecules on the surface are analogous to methane dimer complex free from the surface of graphene. C-H stretching frequency shifts, bond lengths, and binding distances support the presence of CH…HC interactions between two methane molecules. Structures of complexes, binding energies, and C-H stretching frequency shifts agree with available experimental data.

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.

The Al/CRNNW/n-Si device with a coronene nanowire (CRNNW) interlayer was fabricated by a physical vapor deposition technique and characterized under dark various illumination intensities via I–V measurements at room temperature. The device has exhibited rectifying behavior and the rectifying ratio values decreased from 1.16 × 103 to 1.44 at 4 V biases by increasing light intensity from 20 to 100 mW. The Al/CRNNW/n-Si device was characterized by various techniques such as thermionic emission theory, Norde, and Cheung technique, and device parameters were obtained. The ideality factor and barrier height values were determined as 21.33 and 0.75 eV, respectively, under dark condition from the thermionic emission theory. The series resistance of the device is obtained as 3090 Ω from the Norde method and 9840 Ω from the Cheung method for the dark condition. The current transport mechanism of the device was discussed in detail for various regions from lnI–lnV plot. The coronene layer can be thought of and improved as interfacial material for metal–semiconductor devices.

Previous studies of the Huckel-London-Pople-McWeeny (HLPM) ring-currents and bond-currents associated with the neutral and the dianionic altans, and iterated altans, of corannulene and coronene, are here extended to the hexaanions of (altan)n-corannulene and (altan)n-coronene, with n = 1, 2, and 3. The magnetic properties of some of these species were originally studied by Monaco and Zanasi using the ipso-centric approach, which is ab initio in nature. The "topological" HLPM method, by contrast, constitutes a parameter-free, quasi graph-theoretical model requiring knowledge only of the molecular graph of the conjugated system being considered and the areas assumed for its constituent rings. The HLPM calculations are partially presented by means of a novel illustrative device that we call "difference diagrams". One aim of this work is to compare predictions of this very rudimentary HLPM formalism with those of the much more sophisticated ipso-centric ab initio approach when they are both applied to the calculation of ring-current properties in this family of neutral and anionic (especially, hexaanionic) conjugated systems. For those altans and iterated altans for which ab initio calculations are available for comparison, encouraging qualitative, and even quantitative, agreement is found between the predictions of the ab initio and HLPM approaches. Other structures for which HLPM calculations are reported here but which have not yet been studied by ab initio means are offered with some confidence for possible subsequent evaluation using the ipso-centric (or any other ab initio) formalism.

Three-dimensional (3D) triply interlocked catenanes are a family of chemical topologies that consist of two identical, mechanically interlocked coordination cage components with intriguingly complex structures. Although only a few successful constructions of 3D interlocked catenanes have been achieved to date via metal-mediated assembly, these complex structures have thus far only been targeted by metal-nitrogen/oxygen coordination techniques. Here, taking advantage of rational ligand design, we report the efficient construction of a series of 3D triply interlocked [2]catenanes of the formula [Ag3L2]2, wherein the metal ions exclusively form bonds to N-heterocyclic carbene (NHC) units, and their subsequent transmetalation to the corresponding [Au3L2]2 gold analogues. The formation and transmetalation reactions proceed under mild conditions and are generally applicable. A series of characterization techniques were applied to confirm the formation and structure of the desired 3D triply interlocked architectures: multinuclear NMR spectroscopy, ESI-MS, and single-crystal X-ray diffraction analysis. The solid-state structure of [Ag3(1a)2]2(PF6)6 unambiguously confirms the existence of a 3D catenane that consists of two identical, mechanically interlocked trinuclear hexacarbene cage components. The interlocking of two 3D cages into a [2]catenane is driven by the efficient π···π stacking of triazine-triazine stacks with cooperative interactions between imidazo[1,5-a]pyridine subunits. Notably, the triply interlocked organometallic cages exhibit good stability toward various organic solvents, concentrations, and temperatures, and no disassembly occurred in the presence of coronene or pyrene. The future construction of mechanically interlocked architectures using metal-carbene bonds rather than metal-nitrogen bonds may provide assemblies with interesting properties for as-yet-unimagined applications in fields such as sensors and molecular electrical conductors.

