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Dodecaphenyltetracene
摘要： Dodecaphenyltetracene (4), the largest perphenylacene yet prepared, was synthesized from known tetraphenylfuran, hexaphenylisobenzofuran, and 1,2,4,5-tetrabromo-3,6-diphenylbenzene in three steps. The X-ray structure of the deep red, highly luminescent 4 shows it to be a D2-symmetric molecule with an end-to-end twist of 97°. The central acene is encapsulated by the peripheral phenyl substituents, and as a result, the molecule is relatively unreactive and even displays reversible electrochemical oxidation and reduction.
关键词： twisted acenes,polyphenyl aromatic compounds,polycyclic aromatic hydrocarbons
更新于2025-09-23 15:23:52
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X-Shaped Polycyclic Aromatic Hydrocarbons: Optical Properties and Tunable Assembly Ability
摘要： Although a number of synthetic methodologies have been developed to prepare stable polycyclic aromatic hydrocarbons (PAHs), much less research has been devoted to functionalize the peripheral of molecules to tune the self-assembly ability or introduce functional groups without altering their photophysical properties. Herein, we report twisted “X” shaped molecules prepared through annulation of hexacene with benzoanthracene on the zigzag edge, and an investigation of their photophysical properties and self-assembly properties. The shape-complementary “X” shaped molecules prefer to dimerize, while the π-extension would lead to one dimensional π-stacking. Our findings gave some insights into the design of stable PAHs without disturbing the electronic structures.
关键词： Photophysical properties,Self-assembly,Polycyclic aromatic hydrocarbons,Dimerize
更新于2025-09-23 15:23:52
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The Consequences of Adding a Twist to Acenes
摘要： The Consequences of Adding a Twist to Acenes. Significance: Acenes are a unique class of polycyclic aromatic hydrocarbons often employed in organic electronics. The parent acenes are planar, but they are readily twisted out of planarity upon substitution. It was previously assumed that twisting may affect the optical and electronic properties of acenes. However, the effect of twisting could not be directly studied because the substituents were also involved in inducing different twisting angles. Here, Gidron and co-workers synthesize a series of tethered acenes with a twist of various angles to embark on studies on the effect of the twist on their properties. Comment: Ant-Cn were conformationally as well as photochemically stable. X-ray crystal structures of the Ant-Cn series showed that the twisting angle of the anthracene varied from 23° to 38°. Photophysical measurements suggest that, upon twisting, the p-band absorption increases in intensity, as well as showing a bathochromic shift. In addition, the fluorescence quantum efficiency and the rate of radiative decay decreases, while the rate of nonradiative decay increases. Interestingly, the isolated M and P enantiomers of Ant-C5 showed an anisotropy factor (g factor) of 2 × 10–2, which is higher than those measured for [6]helicene and [5]helicene (4–9 × 10–3).
关键词： fluorescence,polycyclic aromatic hydrocarbons,acenes,circular dichroism
更新于2025-09-23 15:22:29
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Toward Longer Phenacenes
摘要： Toward Longer Phenacenes. Polyacene and polyphenacene represent the simplest graphene nanoribbons, but whereas acenes are unstable beyond seven units, longer phenacenes have been successfully synthesized. The authors describe the synthesis of tetracarboxy- and imide-functionalized [8]-, [10]-, [12]-, and [14]phenacenes, the longest reported to date. Comment: Perkin condensation of the appropriate arylene diglyoxylic acids and arylacetic acids, followed by esterification, furnishes the bismaleates, which are converted into the phenacenes by oxidative photocyclization. Optical and electrochemical properties are studied, with the imides exhibiting significantly lower band gaps than the esters.
关键词： phenacenes,graphene nanoribbons,polycyclic aromatic hydrocarbons
更新于2025-09-23 15:21:21
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Giant Star-shaped Nitrogen-doped Nanographenes
摘要： Star-shaped nanographenes are large monodisperse polycyclic aromatic hydrocarbons that extend in size beyond the nanometer and have shown a lot of promise in a wide range of applications including electronics, energy conversion and sensing. Herein we report a new family of giant star-shaped N-doped nanographenes with diameters up to 6.5 nm. Furthermore, the high solubility of this SNG family in neutral organic solvents at room temperature allowed a complete structural, optoelectronic and electrochemical characterisation, which together with charge transport studies illustrate their n-type semiconducting character.
关键词： nanographenes,cloverphenes,starphenes,star-shaped nanographenes,polycyclic aromatic hydrocarbons
更新于2025-09-23 15:21:21
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Five Points for Graphene Nanobowls!
摘要： Given the difficulty of studying the chemical properties of graphene directly, many researchers have turned to the use of small molecules as model systems. In this report, the authors demonstrate the synthesis of a model system for porous nanographenes. Anion binding, electronic properties, and aggregation are probed in the final product.
关键词： Scholl cyclization,polycyclic aromatic hydrocarbons,nanographenes
更新于2025-09-23 15:21:21
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Tailoring Bond Topologies in Open-Shell Graphene Nanostructures
摘要： Polycyclic aromatic hydrocarbons exhibit a rich spectrum of physico-chemical properties depending on the size, and more critically, on the edge and bond topologies. Among them, open-shell systems – molecules hosting unpaired electron densities – represent an important class of materials for organic electronic, spintronic and optoelectronic devices, but remain challenging to synthesize in solution. We report the on-surface synthesis and scanning tunneling microscopy- and spectroscopy-based study of two ultra-low-gap open-shell molecules, namely peri-tetracene, a benzenoid graphene fragment with zigzag edge topology, and dibenzo[a,m]dicyclohepta[bcde,nopq]rubicene, a non-benzenoid non-alternant structural isomer of peri-tetracene with two embedded azulene units. Our results provide an understanding of the ramifications of altered bond topologies at the single-molecule scale, with the prospect of designing functionalities in carbon-based nanostructures via engineering of bond topology.
关键词： open-shell polycyclic aromatic hydrocarbons,atom manipulation,non-alternant polycyclic aromatic hydrocarbons,scanning tunneling microscopy,density functional theory,scanning tunneling spectroscopy
更新于2025-09-23 15:21:01
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Development of a turn-on graphene quantum dot-based fluorescent probe for sensing of pyrene in water
摘要： Polycyclic aromatic hydrocarbons (PAHs) are potentially harmful pollutants that are emitted into the environment from a range of sources largely due to incomplete combustion. The potential toxicity and carcinogenic effects of these compounds warrants the development of rapid and cost-effective methods for their detection. This work reports on the synthesis and use of graphene quantum dots (GQDs) as rapid fluorescence sensors for detecting PAHs in water. The GQDs were prepared from two sources, i.e. graphene oxide (GO) and citric acid (CA) – denoted GO-GQDs and CA-GQDs, respectively. Structural and optical properties of the GQDs were studied using TEM, Raman, and fluorescence and UV-vis spectroscopy. The GQDs were then applied for detection of pyrene in environmental water samples based on a “turn-off-on” mechanism where ferric ions were used for turn-off and pyrene for turn-on of fluorescence emission. The fluorescence intensity of both GQDs was switched on linearly within the 2–10 × 10?6 mol L?1 range and the limits of detection were found to be 0.325 × 10?6 mol L?1 and 0.242 × 10?6 mol L?1 for GO-GQDs and CA-GQDs, respectively. Finally, the potential application of the sensor for environmental water samples was investigated using lake water and satisfactory recoveries (97–107%) were obtained. The promising results from this work demonstrate the feasibility of pursuing cheaper and greener environmental monitoring techniques.
关键词： Polycyclic aromatic hydrocarbons,Pyrene detection,Graphene quantum dots,Fluorescence sensors,Environmental water samples
更新于2025-09-23 15:21:01
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A new SERS substrate of self-assembled monolayer film of gold nanoparticles on silicon wafer for the rapid detection of polycyclic aromatic hydrocarbons
摘要： A facile and rapid method for the SERS detection of polycyclic aromatic hydrocarbons (PAHs) was reported. The Au colloids assemble to form gold nanoparticles (Au NPs) monolayer film at the air/water interface through the modification of n-dodecanethiol (DT), and then the film was directly transferred by tilt-lifting onto the silicon wafer to fabricate uniformed SERS substrate. PAHs could be preconcentrated into DT layer on the surface of the SERS substrate through the hydrophobic interaction, and detected by SERS. The linear range of detection for Benzo[a]-pyrene (B[a]P) is from 10-8 to 10-5 mol/L with a linearity (R2) of 0.92 to 0.99. The recovery rates range from 89.5% to 103.7%. The detection limit can reach the ng/L level. Pyrene (Pyr) and Chrysene (Chr) were also detected by SERS. The substrate had good stability, uniformity, reproducibility and reusability, which demonstrated that the DT-functionalized Au NPs film prepared by the self-assembly method at the air/water interface could be used as a reliable SERS candidate for the rapid analysis of PAHs.
关键词： self-assembled monolayer (SAM),air/water interface,SERS,polycyclic aromatic hydrocarbons (PAHs),gold nanoparticles (Au NPs)
更新于2025-09-23 15:21:01
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Giant Star-shaped Nitrogen-doped Nanographenes
摘要： Star-shaped nanographenes are large monodisperse polycyclic aromatic hydrocarbons that extend in size beyond the nanometer and have shown a lot of promise in a wide range of applications including electronics, energy conversion and sensing. Herein we report a new family of giant star-shaped N-doped nanographenes with diameters up to 6.5 nm. Furthermore, the high solubility of this SNG family in neutral organic solvents at room temperature allowed a complete structural, optoelectronic and electrochemical characterisation, which together with charge transport studies illustrate their n-type semiconducting character.
关键词： nanographenes,cloverphenes,starphenes,star-shaped nanographenes,polycyclic aromatic hydrocarbons
更新于2025-09-23 15:21:01