Asphaltenes are a significant contributor to flow assurance problems related to crude oil production. Because of their polydispersity, model molecules such as coronene and violanthrone-79 (VO-79) have been used as mimics to represent the physiochemical properties of asphaltenes. This work aims to evaluate the emulsion-stabilization characteristics of fractionated asphaltenes and these two model molecules. Such evaluation is expected to better characterize the stabilizing mechanisms of asphaltenes on water-in-oil emulsions. The coalescence process of water-in-oil emulsion droplets is visualized using a microfluidic flow-focusing geometry. The rate of coalescence events is used as the parameter to assess emulsion stability. Interfacial tension (IFT) and oil/brine zeta potential are measured to help explain the differences in the rates of coalescence. VO-79 is found to be better at stabilizing emulsions as compared to coronene. Although VO-79 and asphaltenes have similar interfacial tension and oil/brine zeta potential values, the rate of coalescence differs significantly. This highlights the difficulty in using model molecules to mimic the transport dynamics of asphaltenes.

The structure–electroactivity relationship of graphene has been studied using coronene (Cor), polyaromatic hydrocarbon (PAH), and a subunit of graphene as a model system by chemically modified elec...

Polycyclic aromatic hydrocarbons with hexagons/pentagons or hexagons/heptagons have been intensively investigated in recent years, but those with simultaneous presence of hexagons, pentagons and heptagons remain rare. In this paper, we report dicyclohepta[ijkl,uvwx]rubicene (DHR), a non-benzenoid isomer of dibenzo[bc,kl]coronene with two pentagons and two heptagons. We developed an efficient and scalable synthetic method for DHR by using Scholl reaction and dehydrogenation. Crystal structure of DHR shows that the benzenoid rings, two pentagons and two heptagons are coplanar. The bond lengths analysis and the ICSS(1)zz and LOL-π calculations indicate that the incorporation of two formal azulene moieties has an effect on the conjugated structure. The π-electrons of benzenoid and pentagon rings are more delocalized. Cyclic voltammetry studies indicate that DHR shows multiple oxidation and reduction potentials. Interestingly, DHR exhibits unusual S0 to S2 absorption and abnormal anti-Kasha S2 to S0 emission. Moreover, crystals of DHR exhibit semiconducting behaviour with hole mobility up to 0.082 cm2 V-1 s-1 .

Graphene nanoribbons (GNRs), nanometer-wide strips of graphene, are attracting significant attention in materials science as candidates for next-generation carbon materials. As their physical properties mainly depend on their structures, the precise synthesis of structurally well-defined GNRs is highly desirable to control their properties. Herein, we report a step-growth annulative π-extension polymerization that allows for the rapid and modular synthesis of cove-type GNRs with pyrene and/or coronene diimide repeating units. The structures and photophysical properties of the separated GNRs were confirmed by various spectroscopic analyses. In addition, gas-blow-assisted uniform on-surface self-assembly of the GNRs was accomplished.

This research evaluated the substrate effects of two organic molecules, zinc phthalocyanine (ZnPc) and coronene on a glass/Au/coronene substrate (coro sub) and coronene:C60 BHJ film on a glass/Au/ZnPc substrate (ZnPc sub). The interaction strength of the co-evaporated ZnPc:C60 bulk heterojunction (BHJ) films was measured. The molecular orientation angles of each molecule in the BHJ films were detected by in situ infrared reflection absorption spectroscopy. Coronene molecules in the coronene:C60 film on the ZnPc sub could be precisely controlled to attain a lying-down orientation owing to the strong π–π interaction between the coronene–ZnPc molecules. In contrast, the ZnPc molecules in ZnPc:C60 adopted a standing-up orientation on the coro sub owing to the weak π–π interaction between the ZnPc sub and ZnPc molecules. The present work presents an important finding which indicates that substrate-dependent molecular orientation switches may be possible for both transistor and solar cell applications.

The fabrication of supramolecularly engineered two-dimensional (2D) networks using simple molecular building blocks is an effective means for studying host–guest chemistry at surfaces toward the potential application of such systems in nanoelectronics and molecular devices. In this study, halogen-bonded molecular networks were constructed by the combination of linear halogen-bond donor and acceptor ligands, and their 2D structures at the highly oriented pyrolytic graphite/1-phenyloctane interface were studied by scanning tunneling microscopy. The bi-component blend of the molecular building blocks possessing tetradecyloxy chains formed a lozenge structure via halogen bonding. Upon the introduction of an appropriate guest molecule (e.g., coronene) into the system, the 2D structure transformed into a hexagonal array, and the central pore of this array was occupied by the guest molecules. Remarkably, the halogen bonding of the original structure was maintained after the introduction of the guest molecule. Thus, the halogen-bonded molecular networks are applicable for assembling guest species on the substrate without the requirement of the conventional rigid molecular building blocks with C3 symmetry.

Conducting metal–organic frameworks (MOFs), especially those with high electrical conductivity (>10−3 S cm−1) have shown promising functions in many aspects. Here, nanorods of a novel metal–organic framework (MOF) based on perthiolated coronene (PTC) is synthesized by a homogeneous reaction. The structural, morphological and component analyses reveal that the nanorods are composed of a 2D Kagome lattice with the formula of [Ni3(C24S12)]n. The compressed sample of the nanorods displays an electrical conductivity of ∼9 S cm−1 at 300 K and a weak semiconductor-like temperature dependence. Furthermore, a moderate Seebeck coefficient of 47.0 μV K−1 and an extremely low thermal conductivity of 0.2 W m−1 K−1 result in a figure of merit (ZT value) of thermoelectricity of 0.003 at 300 K. This is the best p-type thermoelectric performance in conducting MOFs ever reported.

The adsorption of nitric oxide and nitrogen dioxide (NOx) to the Buckybowls sumanene and corannulene was investigated. Binding energies were up to 1.8× larger than for coronene as the planar analogue, demonstrating the advantages of Buckybowls for gas adsorption. In agreement with previous reports on carbon dioxide and methane adsorption, the favorable binding energies for NOx were shown to be associated with the curvature of the Buckybowls. It is shown that applying an electric field along the bowl symmetry axis modifies the bowl curvatures and impacts adsorbate binding energies, including the potential to desorb adsorbates. As a proof of concept, it is shown that applying electric fields of different strengths and orientations selectively controls sumanene's preference to bind nitric oxide, nitrogen dioxide, and carbon dioxide, suggesting potential applications for dynamically tunable gas adsorption. Moreover, it is demonstrated that adsorbates can be desorbed by applying suitable electric field strengths, allowing cleaning of the Buckybowls for renewed usage.

The surface growth of soot is a key process in its mass growth, depending crucially on surface properties. In this work, we directly extract the detailed surface properties, such as surface area, number density of reactive sites on a particle and parameter α, from the microscopic configuration of polycyclic aromatic hydrocarbon (PAH) clusters. Five representative PAHs, including pyrene (C16H10), coronene (C24H12), ovalene (C32H14), hexabenzocoronene (C42H18) and circumcoronene (C54H18), are used to build the model configurations of nascent soot. We develop a numerical scheme to determine the detailed surface properties based on the approximation of solvent-excluded surface. The assumption of spherical particles is found to introduce a large uncertainty in the estimation of the surface area, and the error can be a factor of 2.5 in the worst case. The number density of atoms or sites on cluster surfaces does not depend on the chemical composition of a particle larger than 2 nm in diameter, and our study indicates that the number density of hydrogen atoms is overestimated by a factor of 3 in the literature. Finally, we propose a new equation for parameter α, which includes the effects of the size of gaseous species in surface reaction, local temperature, particle size and chemical composition.

The geometric, thermodynamic and electronic properties of Pd–graphene nanocomposites are comprehensively studied through quantum mechanical methods. Geometries of these clusters are optimized with the well-calibrated Minnesota functional M06-2X. The adsorption energies calculated at the M06-2X/LANL2DZ level show better agreement with those calculated from MP2/ANO-RCC-VDZP. Two different representative models for graphene, coronene and hexabenzocoronene, are used. The adsorption energies analysis reveals that the interaction energies increase with the size of the adsorbed cluster. However, for Pdn/hexabenzocoronene, the interaction energies show a sudden drop at Pd8/hexabenzocoronene. The difference in behavior between the interaction energies of Pdn/hexabenzocoronene and Pdn/coronene is attributed to the edge effect present in coronene. The electronic properties, including highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), Fermi level, molecular electrostatic potential (MEP), dipole moment, vertical ionization potential (VIP), vertical electron affinity (VEA), chemical hardness (η), softness (S) and chemical potential (μ) are studied. The VIP and VEA reveal that Pdn/coronene clusters are stable in nature with the least reactivity. The HOMO–LUMO energy gaps are reduced with the increase in cluster size. The electronic properties show irregular trends, where the most favorable electronic properties are obtained for Pd7/coronene and Pd10/coronene.

Oxygen migration and spectroscopic properties of coronene (C24) epoxides and persulfurated coronene (PSC) oxides have been investigated by using density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The rim-oxide is predicted to be more energetically favorable than the oxygen-centered configuration, and the application of an external electric field can accelerate the epoxy migration from the middle to the edge of the molecule. The predicted electronic absorptions and emissions of the C24 epoxides strongly depend on the location of oxygen. In particular, the stable edge-epoxide C24d3 has the largest radiative decay rate (kr) and the smallest non-radiative decay rate (knr), suggesting relatively strong fluorescence emission. On the contrary, absorptions and emissions of the PSC oxides are less changed, compared to those of the pristine PSC. On-the-fly trajectory surface hopping dynamics simulations reveal that the nonadiabatic S1 → S0 decay of the C24 epoxides is triggered by C-O bond stretching, and thus the radiative and nonradiative features depend on the C-O bond strength. The present results indicate that the oxygen diffusion on the basal plane of graphene oxides is easily tuned by the external electric field and their optoelectronic properties show a notable oxygen-site dependence.

Perchlorocoronene undergoes random dehalogenation at elevated temperatures, resulting in the formation of a disordered gold-coronene complex on Au(111) surfaces. The dehalogenation can be guided by introducing intermolecular constraint from accompanying molecules coexisting on the surface. Owing to the intermolecular electrostatic interactions, gold-coronene wires are intercalated between the polyphenylene chains, which hinders the transverse dehalogenation and results in an improved tendency toward linear gold-coronene molecular wires.

Curvature and size effects in halogen interactions with extended aromatic species have been evaluated, employing computational methods, in dimers formed by dihalogens Cl2, Br2 and I2 with both planar (coronene and circumcoronene) and curved (corannulene, sumanene and C60) aromatic systems. The main controlling factor in these interactions is dispersion, so they become stronger as the size of the halogen grows. The nature of the interaction with the halogen changes depending on the curvature and the extension of the aromatic system. As the aromatic species becomes larger, parallel stacked structures are favoured by dispersion increases over halogen bonded ones. Parallel dimers by the concave side are also favoured as the curvature of the aromatic species increases, while the effect is the opposite by the convex side. Overall, halogen bond interactions are not favoured for large planar or curved aromatic systems; only by the convex face of the most curved structures the dispersion contribution decreases enough so as to make halogen bonded structures competitive with parallel stacked ones.

We explore the unusual nature of chemical bonding of thorium atoms with a ring of six carbon atoms (hexagon) in novel carbon materials. Our ab initio calculations of Th-based metallofullerenes (Th@C60 and Th@C20) and Th bound to benzene or coronene at the Hartree-Fock level with the second order perturbation (MP2) correction accounting for the van der Waals interactions demonstrate that the optimal position of the thorium atom is where it faces the center of a hexagon and is located at a distance of 2.01-2.07 Å from the center. For Th encapsulated in C60 it is found at 2.01 Å, whereas the other local energy minima are shifted to larger energies (0.22 eV and higher). Inside C60 the highest local minimum at 1.17 eV is observed when Th faces the center of the five member carbon ring (pentagon). Based on our calculations for Th with benzene and coronene where the global minimum for Th corresponds to its position at 2.05 Å (benzene) or 2.02 Å (coronene) from the hexagon center, we conclude that a well pronounced minimum is likely to be present in graphene and in a single wall carbon nanotube. The ground state of Th is singlet, and other high spin states (triplet and quintet) lie higher in energy (1.62 eV). We discuss a potential use of carbon nanomaterials with the 229Th isotope having its nuclear transition in the optical range, for metrological purposes.

Large polycyclic aromatic hydrocarbon (PAH) compounds with 7 or more rings, such as coronene, can be problematic in petroleum refining processes, where they build up over time and eventually enhance coke formation. In this work, large PAH molecules were characterized in a recycling stream returning the distillation bottoms of a commercial hydrocracking reactor back into the unit. High performance liquid chromatography and Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS) methods were in good agreement on PAH compounds extracted with DMSO, which provided a selective way to determine PAH with up to 10 aromatic rings. However, after Soxhlet extraction with pentane PAH compounds with up to 14 aromatic rings were tentatively identified using FT-ICR MS, extending the naphthalene zig-zag pattern. With the characterization method established, solvent extraction, solvent precipitation, and adsorption processes were tested to remove the problematic, large PAH compounds from the recycle stream....

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.